djnzlab1

HI,
I have a centurion ironman 1986, I wonder what was the gear ratio for that model bike it has freewheel gear, and I may need to replace the freewheel do to excessive hopping and wear to chain and cogs.
I ve had the axle cleaned and degreased derailer, lubed cables, and it stil dosent like the larger gears works best in the smallest or 6th gear.
I ordered a NAshbar 6 spd gear for it, but I am alitttle worried about gear size changes with such a small number of gears. My LBS said get the lowest ratio I can, avoid the MTB gears their not needed on a bike that will be ridden mostly on flat land.
Doug

her's the ratio I ordered. Quote:
((Modern shift ramps and machined teeth in a classic SIS compatible freewheel, all at one great price, what more can you ask for! Use standard Park FR-1 freewheel tool for installation/removal. Choose from 14-24 (14,16,18,20,22,24) ))

dbakl

Not sure of the question. I'd think 14/24 would work on most anything, even 14/28 if you need to go a little lower. Range of freewheel is determined by type of rear derailler and difference between chainrings in front.

Wino Ryder

Actually thats a decent ratio spread in a 6-speed, riding mostly flat land. I have an '85 Centurion 6-speed that I converted to 7-speed with the same ratio spread as yours, but with a 28t low gear over the 24. Works great for me.

OLDYELLR

The teeth increase by 2 for each cog. That does not give you a very good percentage progression through the gears. I.e., the step between the 14 and 16 (14%) is much bigger than the step between the 22 and 24 (9%) and you will feel it. Usually you would expect a 1-tooth difference in the smallest cogs and a larger difference in the larger ones.