BB30 to Hollowtech II Width Issues

deadly radish

Hi all,

I have recently invested in a Stages power meter (Shimano 105) - I was lucky to get a good deal on a (barely) second hand one.

My bike has a stock BB30 FSA Gossamer Crankset (10sp compact) which I decided to replace with a Shimano 105 crankset (5750). I could have gone with the FSA offering from Stages but it doesn't match the drive side crank at all and given the saving I made on the second hand unit it cost a fair bit less to upgrade the whole crankset (as well as pleasing my OCD by completing the 105 groupset).

In order to make the crankset fit I purchased the 'Wheels Manufacturing BB30 to 24mm Crank Spindle Shims' (two very expensive pieces of high-tolerance milled plastic) - nice and simple, or so I thought.

Unfortunately I am not able to screw the Hollowtech II Preload Cap into the non-drive side crank, the axle's end is 6-7mm recessed into the crank arm while the preload cap only reaches in 5mm. I fear the additional width added by the shims (which are really chunky) has made it much too wide. I have been able to attach the crank by tightening the two 5mm nuts and there is no lateral play at all, but I don't feel particularly comfortable with the setup. I've not ridden it yet, and any rides I do will only be on the trainer so the consequences of it coming off are not too great providing it doesn't damage the arm.

My question is what should I do? The chain rings on the drive side seem well setup in terms of distance from frame and the front derailleur did not need adjusting - suggesting it's the same distance from the frame as it was before. Is there a longer preload cap which is designed for this purpose (I spent a while looking and couldn't find anything, but it is possible I didn't know the correct search term)? Should I replace the BB30->Hollowtech adapters, and if so what with? Should I just ignore the issue?

EDIT: I should add I greased the crankset and BB and used a hammer to get everything seated, so I'm happy it is all sitting correctly. That said I spent a good hour searching on the internet and was unable to find anyone else who has had this problem (hence this post)!

Thanks in advance!

k-dog

That should work. There is only one cap and it should engage a couple of threads before it starts to load the bearings.

Have you pressed the adapters all the way into the bearings?

deadly radish

Yes, I've pushed them all the way in and used a mallet to lightly tap them in. What's causing the problem is the bearing covers I'm using - if I remove them it all fits much better, the preload cap's thread engages and I generally feel much more comfortable with the setup. Unfortunately without the bearing covers (which are acting as spacers) the shims rub against the outer BB shell significantly, to the extent that they occasionally stick and the axle rotates within them (i.e. on the greased surface between the shim and axle rather than rotating with the bearing).

The picture below shows the BB without the shims or bearing covers. Without bearing covers the shim rubs on the black plastic surround. With bearing covers it appears to be too wide to allow the preload cap to grab the axle's thread.


While I'm not too fussed about the lack of preload cap (although it doesn't look as good and will be trickier to clean), I fear it suggests the non-drive side crank is not correctly mounted (too much force will be placed on too small an area of axle) and may lead to damage of the axle or, worse, my power meter!

k-dog

That doesn't look right - the adapter should reduce the size of the spindle hole - so you shouldn't see the inner face of the bearing - just the Delrin piece which spins with the bearing.

Pictures here - http://wheelsmfg.com/bb-pf30-universal- ... ranks.html

Then you fit it like you would for a normal external BB.

Yours isn't bb30 but PF30 but you use the same adaptor for both.

deadly radish

Thanks for your reply.

Sorry I didn't make myself clear before, the above image is simply the bearings, no covers or shim. The image below is the shim in place, however as can hopefully be seen the shim has a large flange which contacts with the BB outside shell (the black outer ring in the above picture). This contact causes significant friction. Placing the bearing cover between the bearing and the shim resolves this issue but makes the whole arrangement too wide.

Looking carefully at the article you link (which is the shim I have), it looks like the shim fits on those BBs because the bearing sits slightly proud of the shell, meaning the flange has nothing to contact. On my bike the bearings are recessed into the frame and the flange contacts the outer BB shell.

jgsi

If you are still having trouble then Plan B would be for a full strength Praxis or FSA bb30 adapter.. presumably you are sticking with Hollowtech for a while on this bike?

gloomyandy

Do you have any BB30/PF30 shims that you could use in place of the cover (they can be very thin), that will give you spacing from the frame, but still allow the pre-load to engage?

paul_onabike

A quick look on the net and it appears that there are 2 types of BB adapter, one for sram and one for FSA - yours look like the sram. Since the crankset you are replacing is a FSA I would think you have FSA bearings which are somehow always different to everyone else's

http://www.jejamescycles.co.uk/wheels-mfg-fsa-pressfit-30-to-shimano-24mm-crank-spindle-shims-id82858.html?gclid=CNHU8MCrkcICFSXKtAodaSwANA

deadly radish

Thank you very much for your help all - I'd originally opted for the shims simply because they seemed the simplest option in terms of installation and ease of removal if I ever wanted to change back (can't see why I would, but nice to have the option).

It looks like Paul has identified the root cause of the problem - I just bought the stock shims but they have special ones for FSA, which appear to have slightly wider bearing shells: the shell is 72mm across but the bearing-bearing width is 68mm - meaning each bearing is 2mm recessed into the shell, causing the flange of the stock shim to rub. The FSA shims look like they have a slightly different shape to accommodate this which using spacers on the bearings also achieved - but making it too wide.

I fixed the problem this afternoon by taking some sandpaper to the shims and taking 1.8mm off the front face of both of them - I have a pair of calipers I was using to check the width periodically. I did this by hand (I lack a proper belt sander) which took about an hour each - a testament to the density of the delrin pieces! Then, with the spacers added, it is the correct width (and everything fits perfectly).

I'd recommend anyone else with a similar BB to just buy the correct shims in the first place :oops:, that's what I'll do if I ever need to do this again!