Results 1 to 10 of 10
  1. #1
    mtbr member
    Reputation:
    Join Date
    Oct 2005
    Posts
    17

    new chain, old sprockets

    So I put a new PC-991 on my 1 1/2 year old Stumpjumper (Shimano drivetrain, I think XT stuff), thinking that surely the sprocket teeth hadn't worn down enough to cause the dreaded chainsuck. Wrong. Bad chain suck on the small chainring. So, does that mean the chainring is too far gone? Any chance the new chain is just too stiff and needs working to loosen up? If I replace the chainring, will the rear cassette also need replacing (please say "no," I'm running short of cash.)
    Thanks

  2. #2
    Savvy?
    Reputation: SeanL's Avatar
    Join Date
    May 2005
    Posts
    487
    Don't be surprised if you have to change the chain ring AND cassette.

    I recently replaced a chain with only .75 worth of stretch and to my dismay it brought to light a cassette that was shot...with only 750 or so miles on it.

    I'm not saying you will have to replace the chain ring and cassette, but don't be surprised. Take a look at your cassette, it the teeth have a hooked look to them, then you're most likely gonna have to replace it.
    That which does not kill me, postpones the inevitable.

  3. #3
    *****************
    Reputation: Bikinfoolferlife's Avatar
    Join Date
    Feb 2004
    Posts
    12,378
    Changing a chain after too long will definitely point out other worn components like chainrings and cassette cogs. Usually it will be the rings/cogs you spend the most time in. You getting chainsuck on the little ring all by itself or in conjunction with the middle ring? I wear the middle ring quickest personally...
    "...the people get the government they deserve..."
    suum quique

  4. #4
    mtbr member
    Reputation:
    Join Date
    Oct 2005
    Posts
    17
    Looking closely at the chainring, I can definitely see that the teeth on the small one are not symmetrical. Some do seem to have a slight hook shape. The middle one doesn't look that bad. I can't really see a difference in the cassette teeth. I guess I'll replace the chainring first and hope for the best.

    Time to surf mtbr.com for opinions on chainrings.

    Thanks

  5. #5
    *****************
    Reputation: Bikinfoolferlife's Avatar
    Join Date
    Feb 2004
    Posts
    12,378
    I'd recommend a nice steel granny, especially if you spend a lot of time in it.
    "...the people get the government they deserve..."
    suum quique

  6. #6
    mtbr member
    Reputation:
    Join Date
    Oct 2005
    Posts
    17
    "I recently replaced a chain with only .75 worth of stretch and to my dismay it brought to light a cassette that was shot...with only 750 or so miles on it.:

    BTW, what were the symptoms of your worn cassette? Chain-skipping?

  7. #7
    Savvy?
    Reputation: SeanL's Avatar
    Join Date
    May 2005
    Posts
    487
    Quote Originally Posted by rokbottom47
    BTW, what were the symptoms of your worn cassette? Chain-skipping?
    Under power, in the 3rd and 4th gear the chain was skipping, or felt like it. What was happening was the rollers of the chain were catching on the top of the cog teeth.
    That which does not kill me, postpones the inevitable.

  8. #8
    MTB B'dos
    Reputation: LyNx's Avatar
    Join Date
    Oct 2004
    Posts
    17,540
    Well the replacement of the chainring sounds like a good place to start, but don't be surprised if you also have to replace the cassette as has been said. I just recently got a new XT HT2 crankset and didn't replace the chain at the same time (barely had any wear on it - below 1/32") and just got a new chain and cassette (old cassette had on over 2200 hard miles and I didn't like the fact it was an 11-34t), found out that in under 2 months with a chain that was barely worn - just less than 1/16" wear - I had killed the middle ring on the new XT crankset.
    XT chainrings are soft as hell so I too am looking for replacement chainrings for my XT crankset.
    One day your life will flash before your eyes, will it be worth watching??
    MTB Barbados
    My Phantom pics

  9. #9
    occupation : Foole
    Reputation: Fuelish's Avatar
    Join Date
    Dec 2003
    Posts
    2,545
    Quote Originally Posted by rokbottom47
    So I put a new PC-991 on my 1 1/2 year old Stumpjumper (Shimano drivetrain, I think XT stuff), thinking that surely the sprocket teeth hadn't worn down enough to cause the dreaded chainsuck. Wrong. Bad chain suck on the small chainring. So, does that mean the chainring is too far gone? Any chance the new chain is just too stiff and needs working to loosen up? If I replace the chainring, will the rear cassette also need replacing (please say "no," I'm running short of cash.)
    Thanks
    Yeah, depending on how long you run your chain, there's two trains of thought (well, maybe more, but I digress...) You can keep running your old chain with the old cassette and the old chainrings and they'll likely last quite a while (as a "whole drivetrain" ...... the minute you have to replace one part of the drivetrain (typically chain) it will immediately point out that you need, likely, a new cassette, and possibly a new chainring or two . If you replace your chain fairly frequently (along with proper drivetrain cleaning/maintenance), your cassette and rings will last far longer, possibly offsetting the cost of frequent chain upgrades (too many variables to say if it is more cost efficient to do it one way or another). Hold on to all old parts....in case of disaster, throwing an old worn spare part onto an old worn drivetrain may buy you some more time...... (yeah, I'm a cheap bassturd at heart - my daddy done teached me right )

  10. #10
    mtbr member
    Reputation:
    Join Date
    Oct 2005
    Posts
    17
    Thanks to all. I replaced the front Shimano rings with BlackSpire Pro with the steel granny. This caused some slipping in the rear cogs (as predicted by some of the responders). So I have replaced that with SRAM 950. Everything works well together (except see my post on New Chain and Chainring question about the BlackSpire middle ring). I intend to ride this until it is worn smooth.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •