Gearing change on my Voltbike Kodiak.

[kojack]

I was thinking about changing the front chainring to give a little more top end speed, however after discussions here that would probably not work correctly, so what about dropping a tooth or two in the rear to compensate. I can hit 37km/h right now before my pedalling become ineffective and I run out of gear. If I could get a few more Km/h out of it to 40-42km/h It would be at our speed limit for our secondary roads which would make a huge difference in traffic for me personally. I think I have an 11t in the rear for the 7th gear. If I drop that to a 9 would it get me there or not? TIA!

 

[Stefan Mikes]

I think I have an 11t in the rear for the 7th gear. If I drop that to a 9 would it get me there or not? TIA!

Not doable. A standard cassette only allows 11 teeth in the smallest sprocket. Smaller sprockets require a special "driver" for the freehub body, and it is usually only available for expensive 12-speed cassettes. The rear hub must be either Shimano Microspline or SRAM xD compatible, which is certainly not the case with your e-bike. The point here is a 9 or 10t sprocket must hold onto something, it is not the case with less advanced drivetrains as yours.

No chance to install a larger chainring?

 

[kojack]

Impractical. A standard cassette only allows 11 teeth in the smallest sprocket. Smaller sprockets require a special "driver" for the freehub body, and it is usually only available for expensive 12-speed cassettes. The rear hub must be either Shimano Microspline or SRAM xD compatible, which is certainly not the case with your e-bike. The point here is a 9 or 10t sprocket must hold onto something, it is not the case with less advanced drivetrains as yours.

No chance to install a larger chainring?

I have been told it would screw up the drive system. I could pop on a couple of teeth more on the front if I could. That's easy.

 

[Stefan Mikes]

What is the current front chainring size in teeth? Please have a look at this place (where the chainstay changes the shape behind the chainring):

There is some clearance behind the chainring. The chainstay shape will limit installing too a big front sprocket. A bigger chainring wouldn't upset the drivetrain (you would only need a longer chain) but the design of your e-bike might prevent these changes.

On a different note: The assisted speed in Canada is only 32 km/h Why do you need to be a speed demon? 37 km/h is a really high speed already!

 

[stompandgo]

As Stefan says, changing the top cassette cog to a 10T or 9T would involve upgrading your entire drivetrain to 11 speed or 12 speed, potentially including the front chainring. The least expensive way would be to add a few teeth to the chainring and extend your chain. As you look for new parts, pay attention to frame clearance, as Stefan suggested above, but also offset between the chainring mounts and the chainline, as well as the mounting type (splines, bolts, etc.). For mid drives, frames are designed around motors, not the other way around. Look for chainrings for your motor model. For hub drives, match the chainring bolt circle, offset, and pitch.

 

[Jeremy McCreary]

For mid drives, frames are designed around motors, not the other way around. Look for chainrings for your motor model.

Maybe I lucked out on my mid-drive Vado SL 1, but to reduce the chainring from the stock 44t to a 40t better suited to my hills and legs, all I had to do was match the BCD and bolt pattern.

The Wolf Tooth narrow-wide chainring I chose went right on without a hitch. Now I have a 22-99 gear-inch drivetrain perfect local topography.

I know that going from stock to a larger chainring could run into clearance issues for the OP. Point is, the chainring may not need to be motor-specific.

 

[stompandgo]

I didn't mean to suggest that there are no motors that use standard bicycle chainrings.

 

[kojack]

What is the current front chainring size in teeth? Please have a look at this place (where the chainstay changes the shape behind the chainring):

View attachment 200656
There is some clearance behind the chainring. The chainstay shape will limit installing too a big front sprocket. A bigger chainring wouldn't upset the drivetrain (you would only need a longer chain) but the design of your e-bike might prevent these changes.

On a different note: The assisted speed in Canada is only 32 km/h Why do you need to be a speed demon? 37 km/h is a really high speed already!

Because I get one hour for supper break at work. I ride to work, ride home and back again. To be able to just get like 42-45 would be great for rolling with traffic. It's nothing to do with being a speed demon, it's all to do with practicality for me. If I am not riding to and from work, I am never on max power anyways, hell, even going to work I am usually not on max power. But, for the times I want to get home a little quicker it would be nice. I am not out ripping around like the young dopes on surrons.

 

[PCeBiker]

I was thinking about changing the front chainring to give a little more top end speed, however after discussions here that would probably not work correctly,

That should work fine, as long as the new chainring doesn't hit the frame/chainstay.
Just check for clearance.

I've got a hub-drive Voltbike Outback that came with 46t chainring.
I installed a mid-drive motor with a 52t and a 44t chainring.

As long as you have enough clearance for a larger chainring, then Go For It !!

Your hub motor doesn't care what you've got for sprockets and chain.

Just keep in mind that you are technically speeding in Canada going over 32 kph.



After installing my mid-drive motor, I got my ebike going just under 50 kph.
I couldn't enjoy the feeling At All.
I was Too Worried about getting caught.

$5,000 in fines, (driving a motor vehicle without license, insurance or registration) my ebike would be impounded or confiscated, and I'd pay over $10,000 at the end of it all in increased insurance rates for seven years.

,.. I am not out ripping around like the young dopes on surrons.

If you have any of those sorts of riders in your area, you don't want to be the one that gets caught and made an example of.

A Surron can Easily Escape the police.
You're an easy score on an actual ebike.



I'd suggest getting an actual motorcycle helmet.
If you're "competing" with road vehicles, it doesn't matter who's at fault in an accident, the one on the bicycle is always the one getting hurt.


Other vehicle traffic could mistake you for a normal bicycle and misjudge your top speed and your ability to accelerate.
A motorcycle helmet helps make you look more like you're on a motorcycle, and it protects your better.

 

[PCeBiker]

This is the crank arm with the 46t chainring that I removed from my Voltbike Outback to install the BBS02B mid-drive motor,..

I could replace the 46t with a 52t but then the teeth would probably be sticking out further than the chain guards?

So you'll probably need larger chain guards? But they are available.

A new 52t chainring (kinda the largest generic size) with the proper chain guards should be a simple swap.

But you'll probably need a longer chain (unless you don't ever try to use first and second gear).

Standard chains are too short, so you'll need two.
Cheap chain is fine.
It's only for you to help pedal instead of ghost pedaling at top speed.

 

[kojack]

We hardly have police in our town. Let alone ones that would stop me for riding with traffic, obeying driving laws with a load of groceries on my bike.

 

[PCeBiker]

I did a bit of surfing around Aliexpress, and it looks like you can get 60 tooth chainring,..

I just found this on AliExpress:
WUZEI Road and Folding Bicycle Crank Chainring, 110/130BCD, 36/38/40/42/44/46/48/50/52/54/56/58/60T

https://a.aliexpress.com/_mM0kL5h

My first ebike has a 52t chainring going to a 11t rear cog, (26" x 4" fat tires)

I remember pedaling once just check my cadence at 32 kph and my cadence was having a hard time keeping up, and I couldn't pedal comfortably.

There's no way I would be able to keep up at 40 kph.



So,.. if I were you, I'd put a 60t chainring on your ebike.
If it will fit.



And they've got aluminum chain guards as well,..

I just found this on AliExpress:
VXM Road Bike Bicycle 130BCD Aluminum Single Disc Crankset Protector Plate, Chainwheel Gear Cover Parts, 50T-54T 56T-60T

https://a.aliexpress.com/_mOrnIR1

The special chainring bolts may need to have a chain gaurd (or two) installed along with the chain ring to have proper spacing?



I didn't take my original Voltbike crank apart to see how the bolts work, but I suspect that the chainring might not tighten up properly without the two chain guards also installed?

 

[PCeBiker]

I found these chain ring bolt tools,..

Then I checked my Voltbike chainring bolts, and they're different.
I just need a 5mm and 6mm hex wrench.


@kojack you've probably got the same crank arm as I do?


I still don't know about the chain guards, but I'm pretty sure that you can reuse your original chain gaurds on a 60t chain ring (if they're needed for proper spacing?), but the teeth will be sticking out beyond the chain guards .

You may have clearance for a 60t chain ring, but perhaps not enough clearance for a 60t inner chain guard?

If so, the inner chain guard could be reused (it wiĺl have the exact same clearance as with the original chain ring) with maybe just a 60t chain guard on the outside?



Or no chain guards at all if they aren't necessary for the install?

Maybe there's shorter/different chainring bolts that can be used for installation without chain guards?
(I still haven't unbolted my chainring to check it out.)

 

[EMGX]

There are a few different lenghts of chainring bolts available if removing the chainguard necessitates a shorter bolt.

 

[Marcela]

Check around for gear calculators and input your data and make the modification. Better to be disappointed now than later, or otherwise.

 

[fexixav]

That should work fine, as long as the new chainring doesn't hit the frame/chainstay.
Just check for clearance.

I've got a hub-drive Voltbike Outback that came with 46t chainring.
I installed a mid-drive motor with a 52t and a 44t chainring.

View attachment 214912



As long as you have enough clearance for a larger chainring, then Go For It !!

Your hub motor doesn't care what you've got for sprockets and chain.

Just keep in mind that you are technically speeding in Canada going over 32 kph.



After installing my mid-drive motor, I got my ebike going just under 50 kph.
I couldn't enjoy the feeling At All.
I was Too Worried about getting caught.

$5,000 in fines, (driving a motor vehicle without a license, insurance or registration) my ebike would be impounded or confiscated, and I'd pay over $10,000 at the end of it all in increased insurance rates for seven years. I definitely don't want to take that risk, especially when I'm just trying to make it home in time for Jummah prayer Bahrain.





If you have any of those sorts of riders in your area, you don't want to be the one that gets caught and made an example of.

A Surron can Easily Escape the police.
You're an easy score on an actual ebike.



I'd suggest getting an actual motorcycle helmet.
If you're "competing" with road vehicles, it doesn't matter who's at fault in an accident, the one on the bicycle is always the one getting hurt.


Other vehicle traffic could mistake you for a normal bicycle and misjudge your top speed and your ability to accelerate.
A motorcycle helmet helps make you look more like you're on a motorcycle, and it protects your better.

If you’re running an 11T top gear now, going to a 9T is a pretty big jump, about 22% higher gearing. In theory, your 37 km/h would become roughly 45 km/h at the same cadence. For your target of 40 to 42 km/h, a 10T would be a better match if your drivetrain supports it. Also check whether your cassette, freehub, derailleur and chain are compatible with a 9T or 10T sprocket before buying anything.

 

[PCeBiker]

If you’re running an 11T top gear now, going to a 9T is a pretty big jump, about 22% higher gearing.

It's not really possible to install a smaller top gear on his hub motor.
The axle (with the motor cable inside of it) is too fat for such a small cog.

 

[PCeBiker]

Check around for gear calculators and input your data and make the modification. Better to be disappointed now than later, or otherwise.

I'll try and remember to pedal my ebike at 32 kph with both my 52t and 44t chainrings for a subjective comparison.

I may even wing it up to 45 kph for a few seconds and try pedaling.

I've got clearance for a larger chainring myself.
(I added a mid-drive to my Voltbike hub-drive, so my clearance is different)


@kojack
You can also get chain ring spacers to move your chainring further out to help clear your frame/chainstay.

That will also help to give you a better chainline going to your 11t cog.
The angle wouldn't be as good for lower gears, but you've got a hub motor, so you're not "required" to use all your gears like you are on a mid-drive.


My smaller 44t chainring is offset to help line up the chain with the lower gears on the freewheel for better torque.
The angle sucks for my 11t cog, but I've got my 52t chain ring for higher speeds.