Dura Ace BB and FSA Gossamer chainset- workshop woes!

Mefster
Mefster Posts: 54
edited November 2011 in Workshop
After my FSA bottom bracket started grinding a little, I decided it was time to replace it. I checked online and spoke to the mechanic at Planet X and it apeared my FSA Gossamer compact alloy chainset would be compatible with a Dura Ace external bottom bracket- cheaper replacement and I've always been happy with their durability.

So this evening, old and BB was removed. Fitted the new Dura Ace bottom bracket without event. The hollow axle was very tight through the bottom bracket. I recall fitting an XTR chainset in the past and the chainset needing a tap with a rubber mallet before sliding through. In this case is was more like the force needed to sink a fence post!

In the final stages a managed to round the left hand tensioning bolt by trying to use it as a crank puller (very daft idea in hindsight, although it did feel like it was made from cheese!). God only knows how I'll ever get them off.

Now fitted and spinning nicely, although the chainline is slightly out- I'm unsure if this is BB width differences or if it's still not fully seated.

Anyone else had similar problems?

Comments

  • John.T
    John.T Posts: 3,698
    edited November 2011
    Gossamer chainset should work fine with any Shimano HT2 BB. I have one running in a Tiagra BB and one in an Ultegra one. No problem with either. Not sure why it was so stiff. The bearings have plastic sleeves in them which can be a little stiff to push the axle through but I have never needed to force them.
  • Monty Dog
    Monty Dog Posts: 20,614
    Yup, Gossamer should be fine with regular HTII bottom brackets. I'm running a Gossamer CX on one bike that despite being torque-up correctly has an annoying habit of coming undone leading me to the conclusion that it's a piece of cr@p - I only weigh 60kg so it's not exactly seeing huge torque.
    Make mine an Italian, with Campagnolo on the side..
  • nicklouse
    nicklouse Posts: 50,675
    sounds like the BB needs facing. and the bearings are not aligned.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Thanks for the responses. It does sound as if the bearings aren't aligned. The bike did come from Planet X with an external (MegaExo) bottom bracket and has done a fair few miles on the original BB over the past 3 years without problems until now. I'd have thought that if the bottom bracket needed facing I'd have noticed before now. The cups certainly aren't cross threaded.

    It also wasn't difficult to removed the chainset from the old bottom bracket.

    I've spotted that you can buy spare tensioning bolts for about £3. Still doesn't solve the problem of how to get the old one out!

    I'm tempted to adjust the front mech and give it a go- it only needs adjusting a fraction of a mm and the idea of trying to remove it at this point isn't too tempting!
  • jermas
    jermas Posts: 484
    Just a thought, when you need to remove the chainset and bottom bracket in the future, you might try removing the left side bb cup with the crank still in place (if you have appropriate spanner type tool). This will remove any alignment issues (if there are any) and make it easier to disassemble.
  • markos1963
    markos1963 Posts: 3,724
    Unlikely for the BB to need facing as the OP was already using an external BB and it should have been done on the original build.
    I would have tried installing the RH cup first, then the RH crank and then slip on the LH cup last.
  • markos1963 wrote:
    Unlikely for the BB to need facing as the OP was already using an external BB and it should have been done on the original build.
    I would have tried installing the RH cup first, then the RH crank and then slip on the LH cup last.

    I wouldn't take this for granted as some new frames are fitted with external BBs and are not faced.
  • Wasn't happy with the chainline so did a few investigations to try to work out where the problem lies:

    Removed the non-drive side crank arm. Unscrewed the non-drive side bottom bracket. The axle is so tight in the bottom bracket that as it was unscrewing it pulled the axle and attached driveside chainset further into place the final millimetre or so. I couldn't easily remove the drive side. To check if it was just alignment I reversed the non-driveside bottom bracket and tried to slide it back over the axle. It was really tight- I couldn't slide it more than a few mm onto the smooth part after the splines who ugh fear of not being able to get it back off.

    Turned it back around and refitted the LH cup. It didn't push the axle back out and so all is now running smoothly and well aligned.

    In conclusion: it appears really tight fit of the axle through both BB rings is the likely cause rather than misalignment.