Is a leisurely pedal cadence possible going 25 mph on an ebike?

I've been fretting over my ebike decision for a while now. I tested an aventon pace 500 bike with a 170mm 42T crankset and an 11-32 cassette. I found that, once I got up to 25 mph, I had to have a very high pedal cadence to contribute to the power of the motor.

In my dream world, I would pedal with the pedal cadence and power effort that would get me going 10 mph on your run of the mill 3 speed and the motor would do the rest to get me to 25 mph. Basically, I'd love to get to work not sweating too much. I'm guessing I would need a giant crankset for that, but I'm wondering if there is a different approach that would give me my desired scenario of leisurely pedaling that contributed to a 25 mph ride. I've got a 12 mile relatively flat commute each way.

27 inch wheels with 42T/11T is about 81 strokes/minute at 25 mph which is what a competitive cyclist will do. Me, I think 50 bpm is what I do. That's about 16 mph.

To get 50 beats at 25 mph on your Aventon, my math says I need a 68T front gear. Nope.

I used Excel, but checked it against this calculator.
https://www.bikecalc.com/speed_at_cadence

dne202 said:

In my dream world, I would pedal with the pedal cadence and power effort that would get me going 10 mph on your run of the mill 3 speed and the motor would do the rest to get me to 25 mph. Basically, I'd love to get to work not sweating too much. I'm guessing I would need a giant crankset for that, but I'm wondering if there is a different approach that would give me my desired scenario of leisurely pedaling that contributed to a 25 mph ride.

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If you had a longer bike, like some recumbents and some cargo bikes, you could insert a jackshaft in the chainline between pedals and wheel, and use small input gear and large output gear, to give equivalent ratio to having a giant log-splitting-sawblade-sized crank chainring. I use an IGH as a jackshaft in the SB Cruiser trike's frame to give me *lower* gearing; opposite of what you need to do, but you can still do it to get your results.

You might instead be able to use a large (but not *as* large) crank chainring, and then use a rear wheel built with one of the multispeed IGHs that also has a gear cluster on it. Use the smallest sprocket possible on the outer part of that cluster, and use the IGH gears as a multiplier for the speed.

You'd have to find out what ratio is possible with the IGH and what the smallest sprocket (cog) on it's gear cluster could be, before you can determine the necessary crank chainring size.

There are also systems like the Schlumpf (sp?) that provide gearing from the cranks prior to the actual chainring, that might help with this.

Not sure if any of these things is worth teh cost / etc. to you, but they are options.

29" wheel with large diameter tire, 52 or 53 chainring, 11 cog, will pedal around 60 rpm at 25 mph.

60 rpm cadence is pretty low rpm when developing a lot of power. With electric assist it seems very doable.

This use, pedaling low rpm at 25 mph, seems appropriate for a conversion bike, not an off the shelf ebike.

It can be done. A road bike crankset can use 52, or larger chainrings.

On the Aventon Pace 500's 27.5" tires, a 52t chainring would get you a cadence of about 65rpm at 25mph, which isn't quite "beach cruiser" slow, but it's pretty leisurely.

A 52t chainring is large, but it's not so large that you'll have to go looking for expensive specialty parts or anything like that.

I guess it depends on what you consider leisurely. I've done what MikeSSS mentioned and I have a 53 tooth road crank on my ebike. I got rid of the crank that had the standard 42 tooth and smaller chainrings. You just need to make sure that you have the right bottom bracket offset so that the largest chainring will clear the chain stay. I also have a rear freewheel with an 11 and 13 top two gears. Riding at 25 mph doesn't seem particularly frantic at all to me at 25 mph and I only get into the 11 gear when going downhill since it seems too slow for the 28 mph speed where the motor cuts out (to comply with local laws). The 11 tooth gear feels right to me at speeds higher than 28 mph.

If nothing else, a 48 t front ring should fit, or perhaps a 52, if you can find the right one to fit your existing crank. Road crank will likely not have enough offset, and rub the frame.

But a 48t will help, as would learning to accept cruising at 22 mph.

I went with a 55 tooth. Very pleasant at 28-33ish. Just took grinding some plastic of the battery case, and a little sledgehammering to flatten the frame behind it a bit.


The 175mm cranks give you some leverage too... a couple of weeks ago I actually broke one of those black pedals in the picture in half, just pedaling hard away from traffic on a smooth street. I was stomping those things!

Yeah I break pedals all the time, but I tend to buy cheap pedals. The pedals I splurged on, $20 range, are one piece cast metal of some sort seem to have held up fine.

I purchased a grab bag box full of used stuff last year, because I had a square/square taper, instead of a diamond/square taper and I couldnt get the pedal off or something or other. Its not like I am a hard core cyclist, or that I even pedal, I am lazy and dont pedal, heck for a year there I never installed a chain even. The current setup is a wimpy setup, typical generic 9C with 36V 26A because I have dell chargers and battery setup for 5S+5S split pack, due to dells 20.50V, which is 1.50V off but it gets me around.

I like the fact I am pedaling this year, being under powered forces me to actually pedal, but not being too under powered that I have to pedal all the time, no I just have to pedal on the hard bits. Its a good setup, but I wonder sometimes when its a hard day of riding, and I run out of battery power and I am sweating like mad but I am focused on finding a power outlet there is some deep thinking that happens. Even on hill climbs.

I like the setup, 53/11, though I would say I dont hardly go 30mph(48kph), a few falls here and there and my sweet spot is just cruising around, I'd say its school zone/playground zone speeds even while on the road, here its 30kph which is 19mph.

I ride mostly sidewalks for the boulevard, roads for residential homes on street, and pathways, lots and lots of pathways. Occasionally I have done single track trails, simple ones. It sure brings a smile to my face on the leisurely single track rides. I have done easy ones with lots of ups and downs with roots that are doable, and doable mini dips on trail.

Wow, thanks everyone! @amberwolf I'm interested in the IGH or the schlumpfdrive solution. For the IGH in the rear hub motor idea, what are examples of the kind of IGHs I might be able to use?

I pedall regularly at 30mph on 36 inch wheels with EPLUS DD hub motor
11tooth rear 42 tooth front
It is kind of crazy pedalling but it increases my speed by 2mph eeasly.
So I decide my speed not motor.

dne202 said:

Wow, thanks everyone! @amberwolf I'm interested in the IGH or the schlumpfdrive solution. For the IGH in the rear hub motor idea, what are examples of the kind of IGHs I might be able to use?

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The Grin hub motor with the Sturmey Archer 5 speed might be the only kind...

Voltron said:

dne202 said:

Wow, thanks everyone! @amberwolf I'm interested in the IGH or the schlumpfdrive solution. For the IGH in the rear hub motor idea, what are examples of the kind of IGHs I might be able to use?

Click to expand...

The Grin hub motor with the Sturmey Archer 5 speed might be the only kind...

Click to expand...

Wow did not know that option exists!

max torque it can take? Rohloff is 130 Nm

Well, it just is subject to normal pedaling loads... It's not driven by the motor. It's not like having a 5 speed gearbox powered by the motor

dne202 said:

@amberwolf I'm interested in the IGH or the schlumpfdrive solution. For the IGH in the rear hub motor idea, what are examples of the kind of IGHs I might be able to use?

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Mmmm...unless you're up for a fair bit of machining, you can't put the IGH *in* a rear hubmotor. You'd have to build it into your frame as a jackshaft, as I did.

There *is* a TDCM hubmotor (ebikes.ca carries it, I think) that has an IGH built into it (only the pedals go thru the IGH, not motor power). EDIT: Voltron posted this one above.

If it's a standard bike wheel, then you just use one of the ones (SRAM?) that has a gear cluster *and* an IGH in the same hub. I don't know what model numbers those are. (most IGH only have a single input sprocket, nto a shiftable cluster; all the gearshifting is done only inside the hub).

Which one you use dpeends on how many gears you want out of it, and what ratio you need them to have to get the speed range yo'ure after.

Okay, so the TDCM is 18T sprocket and the gear ratio is .64, so that gets me to something that behaves like an 11T, right? Is there a way to get a smaller sprocket or is that a bad idea?

I see what your saying about possibly using a mid-drive motor and using the IGH without a rear hub. That might make a lot of sense. I see the Luna Fixed Stealth Ebike seems to use that method, but the rear gear is 22T and the IGH goes to .73 so that's just 16T or so with a 55T front gear. So that won't get me slow pedaling, I suspect.

I'm not sure, but you might be able to find a 16T for some IGHs, or make a 14T from a suitable donor.

This page has a fair bit of info on various IGHs, and links to more, plus info on "hybrid gearing", using an IGH with eitehr multiple front chainrings and/or a gear cluster of one type or another on the input of the IGH itself.
https://www.sheldonbrown.com/internal-gears.html

and this section of that page talks about the input sprockets and how you may be able to adapt ones not made for your hub to fit it anyway
https://www.sheldonbrown.com/internal-gears.html#sprockets

dne202 said:

I see what your saying about possibly using a mid-drive motor and using the IGH without a rear hub. T

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:? I didn't say anything about using a middrive motor. (though you could, the IGH might not stand up to it, and even if it did, it means that the gearing would have to be suited for the *motor's* speed to make the bike go the speed you want, rather than being suited to *your* speed to make the pedalling work out for you.)

I was talking about using the IGH in your frame, for just the pedals to go thru, as a jackshaft just to give you extra gearing ratios to get the cadence you're after.

That way you can still use an IGH if you have an existing rear hubmotor (you havent' posted what your motor setup is yet, but I assume your previous reference to a rear hubmotor wheel means taht's what you have on the bike now).

Please look over at my SB Cruiser thread, linked in my signature, for how I did it on that trike, if you're interested in that option. You probably don't have that same option on a typical bike frame; I haven't seen a pic of yours in the thread yet, so can't make any suggestions for how or if your frame could do this.

Thanks, Amberwolf. So is there a difference between what you're saying with the IGH in the front and an Internally Geared Crankshaft like the Patterson, Efneo or Schlumpf? The Patterson might be exactly what I'm looking for, provided I can put a 42T gear on it. Looks the the biggest they sell on the patterson site is 36T. I'll email them. I wonder if I can just drop a patterson on the Aventon 500 and be good to go. Thanks for all your help!

dne202 said:

So is there a difference between what you're saying with the IGH in the front and an Internally Geared Crankshaft like the Patterson, Efneo or Schlumpf?

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Yes. look at my SB Cruiser thread for the IGH in frame pics.
I think this is the original post where I first installed it
http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=67833&p=1230328
it's a ways down the post, but it shows most of the steps of working out how to mount it in my particular frame.

This is a search of that thread for "IGH" so it contains more explanations and there's of course pics of various incremental additions/etc to the trike, starting with most current back to earliest mention in the thread.
http://www.endless-sphere.com/forums/search.php?st=0&sk=t&sd=d&sr=posts&keywords=igh&t=67833&sf=msgonly&ch=-1&start=25

Just about the first working version



not a closeup but you can see how it is now (except the original SA 3speed IGH broke, so now it's an old Sachs 3 speed






Note that I don't have a front derailer, I have to manually move the chain from one pedal chainring to another to get anything other than the lowest gear. Also, there's nothing to keep the chain on any ring, so it will go down to the lowest one by itself after a while or upon any bump at all, because of the chainline to the IGH. The derailer on the IGH is there to take up the extra chain when on the lower rings in front; I don't have multiple sprockets on the IGH input.

Okay, picking this back up again as I've got a little money back in my pocket . So I think the jerkshaft might be too much work on my end. But I think I might have something that could work. I'm inheriting a Surly Cross Check for the donor bike. So If I was to get a sturmey archer 3 speed on the rear and put a front hub motor on it, I could see a lot of benefit. Would I be able to put a 10T cog on the back and a 50T crankset? If I did this, I could put the Sturmey into .75 Gear ratio and get something similar to a 7.5T in the back. That would get me around 25 MPH with 50 RPM.

My two questions would be:
Can the sturmey archer can take a 10T rear cog safely?
How powerful a direct drive front hub can I get on the Surly Cross Check before I start to comprise safety from traction or torque problems?

I've read a lot that front hubs can have traction and torque problems and fewer people have them for higher power motors. But, this is just a commuter bike on pavement (some a little sandy by the beach) where I will mostly be cruising along. I'd also love the fact that I could swap out the front tire and convert my ebike back to a simple bike for rides with the family.

power level on a front motor depends on enough things that it's difficult to predict what is "too much" for any particular setup without testing it out under your specific conditions.

personally i don't think your needs are giongt o require enogh power to worry about it, unless you need massive torque for superquick startup launches or whatever.

however...assuming you've got proper torque arms or plates or pinching/clamping dropouts to prevent axle spinout in the fork, and the crown / steerer interconnect and headtube/frame are strong enough, you can use any amount of power you wish (dozens of kw if your parts are up for it...oh, and it's not really power that is the prblem, it's torque).

at that point it's only that torque is limited by traction in any particular situation, meaning by how much weight you can put on that wheel, and how well the tire grips the surface you're on at the time (which depends on teh tire, it's size (for contact patch size) and inflation pressure).

then it's up to your application of throttle to prevent spinouts, etc, and thats something you just learn just like you would with pedalling and steering a regular bike under conditoins that allow spinout or skidding of wheels, any loss of traction. as long as ou don't slam throttle on under poort traction connditions you won't have

i've run as much as 2kw in a direct drive 26" wheel (with another 2kw in a 20" rear at the same time) on one bike, and another had 1200w in a geared hub in 26" wheel, which eventually broke the clutch in the hub, and at least once destroyed the dropouts and damaged wiring becuase i didn't have secure torque arms.

the geared hub was at least as much torque, probably more, than the dd hub at the higher power level, based on startup times from a stop with similar loading, but it was a lot harder on the hub for those power levels. no actual torque meausrements to objectively quantify this though.

alomst all my riding is on flat roads, so i didn't see this, but people have reported that significant traciton can be lost going uphill with a front hubmotor if the slope is steep enough.


the biggest issue besides traction people run into with front dd hubmotors is that as torque goes up, *and* regen braking is used, it's harder and harder to keep the axle from rocking in it's holders, and eventually spinning out. happens in the rear too, but it doesn't usually cause a severe injury-inducing crash if the rear axle comes out of holders or breaks off, where a front wheel that suddenly stops being able to spin certainly can.

probalby not something you'll hve to worry about at your power and load levels, as long as the axle and mounting hardware is up to those.

regarding gearing...if the sa igh is like any of the ones i've held in my hands, 14t is probably the smallest you could fit for one.

you can get a bunch of sizes here int this randomly found sa 3speed sprocket search
https://www.wheelandsprocket.com/product/sturmey-archer-3-speed-sprocket-and-circlip-245383-1.htm
and 14t is smallest they carry probably for that reason.

Option UPC Store SKU
18t / dished 1/8" 04710944237603
20t / dished 1/8" 04710944239010
22t / dished 1/8" 04710944238518 STU33822520G
24t / dished 1/8" 04710944245141
14t / flat 1/8" 04710944228724
16t / flat 1/8" 04710944236903
18t / flat 1/8" 04710944236927
20t / flat 1/8" 04710944238952
22t / flat 1/8" 04710944238969
14t / flat 3/32" 04710944238976
16t / flat 3/32" 04710944228748 STU35573555G
18t / flat 3/32" 04710944238983
20t / flat 3/32" 04710944238990
22t / flat 3/32" 04710944239003

Click to expand...

it would require a custom made adapter and axle spacers / custom dropout spacing with torque clamps to make a sort of top-hat shaped adapter to go from the diameter of the sprocket mount on the igh out to over the axle itslef, with a bearing inside it to support it on the axle surface, then down in diameter enough to fit the inside of a 10t sprocket.

most cassettes and freewheels only go down to 11t, so even if you have one of the combo type ighs that has a cassette freehub *and* internal gearing, you still can probably only put 11t on it.

if it's got a threaded spot for a regulard freewheel instead of freehub splines, there are cheaply-made 10t freewheels that should fit on that.
https://www.google.com/search?q=10t+sprocket+freewheel
edit, was wron,g, the one i'm thinking of is 12t
https://endless-sphere.com/forums/viewtopic.php?f=2&t=67833&p=1237062
can't find a 10 except on a verys pecific regular bike hub, no gearing inside it. no freewhel eaither, is ifxed so chain would always move whether pedalling or not.

recumpence made one on a jackshaft
https://endless-sphere.com/forums/viewtopic.php?f=28&t=22483
but that's not what ou're after.

however, all small gearing like that wears out quickly, vs larger sprockets, so you may end up replacing it frequently. not as frequently with just pedal power as with motor power, but still more than if you used larger ones.



as for crankset ring size--you would have to meausre the distance between the chainstay as it angles out between bb and dropout, and the intersection plane of the largest ring on your crankset. as long as the diameter of that plane before intersection allows for a ring with as many teeth as your'e after, then you can use one that big. otherwise you're limited to a smaller one.

alternately, if your hips and knees can handle the extra strain, or you have wide hips to start with, then you can use a wider crankshaft to put your rings farther away from the frame, which increases the size of chainring you can use


a check of the surly page for that bike says

Max Chainring (CL)[3]

1x (Road): 50T

2x (Road): 39/53T

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under the frame specs, meaning i fyou use a two ring rankc of that type it'll go up to 53t

http://www.sturmey-archer.com/en/products/rear-hub-sprockets

Going through each one, a few with 12T selection and 2 with 13T selection.
Next question is: Are there are gears interchangable with the notches for the sprocket for the Sturmey Archer geared hubs.
And how much power can they take before they start breaking, for mid drive setup.

Hope did not even go down to 9T and settled on 10T, but there are some with 9T and 10T. Mainly because the chain wrap around the gears would be problematic.
https://www.sheldonbrown.com/capreo.html
https://www.amazon.com/Shimano-Capreo-Speed-FHF700-Cassette/dp/B002Y1CJQG
https://www.vitalmtb.com/product/guide/Cassettes,26/Hope-Technology/11-spd-Cassette,17493#product-reviews/2765/expand
The quote below is copied from the search engine, I couldnt find it inside the link itself.

Hope played around with a 9T sprocket on their prototype cassettes for some time, but eventually ended up settling for a 10T as they found some issue with chain wrap and general transmission efficiency on a 9T. As the sprocket shrinks but the chain links remain the same, a more acute angle is required for each chain link to wrap around the cog.

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You wouldnt want to put too powerful a front hub motor on any bicycle, having a rigid steel fork would give the rider peace of mind, but a front hub is for low power setups. I've been riding a front hubbie for awhile now, and its fine. Takes some getting used to with going over curbs, and slippery situations (ice, mud), and of course you'd want two torque arms on any front hub.
Sandy Beach, you may want to think of getting a fat bike or a plus size tire (2.5+" wide tire) bicycle.
Swapping the front hub back to normal is just as easy for the rear as it is the front.
I have replaced 50 tubes on a rear hub, and its really not that much extra work. There is a technique that is easily self learned for replacing a rear hub flat. What I did was flip the bicycle upside down, unscrew the torque arms from both sides, unbolt the bolts, take the adj wrench and grip it on the wrong end, take the handle and shove it down between the motor and chain stay and yank the chain stay out to free the axle from the axle slot of the frame, do same on other side, and yank the wheel up. Too easy, and easily learned.

Do not compromise on going with a front hub motor, they are thinner so less power. If buying new buy rear hub motor, get that extra power thats always welcomed. Even though you are cruising around a beach, you will get more and better traction with a rear.

dne202 said:

Can the sturmey archer can take a 10T rear cog safely?
How powerful a direct drive front hub can I get on the Surly Cross Check before I start to comprise safety from traction or torque problems?

I've read a lot that front hubs can have traction and torque problems and fewer people have them for higher power motors. But, this is just a commuter bike on pavement (some a little sandy by the beach) where I will mostly be cruising along. I'd also love the fact that I could swap out the front tire and convert my ebike back to a simple bike for rides with the family.

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Thanks, Markz and Amberwolf. Sounds like I should stick with rear hub, I appreciate the advice. It also seems like, given my 50rpm at 25 mph wish, I really should just stick with the planetary geared crankset like the schlumpf high speed drive and a 30T crankset or so. I don't have the welding skills to do the jerkshaft. Just to be sure, there is no way to get this 50 RPM pedal cadence at 25 mph with a mid-drive, right? Mid drives don't allow you to put a multiplier between the pedal cadence and the crank rotations, right?

Man, that schlumpf is expensive. Evidently I have expensive taste