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  1. #1
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    front derailleur & chain ring issues

    What a bummer. I picked up an XTR M961 derailleur to use with my flux frame. Unfortunately, my old Turbine LP crankset has 48-36-24 rings. The max overall ring spread for that derailleur is 22T, and the minimum spread between big and middle is 12T. This means I not only need to buy a 46T ring, but also a 34T. How critical is the minimum spread between the big and middle? I'd love to just have to buy a 46T, but then my spread would only be 10T between top and middle. As it is, I'm having some difficulty in shifting from middle to big.

    For the time being, I think I'll just tune it the best I can, and run what I have. I'll only be able to use the largest two cogs when in the small ring. This is because the chain drags on the bottom of the derailleur when it drops lower onto the smaller cogs.

  2. #2
    Mr.Secret
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    I'd just get the 34/46 combo and get rid of that bike path gearing unless you've got a big red S on your chest

  3. #3
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    I don't mind changing the rings, it's just that I'll be spending money on a 110/74 square taper crankset. I haven't had a problem with square taper in the past, so maybe it's no big deal. However, perhaps there will be more stress against the tapers now that it's hanging on an FS bike instead of a H/T. In which case, I'd be better off changing systems all together. I'm on a BIG time budget.

  4. #4
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    Well, surprisingly, it shifts quite well with the existing chainrings. I'll ride it the way it is while I research a new crankset. Perhaps I'll just keep my eye open for a compact drive ISIS spline Race Face crankset on eBay.

    Is the ISIS really any better than the square taper? If so, does anybody know the history & weight of the top end Race Face cranksets, starting with the Turbine LP? The RF website doesn't show any of the older components.
    Last edited by royta; 03-05-2006 at 04:14 PM.

  5. #5
    Mr.Secret
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    If you go with something other than your square taper, go with an x type crankset. Most Isis BBs aren't very long lived. But realisticly if your square taper is still in good shape keep it in there, I'd still switch the 36/48 for a 34/46 though.

  6. #6
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    Quote Originally Posted by R.T.R.
    If you go with something other than your square taper, go with an x type crankset. Most Isis BBs aren't very long lived. But realisticly if your square taper is still in good shape keep it in there, I'd still switch the 36/48 for a 34/46 though.
    I like the idea of changing rings, I just don't want to invest in rings for a crank arm that is going to go south.

    It's not the BB I'm worried about, it's the BB to crank arm connection. But I guess if the taper was going to wallow out, it would have done so on my H/T.

  7. #7
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    I'm starting to think that at the very least, I should change out to a 94/58 crankset and run 22-32-44. I'm thinking it's a far better match for the M961 front derailleur. Maybe I'll be able to find a lightweight Race Face (non DH or FR) setup for cheap. The ISIS BB's shouldn't be any less lived than a square taper BB, should it?

    If I do end up going to the external BB x-type style, are all of the players the same, or are some a little more blingy than the others?

  8. #8
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    Roy,
    I personally never had a problem with Isis BBs but I have heard of some people going thru them like candy. Some people on MTBR have complained about going through RF XR bbs in a months time. Sq taper is like an old Timex or like the stupid energizer rabbit.

    I gotta agree with RTR if you do upgrade, go with an X-type. The big bling seems to be the FSA Carbon but they are expensive and aside from bling dont offer $$$/sense ratio as they are actually heavier than some less expensive options. Cheezy swears by the Truvativ Stylo GXP and the Shimano ones are very good also. Go ahead and do your over-research and pick the one that suits you best.

  9. #9
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    I like 110/74 Cranks

    Quote Originally Posted by royta
    I don't mind changing the rings, it's just that I'll be spending money on a 110/74 square taper crankset. I haven't had a problem with square taper in the past, so maybe it's no big deal.
    Hey Royta,

    I'm like to gear my bikes outside the box so 110/74 works for me.

    I'm running a 38/28 2x9 set-up on a Middleburn 110/74 square taper crankset on my Flux. I'm not even running ramped and pinned chainrings and it shifts fine with only 10 teeth difference between the rings. The 38 is in the middle position and the 28 is the granny.

    I hate the downshift from the 32 to the 22 on standard cranks ... it always seems to hit at the worst time ... when I'm under the most stress on a big climb and the shift is slow and the change is too big ... I end up losing momentum and hating life.

    With the 28 inner I just hit the hill in the 28 and keep the downshifting while climbing to the rear.

    You have an ideal crankset for this kind of gearing. And like you, I have not had problems with square taper so I'm not sweating it.

    Just another thought.

    -SUB160
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  10. #10
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    CDTofer - I always thought there was physically no difference between the ISIS BB and the square taper BB, other than the crank arm to spindle interface of course. Same bearings, etc. I guess I must have been wrong. I really don't think I want to mess around with the x-type. I know it's probably not noticeable, but the fact that people have to have offset cranks in order to set their chainline is kind of ridiculous. What's with this one size fits all nonsense?

    SUB160 - 28T granny? No thanks. I don't mind the 36 to 24 drop right now, so I'd imagine the 32 to 22 would be just fine. If I rode those wussy hills like you do, it wouldn't be such a big deal. (just kidding) But since there are real hills where I ride, combined with my out of shape legs, I need a real granny gear. (again, just kidding - not about the out of shape legs though)

  11. #11
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    Quote Originally Posted by royta
    CDTofer - I always thought there was physically no difference between the ISIS BB and the square taper BB, other than the crank arm to spindle interface of course. Same bearings, etc. I guess I must have been wrong. I really don't think I want to mess around with the x-type. I know it's probably not noticeable, but the fact that people have to have offset cranks in order to set their chainline is kind of ridiculous. What's with this one size fits all nonsense?
    ISIS/Octalink has a larger spindle, so therefore the bearings are going to be left with less room = smaller balls = much less bearing life.

    ISIS and Octalink is an interface that should have never existed in the first place. IMHO, a step backwards. Skip the ISIS/Octalink 'upgrade' (downgrade?) and go straight for the X-type. Until a new BB standard emerges, like say BMX size BB's, X-type is what we are left with.
    I stopped driving my bike into my garage - I'm now protected with Roof Rack Ranger app for my iPhone.

  12. #12
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    Quote Originally Posted by bikerx40
    ISIS/Octalink has a larger spindle, so therefore the bearings are going to be left with less room = smaller balls = much less bearing life.

    ISIS and Octalink is an interface that should have never existed in the first place. IMHO, a step backwards. Skip the ISIS/Octalink 'upgrade' (downgrade?) and go straight for the X-type. Until a new BB standard emerges, like say BMX size BB's, X-type is what we are left with.
    OK, so Octalink and ISIS are the same, except for spline pattern right? I haven't followed the BB evolution and for some reason I thought Octalink and x-type were the same, and both had external bearings. Again, I thought wrong.

    What about the offset cranks with chain line issues? I guess I need to measure my current chainline before I start dissing on x-type though. For all I know, I might have the exact same chainline as an x-type setup that has been set up as per instructions. A quick question though. If I set up an x-type as per the instructions, will both the left and right side crank arms be the exact same distance from center of BB shell?

  13. #13
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    With the 113mm spindle I'm using, I have a 51.5mm chainline. By setting up an XT x-type as per the instructions (2.5mm spacer on drive side for 73mm shell), I will have a 50mm chainline, correct?

  14. #14
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    OK, I won't be buying an ISIS crankset. Now I'm wondering if I should hold off and try to find a compact drive Race Face Turbine LP, or if I should just get an x-type. If I do go with x-type, I'm not sure if I want Deus XC or XT 760.

  15. #15
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    Well, good news for me. I picked up a couple cranksets off of ebay. Both are black RaceFace turbine lp compact drive square taper. One is set up for single speed, and the other has the 22-32-44 rings. One is older, just like my current standard drive set purchased in January 1997, that says Race Face Forged and needs the spacers for the inner ring. The other says Race Face Turbine Forged, and has a built up area on the cranks so that spacers are not necessary to be run on the inner ring. I'm not sure what year that version came out. Does anybody know?

    Since I have now have both sets, and have the option to run either, which is the more desireable to run? Was one lighter, or stronger, or just cooler? Or is there absolutely no difference except for the inner ring built in spacers and the fact that one of them you can't see the bolt ends on the inner ring? Is one more preferable simply because of the age? Give me the scoop nostalgic crankset people.
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  16. #16
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    Quote Originally Posted by royta
    What a bummer. I picked up an XTR M961 derailleur to use with my flux frame. Unfortunately, my old Turbine LP crankset has 48-36-24 rings. The max overall ring spread for that derailleur is 22T, and the minimum spread between big and middle is 12T. This means I not only need to buy a 46T ring, but also a 34T. How critical is the minimum spread between the big and middle? I'd love to just have to buy a 46T, but then my spread would only be 10T between top and middle. As it is, I'm having some difficulty in shifting from middle to big.

    For the time being, I think I'll just tune it the best I can, and run what I have. I'll only be able to use the largest two cogs when in the small ring. This is because the chain drags on the bottom of the derailleur when it drops lower onto the smaller cogs.
    I put on the new cranks Friday evening, and put my first ride in yesterday. Wow, what a difference. The 22T granny is fantastic, and the 32T middle is much nicer than the 36T I used to run. I can spend lots more time in the middle than before. I really like this setup for riding in the Santa Ana's.

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