Do you use an fairing or partial fairing on your ebike, emoped or BSM?

General Discussion about electric bicycles.
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Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

Post by ebike4healthandfitness » Jan 08 2022 8:25pm

That Electrom is nice. I like how it takes off so smooth as well.

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Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

Post by tigcross » Jan 09 2022 5:00pm

ebike4healthandfitness wrote:
Jan 08 2022 8:25pm
That Electrom is nice. I like how it takes off so smooth as well.
thanks, yes it's coming along nicely.

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Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

Post by ebike4healthandfitness » Jan 09 2022 10:39pm

About how many watts for the Electrom at 35 kph?

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Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

Post by BalorNG » Jan 10 2022 1:00am

Interesting thread, lots of good points.
Problem is, however, that one should first read this article and think REALLY hard:

https://motochassis.com/Articles/Aerodynamics/AERO.htm

Basically, 'partial' fairings work very poorly (or even increase drag) - only if your position is truly horrible to begin with - which is the case for a bicycle/motorcycle to be fair.

To *streamline* something imply a fairing that allows *pressure recovery* - as in 'smoothly parting the air in front and converging it in the back'. Partial* fairings do not really allow that, even those that have converging tail section, AND if your ride is stable in high crosswinds it can only mean one thing - the farings is not very effective - a highly streamlined bike is like a wing put on it's side and will inevitably create considerable 'sideways lift' that has significant propulsive component, by the way, but creates even more lateral push that destabilizes that bike and creates a toppling moment proportinal to speed and angle of apparent wind and hight of your CP.

There can be interrupts in the fairings, but they need to be small, and the converging tail needs to be really large to work given imperfect form... it also allows to shift CP rearward, away from steered wheel and therefore decrease the lever side force has on your *trail* lever arm to affect steering directly (very nasty phenomena).

If you want a moto fairing that truly works as intended (decreses your 'MPG' equivalent) and are 'more or less pratical' - look at Vetter fairings .
http://craigvetter.com/

You should still build a bike *around* a fairing by going very low or even zero 'trail' and using other means of getting return-to-center force, preferably a virtual pivot steering, but given previus threads I don't find that eb4hf will understand what I'm even talking about :)

Otherwise, you can expect only a small effect at best and if your bike have high CRR tires (moped/moto) - even less, because it will be swamped by rolling resistance, but all things that Chalo bought up - weight/bulk/noise/possiblity of damage and if you build it from 'many layers of carbon/kevlar' - COST - are still in effect.

Using a combination of front and rear fairngs AND a flexible lycra sock between them (F40 recumbent, faired LWBs) do work much better than the sum of the parts, but exacerbate 'rider cooling issues' (not a problem on motobike I presume), create significant ingress-egress issues and looks, well, dorky... and still works way from perfect.

I have some ideas how to work around that by using partial and *wearable* fairings that would eliminate the 'ingress/egress' issues by upping the dork factor to eleven but I'm way past caring about that :)

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Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

Post by ebike4healthandfitness » Jan 10 2022 1:33am

    BalorNG wrote:
    Jan 10 2022 1:00am
    Interesting thread, lots of good points.
    Problem is, however, that one should first read this article and think REALLY hard:

    https://motochassis.com/Articles/Aerodynamics/AERO.htm

    Basically, 'partial' fairings work very poorly (or even increase drag) - only if your position is truly horrible to begin with - which is the case for a bicycle/motorcycle to be fair.

    To *streamline* something imply a fairing that allows *pressure recovery* - as in 'smoothly parting the air in front and converging it in the back'. Partial* fairings do not really allow that, even those that have converging tail section, AND if your ride is stable in high crosswinds it can only mean one thing - the farings is not very effective - a highly streamlined bike is like a wing put on it's side and will inevitably create considerable 'sideways lift' that has significant propulsive component, by the way, but creates even more lateral push that destabilizes that bike and creates a toppling moment proportinal to speed and angle of apparent wind and hight of your CP.

    There can be interrupts in the fairings, but they need to be small, and the converging tail needs to be really large to work given imperfect form... it also allows to shift CP rearward, away from steered wheel and therefore decrease the lever side force has on your *trail* lever arm to affect steering directly (very nasty phenomena).

    If you want a moto fairing that truly works as intended (decreses your 'MPG' equivalent) and are 'more or less pratical' - look at Vetter fairings .
    http://craigvetter.com/

    You should still build a bike *around* a fairing by going very low or even zero 'trail' and using other means of getting return-to-center force, preferably a virtual pivot steering, but given previus threads I don't find that eb4hf will understand what I'm even talking about :)

    Otherwise, you can expect only a small effect at best and if your bike have high CRR tires (moped/moto) - even less, because it will be swamped by rolling resistance, but all things that Chalo bought up - weight/bulk/noise/possiblity of damage and if you build it from 'many layers of carbon/kevlar' - COST - are still in effect.

    Using a combination of front and rear fairngs AND a flexible lycra sock between them (F40 recumbent, faired LWBs) do work much better than the sum of the parts, but exacerbate 'rider cooling issues' (not a problem on motobike I presume), create significant ingress-egress issues and looks, well, dorky... and still works way from perfect.

    I have some ideas how to work around that by using partial and *wearable* fairings that would eliminate the 'ingress/egress' issues by upping the dork factor to eleven but I'm way past caring about that :)
    You claim a person should use zero trail in order to keep their bike from being affected by crosswinds....but even the author of the first link (which I quoted below) claims he has a confounding factor of increased lateral stiffness of his new suspension which he believed is the reason for the reduced suspectibility of the crosswinds.

    "In 1986 I converted a Gold Wing from telescopic forks to one of my "hub centre" front ends, for its owner, Wayne Boys. After he had had it for a while we discussed the various effects that he noticed in normal riding, many observations were as I had expected but I was a bit surprised when he pointed out that it was far more stable in gusty side winds. At first I thought that this was probably just due to the greater lateral stiffness of the new suspension, which is generally more stable anyway. But a bit more thought as to the differences between the two setups, shed a bit of light on why they should behave so differently under these conditions. There seemed to be three main differences, in addition to the stiffness already mentioned ;----- 1. 16" wheel instead of 19", 2. Less trail, 3. A 17 rake angle which needed zero offset between the steering axis and the wheel centre-line to achieve the desired trail. It can be argued that all three of these changes work toward improving the performance in gusts."

    Not convincing evidence to reduce trail to very low or zero. His theory needs more work and investigation which would include an experiment to isolate variables.

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    Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

    Post by BalorNG » Jan 10 2022 2:43am

    ebike4healthandfitness wrote:
    Jan 10 2022 1:33am
      BalorNG wrote:
      Jan 10 2022 1:00am
      Interesting thread, lots of good points.
      Problem is, however, that one should first read this article and think REALLY hard:

      https://motochassis.com/Articles/Aerodynamics/AERO.htm

      Basically, 'partial' fairings work very poorly (or even increase drag) - only if your position is truly horrible to begin with - which is the case for a bicycle/motorcycle to be fair.

      To *streamline* something imply a fairing that allows *pressure recovery* - as in 'smoothly parting the air in front and converging it in the back'. Partial* fairings do not really allow that, even those that have converging tail section, AND if your ride is stable in high crosswinds it can only mean one thing - the farings is not very effective - a highly streamlined bike is like a wing put on it's side and will inevitably create considerable 'sideways lift' that has significant propulsive component, by the way, but creates even more lateral push that destabilizes that bike and creates a toppling moment proportinal to speed and angle of apparent wind and hight of your CP.

      There can be interrupts in the fairings, but they need to be small, and the converging tail needs to be really large to work given imperfect form... it also allows to shift CP rearward, away from steered wheel and therefore decrease the lever side force has on your *trail* lever arm to affect steering directly (very nasty phenomena).

      If you want a moto fairing that truly works as intended (decreses your 'MPG' equivalent) and are 'more or less pratical' - look at Vetter fairings .
      http://craigvetter.com/

      You should still build a bike *around* a fairing by going very low or even zero 'trail' and using other means of getting return-to-center force, preferably a virtual pivot steering, but given previus threads I don't find that eb4hf will understand what I'm even talking about :)

      Otherwise, you can expect only a small effect at best and if your bike have high CRR tires (moped/moto) - even less, because it will be swamped by rolling resistance, but all things that Chalo bought up - weight/bulk/noise/possiblity of damage and if you build it from 'many layers of carbon/kevlar' - COST - are still in effect.

      Using a combination of front and rear fairngs AND a flexible lycra sock between them (F40 recumbent, faired LWBs) do work much better than the sum of the parts, but exacerbate 'rider cooling issues' (not a problem on motobike I presume), create significant ingress-egress issues and looks, well, dorky... and still works way from perfect.

      I have some ideas how to work around that by using partial and *wearable* fairings that would eliminate the 'ingress/egress' issues by upping the dork factor to eleven but I'm way past caring about that :)
      You claim a person should use zero trail in order to keep their bike from being affected by crosswinds....but even the author of the first link (which I quoted below) claims he has a confounding factor of increased lateral stiffness of his new suspension which he believed is the reason for the reduced suspectibility of the crosswinds.

      "In 1986 I converted a Gold Wing from telescopic forks to one of my "hub centre" front ends, for its owner, Wayne Boys. After he had had it for a while we discussed the various effects that he noticed in normal riding, many observations were as I had expected but I was a bit surprised when he pointed out that it was far more stable in gusty side winds. At first I thought that this was probably just due to the greater lateral stiffness of the new suspension, which is generally more stable anyway. But a bit more thought as to the differences between the two setups, shed a bit of light on why they should behave so differently under these conditions. There seemed to be three main differences, in addition to the stiffness already mentioned ;----- 1. 16" wheel instead of 19", 2. Less trail, 3. A 17 rake angle which needed zero offset between the steering axis and the wheel centre-line to achieve the desired trail. It can be argued that all three of these changes work toward improving the performance in gusts."

      Not convincing evidence to reduce trail to very low or zero. His theory needs more work and investigation which would include an experiment to isolate variables.
      Yup, just like I said :)
      I've already build an LWB with close to zero trail plus steering damper and installed a huge front fairing that was, to be frank, not very effective aerodynamically but effect on STEERING was indeed absolutely minimal to nonexistant... btw, is very flexible due to being tacked together with 3d printed joints and steered 'vaguely' at best, so I daresay if *it* was good in crosswinds - anything would.

      Basically, you need to understand what trail *really* stand for, not just lines on paper, and what it does your bike is subjected to considerable impulses of lateral force - can be easily tested by having someone prop up the bike w/o holding the bars and giving the bike a sideways shove. The steering will inevitably point in the same direction - that's what trail does.
      If you dig deeper, one may say that 'that's a good thing' (just like described in Foale article), BUT if you dig deepre yet that's 'too much of a good thing' and even with zero trail same effect will be apparent *when moving' due to pneumatic trail effect.
      Yup, nobody said that bicycle dynamics is simple subject, and neither is aerodyanmics, and combination of both is, obviously, EVEN more complex yet.

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by ebike4healthandfitness » Jan 10 2022 1:51pm

      BalorNG wrote:
      Jan 10 2022 2:43am
      Basically, you need to understand what trail *really* stand for, not just lines on paper, and what it does your bike is subjected to considerable impulses of lateral force - can be easily tested by having someone prop up the bike w/o holding the bars and giving the bike a sideways shove. The steering will inevitably point in the same direction - that's what trail does.
      That is not trail, that is wheel flop. (High amount of Wheel flop is a side effect that can happen with certain steering set-ups targeting X amount of trail. However, Not all steering set-ups with X amount of trail will have Y amount of flop. Here is a calculator that determines flop along with trail http://yojimg.net/bike/web_tools/trailcalc.php)

      Note it is possible (using the calculator) to have high trail with low wheel flop by having a steep head tube angle combined with low or no fork offset.

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by Chalo » Jan 10 2022 2:07pm

      ebike4healthandfitness wrote:
      Jan 10 2022 1:51pm
      That is not trail, that is wheel flop.
      No, it's not. Flop is a vertical measurement. Trail is a horizontal measurement, and you obviously don't understand it very well.

      You might try thinking of trail as the lever length by which a lateral force on your bike is translated into a steering torque. When it's working to balance the bike while rolling, the "lateral" force is the force of gravity, because the bike is leaning and there's a force component that's normal to the plane of the bike frame. It steers into the lean, thereby reducing the lean angle. But a sideways push from wind does the same kind of thing even when there's no lean, and the steering input isn't wanted.

      When a three-wheeler has steering trail, both the slope of the surface and centrifugal forces from turning result in undesired steering inputs. That's why trikes should have near zero trail.
      This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by ebike4healthandfitness » Jan 10 2022 2:11pm

      Chalo wrote:
      Jan 10 2022 2:07pm
      ebike4healthandfitness wrote:
      Jan 10 2022 1:51pm
      That is not trail, that is wheel flop.
      No, it's not.
      If a person is pushing on his bike with a certain lateral force and the front wheel ends up turning in the direction of the lateral force that is is caused by wheel flop.

      Not all bikes will do that, but bikes with high wheel flop will.

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by Chalo » Jan 10 2022 2:17pm

      ebike4healthandfitness wrote:
      Jan 10 2022 2:11pm
      Chalo wrote:
      Jan 10 2022 2:07pm
      ebike4healthandfitness wrote:
      Jan 10 2022 1:51pm
      That is not trail, that is wheel flop.
      No, it's not.
      If a person is pushing on his bike with a certain lateral force and the front wheel ends up turning in the direction of the lateral force that is is caused by wheel flop.

      Not all bikes will do that, but bikes with high wheel flop will.
      The steering force will happen even if the steering axis is vertical and there is no wheel flop. That's how you turn a shopping cart. Trail is the lever by which you move the wheel's angle.

      Ride more. Build more. Tell other people how it is a lot less.
      This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by ebike4healthandfitness » Jan 10 2022 2:39pm

      Chalo wrote:
      Jan 10 2022 2:17pm
      ebike4healthandfitness wrote:
      Jan 10 2022 2:11pm
      Chalo wrote:
      Jan 10 2022 2:07pm
      ebike4healthandfitness wrote:
      Jan 10 2022 1:51pm
      That is not trail, that is wheel flop.
      No, it's not.
      If a person is pushing on his bike with a certain lateral force and the front wheel ends up turning in the direction of the lateral force that is is caused by wheel flop.

      Not all bikes will do that, but bikes with high wheel flop will.
      The steering force will happen even if the steering axis is vertical and there is no wheel flop. That's how you turn a shopping cart. Trail is the lever by which you move the wheel's angle.

      Ride more. Build more. Tell other people how it is a lot less.
      Chalo, you don't know what you are talking about.

      Here is a good article that will straighten you out:

      https://rothrockcyrcle.wordpress.com/20 ... bikes/amp/

      "Why is flop not a good thing, generally? Well, it is critical to understand that flop fights against the stabilizing force of trail. Trail wants to center the steering as noted above, but flop wants to do the opposite and take any small turn of the bars and turn into a bigger turn. Flop does this because Mother Earth is always trying to bring us down (literally), and flop helps gravity out by lowering the elevation of our center of mass. Flop also makes the steering torque higher because it forces you to do work to lift the front end of the bike (and rider/bike system center of mass too, of course) when you try to straighten the handlebars. This likely leads to over-correcting by most riders. Too much force leads to overshoot, so to speak. Because flop is ‘powered’ by gravity, the heavier you are, or the more forward biased the the bike’s weight distribution is, the worse flop gets. The following image is an analogy of the effect of varying degrees of flop has on the rider trying to pilot his bike in a straight line.


      Flop Analogy

      Riding a bike with lots of flop is riding on a knife edge. A little turn of the bars makes it feel like the bike is trying to take that little molehill nudge and turn it into a mountainous directional change. Gravity is working with flop to bring you down a hill, in a semi-literal sense. But what happened to our buddy trail – why didn’t he keep the bars from flopping way over just because we wanted to make a small steering correction?

      The self centering force provided by trail increases with speed because the rolling resistance drag force is proportional to speed. Flop is an essentially constant force, that is independent of speed, because gravity is a constant. When speeds are decent, the self centering force provided by trail is high enough to win the battle over flop, and the bike feels stable. BUT, when speeds are low, the center force provided by trail gets weaker, and flop can win, encouraging over correction on the steering. Again, you’ll end up looking like the stereotypical bent rider zig-zagging all over the road."

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by Chalo » Jan 10 2022 2:54pm

      I have already discussed flop with you in another thread. I understand it from observing it for myself. But that's not what we're discussing. We're talking about how steering trail allows crosswinds to steer a faired bike. Flop allows the force of gravity to steer a bike once the steering angle departs from center. That's different.

      Trail is the lever that converts a sideways force into a steering input.
      This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by MoneyPit » Jan 10 2022 4:46pm

      Frank wrote:
      Jan 05 2022 6:03am
      I still ride with a 40 year old Zzipper on my road bike. It's worth two gears and is extremely light.
      I just found mine cleaning out the back bedroom over the weekend. Sent it straight into storage. Mine is a *really* old one that predated the handlebar rods and fit over top of the brake hoods on ram-horn style road bars. You velcro'd it on and pretty much rode on the drops only, which kept you in a tuck. It was the smaller of the two sizes shown above. And yes it was a freaking miracle for drag reduction. Worth two gears? That sounds about right. I rode with mine on downhills in the Lower Sierras and you could well exceed what was otherwise terminal velocity for a road bike. Into the mid-sixties instead of the mid-fifties. Needless to say once you started rolling, on 700x20C analog racing bike tires you tried very hard to never touch the brakes.

      Everything was great until you spun around a corner and experienced a crosswind, which would always take you within a hair of having the handlebars torn right out of your hands. It was terrifying, but you ride like that for the adrenaline so it didn't stop me (being aged 16-18 didn't help). That and the inability to comfortably lean on the hoods were the 'only' drawbacks.

      Frank wrote:
      Jan 05 2022 1:50pm
      I also used to ride with some of those mylar wheel discs on the rear wheel (until they got ripped during a move). I tried them on the front wheel but when a gust of wind almost blew me off the road I changed my mind, lol.
      oh my god I had totally forgotten about those. Mine were some kind of rigid plastic that clipped to the spokes. the fact they didn't flex with the wheels at high speed and rattled a lot was one issue, but the whole barn door thing was the dealbreaker. I can remember leaning waaaay over to one side trying to keep from getting blown off the road ripping down the Los Laureles grade and that was the last time I played with those.

      Nowadays, I think motors take the place of the benefit of fairings at the kind of relatively low speeds ebikes achieve.

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by BalorNG » Jan 11 2022 1:23am

      Chalo wrote:
      Jan 10 2022 2:54pm
      I have already discussed flop with you in another thread. I understand it from observing it for myself. But that's not what we're discussing. We're talking about how steering trail allows crosswinds to steer a faired bike. Flop allows the force of gravity to steer a bike once the steering angle departs from center. That's different.

      Trail is the lever that converts a sideways force into a steering input.
      That's a good article that he linked, and my expriments with vertical angles along with experience of riding low-flop bents inspired Tom to write it actually :) We are buddies on facebook and Bentrider... but point is, the trail does ALL those things and more besides, and eb4hf is a great example of how, no matter how good the material you ingest, you still will only understand what you are ready to - and, most importantly, what you WANT to :)

      And things are even MORE complex:

      First, the 'side force' acting on *front wheel* depends not just on raw side force magnitude (side area, wind strenth, angle of attack), but on location of CP (center of pressure) along your wheelbase. Think of *rear* wheel as the fulcrum, effective CP as force application point and resulting *lever* will actually affect your steering.
      This is why long-wheelbase bikes, while may be larger overall and having larger lateral area, are LESS succeptable to 'wind steer' because they have very little of a fairing area in front of the front wheel, therefore CP is shifted further to the rear wheel and does not have as much leverage to push it sideways and create actual steering input, and why some streamliners actually installed large 'tailfins' to shift CP away from front wheel to rear wheel:
      Image
      Despite the fact that it increases overall lateral area, rises CP and costs drag - the bike is just plain dangerous w/o it. They are still rarely used on Battle Mountain liners because there is even an 'illegal wind' condition - even if you start the ride and wind picks up, your record will not be counted because due to physics of a highly streamlined fairing ANY wind, any at all, from pretty much any direction other will direct headwind will add speed to your bike, and maybe even considerable one.

      There is also CG/CP location to consider:

      https://www.grc.nasa.gov/www/k-12/rocket/rktstab.html

      But I do not think that is directly applicable - because bikes are not in 'free flight' and have 'anchor points' that are wheels - so long as you have TRACTION, that is. This is why velomobiles are highly unstabile if you lose rear traction due to rear wheel blowout, often doing a 'ground loop' and rolling over.

      And again, like it is written in Foale article, it might be *possible* to have side force steering input and self-stability in the same manner as the bike is self-stable due to trail, because the steering input is in the 'desired' direction... HOWEVER, it is entirely possible to have 'too much of a good thing' resulting in overcorrection of course, and this is exactly what happends with 'standard' amount of trail I presume... plus, if you think about it, what is 'flop'? Is is force that is coincident with direction of the steering correction that you actually want to turn (usually)... but as it is apparent, you want a 'return to center' force instead in a form of positive trail! I'm positively sure it comes down to control of steering overshoot - talking of an other great article that eb4hf is unlikely to actually read and even less (MUCH, MUCH less) to understand:

      http://www.bicycle.tudelft.nl/Proceedin ... cation.pdf

      So, what is this all about?
      Basically installing ONLY front fairing without matching rear one is not only pretty useless aerodynamically unless your position is worse then that of a brick, but also adding a rear faring that extends considerably behind the rear wheel will actually improve your handling - of course, all within limits... and only way to REALLY reap aero benefits is to merge those fairings into a more or less seamless whole - either by absolutely minimising the gaps between them, or by filling them with, say, lycra:

      https://www.lightningbikes.com/f40/index.html

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by BalorNG » Jan 11 2022 1:54am

      Too bad that this is not THAT important on this forum, because if eb4hf would want a truly high-grade 'technicall trolling' thread, his next thread would be 'Does frame flex costs you watts, how much and why'?

      As I was researching this subject, a rather knowledgeable person on one board said that 'to prove that in a controlled experiment is about as complex as prove existence of God', and this is not that far from truth I guess - because this is extremely complex interaction of *dynamic* frame properties, biomechanics (an extremely complex field if ever was any) and psychology (something we only started to scratch the surface of using scientific tools).

      Personally, I think this is possible to actually gain some power at certain resonance frequencies as per 'planing' experiments of Heine, but I'll be damned if I'll claim that I truly understand underlying minutia or even utter it with high degree of confidence.

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by ebike4healthandfitness » Jan 11 2022 1:59am

      Chalo wrote:
      Jan 10 2022 2:54pm
      We're talking about how steering trail allows crosswinds to steer a faired bike. Flop allows the force of gravity to steer a bike once the steering angle departs from center.
      Trail is what resists crosswinds steering the bike.

      In that Foale article (Balor linked) he attributes the reduction in trail, reduction in wheel size and elimination of fork offset as part of the reason the motorcycle became less resistant to crosswinds. However, it is very obvious any contribution from those changes was due to the much greater reduction in wheel flop that was made. (Trail was reduced, but wheel flop was reduced by a much greater amount than trail was.)

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by BalorNG » Jan 11 2022 2:28am

      ebike4healthandfitness wrote:
      Jan 11 2022 1:59am
      Chalo wrote:
      Jan 10 2022 2:54pm
      We're talking about how steering trail allows crosswinds to steer a faired bike. Flop allows the force of gravity to steer a bike once the steering angle departs from center.
      Trail is what resists crosswinds steering the bike.

      In that Foale article (Balor linked) he attributes the reduction in trail, reduction in wheel size and elimination of fork offset as part of the reason the motorcycle became less resistant to crosswinds. However, it is very obvious any contribution from those changes was due to the much greater reduction in wheel flop that was made. (Trail was reduced, but wheel flop was reduced by a much greater amount than trail was.)
      If you say one thing about eb4hf, one thing only - is that that he can be relied upon :)

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by BalorNG » Jan 11 2022 2:45am

      MoneyPit wrote:
      Jan 10 2022 4:46pm
      Frank wrote:
      Jan 05 2022 6:03am
      I still ride with a 40 year old Zzipper on my road bike. It's worth two gears and is extremely light.
      I just found mine cleaning out the back bedroom over the weekend. Sent it straight into storage. Mine is a *really* old one that predated the handlebar rods and fit over top of the brake hoods on ram-horn style road bars. You velcro'd it on and pretty much rode on the drops only, which kept you in a tuck. It was the smaller of the two sizes shown above. And yes it was a freaking miracle for drag reduction. Worth two gears? That sounds about right. I rode with mine on downhills in the Lower Sierras and you could well exceed what was otherwise terminal velocity for a road bike. Into the mid-sixties instead of the mid-fifties. Needless to say once you started rolling, on 700x20C analog racing bike tires you tried very hard to never touch the brakes.

      Everything was great until you spun around a corner and experienced a crosswind, which would always take you within a hair of having the handlebars torn right out of your hands. It was terrifying, but you ride like that for the adrenaline so it didn't stop me (being aged 16-18 didn't help). That and the inability to comfortably lean on the hoods were the 'only' drawbacks.

      Frank wrote:
      Jan 05 2022 1:50pm
      I also used to ride with some of those mylar wheel discs on the rear wheel (until they got ripped during a move). I tried them on the front wheel but when a gust of wind almost blew me off the road I changed my mind, lol.
      oh my god I had totally forgotten about those. Mine were some kind of rigid plastic that clipped to the spokes. the fact they didn't flex with the wheels at high speed and rattled a lot was one issue, but the whole barn door thing was the dealbreaker. I can remember leaning waaaay over to one side trying to keep from getting blown off the road ripping down the Los Laureles grade and that was the last time I played with those.

      Nowadays, I think motors take the place of the benefit of fairings at the kind of relatively low speeds ebikes achieve.
      It is interely possible to have more or less stable front disk, but it must have VERY considerable *negative* offset not to add instability - resulting what amounts to 'negative aerodynamic trail'. I've used front disks on my by MBB for some time, and they add considerable speed AND extremely low steering input - still do, but not much. You need like 10cm of negative offset to truly bring CP to steering axis and more to actually add stability - mine has only about 6.

      Brown added a 'weatherwane wheel fairing' to achieve the same thing:

      Image

      Too bad wheel disks truly work only with very narrow tires, and I hate them...

      And of course, if your fairing is large enough to encompass your tires (which is what you want for maximum efficiency) this is no longer a factor, for better or worse.

      ebike4healthandfitness   10 kW

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by ebike4healthandfitness » Jan 11 2022 3:28am

      BalorNG wrote:
      Jan 11 2022 2:28am
      ebike4healthandfitness wrote:
      Jan 11 2022 1:59am
      Chalo wrote:
      Jan 10 2022 2:54pm
      We're talking about how steering trail allows crosswinds to steer a faired bike. Flop allows the force of gravity to steer a bike once the steering angle departs from center.
      Trail is what resists crosswinds steering the bike.

      In that Foale article (Balor linked) he attributes the reduction in trail, reduction in wheel size and elimination of fork offset as part of the reason the motorcycle became less resistant to crosswinds. However, it is very obvious any contribution from those changes was due to the much greater reduction in wheel flop that was made. (Trail was reduced, but wheel flop was reduced by a much greater amount than trail was.)
      If you say one thing about eb4hf, one thing only - is that that he can be relied upon :)
      Balor, your recommendation for zero trail set up in bicycles to resist crosswinds is absurd just like your previous idea that low center of gravity hurts stability in single track vehicles.

      Hopefully we don't have to go 10 pages in this thread like we did the other one so you can figure it out.

      I mean seriously it is just common sense that you need to do some more reading when you thought the vehicle shown below poor handling was due to low center of gravity.
      Chalo wrote:
      Oct 31 2021 3:45am
      Excellent low center of mass handling qualities:

      In contrast, just look at how the Electrom (which is also low center of gravity) in it's YouTube videos handles so beautifully in comparison.

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by BalorNG » Jan 11 2022 3:41am

      ebike4healthandfitness wrote:
      Jan 11 2022 3:28am
      BalorNG wrote:
      Jan 11 2022 2:28am
      ebike4healthandfitness wrote:
      Jan 11 2022 1:59am
      Chalo wrote:
      Jan 10 2022 2:54pm
      We're talking about how steering trail allows crosswinds to steer a faired bike. Flop allows the force of gravity to steer a bike once the steering angle departs from center.
      Trail is what resists crosswinds steering the bike.

      In that Foale article (Balor linked) he attributes the reduction in trail, reduction in wheel size and elimination of fork offset as part of the reason the motorcycle became less resistant to crosswinds. However, it is very obvious any contribution from those changes was due to the much greater reduction in wheel flop that was made. (Trail was reduced, but wheel flop was reduced by a much greater amount than trail was.)
      If you say one thing about eb4hf, one thing only - is that that he can be relied upon :)
      Balor, your recommendation for zero trail set up in bicycles to resist crosswinds is absurd just like your previous idea that low center of gravity hurts stability in single track vehicles.

      Hopefully we don't have to go 10 pages in this thread like we did the other one so you can figure it out.

      I mean seriously it is just common sense that you need to do some more reading when you thought the vehicle shown below poor handling was due to low center of gravity.
      Chalo wrote:
      Oct 31 2021 3:45am
      Excellent low center of mass handling qualities:

      In contrast, just look at how the Electrom (which is also low center of gravity) in it's YouTube videos handles so beautifully in comparison.

      To be frank, 'zero trail' is likely not optimal as well, but extremely short is likely the way to go, and you want a steering damper to accompany it... you want it anyway!

      As for common sense and figuring it out... let's just say: LOL.

      And judging fine nuances of steering based on a few youtube videos is SO rational and scientific :))

      ebike4healthandfitness   10 kW

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by ebike4healthandfitness » Jan 11 2022 3:53am

      BalorNG wrote:
      Jan 11 2022 3:41am
      ebike4healthandfitness wrote:
      Jan 11 2022 3:28am
      BalorNG wrote:
      Jan 11 2022 2:28am
      ebike4healthandfitness wrote:
      Jan 11 2022 1:59am


      Trail is what resists crosswinds steering the bike.

      In that Foale article (Balor linked) he attributes the reduction in trail, reduction in wheel size and elimination of fork offset as part of the reason the motorcycle became less resistant to crosswinds. However, it is very obvious any contribution from those changes was due to the much greater reduction in wheel flop that was made. (Trail was reduced, but wheel flop was reduced by a much greater amount than trail was.)
      If you say one thing about eb4hf, one thing only - is that that he can be relied upon :)
      Balor, your recommendation for zero trail set up in bicycles to resist crosswinds is absurd just like your previous idea that low center of gravity hurts stability in single track vehicles.

      Hopefully we don't have to go 10 pages in this thread like we did the other one so you can figure it out.

      I mean seriously it is just common sense that you need to do some more reading when you thought the vehicle shown below poor handling was due to low center of gravity.
      Chalo wrote:
      Oct 31 2021 3:45am
      Excellent low center of mass handling qualities:

      In contrast, just look at how the Electrom (which is also low center of gravity) in it's YouTube videos handles so beautifully in comparison.

      To be frank, 'zero trail' is likely not optimal as well, but extremely short is likely the way to go, and you want a steering damper to accompany it... you want it anyway!

      As for common sense and figuring it out... let's just say: LOL.

      And judging fine nuances of steering based on a few youtube videos is SO rational and scientific :))
      Comparing the Electrom to that sloppy handling low racer is anything but fine nuances. It's a night and day difference in stability.

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by BalorNG » Jan 11 2022 3:56am

      Talking of videos...

      https://youtu.be/yWvE6yLxuJo

      By the way, does this (rideable jig of a) bike look unstable to you? It has pretty much exactly zero trail. Not much more vids, but I'm not a 'blogger'.

      Unfortuantely, I've yet to construct a full fairing, but I did ride around with a huge nose cone in high winds and it was fine *to me*, and, again, unfortunately I'm quite a clumsy rider and if something is *good enough* for me it can be said with reasonable certainty that it would be good enough for anyone if he can ride a bicycle (working sense of balance) at all...

      BalorNG   1 kW

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by BalorNG » Jan 11 2022 3:59am

      ebike4healthandfitness wrote:
      Jan 11 2022 3:53am

      Comparing the Electrom to that sloppy handling low racer is anything but fine nuances. It's a night and day difference in stability.
      Right. If your 'the lower CG, the better' theory is correct, than why this is not the way around? :) There are other factors, I agree, but THAT IS MY POINT - just like I keept telling you (and you finally get it) that oodles of trail does not automatically mean stability, so is bicycle 'rideability' is combination of interacting/conflicting factors that are hard to disentangle and need either extremely good knoledge of theory, or a lot of MINDFUL practice, preferably both.
      You had neither. Still don't, but at least there is some progress :)

      ebike4healthandfitness   10 kW

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by ebike4healthandfitness » Jan 12 2022 2:35am

      BalorNG wrote:
      Jan 11 2022 3:59am
      bicycle 'rideability' is combination of interacting/conflicting factors that are hard to disentangle and need either extremely good knoledge of theory, or a lot of MINDFUL practice, preferably both.
      And yet you don't understand any of this.

      Here is the excerpt from to the Tony Foale article which you use to base your recommendation of zero trail for upright bikes to have resistance to crosswinds:

      "In 1986 I converted a Gold Wing from telescopic forks to one of my "hub centre" front ends, for its owner, Wayne Boys. After he had had it for a while we discussed the various effects that he noticed in normal riding, many observations were as I had expected but I was a bit surprised when he pointed out that it was far more stable in gusty side winds. At first I thought that this was probably just due to the greater lateral stiffness of the new suspension, which is generally more stable anyway. But a bit more thought as to the differences between the two setups, shed a bit of light on why they should behave so differently under these conditions. There seemed to be three main differences, in addition to the stiffness already mentioned ;----- 1. 16" wheel instead of 19", 2. Less trail, 3. A 17 rake angle which needed zero offset between the steering axis and the wheel centre-line to achieve the desired trail. It can be argued that all three of these changes work toward improving the performance in gusts."

      Here is what I see:

      1. We know the new suspension has increased lateral stiffness.

      2. We know the new wheel is smaller which reduces trail and reduces wheel flop. The smaller wheel also presents a smaller surface area for crosswinds to work on.

      3. The new fork has no offset which increases trail and somewhat increases wheel flop.

      How are we getting the idea of zero trail from the above info? If anything the trail reduction is probably very small because the removal of fork offset is going to cancel out a good amount of trail reduction brought about by the reduction in wheel diameter. If anything I see this an being an experiment in reducing wheel flop, reducing wheel surface area for the wind to act on coupled to a suspension with increased lateral stiffness (which also helps in crosswinds). The reduction in trail will actually hurt stability in crosswinds, but it is very likely only a very small reduction in trail so it's negative effect in the big picture would also be very small.

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      Re: Do you use an fairing or partial fairing on your ebike, emoped or BSM?

      Post by BalorNG » Jan 12 2022 3:15am

      ebike4healthandfitness wrote:
      Jan 12 2022 2:35am

      Here is what I see:

      1. We know the new suspension has increased lateral stiffness.

      2. We know the new wheel is smaller which reduces trail and wheel flop. The smaller wheel also presents a smaller surface area for crosswinds to work on.

      3. The new fork has no offset which increases trail and somewhat increases wheel flop.

      How are we getting the idea of zero trail from the above info? If anything the trail reduction is probably very small because the removal of fork offset is going to cancel out a good amount of trail reduction brought about by the reduction in wheel diameter. If anything I see this an being an experiment in reducing wheel flop, reducing wheel surface area for the wind to act on coupled to a suspension with increased lateral stiffness. The trail reduction is almost laughable compared to the impact of those other three factors.
      It does not have to be 'zero' trail, just less than conventional.
      And that is the whole point - I *did* (well, sort of) isolate the variables by using a very flexible frame (not exactly on purpose, but the bike is experimental), near zero trail and a large nose cone. (Which did very little to actually improve aerodyanamics, which I fully expected to).

      Image
      Image

      By the way, I did experiment by using a smaller wheel and turning it around for a ton of trail with very little flop... it made things considerably worse!
      Yea, the bike is ugly as sin, but it was never intended to be nice or even practical, just a test bed of my ideas - I'll be remaking it in carbon.

      Anyway, the fact that lots of trail is destabilizing on a fully faired HPV is well-known among HPV builders, and yea, I also was kinda stumped for while how that could be so - before I've read that Foale article, which you also did, but obviously failed to understand the implication... which brings us to the fact that you may bring up scientific method often - but you are using it not as intended (to understand nature of things), but as a weapon to hammer your own point of view, like a caveman wielding a microscope as a club.
      You have a cargo cult of science, not the real thing.

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