slickrock
Active member
- Thread starter
- #31
So,Houston, we have a problem.
Today I have received the 122T belt. So far I have the following belts: 120T, 122T and 125T.
The problem I discovered is the chain growth:
I suspect the chain growth is too great for the existing setup (Pinion BT1 chain tensioner, 39T front sprocket, 34T rear sprocket).
- The 120T belt is too short. Nothing to add here.
- The 122T belt is slightly too long when the bike is unweighted. Yet it is too short when and no full wheel travel could be achieved.
- The 125T belt is too long when the bike is unweighted. It allows, however, the full wheel travel.
So far this is a bike stand-testing. Next week I will have my forks ready so once they are fitted, I will test the system with my own weight. I do not expect different results but I want to confirm it.
So, it is time for the collective brainstorming. What to do here? Any thought and/or suggestions?
- If you are planning to use a SpeedHub, then AFAIK, you can only use 19, 20, and 22 Tooth sprockets as those are the only available.
- Minimum gear ratio for this hub is 1.90, so if you are using a 39T chainring, a 34T sprocket would be way below that and would break warranty. If you stick with the 39T chainring, then largest rear sprocket would be 20T. A 19T would probably provided a more suitable ratio since this is an EMTB.
- If this ratio is still too low then you would need bigger front sprocket, like a 42T or 46T
- The consequence of these changes is that the belt lengths available in the suitable range: 118T, 122T, 125T and 128T - one these combined with your choice of front chainrings and rear sprockets with your desired gear ratio, might get you a combinatorial belt deflection that gets you in the ballpark with your tensioner kinematics, while supporting the chain growth limits of the Voima. BTW, what is the chain growth of your Voima?