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

pegnose

Member
Jun 11, 2019
70
28
Berlin, Germany
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

New Member
Sep 8, 2019
23
11
Maidenhead
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.
 

steve_sordy

Wedding Crasher
Nov 5, 2018
8,361
8,587
Lincolnshire, UK
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?
 

steve_sordy

Wedding Crasher
Nov 5, 2018
8,361
8,587
Lincolnshire, UK
A) You are right. I am so stupid. ;)
B) You assume my chain is not properly sized?! :unsure:

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.
 

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