Originally Posted by
andiewithanie
chain tension could have been an issue (I bought the bike s/h and my preference is for a looser chain), but i doubt it contributes much to the wear issues compared to pedalling forces, which could be as high 3.5-4k newtons according to this dude
https://odysseybmx.com/2003/12/67-super-small-gearing/ (i have no idea how to calc forces at driver - 250 over 20 x ????)
i've tried making sense of the tech but unfortunately i'm too thick. i might be able to go up to an 11t driver at rear without messing up the chainline too much, and i'm hoping that with the right bearing choices (including perhaps shims), i might get a drive train that is reasonably reliable (i've already blown up one chain)
you need to add the pedalling force to the tight chain loading... and the excess chain load is way beyond the pedal force load....
if you have a need for doing stunts that include handrail riding and sliding your bike along angle iron bowl lips, then the tiny drive train is justified, and expect high maintenance frequency and costs..
if there is no need for those stupid-small gears, GET RID OF THEM, FRONT AND REAR, and go with a more reasonably sized setup. 42/16, and the much more substantial freewheel possible.
i regularly replace hubs and entire rear wheels with 9-10t freehubs in them..... i swear the things are built to break.... internal bearing failures and broke ratchets... the last one i did was lubed with WD-40 until NO Grease remained, and the guy left the Jam Nuts loose on the axle too... A Cone finally Shattered.... the beginning of the problem was traced back to An Over-Tightened CHAIN... and the chain was then Over-Tightened AGAIN... i tried to get the dad to bring the entire bike here, but he assured me he knew what he was doing... The repaired hub lasted about 20 minutes.
49 new balls, a new cone, a half hour of labor.. all for naught.
and then, there's the rapid tooth and chain wear on them too... and the neglective habits of the owners, regarding lubing a chain... YIKES!