-
Drive side crank arm is heavier than non drive side, so would adding car wheel weights to non drive side balance this out ?
No. The excess mass on the drive side is more or less uniformly distributed about the rotational axis, so it's not really contributing to the wobble. The problem is that all bicycle crankshafts have a large rocking moment, the way to fix that would be with counterweights on both sides, so that the drive side and non-drive side cranks are each individually statically balanced. Obviously nobody in their right mind would bother about this, since the moment is tiny relative to the non-rotating mass.
Notwithstanding crank balance, the problem when actually riding has nothing to do with the metal bits of the system, it's an issue with the meat parts (huge rocking moment from the unbalanced legs) and the rubber parts (vibration from the leg imbalance excites resonance with the pneumatic tyres as the spring). That's why you feel "bounce" at a certain cadence, and in all probability why the bounce will vanish again if you push on to a higher cadence. The cadence value at which the system resonates will depend on the mass (bike and rider combined) and the spring rate, which is mainly a function of tyre pressure and cross section. On my RollerFort, it's somewhere around 140rpm, but it's smooth again at 160.
You are reading a single comment by @853Superfly and its replies.
Click here to read the full conversation.
gbj_tester
@853Superfly
Drive side crank arm is heavier than non drive side, so would adding car wheel weights to non drive side balance this out ?
More of a mountain biker so not used to high RPM spinning, but i do get what you mean when playing on my beater SS, a smooth cadence/spin cycle with legs and no dramas, when going faster or mashing on the pedals then i can feel a wobble when seated.
I always put it down to technique and not spinning smoothly. Curious on others take on the question.