BB30 Bottom Bracket Replacement

[Vitara]

I can no longer put off replacing the creaking Bottom Bracket on my Jamis Xenith Endura, but need to make sure I've bought the correct part before I start the job and have it out of action.

The technical spec of the bike from Jamis says it's a BB30 Push Fit cartridge & a sticker on the frame says the same.

There seem to be limited BB30 cartridges for sale, and the one I have found are advertised as PF30/BB30, but my research says that these are different sizes; PF30 fits into a 46mm shell and BB30 fits into a 42mm shell. To further confuse the issue I've measured what looks to be cartridge and I would say its 46mm, but this contradicts the technical spec and frame sticker.

I'm also wondering whether fitting an adapter to allow me to fit an English Thread BB would be a better short and long term option than simply replacing the BB30 (or PF30) BB. Same problem applies though I need to determine which adapter to buy.

[Brucey]

clearly the solution to this problem is owning another bike that you can use whilst you fettle the first one....

You clearly need to remove the old one before you can be 100% sure of what you have, IMHO.

cheers

[Gattonero]

I can no longer put off replacing the creaking Bottom Bracket on my Jamis Xenith Endura, but need to make sure I've bought the correct part before I start the job and have it out of action.

The technical spec of the bike from Jamis says it's a BB30 Push Fit cartridge & a sticker on the frame says the same.

There seem to be limited BB30 cartridges for sale, and the one I have found are advertised as PF30/BB30, but my research says that these are different sizes; PF30 fits into a 46mm shell and BB30 fits into a 42mm shell. To further confuse the issue I've measured what looks to be cartridge and I would say its 46mm, but this contradicts the technical spec and frame sticker.

I'm also wondering whether fitting an adapter to allow me to fit an English Thread BB would be a better short and long term option than simply replacing the BB30 (or PF30) BB. Same problem applies though I need to determine which adapter to buy.

It's pretty easy to say:
BB30 is bearings directly pressed in the frame
PF30 is bearings housed in nylon cups pressed in the frame

The BB30 shell is 68mm wide with 42mm ID, outside you can only see bearing covers.
A PF30 shell is 68mm wide too, but it 46mm Id and you can see the little step of the cups.

BB30



PF30



Both can b converted to BSA thread by semi-permanent bonding of a threaded sleeve inside.

[Valbrona]

PF30

Not sure what someone is doing there with both a wave washer and a pre-load ring.

[Gattonero]

PF30

Not sure what someone is doing there with both a wave washer and a pre-load ring.

You have a point.
But I note that the preload ring is set to zero -or almost to- which is somewhat typical of how under-engineered is that part. On Sram BB30 cranks like that, the preload ring threads onto a very flimsy nylon collar that is simply pressed onto the crank spindle. All the power of the pedal stroke is held by a 0.5mm nylon thread pitch (I may be wrong, but is not too far from that) so it's not great to begin with.
Those cranks look like a new installation so they're faulty or someone didn't read the assembly instructions

It could work better if the preload ring and collar were made of metal, or been slightly more substantial given that I've seen several becoming useless after a short while, this resorting to a wave washer and trial-and-error of adding those thin spacers.

When the worst happens, the ring fails and does not keep the cranks in position, it's not the end of the world for the cranks per se, as the movement is litterally a couple of mm. The problem is that such movement is enough to make a mess with a 10 or 11sp setup, the chain gets thrown off the chainring(s) which is likely to mark/scratch the cranks or the frame, if not making the chain to jam in the RD or rear wheel.

[Vitara]

clearly the solution to this problem is owning another bike that you can use whilst you fettle the first one....

You clearly need to remove the old one before you can be 100% sure of what you have, IMHO.

cheers

The Jamis, with it's mudguards and hub dynamo is essentially my do everything bike. I have a spare but sans mudguards it isn't a lot of use for the type of riding I normally do.

Anyway I did bite the bullet and removed the BB. This revealed that the BB30 shell already has an adapter in it which takes an FSA Bb-8420st Power Drive.

This explains a) why the external appearance did not look like a BB30 push fit BB, and b) Why I couldn't locate a 68 x 108mm BB30 bottom bracket.

The good news is that the screw fit Power Drive came out without too much trouble. I suspect trying to remove a Push Fit BB would have been a much more difficult ball game.

The bad news is that the new Power Drive is not stocked in the UK in the size I need & needs to be shipped from the US where Jamis bikes are made and are much more common. So the old BB is back in the bike and creaking away happily while I wait for the new one to arrive.

[531colin]

Such is "progress" in the bike-building trade.
Got any remote tours planned?

[Valbrona]

I am inclined to think the OP could have got a square taper cartridge BB to fit - available in a range of axle lengths - but which would have necessitated the purchase of a new crankset.

[reohn2]

Such is "progress" in the bike-building trade......

Agreed!
Life used to be simple,however why have simple when you can have "progress"

The OP has my sympathies.

[Vitara]

I am inclined to think the OP could have got a square taper cartridge BB to fit - available in a range of axle lengths - but which would have necessitated the purchase of a new crankset.

I did consider that option, but decided it was better to stick with what I knew would fit. Cost of purchase and shipping wasn't excessive and the bike is still rideable while I wait for it to arrive.

The current BB has lasted for over 27,000km, many of those in poor conditions, so I've got good service out of and probably should have considered replacing it sooner.

I've got plans for a new bike in the not to distant future, the Jamis will probably then become my winter and pub ride bike & the new BB may well last its lifetime.