BB and spindle diameter

MidlandsGrimpeur2

I am taking out an old sram red crank and replacing it with a shimano 105 r7000.

I have a Wheels Manufacturing BB30a to 24mm Shimano BB. Having spoken to the bike shop, this is the correct one for a 24mm Shimano spindle.

Having tried to install it, The spindle will only go in around 2/3 of the way and then gets stuck. Tried tapping it but it will get well and truly wedged if I continue.

I have measured everything up with a Vernier caliper and the crank spindle appears slightly wider towards the point it meets the chainrings. I have this at 24mm, as opposed to 23.86mm along the rest of the spindle.

1) I assume this is just poor milling and the spindle should all be slightly under 24mm all the way along to allow for insertion into the BB?
2) Do I ask for a replacement or should I get one of my engineers to shave 0.2mm off the spindle and save myself the bother of warranty?

Any thoughts?

i.bhamra

They do sometimes need a bit of persuading to get in (and back out) in my experience. A few firm taps with a mallet (block of wood between mallet and crank for protection) normally does it. Does it go in far enough to get the non-drive side crank arm on? If so and you can thread the pre-load bolt then you can can pull it into a fully seated position by tightening the bolt if you'd rather not hit it with a hammer! If the spindle is not coming through the non-driveside cup give the spider a bit of a wiggle to make sure the spindle is not not fouling the inner edge of the cup rather than coming through perfectly straight.

MidlandsGrimpeur2

Cheers. No, not far enough to get the NDS crank on to the spindle. I have given it to my Quality Manager to have a look at. He thinks where the spindle has been attached to the chainrings (a process called swaging), the metal has expanded which accounts for the varying diameters across the length of the spindle.

He can't mill it as you would need to remove the spindle from the crankset which cannot be done without destroying it!

The spindle diameter at 24mm is wider than the BB so he says there is no way it can be properly installed, even if I hammered it in it wouldn't spin properly as the fit is too tight.

Looks like it is going to be a warranty replacement!

sungod

fwiw when fitting the cranks back in mine after a clean/grease, i use freezer spray inside the spindle to shrink it a bit so that it slides in without needing force, it's bb30 but same principle should work in others

putting the spindle in the deep freeze should also work

MidlandsGrimpeur2

Cheers SG. I had read about this. My only query was after freezing, would the metal expand again and cause issues?

I take it this has not been the case with yours?

sungod

not been a problem for me, bb30 spindles are an interference fit, once it warms up the spindle is tight enough that it won't move but the bearings run free

with the differential expansion of aluminium alloys and bearing steel, the fit will always vary a bit with temperature - al alloys will shrink/expand more with cold/heat than steels

using the freezer spray i find it only takes 2-3 seconds blast into the hollow spindle to chill it enough to slide through, i'd guess this is creating a temperature differential of around 20c vs. the bearings

MidlandsGrimpeur2

Thanks again SG. I am waiting to hear back from the shop on a possible warranty.

If there is any issue and I can't get it replaced I will revert to the freezer trick and see how that works.

masjer

I think the Hollowtech spindles are steel, so freezing might not be as effective. I always coat with grease to install.
This might be the reason Shimano manufacture their BB’s with a plastic ‘tophat’ insert to account for slight variations in tolerances.

whyamihere

Have you checked it's definitely not a SRAM GXP BB? They're 22mm on the NDS, that could be stopping it.

MidlandsGrimpeur2

Yep, definitely not the sram gxp. The 24mm is actually replacing the wheels mftg 22mm sram gxp one, so I know I have the correct model.

You are right though, easy mistake to make as my lbs got similar bb's mixed up on another bike of mine with disastrous results!

trevor.hall12

Most likly the frame itself being slightly off from 1 side to the other .See a few bikes like this that the BB shell isn't straight .Did the drive side go in by hand or did it need pressed in ? Shimano cranks should be 24mm and the bearing the same .Try taking the BB out again and fit it on the spindle while it's off the bike ,that will tell you if it's the frame that the problem is .