Bottom Bracket - fitment question

stevee_p

Hi,

Hopefully an easy question to answer. I'm new to replacing bits on my roadie, until recently its performed flawlessly with just the usual clean / tighten every now and then.

However, my crank arms have become a tiny bit loose, and have begun creaking. So, after seeing my knowledgable mechanic friend, he informs me the bottom bracket needs replacing.

So....i've ordered a Shimano Dura Ace 7900 from Wiggle, will this fit my Boardman with Truvativ Elita GXP crankset?

As far as I could figure out, the only thing to consider was either British or Italian thread?

Any thoughts on this are much appreciated as I really want to get out on the bike at the weekend, and I can order a replacement in needed!

Thanks!

Amateur Steve....

desweller

I think that's an ISIS chainset so the HTII BB you've ordered won't fit. You'll need an ISIS bottom bracket.

stevee_p

thanks for the reply,

quick question, whats the difference?!

Not to sound like an idiot (hopefully) but the bb i ordered certainly looks about right (thread sizes apart). No crank puller was required to get to it, and by the looks of the ISIS ones online, they look different to the one already in the bike?

warpcow

Can't comment on whether it's ISIS you have or not, but if the details you gave in the first post are correct (about you having a GXP chainset) the Shimano one won't fit anyway. Shimano and Truvativ axles are a different diameter (or at least GXP are tapered iirc).

stevee_p

hmmm,

thanks for the reply aswell, i'd hoped that it would have been the correct choice, but its not sounding like it!

I guess i'll be re-ordering a new one then and sending the old one back!

Thanks

kfinlay

If it's a GXP then look for SRAM GXP BB's to fit - Truvativ make SRAM chainsets (or vice versa - can never remember which way it is)

stevee_p

Hi,

From your advice, would this fit?

http://www.evanscycles.com/products/sra ... %20bracket

Is this the full bottom bracket? If so, what are the 'cups'?

micken

The cups are the threaded bits and you'll need a tool to fit them with, it's the same as Shimano. Ask your mate I bet he's got one, or knoes someone who has.

Cleat Eastwood

the cups are the 'cups' with threads on them. When you install it it will tell you on the BB which side should be inserted on the left and on the right, or in that BB's case which is the driveside.



The driveside, the side with the cogs on screws in a different direction than the non drive side, the threads are different.



And do make sure you use some anti seizing grease it will make it a whole lot easier if you need to replace them.

And do take your time installing them, its not nice buggering up the threads.....

stevee_p

Ok,

Firstly a big thanks to all who replied, much appreciated.

Secondly, I wish i'd listened to you.

I went home with the Shimano BB, and sized it up roughly against my existing one.....seems the same size.......threads the......what the hell, i'll fit it and see what the difference is......went on ok......hmmmm, perhaps it will fit after all.

Turns out the internal diameter of the bottom bracket is ever so slightly bigger than the internal diameter of the old bb. (I know I know, "I told you so" all round)

I was so p1ssed off - i'd wasted £30 on a bottom bracket which I blatantly won't be able to return, and if i'd have just taken your word for it, i'd have saved my self a lot of hassle and frustration.

Lesson well and truly learnt!

Sram GXP BB set on order from Evans as we speak.

As an aside, it appears the new bb set just has the 'cups' included (http://www.evanscycles.com/products/sra ... %20bracket)

Does this mean I will still retain the existing centre tubing?

And when a bottom bracket 'goes' as in starts getting wobbly / loose, what is it that has failed? The ball bearings I presume?

Thanks

Embarrassed Steve... :oops:

keef66

Post a pic of the DuraAce cups on here. As long as you haven't mashed them, somebody will make you an offer I'm sure.

I can't imagine that a new BB doesn't include the plastic middle bit, but if so then yes, re-use the old one.

The ball bearings and the races they run in do wear out, hence the play. Quicker if the seals are rubbish and you ride in wet / muddy / salty conditions without mudguards.

Anonymous

keef66 wrote:

Post a pic of the DuraAce cups on here. As long as you haven't mashed them, somebody will make you an offer I'm sure.

I can't imagine that a new BB doesn't include the plastic middle bit, but if so then yes, re-use the old one.

The ball bearings and the races they run in do wear out, hence the play. Quicker if the seals are rubbish and you ride in wet / muddy / salty conditions without mudguards.

Or failing that you can buy a kit of shims to reduce the inner diameter down to fit a GXP chainset.

Costs about £6 I believe. I know this as like you I've recently been through the BB learning curve.

stevee_p

Hi

Yeah - I must admit, I was thinking about advertising them on here. The metal cups are ever so slightly scuffed (as I imagine 99% of cups are when fitted) so hopefully ill be able to sell them on.

Cheers for the advice on the tube, I imagine the cups / bb's are the expensive part of the bottom bracket, not the inner tubing, so hopefully it will be included.

maddog 2

sell the BB

I'm surprised no one picked this up earlier

you can get Hope shims to convert a Hope HT2 BB into a GXP but they only fit Hope BBs, not Shimano. Shimano run placky top hats, Hope don't.