DH frames for freeriding

Very interesting to see the difference in opinion. It's tempting to run batteries mounted on the downtube and not deal with backpack cable routing (still think I'd rather have it forward away from any moving parts).
The Slab definitely can't take a triangle bag. I've thought perhaps I could make a moto-style seat and put some batteries (or the controller) under it. But I'd lose stand over height which is something I like about a DH frame.
Width at the knees and cranks is also an issue.

Of note I'm running 10X hover board batteries with individual BMS/cases so I can distribute weight effectively and/or scale my battery weight to the task. I may even run a fork mount to get some weight forward for climbing.

Dingus:
Is that a 3000w cyclone? Total reduction of 2.75:1 from gearbox output to wheel? What voltage?
 
Your seat looks like it's facing the wrong way to me narrow at the rear but it looks comfy and it suits the bike in a position sense.

I had my first ride yesterday on the bike, I noticed the weight is fairly light and low down so I can steer through the foot pegs and have good feedback to position the bike and not to over sensitive.

I stand 5.11 tall and weigh 70kg the bike had no issues pulling me around, with the bars set forward my arms had a good feel not to small like i feared but the seat could do with some more cushion i had a dead arse after an hour riding and the foot pegs are on the small side along with narrow 31.8/680mm bars so maybe a direct clamp in future with 35/800mm 40mm rise bars and some billet pegs.

It also needs a front mudguard after 15mph water/mud can become an issue but other than that no major design flaws found yet the rear shock is not the best but it's adequate and gives room to improve the bike down the line and a battery rebuild in a few years should see a major range increase from the 1kwh usable to nearer the 2kwh mark to get near the 40 mile range at up to 50mph, when i swap the rear hub to one that accept go kart sprockets, if I can squeeze a large cell format like the 21700 in a high discharge variant I can get some good gains and still keep it's fairly low kurb weight.
 
Did a quick swap from the HT to Slab and had a quick ride. Vastly better at climbing rough hills. A previously impossible hill was no problem and I went significantly further up the other much harder one.
Obviously I need a better battery attachment than the jumbo zip ties. But I did find it very planted with the weight down low.

I'm rehabing some significant injuries at the moment so can't give it a proper thrashing, plus I have shoulder surgery on the 24th.

But while I'm waiting for the OK to get back riding I'll build a total new mounting plate with integral bash guard and chain guides for both the primary and secondary chains.

-Grant
 
Grantmac,


Dingus:
Is that a 3000w cyclone? Total reduction of 2.75:1 from gearbox output to wheel? What voltage?
Click to expand...

Yes, a Cyclone 3000. Currently the max voltage is 3 x 25.2 = 75.6 volts.

Gearing: 1/(22/44 x 32/44) = 3

Since you'll have two considerations when deciding gearing which are enough torque to get your bike and rider (weight total) up some steep Grade % you choose and top speed, my ratios and voltages may not be ideal for you. That is, how steep of a smooth slope(essentially good traction) do you want the bike to carry you without pedal assist?

I have found a short hill that arises out of a "V" gully with a 67% Grade (26 degrees) which is the natural talus angle of sedimentary chunks. With this gearing the bike can barely pull me up the 26% Grade when the soil is moist. If the soil is dry the wheel spins mostly in one place. If one has motor with enough power and an aggressive tread tire, they might be able to spin their way up the hill, rocket propulsion fashion, like the fellow with the 300 cc KTM -- plenty of power and we get a big groove in the trail from the dirt torn out.

Top speed: More voltage can increase that if we talking on the level.
 
Ianhill,


The seat attitude on this uphill bike was modified this AM. It now has a low spot (dip) which is somewhat ahead of a traditional seat location as those seats are set up for getting the best power angle on the pedals. Also the 8" of rear wheel travel has clearance with respect to the back of the seat.

I have yet to test this new position but the dip will cradle my ass a little when I am being dragged uphill holding onto to the handlebars with arm stretched out.




Thanks for the commentary on it!
 
I bet there's some late nights and lots of head scratching to get to the point you have with it and from what I see you have done extremely well nice solid good performing with decent range and power to get anywhere needed if you ask of it so there's a tap on the back from me Ive done stand on scooters to 50mph and a a2b metro bike with a mxus 3k hub single speed conversion and 16 inch moto rims but none of them had as much revision as you have performed it's a complete new animal.
 
That looks really good Dingus. The higher rear portion of the seat should allow for some peddling while the lower front let's you get weight on the front to climb. I don't think I'd want my bars that far forward but the position does make sense for climbing. I'm just uncertain if I'd want to decend or cross logs like that.
Do you peddle at all or are they just for show?

Right now I'm running 14/44-44/32 as my lowest gear for an overall ~2.30:1 (plus the 5:1 planetary gearbox on the cyclone) and the limiting factor for climbing is keeping the front wheel down or traction depending on surface. I rarely climb at more than 50-70% throttle and I only use a smaller gear if I'm cruising and want to peddle. 30mph is as fast as I'm interested in going.
 
Grantmac,

The pedals for cranking are recovery tools and used in just two situations: the failure of power transmission from the motor to the BB and a last ditch effort to climb one more step hill when the batts are low. Here they are used as assist.

"Do you peddle at all or are they just for show"? For show? No...the petals are what I stand on.


The long tiller stem? Yes the length is to long to readily & easily keep my ass at the very back of the seat when on Hills steep enough that just the rear brake applied cannot hold the bike still and I skid downhill. The bike cannot in general climb a hill of this steepness unless it is short or I can get sufficient speed to carry me through.

Anyway my interests are not in the ease of very steep descents at the expense of poor uphill handling. I do freeride to rocky hill tops and do loops across some Mtn ranges where there is not a complete trail loop for the zone I wish to do the loop.

There is a very positive aspect of ridding in wheelie position: You get the most traction to the rear wheel when in wheelie position! No steering when the front is off ground? Not entirely so, you can put some opposite body English into the bike and get it to turn the bike's direction axis on the rear wheel.

I generally try steep hills sort of vibrating the throttle while at the spinning--wheelie cusp. My rear brake is controlled with the left hand, which when applied will quickly end a wheelie and the right hand on the throttle. And now add that backpack full of batteries while you are doing these delicate maneuvers about a small orbit zone above the seat?
 
I ride quite a lot of ascents and descents of roughly that steepness. I don't ascend the steep stuff in the seat, I do it with more of a trials body position (bars into your body and pushing through your feet). On the descent I'm way behind the seat. Mostly I'm on either loose dirt/small stones or moss covered rock which is very slick.
I have a 1" longer stem I may try. My bars are also taller which I prefer.

With my current gearing I'm limited by traction more than anything else. Would you say that it's similar for you?

I think that backpack batteries are less of an issue the more you move your body around the bike. If you are just sitting on the seat most of the time then having that weight up high will work against you. When I'm in the seat my climbing is limited by keeping from looping out backwards.
 
Grantmac,


With my current gearing I'm limited by traction more than anything else. Would you say that it's similar for you?


Gearing? No, I can do burnouts. Traction? You never have enough. Tires? To get a more aggressive tread (I am have the most aggressive out there)) I would have to switch to a motor cycle tire and rims (more weight) but it's width (even a front tire) may be too wide. I sort of am at some machine limits: weight without bats about 67 lbs and one of my Big Hit has a 44" wheel base and I can pedal these machines. No such stats for the Sur-Ron and the likes of such.


I can go places that the local KTM riders say is quite difficult for them and not so for my rig. They do more trail modification (destruction ) in one pass than I do in a dozen passes but we get along. I just try to ride what they leave (dust grooves and many up ended rock to bounce off). More motor or more amps will likely tear up the trail more and I will get a few more places and leave a rocky fall line for others to follow?

I am to the feelings that my answer is more riding skill can be gained and the edirtbike sport is something different than gas powered dirt bikes. I suppose a pure free rider could care less which can be sometimes unfortunate for the rest of us.
 
Grantmac,

You say,

I think that backpack batteries are less of an issue the more you move your body around the bike.

I would say a better wording would be: backpack batteries are more of an issue the more you need to move your body QUICKLY to correct the bike attitude. Simply F = Ma, the More M, the more F you need to accelerate to a new location on your bike.

You need agility above the seat when doing difficult featured hill climbs. I really wonder how difficult the hills are that the proponents of back pack batteries try & do with the batts on their backs? Do you get it? A name like Hillhater?

Would you wear a pair of downhill ski boots to run an agility course?
 
So your gearing would allow you to accelerate up your steepest hill provided you could get traction?
With my lowest gear ratio I can't "stall" the motor, it either spins or loops. I'd like to play around with a slightly taller gear to see where the limit is and gear for that. The motor is never beyond warm, but it's also 5-10c here right now.

Getting the batteries off the bike should alow me to transfer their weight to where I need it for crossing obstacles. Right now I have 9lbs of battery under the downtube and the bike is quite planted. But I can't fit the full 22lbs under there.

For instance I'd rarely touch the seat on your bike unless it was a gentle hill. So perhaps that's a difference of techniques.

Does anyone in your area ride a trials motorcycle?
 
I did a test ride with ~18# of battery on my back and I was not a fan. Front end less planted and a little more maneuverable, perhaps a bit nicer over some small jumps but I could really feel the added momentum on my body. Was very hard on my damaged but healing shoulders compared to weight on the bike. Plus when I unloaded the pegs and bars for certain moves lots of traction left as well. For powered trials there is a degree of momentum in the bike that can help get over/up things. Probably if I had a bicycle background I'd prefer the lighter bike.

Now onto a decent mounting solution. It doesn't seem like under the downtube will be possible so I'm going to try and keep the weight centered under the seat.
 
Grantmac,

So your gearing would allow you to accelerate up your steepest hill provided you could get traction?


No, no acceleration, on the my steepest climb as measured with a digital level: (67% Grade) with 0 mph at the "V" of the gulley. Only when conditions are right ( dryness/wetness ) do I get enough traction to do this descent & climb. The C3000 is pulling near max: rider and bike 235 lbs.

This condition of enough traction for this long hill is while I am at the verge of doing a full on wheelie. For more traction I would need to get a motorcycle tire with more tread depth but they will not fit if they have more width.

I am nearing some limits of using this particular frame: the Bighit 3. Unless a bike tire becomes available that has more tread depth?
 
40a or do you have it pulling more?

I'm considering a bigger motor and ditching the gearbox.
2 months until I can ride again gives me a long while to think.
 
Grantmac,

Currently you are asking? All 3 edirtbike have the OEM nominal 40 amp controller included with the kit. 2 of them are the programmable version.

I did have the 60 amp controller on one them. This bike was quite jumpy towards wheelies on any of the fast start settings and on the least soft start setting the response was too slow. Using the programmable 40 amp controller I have both the fast at zero and the slow at zero. I may increment the fast start to setting 1 or 2.

The bike with the non programmable controller has a Cycle Analist programmed to some other ramp up than standard and that bike has the best throttle response.
 
Thinking of some sort of direct drive bigger motor (Cyclone, LR, etc). Ditch the planetary and primary reduction in favor of a 219 12:103 if I can make that work. Even with the 12t driver it should be fairly quiet from losing all the extra stages (not that I care).
I'm totally good with full power immediately provided it's scalable to the throttle. I don't want 10% movement to yield 50% more torque.
To that end I might look into a controller that can do torque throttle like I believe some Kelly's will do. This would also act slightly like traction control.
 
Grantmac,

This LR big block looks like an increment up over the C3000 so to speak -- both in watts and $$$700.00 plus controller.
We know the C3000 can do 4kw.


http://lightning-rods10.mybigcommerce.com/one-stage-big-block-drive/

You can get low enough gearing with a big rear chain ring and this size will likely preclude using any derailleur.

I see a 6kw Cyclone Tiawan motor is $289 and the 7.5 kw goes at $429 plus ship fees. No mounting frame included.


I have had 3 Kelly controllers, but the 120v model I used on a C3000 did not last long. -- up and died after burning up a motor (in deep snow and too high of a gear). The throttle programming features on that model were not as good as what you get adding a Cycle Analyst to the OEM 40 controller. LR recommends the CA on the above kit.

As for throttle/traction control/response I oscillate the throttle somewhat on hill etc but not at a regular cadence but more adjusted to traction noise, front end lifts and perceived additional power needed.

You say, I'm considering a bigger motor and ditching the gearbox.
2 months until I can ride again gives me a long while to think.


Good for you. I see LR says a one month wait.. when I bought his mid drive he said six weeks but it was six months before l got it. You likely will have plenty of time to read posts of his other ongoing projects until shipment day. By the time you get the kit you could have ordered the Cyclone 6kw and had it up and running. While I was waiting for L R Mid D kit I bought my first c3000 kit and had it up and running long before the mid drive arrived.

My next wait for him was when the Gates belt broke on the bikes first hill climb. Headwalling with a hardtail. No No
 
DingusMcGee said:
Grantmac,

You say,

I think that backpack batteries are less of an issue the more you move your body around the bike.

I would say a better wording would be: backpack batteries are more of an issue the more you need to move your body QUICKLY to correct the bike attitude. Simply F = Ma, the More M, the more F you need to accelerate to a new location on your bike.

You need agility above the seat when doing difficult featured hill climbs. I really wonder how difficult the hills are that the proponents of back pack batteries try & do with the batts on their backs? Do you get it? A name like Hillhater?

Would you wear a pair of downhill ski boots to run an agility course?
Click to expand...

Every bike rider from Pro Superbike, MotoX, Trials, mountainbike, Tour riders, and Amature Road bikers, etc etc...knows that a lighter bike is a better bike, and spends a fortune to loose a few gms (carbon frames, wheels , etc)
So losing 5-10 kg from a 20 kg bike must make sense . (25-50% bike weight) ..??
An extra 10 kg in a backpack (5kg is usually more than enough for most...mine is 3 kg !). Is only the difference between a small rider and a slightly larger rider (5% body weight)
Being able to "twitch" hop, and move the bike quickly , has benifits which most riders appreciate.
Those downhill skiboots are more akin to a heavy bike frame + battery, on an agility course !
PS.. Im " Hillhater". because i hate pedaling or walking up hills ..which is why i ride ebikes !
 
🤯🤪, There's engineers pulling out hair reading this one for sure.

If the mass is removed from the bike an added to yourself then the benefit of removing mass is just not there you still have the same total weight but it's also got a worse centre of gravity higher up the bike but surely your shitting me and this thread is just a wind up you got me guys lmao :bigthumb:
 
Ianhill said:
🤯🤪, There's engineers pulling out hair reading this one for sure.

If the mass is removed from the bike an added to yourself then the benefit of removing mass is just not there you still have the same total weight but it's also got a worse centre of gravity higher up the bike but surely your shitting me and this thread is just a wind up you got me guys lmao :bigthumb:
Click to expand...
If they are , then they are not bike riders and do not understand the dynamics of bike handling.
It the same principle as sprung and unsprung weight where the total is the same but the "location" and behaviour of that weight gives dramatically different effects.
 
Ianhill,
"There's engineers pulling out hair reading this one for sure."

??

I doubt they would be over the issue you have brought to this thread: invariance. What you have discussed are zeroeth and first order effects. Meaning position is important and yes less weight is easier control.

In engineering terms, a simplistic feedback control system for a rider on a bike might be referred to as a motor-governor control system. The rider being the governor. The bike-rider control system is not a bang-bang control system but is an inertial control system, meaning accelerations and velocities (both linear accelerations and rotational accelerations) are important for control and they are second order effects. These effects are measured about the pitch, yaw and roll of the bike and rider and are non linear. They are non linear because these effects vary with the square of the distance from the rotational axis which is often the ground for this system.

Some of the hill paths I try to ride up may take me twenty tries to learn the moves and do the path -- in good style. And some runs I just cannot do in good style. Should I add a pack of batteries to my back? Flocking stupid..... The paths are a far cry from a simple flat path up the fall line like I have seen in most of the GoPro videos posted on this site. It is obvious Hillhater and I do not ride the same kind of hills-- to seek our standard of perfection?

On some of my dismounts while attempting quite rough terrain I am not fortunate enough to land on my feet. But wouldn't it be a pleasure to have an 18 lbs battery pack smashing me in the back of the head? Flocking stupid.
 
If I could somehow carry the batteries on my legs I'd probably not mind they being human mounted. Or if perhaps I was very used to bicycling. Mounting them low on the bike makes it handle closer to what I'm trying to emulate (trials). If I could elegantly mount everything on the bottom tube I would. That would add other complications which I'm less interested in however (I want fairly easy removal).

A note on pros:
They are in the gym dropping fat every day. I've dropped 32# this year and the difference for all my sports has been amazing. I don't want to put it all back in one concentrated spot. I'm used to doing this stuff on a 150# bike, 80# is nothing.
 
Grantmac,


You opened this thread with the question of whether DH frames make good freerider frames but now you just announced that your interest is trials riding. I have looked into the Mtn biking sport of trials riding and see it started in Spain. But more noticeable was the acute dip in the frame of these very specialized sport bikes. No such dip in DH frames...... I suppose you will need the precise stopping & holding features these speciality Mtn bikes require? Hydraulic rim brakes?

While you are mimicking the pros and losing that weight, why stop at 132 lbs? If you got to 100lbs the less than 30lb motorless bike would seem like zero? Do you really need a motor assist as big as the Cyclone 3000?


If batteries must be mounted on the body, then you would put them on your legs? I have never entertained that hypothetically constrained position for them as once I accepted that using the capacity of a 3000 watt motor meant little pedaling, there is plenty of room for batteries on sides of the frame going up from the down tube. They are supported from a platform attached to the bottom of the down tube. This addition makes the ebike wider than an Mtn bike but who pedals such 70+lb beasts up untracked rocky hill sides?
 
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