Crankset axle wear?

[Mr.Gib]

I have a identified what I believe to be play between the alloy axle of my three year old BB30 cranks and the bottom bracket bearings. I can literally rock the crankset back and forth with my hands. The movement is very slight but it is definitely there. I wouldn't care but it makes a click with every crank rotation out of the saddle. There is zero lateral play so it's not that. Is it possible that the harder inner race (NTN bearings) has worn the axle to the point where play is now noticeable? I keep everything perfectly clean an well greased. I changed to a new set of bearings just to test and same problem. The crank appears fine on inspection but the bearing definitely seems a bit of a loose fit on the axle. The problem is non-drive side.

Is there any solution to this? Or is the crank dead. I wouldn't have though such wear was possible in such a short time.

[TobinHatesYou]

I have a identified what I believe to be play between the alloy axle of my three year old BB30 cranks and the bottom bracket bearings. I can literally rock the crankset back and forth with my hands. The movement is very slight but it is definitely there. I wouldn't care but it makes a click with every crank rotation out of the saddle. There is zero lateral play so it's not that. Is it possible that the harder inner race (NTN bearings) has worn the axle to the point where play is now noticeable? I keep everything perfectly clean an well greased. I changed to a new set of bearings just to test and same problem. The crank appears fine on inspection but the bearing definitely seems a bit of a loose fit on the axle. The problem is non-drive side.

Is there any solution to this? Or is the crank dead. I wouldn't have though such wear was possible in such a short time.

Inspect the spindle. If you can't see an obvious shelf, it could be radial play in the cartridge bearing itself.

[Lucendi]

If the bottom bracket bearings are not a tight fit on the crankset axle, the crankset axle will wear down as the bearing spin around it.

You can probably fix it by using a bearing retaining compound, such as Loctite 641. https://www.henkel-adhesives.com/us/en/ ... e_641.html

[Karvalo]

As Tobin said if the axle is worn to the point of play there will be an obvious groove that you would be able see and feel if you take the crank out and inspect it.

[kode54]

I have a identified what I believe to be play between the alloy axle of my three year old BB30 cranks and the bottom bracket bearings. I can literally rock the crankset back and forth with my hands. The movement is very slight but it is definitely there. I wouldn't care but it makes a click with every crank rotation out of the saddle. There is zero lateral play so it's not that. Is it possible that the harder inner race (NTN bearings) has worn the axle to the point where play is now noticeable? I keep everything perfectly clean an well greased. I changed to a new set of bearings just to test and same problem. The crank appears fine on inspection but the bearing definitely seems a bit of a loose fit on the axle. The problem is non-drive side.

Is there any solution to this? Or is the crank dead. I wouldn't have though such wear was possible in such a short time.

Inspect the spindle. If you can't see an obvious shelf, it could be radial play in the cartridge bearing itself.

Happened to a friends spindle…worn spindle that had a “shelf” or groove. Couldn’t find anything wrong with the bottom bracket. Changed the crank with spindle to a spare I had and the annoying click went away although I suspect that the BB bearing races are a tad loose because of all the wear n’ tear.

[iow]

If the axle is worn it may be caused by BB bearings which are not concentric and/or parallel. If this is the case the play will usually decrease or disappear at some point/s in the axle rotation.

[Mr.Gib]

Thanks for all the on point responses but the exasperating thing is that there is no visible "shelf" from wear, and this particular bottom bracket is extremely well built. It is an aluminum shell and the bores seem round and perfectly aligned. Impressive spin test. I guess it's time to pull it apart again and get out the digital caliper.

[Cleaner]

There are (should be) specifications for the radial fit for the bearings on the crank spindle. The definitive way to check this unless the wear is obvious (you can see/feel the worn area on the spindle). If you can see/feel the worn area on the spindle then it is almost certainly out of spec. Measure the diameter of the spindle on the bearing lands. These areas will typically be turned on a lathe and appear as a different sufrace finish. You can then check this diameter (O.D. of the spindle) and the ID of the bearing to determine if they are in spec. You will need a micrometer for a good manual check but could use a set of calipers for a sanity check.

Look at an image of a colored anodized Cannondale spindle for obvious example of the bearing land locations if you are not familiar with them.

Retaining compound is an option to try but will only address very small irregularities, if you can feel play this is not likely to work.

Most designs for BB30 I have seen should use a transition fit for the spindle on the inner races of the bearings. A verbal description of this is as follows.
Negligible clearance or interference fit which can be assembled or disassembled with a rubber mallet, e.g., hubs, gears, pulleys, bushes, bearings

This is so that the spindle never rotates relative to the inner race to prevent the wear you are suspecting.
I am assuming that the class of fit is specified on the basis of the nominal shaft diamter of 30 mm so that would be a shaft/bore fit of K7/h6.
The tolerances required of this for a 30 mm nominal dimension are assuming an h6 fit are: -0/-16 micrometers. This implies the limit dimensions of the shaft O.D. at the bearing land would be 29.984 mm up to 30 mm.

I have not seen any dimensions for the BB30 spindle that address fit to the bearing bores under the BB30 standard. I have only seen bottom bracket shell dimensions with tolerances. So there may not actually be a spec for this. Surely the crank manufacturer uses something for QA in manufacturing but they may not reveal that to you.

[Hexsense]

^
There should be such standard, but unfortunately, my old Sram Red bb30 slip on very easily. Even worse, I fell for guide that say to grease the spindle. That makes spindle spin around the bearing even more easily.
Eventually, that area is discolored and I can feel the edge running finger through that area.
Glad they went with Dub now, which allow plastic hat if bearing has 30mm ID.

[Mr.Gib]

The tolerances required of this for a 30 mm nominal dimension are assuming an h6 fit are: -0/-16 micrometers. This implies the limit dimensions of the shaft O.D. at the bearing land would be 29.984 mm up to 30 mm.

My BB30 crank spindle measures 29.90 on my digital calipers. When I rotate the spindle in the caliper it ranges up to 29.94 so it's not even round. There is very little sign of wear - some of the shine has come off the bearing lands but no ledge that you can feel with a finger nail. I think this spindle was always undersize and it took very little wear for noise to start. What a piece of crap. Used for 3 months a year for three years and it's done. Unbelievable.

[PoorCyclist]

what brand is it? I have SRAM red and force cranks on my bikes and they need to be tapped in and out.

Maybe try a different bearing it may end up with a better fit. They are not too expensive now.

[Mr.Gib]

what brand is it? I have SRAM red and force cranks on my bikes and they need to be tapped in and out.

Maybe try a different bearing it may end up with a better fit. They are not too expensive now.

Sram of course. Bearings are NTN so it's not the bearings. Also tried other bearings and same problem.

Fact is spindle is 29.90mm! I guess that is just too small to keep from sloshing around.

[Lucendi]

Fact is spindle is 29.90mm! I guess that is just too small to keep from sloshing around.

You can increase the diameter of the axle if you have no other option.

A center punch will create both divots and ridges, the ridges will affectively increase the diameter of the axle and get a good hold of the bearing.

[Mr.Gib]

wow - genius.

[RDY]

what brand is it? I have SRAM red and force cranks on my bikes and they need to be tapped in and out.

Maybe try a different bearing it may end up with a better fit. They are not too expensive now.

Sram of course. Bearings are NTN so it's not the bearings. Also tried other bearings and same problem.

Fact is spindle is 29.90mm! I guess that is just too small to keep from sloshing around.

I assume it's the old 3 bolt PF30? From what I heard, they had a particularly bad reputation for developing play.

Mechanics I use complain bitterly about them, and aren't keen on anything pre 8-bolt AXS. They sing the latter's praises and claim never to have had an axle / bearing play related issue with Force or Red that couldn't be easily fixed on cranks that hadn't seen very heavy use - though I know others' experience differs.