24mm BB-axled cranks

Any one other than Shimano make nice ones?

Turns out I’ve managed to kill my XTR M9120s. I ran them on a Hope BB for 3 years and somehow the steel bearings managed to eat grooves in the steel axle. I’ve tried using Shimano BBs for the last couple of months but the step in the axle manages to cut through the plastic top hat/sleeve thingy, and I’ve just spent the last few hours pedalling round with a clonky crank which has driven me potty.

XT are out as black cranks look shit within a couple of rides the way I rub my heels on them. SLX are not much better being dark grey (and well, I’m a tart, I don’t really want SLX on an otherwise top drawer spec bike – although that’s the most likely solution). I’m not blowing another wedge on XTR if they’re going to be dead in 4 years.

I’m quite pissed off with this as the 2-fold justification for the spend on the XTRs was 1) they were the closest option to a silver finish 2), I’ve been running old XTR M970s across several bikes since about 2010 and they’ve been bombproof and I’m expecting Keith Richards to be still riding around on them post the apocalypse. The only reason they’re not on this bike is they don’t clear the chainstays (because boost <<sigh>>). I was expecting to get at least a decade out of the 9120s.

Not interested in 30mm axle cranks. The frame has a BSA BB shell, and you can’t fit a sealing tube between the bearing cups with a 30mm axle in there, and that’s a red line for me in terms of durability and servicing.

Light is good – no boat anchors please; no carbon and needs to have a 28T oval ring available to fit them.

Suggestions…?

Thanks

XT and wrap them .

Or.

XT and polish them.

How about going back to square taper?

I believe Wheels Manufacturing offer a BSA30 with a centre sleeve

Middleburn RS8-X are, I believe, 24mm axle

Just helitape (or with black, just insulation tape)  whatever you buy and run whatever you like.

Alternatively, sort your cleats/feet out so you don’t rub the shiznit out of them.

Ha. Some of us really do have duck feet and no amount of cleat positioning will help :-)

I have heel rub on some of my frames!

Nukeproof 30mm bbs also had a centre tube. Sure plenty of other will as well.

What about middleburn, available in silver.

XT and wrap them

This^^^^

A mate has some that are around 5 years old, m8000 I think, wrapped before he used them and they still look like they did the day he bought the bike. I have xtr’s and didn’t bother with the wrap, they look awful but personally I couldn’t care less

PVC tape will last minutes, helitape lasts maybe 2 rides. I had some GRX ones Cerakoted silver,  that lasted a couple of rides (but at least doesn’t show too much). Wet peaks grit at 80-90rpm is great grinding paste. I have polished cranks in the past, but it’s a bugger of a job to do well

My cleats are located for happy knees. It’s been much more of a problem since Boost became a thing as now I’m working my way through chainstays too (although they tend to be steel, so it’s just cosmetic). Road bikes are better, although I still rub the ankles of my winter boots on the cranks of my winter roadie, although it’s minor scuffs rather than big gouges.

I still don’t understand how the fretting in the BB axle happened. The M970s in my Soul have been on it since early 2018 also on a Hope BB, have done mega miles and the axle is mint, and they weren’t new when I built the bike.

XTR again but don’t use them with Hope BB or similar?

Maybe this is old info but I though SLX & up had alloy axles, hence this problem happens when you put them in a steel bearing.

Put helicopter tape on the crank arms. Or similar

just read your post above. Very impressed that you can wear through helitape.

There’s a reason Shimano BBs use plastic top hats. Any crank is susceptible to that issue with metal race directly on the axle.

Middleburn have 24 mm axles and are available in silver

Another vote for the Middleburn RS8x here, but that may be because I’ve wanted a set for years.

There’s a reason Shimano BBs use plastic top hats.

I thought it was so they were completely unserviceable so you had to buy again…

Combined with making the top hats out of egg shell so they shatter as soon as you touch them.

Never had a problem in over 20 yrs of using them.
Bearing life is IME better than supposedly posher ones inc my Chris King one.

Putting aside my arsey post above…

When a crank axle has been scored/grooved – is there any mileage in using something like JB Weld and then filing/sanding it down?

Any crank is susceptible to that issue with metal race directly on the axle

I’ve been using Hope BBs with Shimano cranks since 2008, 2009 ish. First time I’ve ever had an issue. We’ve got maybe half a dozen hope BBs in the house between my bikes and hers, most of them on their original bearings.

Middleburn have 24 mm axles and are available in silver

Ooh. Interesting. But no 28T and no oval rings… (and no 38T oval either, or I’d consider them for the gravel bike!)

I think the short term (bodge) solution is going to be tapping the LBS up for some old MT801 BB cups that are heading for the bin and just swapping fresh top hats in to my DS one as a periodic maintenance thing.

I always fancied a set of Middleburn cranks but the direct mount chainrings are £80 a pop!

is there any mileage in using something like JB Weld and then filing/sanding it down?

Quite possibly – but I suspect I couldn’t make a good enough job of the sanding down bit to get an accurate fit. If I could set it up in the lathe that I don’t own, it’d be absolutely the right answer! Its a fair point and I’ll have a think though. I wonder if there’s a way to turn a 30mm ID bearing inner race into some kind of cutter type affair.

As an aside – how come this isn’t a known, talked about, failure mode with 30mm axle cranks, which are all aluminum axles interfacing with steel bearings – I would have thought they would get chewed up in no time??

I’ve a 30mm FSA crankset in a BSA bb with a sealing tube.

What about wider spindle pedals to move your feet away?
I appreciate your helitape issue, my kid has worn though the helitape and the top layer of carbon on his fancy E13 cranks that have only seen about 15 bike park days

Heel rub through his chainstay ridewrap too after a couple of rides. The stuff doesn’t work well with repeat friction ime.

I’m not blowing another wedge on XTR if they’re going to be dead in 4 years.

I’ve had 12 yrs so far from the XTRs on my ss and they get regular use, I’ve been through 1-3 XT BBs a year on that bike. Shimano cranks and BBs are a good match, BBs don’t last that well but more recent M8000s are ok.

Shimano XTR M9100 Crank Protectors

These have lasted me years on different Shimano cranks.

“As an aside – how come this isn’t a known, talked about, failure mode with 30mm axle cranks, which are all aluminum axles interfacing with steel bearings – I would have thought they would get chewed up in no time??”

It is pretty common – I’ve seen plenty personally and many pics posted on here.

“I’ve been using Hope BBs with Shimano cranks since 2008, 2009 ish. First time I’ve ever had an issue. We’ve got maybe half a dozen hope BBs in the house between my bikes and hers, most of them on their original bearings.”

Are the bearings rough in the BB that wore the axle?

Sanded Shimano cranks look ace, brushed aluminium look if you use a slightly larger grit. Or you can put some sort of acid on them and get the annodizing off like that

As an aside – how come this isn’t a known, talked about, failure mode with 30mm axle cranks, which are all aluminum axles interfacing with steel bearings

The worst I’ve seen ironically is a DUB 30 “waisting” away at a sram alloy spindle, like 24mm, the DUB has a plastic sleeve, so not steel on alloy.
This bike was going through a DS bearing once a month

Steel BB bearings tend to leave a rusty ring that a quick pass with some wet and dry paper gets rid of.

Unite do a 24mm option that looks pretty nice but tbh shimano do the best cranks, even if they do love to **** with you on chainring fitting.

How about getting them refinished? Polishing is fine but will tend to corrode and go ugly, I’m thinking I might get my xtrs cerakoted. It’s generally a more abrasion resistant finish than paint or ano

Turns out I’ve managed to kill my XTR M9120s. I ran them on a Hope BB for 3 years and somehow the steel bearings managed to eat grooves in the steel axle

This happens to me too. And Hope bearings don’t last me long in the conditions I ride in either. I had a similar thread here a year or two back. Ended up going back to shimano disposable bottom brackets

New set of XTR with Shimano BB that you replace every 12-18 months or so because 1. routine maintenance, and 2 the BB is cheap.

I’m thinking I might get my xtrs cerakoted.

As I said up-thread, I got my GRX’s done after 18 months of use. It lasted 2 rides before I’d taken some of it off.

On the plus side, I’d had them done in silver, so they don’t look entirely rubbish with big chunks of the coating missing.

(for the cost, time and faff involved in the Cerakote process, it would have been more efficient to just buy new cranks)

Unite only seem to do Dub or 30mm?? (and I’ve not heard much good about their CS!)

I’ve double-wrapped the chain stays with heli-tape to get it to stay on better (so it’s sticking to itself) to try stop it peeling off on slender chainstays.

Or on the good old days, used Lizard Skins neoprene protectors wirh good success.  In fact the Orange 5 has 2 if them doing a good job protecting the swing arm from my heels still.

Cranks – yep got several bikes with scuffed up cranks from rub.

(Road bike has survived OK with Helitape, obvs it’s not getting anywhere near the level of liquid gritstone on it than the mountain bike.

I went back to an LX crank on one of the bikes the last time I’d chewed through the crank arm on the mountain bike with the inside of my foot as I couldn’t face spending more just to wreck it.

Fretting usually happens when a bearing seizes. It might free-up but any period of seize would immediately result in fretting. The plastic top hats give a little bit of protection from that. Anyway, stick to shimano, find a shape you like and polish it up if don’t want black/grey. Or for ultimate durability, square taper and middleburn.

I wore the axle on a set of X01 carbon cranks using a a hope bb, few thousand miles and the axle was scrored.

Shimano cranks, always a shimano bb. XTR’s on my stumpy must have 5000miles on them with no wear.

I think the problem with things like Hope BB and its true of lots of aftermarket parts is that they lull you into a false sense of security with their claims of longevity.

The answer to most of these sorts of issues on mountain bikes is ‘disassemble it, and have a proper look’, but the vast majority of us, when faced with dropping the forks or taking off the cranks is in fact a well-worn three stage test that goes:

1. When did I fit this?

2. What’s my presumption of it’s lifespan given how much I paid for it, and the internet’s opinion of how long it should last, and then;

3. Give the thing a turn or a spin and do the ‘does it feel rough’ test. If it doesn’t it’s wheeled back into the garage/shed without nary a backwards glance, and lo; sometime later  you’ve **** something (almost always something quite expensive)  terminally…

Done similar gouging on a DUB with GX crank and SRAM Dub BB x 3 :(

Over the years I’ve had similar experience with axles. Steel shimano ones tarnishing at the bearing point, and pitting so much it developed a small, but irritating amount of play. However, these were run on lots of different bikes, with lots of different BB’s, and I think in the end a cheap stainless BB killed it proper after a bearing siezed and I didn’t notice until it’d worn through the top hat.

my RF 30mm turbines seem OK with the nukeproof BSA30 BB I was using, and are now happy with the non sleeved PF41 30mm hope BB, although I do now pay a little more attention to how rough or smooth my bb is.

the most robust axle I’ve found was on a set of RF Aeffect cranks. 24mm, hard as nails.

I too suffer from big wonky feet, so scuff up cranks and chainsays really quickly. I’ve worn through a cannondale chainstay with my feet and also a driveside XT crank arm. I’ve come to just accept that it’s going to get shitty, though the least scuffed cranks I have are a set of M980 XTR cranks. The XTR label kinks inwards just at the touch pint and the face side of the crank is brushed alu so scuffs don’t notice that bad. kinda similar to the new XTR.

oh and I’ve had no problems with that crank axle either, but I think it’s titanium.

SLX crankarms are marginally lighter than XT, if I remember right

And very durable IME

So I’d say get over yourself and just buy them

Or post a pic of your super-special bike so we can understand how it’s too good for SLX