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FSA Mega Exo crank installation issue

fenskifenski Posts: 119
edited September 2017 in Workshop
I've been replacing the BB on my Roubaix which has an FSA Mega Exo crankset. All's gone well until the last bit when I'm trying to re-attach the non driveside crank. I just cannot get the thing to re-thread... I'm not sure if the thread has been damaged at some point during removal or re-installation, or if I'm missing an obvious step. I thought I'd try taking the crank bolt out of the crank to see if I could screw it in by hand minus the crank, however judging by the 6 holes in the bolt, it appears to require a special tool or attachment to get it out.

I don't want to ditch this crankset just because of this, but I'm running out of ideas... I guess next step is to take it to my LBS, but before I do, does anyone have any tips?



  • Is it a self extracting bolt? Post a pic
    I'm sorry you don't believe in miracles
  • fenskifenski Posts: 119
    Is it a self extracting bolt? Post a pic

    This is it.
  • ErasmusErasmus Posts: 48
    Hi, the 6 hole part looks like the end cap/stop, which is left hand thread, and doesn't need to come out. It is the internal bolt which locks the crank, which is right hand thread, and turns independent of the end stop.

    Mine takes a 10mm allen key - yours seems similar, but just be careful as it looks just slightly different to mine. Good Luck, John.
  • fenskifenski Posts: 119
    Thanks. I was hoping to remove the crank bolt from the crank so I could then see why it wasn't screwing in to the axle thread, hence my interest in removing the end cap (6 hole bit). I've checked a Park tool video - apparently I need a pin spanner to remove the end cap.
  • fenskifenski Posts: 119
    I tried fitting the crank back on again this afternoon. The bolt just spins freely and refuses to screw in. I think I must've stripped the thread or something in previous cack-handed attempts to re-attach it... think a trip to the bike shop is on order, and I hope this doesn't end up in a new crankset... :?
  • ErasmusErasmus Posts: 48
    Might be worth checking if it's getting restricted/caught somehow with the end cap, and not properly engaging with axle. If you don't want to go to the expense of the Park tool on a "what if", maybe you could Heath Robinson getting the bolt and cap out. I've done this using 2 allen keys, at 9 and 3 o'clock, pushing down on the 3 o'clock and up on the 9 (left hand thread. Others have used nose pliers, or a spoke which can be bent and shaped like the proper tool.

    The bolt itself is right hand thread, and I'd try to get the crank on with just this turning clockewise (not the end cap, which can be put back on later if it works).

    Lastly you can get replacement bolt and end stop for about a tenner, I got one recently from J E James. Oh, and sorry if I seem patronising going on about the left hand /right hand thread. I knew all this when I worked on my own, but still kept having Homer 'Doh' moments!
  • fenskifenski Posts: 119
    Yeah, if I can get the end cap off - I can take the bolt out and see exactly what's going on with the threads. I'll try with a couple of Allen keys, however the bikes about 10 years old and it's never been off before - might take a bit of loosening!
  • trailflowtrailflow Posts: 1,311
    What kind of BB does the Rubaix frame have ? Press in style bearings or press in cups ?
    Are you sure your crank is Mega Exo and not BB30 ?
    Is the new BB the correct BB for the frame ?
    Has the new BB that was installed made the overall shell width wider than before ?
    Is the BB fully pressed in ?
    Is the right drive side of the crank fully inserted ? Did you give it a tap with a soft hammer ?
  • fenskifenski Posts: 119
    Well I took the crankset to the bike shop today and they took the self-extracting bolt out for me. The thread was stripped and they didn't have the right bolt in stock. Now the bolt is out, the non drive crank is still not fitting properly on to the axle. Think I must've damage splines or the end of the axle at one point during my amateur attempts at removal.

    Having thought about it, and as the chain rings are pretty worn anyway, I think I might pull the trigger on a new crankset - probably a compact rather than the triple. I can get a Tiagra compact for less than £60 at Chainreaction. I could stick with existing FD, but they're pretty cheap so might as well get a new double.

    Ach well... You live and learn...
  • fenskifenski Posts: 119
    So I got a replacement Tiagra 4700 crank set - it's installed, adjusted and i'm ready to go for a ride :) The only thing I'm wondering is that it didn't appear to come with an end cap for the non drive side crank arm. Anyone know if that's normal? I would've thought it would at least have a dust cap to stop water and dirt getting in to the axle - am I missing something?
  • fenskifenski Posts: 119
    Ignore me - I've found the right part.
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