I normally ride on a bontrager wheel (on my trainer) with a 10-speed 12-25T cassette.
Recently I purchased a HED Stinger 90 rear wheel and also got a 10-speed 12-27T cassette for racing. The main reason is I am racing in IM-WI and the course is hilly. So I wanted a slightly bigger gear for that course.
How much “tweaking” should I have to do to get these two cassettes to be interchangeable.
The 12-25T works perfectly. Shifts with no problems, rides smooth.
But when I put the 12-27T on there, nothing but problems. Shouldn’t this be a pretty easy switch?
When it comes to tuning a bike, I am a complete novice, but learning. So before I take it into a shop, I wanted to try to get this to work on my own.
the problem is with the cassette body spacing of the two wheels not the cassette itself.
Hopefully you will not have to mess with the limit screws when swapping wheels, but you will have to play with the barrel adjuster to move the der. to the right spot.
When switching, shift to the smallest cog, swap the wheels, while the bike is on the stand turn the cranks while playing the adjustment of the barrell in or out until the drive stops making noise or skipping gears while shifting. After a coulpe tries this should take you about 30sec to adjust.
might need to adjust your rear derailleur to align with the cassette
.
This is what I’ve been doing…and with the 12-27T I have not been able to get it to work.
Is it possible that a new cassette will make more “noise” than the old? The old one is nice and smooth while this one seems to rattle. That may not be the right word, but the chain and cassette don’t seem to work smoothly together. I did go from a shimano 105 to an ultegra.
the 27T is typically the problem too…
Two thoughts…
First, how old is the chain? Is it possible that the chain and old cassette have worn out together, now you have a shiny new cassette with a cruddy old chain and the teeth aren’t lining up properly?
Second, if the noise is predominately in the 27T cog, perhaps it’s a ‘B’ screw adjustment issue - this is the screw that adjusts the gap between the upper pulley on the derailleur and the cogs.
There are a lot of resources… Zinn’s “Zinn and the Art” books are good… also check out Park’s website. Specific to your problem, see
http://www.parktool.com/repair/readhowto.asp?id=64
Hope this helps… let us know if you get it figured out. Learning to fix this kinda stuff is easy & pretty rewarding…
(edited to spell Mr. Zinn’s name correctly)
When changing to the 27 cog are you in the inner (small) chainring? If you are in the big ring then the chain may be too short. Not good to cross- chain like that anyway.
Depending on the age and wear of the two cassettes and chain you may have some problems. or chain length (although i doubt it). if it were me I’d see if I needed to move the upper stop for the 27 to get it to work. Also check that the lockring is torqued properly. (if you are running a 105 chain it may not like the extreme cross chaining form the 53 to 27 either)