Jam2: Replacing the 34T front sprocket with a larger one?

[pegnose]

Depending on the road I sometimes could go faster than 25 km/h, but I would have to pedal faster than comfortable. My bike comes with a 34T front sprocket. Could I upgrade it to a larger one? What would be the downsides?

I admit that the highest gear with the 34T fits the max motor speed very well and will be good for the regular biker. But I rarely use the lowest 2-3 gears, so maybe even gear usage would be more evenly distributed.

 

[Luke0770]

Hi,
You would loose acceleration for top speed gain, but being a ebike acceleration and hill climbing is less of a problem!

Try using a gearing calculator like this one:

Bike Gears calculator

Very helpful to work out what you need.

 

[Luke0770]

Chainreaction, Evan's and wiggle sell a 38t front sprocket for the shimano e8000 motor.

 

[pegnose]

That one looks ideal to me, will think about it for the next season!

EDIT: I probably should pair this with a longer chain, right?

 

[steve_sordy]

...........

EDIT: I probably should pair this with a longer chain, right?

Yes!

 

[pegnose]

Probably around 4 links more or something?

 

[steve_sordy]

For 34 to 38, two would do it, the chain only wraps around half the ring.

But why not go back to first principles and set the chain length properly?

 

[pegnose]

A) You are right. I am so stupid.
B) You assume my chain is not properly sized?!

 

[steve_sordy]

A) You are right. I am so stupid.
B) You assume my chain is not properly sized?!

A) Stupidity was not assumed. Most people have just never thought about it.
B) I don't know whether your chain is properly sized or not, it probably is. But there is a chance it isn't. I have seen bikes where a new chain has been fitted straight out of the packet it came in and it was obviously way too long. But that is most unlikely in your case. What I was aiming at was that you have an opportunity to make sure that the chain is exactly the right length for you, one link here or there may make a difference. When you see how many different ways there are of deciding what length chain you need (I know of at least six) you can see how the result might vary.

 

[pegnose]

You are absolutely right, Steve. Thank you for the explanation. When I decide on the new sprocket, I might get back to you on that.

 

[SEBA]

So .. , how many links for 38T front chainring ?