r0x0r

I have a Focus Urban (2014 model) belt drive bicycle, which is all around a fine bike. My only gripe is that it could be a little bit faster. So I've been wondering if it is possible to upgrade the front sprocket to a bigger one. The current gear ratio is 46/22 and I've been pondering to make it 50/22 or even 55/22. The problem is the space between the frame and the sprocket is pretty tight. So it is not clear whether the frame could accommodate a bigger sprocket. The pictures of the sprocket can be found here: https://m.imgur.com/a/b96ly

I could not find dimensions of Carbon Drive sprockets anywhere and inquiries to Focus led to nowhere. Anybody have any information if such an upgrade is feasible? Many thanks in advance.

jimc101

How about looking at the manufactuers website, all the details are on there - Gates Carbon Drive Belt System

dsbrantjr

A couple of measurements of your current sprocket and some simple algebra should yield the information you need.

r0x0r

Already did. They do not list dimensions, only weight and teeth number.

dsbrantjr, good idea! Haven't thought about that.

mconlonx

Gates are nice people -- you might email them and ask if they could provide the measurements you need to establish compatibility.

fietsbob

subtile, size down a couple rear teeth 22 to 20t ?

maybe the existing belt tension adjustment can cope with that?


Applied Maths:
Measure the teeth spacing [11mm] its 1/ 46th of your circumference ..

from that you can calculate new circumference when there are 50 of them rather than 46,
and from that work out the diameter.





./.