Author Topic: Failing Ultegra Octalink BB  (Read 401 times)

Failing Ultegra Octalink BB
« on: October 05, 2019, 04:23:48 pm »
This had been clicking for a while, and more recently loosening itself, and now making more ominous sounds and feeling rough, so definitely time to replace.  The crankset is a triple (48/39/30) with a 9-speed cassette, all of which I want to retain.

I want to review my options, and I see that the world of bottom brackets has become quite a minefield.

Option 1
Can I keep my existing Ultegra Octalink cranks with a replacement Octalink bottom bracket?  Can’t see any Ultegra ones, only Dura Ace for the track, so no good for my triple, or a downgrade to this 105.

Option 2
Convert to a Hollowtech option?  That would mean replacing my cranks, I guess?  Would I be able to keep the existing chainrings, which were replaced not too long ago?  No experience with these.

Option 3
Convert to a high-quality square taper option?  That would also mean replacing my cranks but I should be able to keep the existing chainrings.  I guess the fixed gear fraternity have encouraged the wide range of square taper BBs, such as this from IRD.  I see they also do a more modest option and an even more modest version.  Anyone any experience with these?

I would ideally want to keep the same chainline, so that gear-changing remains familiar.  Can I assume that any 118mm spindle BB will achieve this with my triple?

Re: Failing Ultegra Octalink BB
« Reply #1 on: October 05, 2019, 04:50:57 pm »
They're a faulty design; the splines aren't tapered so they end up developing play.  Usually the LHS goes first.  What's the BCD?

Shimano UN55 BBs usually last years and years but are a bit heavy.  A Token carbon-sleeved one is often inexpensive and is much lighter (hollow axle).  Spa will sell you their own 110BCD double or triple cranks for about £20.  You need something like a 110mm BB for the triple.
Never tell me the odds.

Re: Failing Ultegra Octalink BB
« Reply #2 on: October 05, 2019, 04:59:28 pm »
Thanks, rogerzilla.

Current BCD is 130mm.

You're right - it's the LH which has failed.

Do you think the IRD offerings are no better than the Shimano UN55?

Re: Failing Ultegra Octalink BB
« Reply #3 on: October 05, 2019, 06:27:26 pm »
is

a) the LH crank coming loose on the BB spindle or
b) the bearings/cups loose in the BB shell?

If the former, probably the crank is scrap (*). If the latter you just need to buy a new BB unit. The 5500 '105' unit will be fine (well, as fine as they get.... ::-) ); IIRC it just varies in external finish from the Ultegra model which is now NLA.


Yes the 5500 unit will fail, probably at a lower mileage than a (good, most are not) ST unit. But the failure mode is usually graceful, and (IME) Octalink BBs look positively durable when compared with HT-II units. The saving grace for HT-II is that the BB bearings are both cheap and fairly easy to replace. A downside is that the BB shell in the  frame usually needs to be faced  when such a BB is fitted for the first time.

Assuming your cranks are OK a new ES500 bottom bracket is by far the least expensive solution

(*) I have known cranks that had lost their fit slightly go on to work OK if they are fitted with an adhesive of some kind, but its pot luck really.

cheers

Re: Failing Ultegra Octalink BB
« Reply #4 on: October 05, 2019, 07:15:25 pm »
is

a) the LH crank coming loose on the BB spindle or
b) the bearings/cups loose in the BB shell?

Both of these.  The BB is now making very nasty graunchy noises, and I can feel, while pedalling, that there is loose gubbins in there.

As so often, it's a choice between the quick fix and the upgrade with a long view.  I think I'll be going for the quick fix, while I figure out the best long-term solution.

Thanks for the help.

Torslanda

  • Professional Gobshite
  • Just a tart for retro kit . . .
    • John's Bikes
Re: Failing Ultegra Octalink BB
« Reply #5 on: October 05, 2019, 07:41:28 pm »
Any HII road triple and the matching BB will happily accept your new(ish) chainrings.

Chase and face the shell - HII are easily knackered if misaligned - and don't forget the 3mm spacer for the LH crank. Don't buy a used triple without it, a new one should come complete.

You will have to accept that the HII BB is a consumable but they're relatively cheap and simple to replace. If you're buying used look for scoring or wear on the axle where the bearing run. If it ain't perfect don't buy it. Life of a new BB on a scored axle can be measured in days.

By no means exhaustive - these are some of the cranks you can use with your existing rings:

Sora: 3300, 3400
Tiagra: 4500, 4600
105: 5600, 5700
Ultegra 6600, 6700 (rings will fit but look sh1t)
VELOMANCER

Well that's the more blunt way of putting it but as usual he's dead right.

Re: Failing Ultegra Octalink BB
« Reply #6 on: October 06, 2019, 08:21:29 am »
I have Cyclus chasing and facing tools if you CBA to bring the bike to Swindon.  I also have the HT2 spanner.
Never tell me the odds.

Re: Failing Ultegra Octalink BB
« Reply #7 on: October 06, 2019, 10:45:39 am »
Thanks for the help and advice everyone.

A cunning plan is evolving which, because of limited time, and shortly off on holiday, will involve LBS and a bit of a delay.

Cheers! :thumbsup:

Re: Failing Ultegra Octalink BB
« Reply #8 on: October 06, 2019, 05:49:44 pm »
I have Cyclus chasing and facing tools if you CBA to bring the bike to Swindon.  I also have the HT2 spanner.

And I've got similar in SE London, though given the location in your (well, Martin109's) profile that's more likely to be helpful to other people.