Forum

[Presto]

Isn’t there a limiting factor in these calculations about increased road speed with higher gearing? Isn’t it false to assume that an increase in gear ratio will give an inevitable increase in road speed? Thack says: ‘Whatever your top speed was in each gear add x percent and that’s the new top speed with x number of teeth on the front sprocket.’ Doesn’t a significant increase in road speed (and a claimed 10mph is a significant increase) depend on the engine having a significant increase in hp to pull a higher gear ratio?

[Dennis C]

Preso you are correct, we can only use ball park figures, and Thack's figures are pretty darn close, the claim of 10 mph in every gear may have been a mistake if not it is an outrageous claim, 10 mph in in top would be closer but on one tooth increase in the sprocket very optimistic, easy to work out the ball park figure using Thack's method with the given sprocket info.

[Revband]

Out of interest, the maths on the latest supplied info equates to an increase of 4.998 MPH at maximum speed in top gear this makes no allowance for the increased engine load or wind resistance.Go figure?.

[Thack]

Presto: Yes, you are of course perfectly correct that the bike will only pull a higher top speed with a higher gear if it has sufficient power to overcome the additional air and rolling resistance.



I didn't go into that simply because I was talking only about the ratio difference from a sprocket change. Going from 18 to 19 teeth (or 17 to 18) won't add 10mph in ANY gear. Even hagis's bike will obey the laws of physics.

[RayBeech]

Did you buy the Electra Pathfinder - or loose the will to live?