Originally Posted by
Russ Roth
Junior gearing would be my guess, up till last year Jrs were restricted in their road gearing. Often a 14t cassette was a solution to make it work. I built my kid's bike with a 40t 1x and 11-34. That 40/11 squeaked the rollout by a hair and better than the more common which was I think 50/14. But not all gearing is the same and different brands can produce different roll out which is why distance and not gearing is the determiner for passing. Her current track bike technically has the wrong gearing, the chainring is 1 tooth "too big" but has now passed rollout in 3 state races, the NE regionals and one Nats race.
Good explanation, but I would debate the bolded above; Chain driving toothed cogs is about as discrete, dare I say digital, as it gets. These are not frictional belts. Perhaps as you get to very small cogs, if not good teeth profiles, so less smooth tooth transitions, you can get very slight rotational speed variations, but in terms of displacement per rotation, it should still be same. Discuss.
Anything affecting tire rolling circumference, different story, that can change rollout for same gearing.