Changing Cassettes (11-28 for 12-23)

[h1bda00]

I found out (thanks for the help on my earlier post) that I have a 10 speed, 12-23 shimano 105 cassette on my current bike. It's quite hilly where I live and I typically do around 400-500m vertical climb each day. Am considering swapping current cassette for an Ultegra 6700 10 sp, 11-28 cassette, as this should help somewhat with the climb.

Assuming that there are no compatibility issues with installing an 11-28 with my current rear derailleur (Shimano 105 5600), does the swap require:
1) that my rear derailleur be adjusted afterwards, and
2) that the chain length be altered

Or can I just pop the wheel on and go (safely, that is)?

Many thanks in advance for any help.

[Tim M]

(04-04-2011, 03:32 PM)h1bda00 Wrote:  1) that my rear derailleur be adjusted afterwards, and
2) that the chain length be altered

Or can I just pop the wheel on and go (safely, that is)?

My 2 cents:

1) probably, that's normal and relatively easy. Remember drivetrains are a system, so you'll probably have to tweak front der. Treat it all as a tuneup.

2) reluctant to make absolute statements, but the rule of thumb is to replace the chain when replacing the cassette (even if the cassette is a simple new for old swap). I'd get the Ultegra 6700 chain and size it as necessary, those chains are found at $40-$50.

More of a performance issue than a safety issue.

In any case, I believe Shimano makes an 11-28 cassette for 105 (CS-5700) that runs $15 less than the 6700 cassette, might as well replace the chain with CN-5701 if you do that.

Impossible to know whether going to 11-28 is worth it.

[wazgill uk]

(04-04-2011, 03:32 PM)h1bda00 Wrote:  Assuming that there are no compatibility issues with installing an 11-28 with my current rear derailleur (Shimano 105 5600), does the swap require:
1) that my rear derailleur be adjusted afterwards, and
2) that the chain length be altered

Hi there, I've just done exactly the same thing, gone from a 12 - 25 5600 to a 11 - 28 Ultegra 6700 on a new set of wheels. It went OK, but I had to tweek the indexing on the rear derailleur as short cage Shimano only recommend going to a 27. However, with a bit of fine tuning mine is running perfectly. As for the chain, I didn't change mine as I believe the length is the same, however, mine is only six months old, yours may be older and therefore it may be worth replacing.

For what it's worth, I climb some stiff hills here in the UK and I think the 28 is too low, I should have bought a 12 - 28, but Ultegra don't do this cassette.

If all else fails a LBS will index your gears for £10 - £15.

Hope this helps.

W.

[h1bda00]

Many thanks for the replies.