Bicycle Mechanics - Cogs
Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.
05-25-03, 05:59 AM
I have a standard HG70 cassette 13-23 -8speed, and the maximum jump from one cog to the next is 2 teeth. LBS says I cannot have more than 2 teeth jump between cogs. I tried today replacing the 23 cog with a 25, so the jump is 21 to 25 and it works very well.
Will a 19 to 25 jump work? I have a standard SORA triple rear and FD.
I also have a triple Sora and the cassette that came with it was 11-28 (8 speed), obviously there are jumps in there of more than 2 teeth. If you want I'll checkout and post each cog. The largest cog is significantly larger that the next on over, it looks like 4 teeth.
What I can say is that a 19 to 25 jump from cog to cog probably isn't smart just from a pure cadence point of view. Even if it does work on the chain, I don't think its smart. If you want a 13-25 you could get 13-14-15-17-19-21-23-25
05-25-03, 06:25 PM
It should. My cassette has 12-14-15-16-17-19-21-25-32... which means 4 and 7 teeth near the end. No problem.
If you put a very large jump, ease the pressure while you shift. That could be a problem in racing, but not in more "casual" cycling.
Regards also from Montréal,
32 as a largest cog? what kind of bike is this road or mountain? That seems pretty huge for a road bike (I though mine was large, too large, at 28)
05-25-03, 08:16 PM
The largest "road" cog is 27t, but with the right der. you can run a 34t
05-26-03, 04:21 AM
thanks guys for the input. I have ordered a 18T cog so I will have
13,14,15,16,17,18,19,25. The 25 is for hills or 'emergency!'
05-26-03, 01:50 PM
My bikes are touring bikes. The bike I was talking about is a Trek 520 touring bike (vintage 2000). "Touring" configurations don't officially exist in Shimano catalogs, so makers of touring bikes and especially of light touring bikes mix a road crank with an MTB cassette and rear derailleur. By default, my bike came with 52-42-30 "105" crankset and an 11-30 8-speed cassette with an LX derailleur. However, I had the drivetrain swapped at time of purchase for a 44-34-22 XT drivetrain
Back when most bikes had only 10 gears, I experimented with various combinations of cogs, a few of which included fairly radical "granny jumps." I set up my wife's bike with 52-42 / 16-18-21-24-32, which met her transportation needs around hilly west Los Angeles quite well. Sheldon may still sell a (factory-standard!) 14-16-18-20-22-24-32 Shimano freewheel. I use its tighter 14-16-18-20-22-24-28 cousin on the Capo and hold the 28 in reserve in case I encounter a tough hill at the end of a long ride. I use an old SunTour V derailleur, without a spoke protector, and have never had a problem with the 24-28 shift.
Powered by vBulletin® Version 4.1.12 Copyright © 2013 vBulletin Solutions, Inc. All rights reserved.