Forum home Mountain biking forum MTB workshop & tech

Truvativ Firex GXP crank arm removal

teulkteulk Posts: 557
edited July 2010 in MTB workshop & tech
How do i get the crank arm off, As you look at it there are two allen key holes, Do i simply just undo the (inner) smaller crank nut or do i have to take the larger (outer) nut off first ?
Boardman Team 09 HT
Orbea Aqua TTG CT 2010
Specialized Secteur Elite 2011

Posts

  • nicklousenicklouse Posts: 50,675 Lives Here
    yes just the inner. it is self extracting.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • teulkteulk Posts: 557
    Thanks, do you know if i will be needing any spacers when i fit the new Truvativ GXP BB to my boardman ?
    Boardman Team 09 HT
    Orbea Aqua TTG CT 2010
    Specialized Secteur Elite 2011
  • nicklousenicklouse Posts: 50,675 Lives Here
    yes the same as are on now.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • BG2000BG2000 Posts: 517
    teulk wrote:
    Thanks, do you know if i will be needing any spacers when i fit the new Truvativ GXP BB to my boardman ?

    I'm sure I've already answered this in another thread?

    You need to measure the BB shell width on your old frame and on the new one. They can either be 73mm or 68mm. Your GXP unit is set for a 73mm shell, so you'll need a 2.5mm spacer between the shell and each cup if your new frame has a 68m shell.

    To remove the LHS crank arm, use an 8mm allen key. Then, use a mallet to knock the BB axle inwards, and the RHS (drive) crank will pop out.

    And it's reverse thread to unscrew the drive side BB cup.
  • AnonymousAnonymous Posts: 79,667
    Sorry to hijack the thread, but just an additional question from myself. Same crank, and I'm just wondering how much force is required on the 8mm key. I've got a long armed 8mm key tool that fits fine but I'm finding it a hell of a problem shifting the thing. It doesn't help that the crank turns, so is there a recommended way of fixing the crank to undo the thing?

    Oh, and I'm right in turning it anti-clockwise?

    I can just see me slipping and shredding my arm on the chainring or something :D
  • deadkenny wrote:
    Sorry to hijack the thread, but just an additional question from myself. Same crank, and I'm just wondering how much force is required on the 8mm key. I've got a long armed 8mm key tool that fits fine but I'm finding it a hell of a problem shifting the thing. It doesn't help that the crank turns, so is there a recommended way of fixing the crank to undo the thing?

    Oh, and I'm right in turning it anti-clockwise?

    I can just see me slipping and shredding my arm on the chainring or something :D

    Anticlockwise is correct. Tie the crank to the chainstay.
  • MrRadishMrRadish Posts: 2
    Hi,

    Can anybody tell me what the outer allen key nut is for (not the 8mm crank release). I recently came off my bike hitting the pedals and this nut no longer looks like it is evenly flush with the left hand crank arm.

    Thanks in advance,

    Clive
  • nicklousenicklouse Posts: 50,675 Lives Here
    it is the extraction ring. the inner bolt presses on it to allow you to pull the crank arm off.

    you will need an ISIS crank puller now to remove your arm.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • MrRadishMrRadish Posts: 2
    Thanks for the info
  • Chunkers1980Chunkers1980 Posts: 8,035
    Oh and btw - It's possibly the worst system I've come across.

    They have made an external bearing system that still requires a crank puller. :roll:

    That's the genious of the Shimano ones - you need and allen key and a tensioner tool which you can get away without having if needed in the field.

    Mine are now gone and replaced with HT2 Deore LX ones and they are much better, not to mention about the 200 grams saved....
  • AnonymousAnonymous Posts: 79,667
    They have made an external bearing system that still requires a crank puller. :roll:
    It doesn't need a crank puller. It's a self extracting bolt.

    nicklouse just said about the puller probably because he assumes MrRadish wrecked the outer screw. If the outer screw is okay all you need is the 8mm key (and brute force to crack the inevitably seized or overtightened bolt).
  • In my opinion they are much better than the others out there. So simple and never had any issue with GXP on either of my bikes.

    Mates have had ISIS, hollow tech etc and all had issues of one sort or another.
  • Chunkers1980Chunkers1980 Posts: 8,035
    I now see how they work, the bolt extracts IF you leave the outer ring in, no outer ring no extraction.

    vfr800essex

    Why do you think it's better than other systems. Shimano HT2 can be removed with a 5mm allen alone in about 30 seconds (the tensioner can be undone by hand once the pinches are undone) - GPX you need 2 allens and one that is oversized and wouldn't really carry in the field.
  • nicklousenicklouse Posts: 50,675 Lives Here
    I now see how they work, the bolt extracts IF you leave the outer ring in, no outer ring no extraction.

    vfr800essex

    Why do you think it's better than other systems. Shimano HT2 can be removed with a 5mm allen alone in about 30 seconds (the tensioner can be undone by hand once the pinches are undone) - GPX you need 2 allens and one that is oversized and wouldn't really carry in the field.

    Gpx you just need one allen key to fit and remove it.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Chunkers1980Chunkers1980 Posts: 8,035
    Must be missing something here Nick...

    Don't you need another allen to undo the outer bolt - the one you'd screw the puller into?
  • bails87bails87 Posts: 12,998
    No, you don't need a puller. You shouldn't ever touch the big bolt. You just undo the 8mm bolt, and the crank comes off. Simple.

    If people read the manual they wouldn't take off the big bolt and they wouldn't need crank pullers!
    MTB/CX

    "As I said last time, it won't happen again."
  • Chunkers1980Chunkers1980 Posts: 8,035
    Thanks it's crystal now - shame they are assigned never to be used again with c.10 miles on them.

    8mm allen is a bit of a faff though - lucky I can just forget all about them now then.

    Cheers for clearing that bails.
Sign In or Register to comment.