General Discussion Triathlon Talk » Gear shifting problems after installing new wheel/cassette Rss Feed  
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2012-05-02 10:01 AM


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Subject: Gear shifting problems after installing new wheel/cassette

I'm really new to triathlon, but wanted to learn everything I could so I could ride and work on my bike. With that said, I recently installed a new wheel set (SRAM S60) and cassette (SRAM PG1070 11-28T) on my bike. After installing though the gears are shifting hard and making a bunch of noise (like the chain is lose) but only in some of the gears. The chain is also now rubbing on the front derailleur guide in the highest and lowest gear and sometimes slips off when shifting into the big gear.

The bike is really brand new with less than 300 miles on it. Before installing the new wheel set I was riding on a Shimano 105 cassette on the old wheel set. I've tried to adjust the cable tension on the rear derailleur with limited luck.

Does anyone have any suggestions or web resources I could read up on to correct my problem? Any help is very much appreciated.

Signed frustrated new triathlete in training



2012-05-02 10:08 AM
in reply to: #4185924

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Subject: RE: Gear shifting problems after installing new wheel/cassette
Take it to the LBS with both wheels and ask the same thing.

My complete and utter guess without seeing the wheels in question is you've got two things going on

Cable stretch - you're right at the point (300ish miles) where you need to tighten up both front and rear dérailleurs which is making number two even more pronounced.

One of your wheels has the bazillionth of an inch spaces between the cogs and the wheel. That will throw your entire chain setup in the trash as soon as you change wheels. Figure out which one has or doesn't have the spacer and make the other one the same.

2012-05-02 11:26 AM
in reply to: #4185924

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Regular
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So Cal
Subject: RE: Gear shifting problems after installing new wheel/cassette

Without knowing a little more detail like what kind of derailleurs you have or what crank (compact, standard or triple) and what prior cog combo cassette, there are many variables to consider.

That said, here's some quick items to check. If you installed the SRAM cassette on your S60 wheel yourself (and you have experienced changing cassettes on your prior wheelset with Shimano cassettes), SRAM does not need a 1mm spacer/shim that Shimano requires. SRAM cassettes are a bit more noisy compared to Shimano on a good day so what you hear may be normal. Also, the S60 wheel does have some offset from other wheels. I say that with caution because it varies from frame to frame mfg tolerances. I experienced changing from Mavic Aksiums to S60's and never had any chain rub from the FD until then. In your case you mention FD chain rub on the highest and lowest gear - do you mean the rear cassette? If so, are you cross chaining? If you are (and never a good idea), you might only have an opportunity to reduce chain rub on only one end. You may have to slightly adjust the FD angle and/or also adjust your high limit screw to prevent your chain from falling off (the big ring/pedal side).

Because you changed to an 11-28 cassette (again don't know what you had on before) you may have to adjust your B-screw. To do that, shift your chain to the small chain ring and check the gap between the tip of the smallest cog and the tip of the guide pulley (jockey wheel). It should measure about 6mm. 

2012-05-02 4:58 PM
in reply to: #4185924

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Expert
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Subject: RE: Gear shifting problems after installing new wheel/cassette

Learn to adjust your rear derailleur - once you figure out how it really works, it's easy to figure it out.  Go on youtube and there are a lot of tutorials.

This just happened to me when I switched out my zipp 404 to my zipp 808 in the rear last week (a mini emergency - had a flat that I didn't have time to change prior to the ride on the 404).  I was having some shifting issues and tried to fix it with the barrel adjuster during the ride but it only helped but not fixed the problem.

The best way for me is to remove all tension to the rear derailleur, get it aligned just right with the smallest cog of the cassette (the one closest to the derailleur), tighten it down , and then it usually only requires a quarter turn or two of fine tuning on the barrel adjuster to get it just perfect.

2012-05-02 6:01 PM
in reply to: #4185924


5

Subject: RE: Gear shifting problems after installing new wheel/cassette

Thanks for all the help. It's been very helpful. YouTube has been great! I acutally went and uninstalled the SRAM cassette and put the 105 on the new wheel. It shifts great now. So until I'm ready to switch to the new cassette (which will go to the LBS), I'm going to just keep with the old 105 on for now.

Thanks again everyone for the help.

2012-05-03 8:28 AM
in reply to: #4187117

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Slower Than You
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Subject: RE: Gear shifting problems after installing new wheel/cassette
Different wheels and cassettes, despite being compatible with each other, can have minute spacing differences that can throw your shifting off a bit when swapping.

Learning to tune your rear shifting via the barrel adjuster on the rear derailleur (where the cable enters it) will save you lots of time and frustration. Tuning the shifting to a new wheel/cassette usually takes about 5-10 minutes once you're used to it.


2012-05-11 3:29 PM
in reply to: #4185924

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Veteran
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Racine, WI
Subject: RE: Gear shifting problems after installing new wheel/cassette
Sometimes simply adjusting the high and low adjustment screws on the rear derailleur itself will solve the problem.  
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