Acceptable component failure rate rant

DUB and GPX don't last long. I tend to re grease mine if I've had a particularly boggy ride.

I've had great success with the NP horizon Dubs
however.. if there's an alignment issue in the BB on the frame you could struggle, so rather than the BB being at fault, the frame could be

DUB on our Privateer is 12 months old of complete and utter slop fests regularly.. still working nicely

My experience of Dub has been woeful. I managed to get two months of summer riding (without jet washing) out of a Nukeproof one. That was replaced under warranty but went through 3 in less than 1000 miles. The last one (touch wood) has lasted a whole year and is still ok. (I say whole year... it is on a bike I only use in summer).

I've also had a couple of instances of the tensioner working loose mid ride. 

I've switched to a Praxis works BB - I just replace the bearings !

I'm still on GXP... pop a new one in every spring... need to do one now (no, it's not spring, but it's gone early).

I have no personal experience with Sram DUB BBs, but it could be misalignment of the BB shell faces and/or threads causing premature wear of the BB. It would be worth getting the BB shell faced and chased to rule this out. All it takes is for there to be paint on the BB shell faces or paint/swarf  in the threads or the shell faces not being square, to set up the condition for rapid BB wear.

Check the facing on the BB shell.

Theres a paucity of material in the alu bearing of a dub BB cup (assumed BSA) due to the increased bearing size and if the BB shell isn't flat you get deflection in the BB once its tightened against a non flat face. Then you under-rotation from bearing binding. Also check the alloy crank axle for witness marks that show this.

They are poor in my experience. Tiny bearing size and rust up if not attended to. Might be worth a hope with stainless bearings or similar for longer term...

MTB component longevity and reliability is an absolute joke.

BB's are particularly bad for clearly not being upto the task intended by design.

But SRAM brakes and their godawful lever reliability.
Shimano brakes and their calipers.
Crank brothers and their pedal bearings.

I think everyone accepts that stuff doesn't last in the UK in winter. We either pay HOPE or Chris King money for a BB, or pay £10-£20 and replace it as often as required. I'm sure some people make use of the CRC 365 days returns, but a lot of us just don't bother.

And to an extent other stuff breaks because it's used in a harsh way. Shocks blow up, things bend, etc. It may as well say 2 year warranty unless actually used. It's the same deal as motorbikes outside the road-going mainstream. Ohh your KTM TPI blew up another engine for the 2nd time this year, tough, page one of the warranty says there is no warranty.

But the amount of stuff that's just badly designed for the job. FFS, people didn't look at GXP and think it needed to be lighter*, they complained it had awful durability. DUB should have been SRAM quietly admitting that a "Durable Unified BB" looked like a 24mm spindle like everyone else.

*I assume my GX crank is probably heavier than SLX, but it's the longevity that'll mean it goes in the bin in favor of an "upgrade" to a 10 year old shimano crank from the spares bin, not the weight.

Axle being 30mm the bearing are too small, get a BB with oversized cups so the bearing are bigger. Options are Hambini, Wheels Manufacturing, probably others too but they are expensive.

Also as above could be poorly faced or misaligned BB shell.

A previous thread about poor DUB BB's

https://singletrackworld.com/forum/topic/sram-dub-replace-bearings-or-just-replace-whole-unit/

bloody stupid BB tool to go into my box of obsolete StOOpiD tools like square taper crank-pullers

Well it sounds like you’ll get plenty of use out of that new tool.
Every cloud and all that.

my road bike's dub bb is clunking at around 2000km old. That's more than some of the mountain bikes, but poor for something that has relatively few rotations per mile and comparitively few impacts

3,500 miles on the stock DUB that came with my Spur, still going strong. Usually bone dry where I live though so could be an issue with crappy sealing?

Yeah, it the wet that kills Sram BB (other replacement brands may differ) for sure.

I used to go through a couple of XT bottom brackets a year when I lived back in North Yorkshire. Water ingress does indeed knacker BBs.

Dub threaded bottom bracket is a disaster. Just because the odd one has lasted doesn’t mean they are ok. Shop mamechanics are clearly not seeing great life from them either

I’m have a sram dub that was on a bike I had for three years and never touched it, moved it to the next bike and that’s also been two years without any action needed on it. Ridden in all conditions.

Obviously they are not reliable for many people but I’ve been lucky it seems. Mind you I struggled to believe the threads about shimano brakes until I then had a run of micro leaks 😂🤦🏻‍♂️

As others have already mentioned, I’d bet the BB shell isn’t square.

The NP BB on my Scout didn't even make 150 miles (and that's being generous). I'll flush it out and repack it with grease and it'll do as a spare. It's nowt but brown murkiness in there at the moment.

It's nothing to do with luck. Premature failure is because its been overtightened on the preload collar .

It’s nothing to do with luck. Premature failure is because its been overtightened on the preload collar .

thats my view - I normally leave a tinsy bit of side to side play - somewhere between a smidge and a gnats baw hair. can't remember when I last had to replace a BB bearing

there is almost no side to side forces and no need to load up the bearings - there is no sleeve taking the load between the two inner races so any preload will be stressing the bearings

Edit - I also believe the failure mechanism is the bearing fails, allows excess radial movement and this destroys the seals allowing water in - so superficially it seems like a water penetration has caused the failure but in most cases I believe its the other way round

Over tightening - and (over) washing. Recently replaced an MT800 on the mountain bike at 6870km (still useable, just a bit rough on the LHS). The gravel/commuter is smooth with a lot more mileage than that on it. Never bothered facing BB shells.

They don't last as long as good quality square taper but, viewed as drivetrain consumables, I'll take that in exchange for ease of installation/removal (and not occasionally having to remove nice cranks with an angle grinder).

I've always faced my frames BB shells and had decent longevity out of almost every BB (Shimano XT or Uberbikes usually) apart from a ceramic one that went a bit crunchy within a couple of months but only the driveside cup, never trusting ceramic bearings again. Threaded BB shell is a must for me along with Shimano's trusty 24mm axles, I wouldn't dream of using any 30mm or dub axles in threaded BBs or dub full stop.

Firstly BB are a disposable item. You may not feel like they should be, but component manufactures are making them like that. Secondly, echo the comments about longevity and installation, they need to be just put in, not tightened enough that they'd hold back a locomotive. I normally get 18 months-couple of years and 2-3k of mileage from DUB BB, and got the same from Shimano, It's entirely possible that its not the component that's the issue. 

GXP on my last bike. First one lasted 300 miles. The next one (Hope) lasted 7 years.

DUB on my Whippet is 3 years old and seen plenty of mud. Still fine.

I'd still bring back aquare taper though. Nothing wrong with them and lasted forever.

First dub bb    2000 miles    second one is now 1500 miles in ..   I dont see some things as fit and forget . Strip and quick grease .

Of course I'm not suggesting the thing should last for ever, and yeah there could be other factors at play of course, just fancied having a moan.

Installed the Nukeproof last night, bb shell on the vandal looks well made, threads are clean, I don't have tools to check how aligned the faces are (does anyone?) or face them if not.

Nukeproof bb is definitely a step up in quality, and with replaceable bearings, that have a two year warranty I guess that's as good as it gets for £50.

I used a torque wrench to install the cups, despite my petty rant about having to use a new tool to remove/fit DUB bb I was actually impressed by how much more secure it was on the bb cup compared to the Shimano equivalent, so that's an improvement I wasn't expecting, and I was careful not to over-tighten the DUB crank tensioner and then went for a ride.

All feels nice and smooth, had a nice ride and a couple of pints, all good.

@Scienceofficer agreed on the facing. I went through ca.£140 of bearings, not bottom bracket assemblies, bearings with my Trek Crockett due to the bb shell being 1.5mm out on the NDS. The fault would have been spotted sooner but due to the great plague the shop couldn’t get hold of a T47* facing and chasing tool for some months. Trek immediately replaced the whole Frameset.

As many of my bikes as possible now, I fit square taper to. I’m done with being a contributor to waste through external bb’s.

*T47, because of course we need yet another standard.

Nukeproof bb is definitely a step up in quality

I got about 2 years from mine. The mechanic that I use to change bearings on my frame described it by that point as "****ed beyond anything I've ever seen, you're an idiot for leaving it in that long" while I maintain that I got my money's worth. We've agreed never to speak of it again.

5300 miles on an XT BB, ridden in all weathers. Bike gets carefully pressure washed.

Alignment of the BB faces is super important for bearing life. Sworks stumpy frame has been done by the shop and it goes to show. The Geometron is also on the same BB I fitted 3 years ago, 3500 miles of being battered and mistreated and its still fine.