Replace Cassette before my tuneup?
 

My chain and shifting was having some issues. I replaced the chain which was stretched beyond the 1% mark on the chain tool. Shifting improved significantly. However, with the chain so stretched and about 2,000 miles on the cassette, I figure I should swap that out as well. I honestly can't tell if cassette is worn out or not. I will tell you this, I was in the granny gear (or thought I was) going up a steep hill, standing up, and the chain made a crunching sound and I assume popped into the granny geat at that point. Sign of bad cassette? Or just a derailer needing adjusment?

If I had to guess, the cassette, which was new prior to 2K miles being put on it, probably had that stretched chain running through it for at least 1K miles...maybe more.

Here's my question - I plan on bringing bike in for a tuneup to LBS. I just ordered the cassette (Sorry, LBS - $50 instead of 80-90). Should I wait until I get and install the cassette THEN get the tuneup? Or is it immaterial? That is, will whatever derailer adjustments made will not change when I put in new cassette. the new cassette has same teeth, just going from a 105 to an Ultegra.

I kinda of thing the unamimous answer will be that I should wait, but just want to confirm. Rain is in the forecast, so I figured good time to drop off the bike.

A slip could be chain and cassette wear mismatch or slightly out RD adjustment.

You could check on the 2nd or 3rd largest rear cog and make sure the chain is dead center on that cog. You should see equal slivers of light on each side of the chain looking straight on from the back.

Depends on the weather, but you should get 2000 on a chain, 4000 on a cassette and 8000-10000 miles on a chain ring. That's more of a rule of thumb though and a lot of YMMV. It is also assuming you keep your drive chain clean and lubricated and that you don't spend huge amounts of time in favorite gears.

I've never replaced a cassette with less than 6-8K miles on it. Even a chain I'll usually run all season, about 3K. But as long as you already bought the cassette I'd put it on and then have the tuneup done. I'd also keep the old cassette "in stock".

Shops don't really like to install provided parts for a number of reasons, I wouldn't ask them to do so. If you replace the cassette before the tune up they, during the service, will correct any issues that you might not have done well. In fact I would suggest that you mention this at the drop off. If you wait till after, the work they do to adjust the read der might be useless as often tweaking adjustments to ders and cables is needed with different cassettes.


I always tell my customers that if they want to do any work (to save cost, learn, whatever) to do so before we work on the bike. At best we have an easier time and the customer saved some $. At worst we take care of improper work and the customer still has a reliable bike. Andy

if the shop/mechanic complains about, or refuses to put on parts you provide, find another shop. That amounts to being childish, and whining about them not getting to make more profit off of you.

that said,,, 105 and ultegra cassettes of the same gear and tooth count should swap with virtually no change to the fine tuning of the rear derailleur.

I see a difference between bring in used parts to be installed on a bike and new parts that the shop could otherwise had provided. Some shops I've worked in will install their provided parts at a labor discount (10% at one shop) and a labor up charge at other shops (up to 25%).


This is also the case for many auto service shops. Until one has worked the dirty side of a bike shop's service counter one might not have seen the range of assumptions and possible "challenges" that dealing with customer supplied parts can result in. I have had customers blame my shop for their mistakes in why the part doesn't work/fit right.


As to the interchanging of cassettes and tweaks after- In an ideal world where manufactures' tolerances are tightly held and are the same I agree that no after installing a cassette adjusting would be needed. I only wish this perfect world was the one that we live, work and ride in. The pro shop will not assume that the interchange is a perfect one with no other concerns or needs. They will double check and make (minor, nearly always) corrections to the der adjustments as needed to have their work be the best it can be. Shops that don't care about their reputation or that place profit over customer satisfaction might only install the part and do no more follow up. Andy.

Shops vary in their willingness to install customer provided parts, first because they don't make any money on the parts and second, if the provided parts don't fit properly or aren't compatible with the bike or don't work right afterward it can become contentious issue with the customer.