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  1. #1
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    Bonking ... not feelin' well Truvativ Powerspline BB problem

    Hi all,

    Sorry for the double post but I wasn`t able to find a way to remove or close the thread I posted on the beginners section...

    I have a Truvativ powerspline BB with a matching isoflow chainset.
    I`ve noticed that the chain was touching the front derailleur and on closer inspection it seems that the chainset is oscillating (a couple of mm left/right).

    The chainset is almost new so I don`t think it`s bent, but just to be sure I checked with another and found the same oscillation.

    I mounted the chainsets myself (standard M8 screws, used a socket wrench), are there any issues I should be aware of (like pressing for the square ones) - or is it more likely that the bb is bent?

    The oscillation is only a couple of mm, could it affect the chain?

    What would you recommend as a replacement for XC ?

    Thanks

  2. #2
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    I've seen this before on lower-end Truvativ cranksets, you may be able to use a crescent wrench to straighten the chainring a little. I have done this with fine results especially if it's steel rings, aluminum big ring maybe a bit, but you could weaken it. However, that is a really low-end crankset and buying new rings may not be the best option as you can buy a lower end crankset for not much more, but it would be lighter and stronger than the Isoflow. There are many good deals around if you are comfortable changing the crank and BB and have the tools? Jenson has the Raceface ride 22/32/bash guard with BB for under $60, but that is 2 rings, will you be happy with that setup? Deals like that are around (though more so after the season slows in Sept).

  3. #3
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    Quote Originally Posted by Aresab View Post
    I've seen this before on lower-end Truvativ cranksets, you may be able to use a crescent wrench to straighten the chainring a little. I have done this with fine results especially if it's steel rings, aluminum big ring maybe a bit, but you could weaken it. However, that is a really low-end crankset and buying new rings may not be the best option as you can buy a lower end crankset for not much more, but it would be lighter and stronger than the Isoflow. There are many good deals around if you are comfortable changing the crank and BB and have the tools? Jenson has the Raceface ride 22/32/bash guard with BB for under $60, but that is 2 rings, will you be happy with that setup? Deals like that are around (though more so after the season slows in Sept).
    Hi,

    Thanks for the reply!
    The chainrings appear to be ok. The whole crankset oscillates... unless both of the ones I tested with are bent...
    The thing is, even with the chain removed, I can feel a small irregular vibration in the frame... although there are no spinning impairments...
    Well... I suppose that`s why they call `em low-end.

    I will go for a RaceFace or similar set next season. Most of the sets I see are for 9/10 speed configurations, I have an 8 speed bike so I guess I`ll have to do some digging

    Thanks again

  4. #4
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    The 9 speed ones are typically fine with an 8 speed, I was using a Truvativ FireX that way for years, 10-speed not so much with the thicker chain as it would probably rub. You could run a 10 speed chain though. One of the things you can try is to remove the drive side crank arm, grease the splines really well and reassemble it. I have seen them slightly cocked during install at the factory. It is also possible it is a mold problem from SRAM. The Isoflow is a cast aluminum crank rather than forged on the higher-end models.

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