[Closed] Why are Hollowtech II bearings so terrible?

They're only a tenner at the moment. Stop moaning. 😀

Lack of grease from the factory?

Before fitting new ones ,I now take them apart and pack with marine grease.
Get 2-3 years out of them ,and a lot,lot longer on the road bike sets.

They're failing through their exposure to shite and insufficient sealing.

Stiffness, strength, capacity, simplicity... yeah, great. However the Evolution to HT2 sacrificed the sealing and longevity. In dry, contamination free conditions HT2 would likely last longer, bu that's not the real world.

Before fitting new ones ,I now take them apart and pack with marine grease.
Get 2-3 years out of them ,and a lot,lot longer on the road bike sets.

Sounds good Fasthaggis. How do you disassemble them, is it something that can be done with readily available tools? I've read online that the bearings are a non-standard size so I suspect the 2x pairs Ive got that need replacing are goners.

Directly in the line of fire from crap from the front wheel. Small bearings, high load. Little space for seals. Design is conducive to numpty over tightening.

The first couple of sets I had were awful but they are pretty good these days I generally get well over a year/2500km per BB.

BUT I don't jetwash my bike.

I throw the Shimano ones away and use the same Chris King BB I've been running for 5 years.

2004 called, they want their rant back.

I get about 2000miles off road, mostly muddy from XTR bearings (£12 from germany).

Even my cheap X5 cranks BB is putting in a good showing, and old GXP cranks really did deserve their reputation.

The bearings are fine, they're just not as well aligned as they were in cartridge BB's. Old square taper BB's weren't even threaded, they sat in the frame and two slightly wedge shaped threaded cups went in either side to hold it. Then shimano started putting one of the threads into the cartridge. But because the bearings were in the cartridge not the frame they were perfectly aligned with each other and the axle (until it bent which they were prone to do), they lasted a fair while. Then when HT2 came along it seemed to take a few years for frame QC to catch up and frames to come out perfectly aligned, and some bearings were just woefull (race face and truvative GXP being by far and away the worst offenders) which compounded the problem.

Having said that, I just fitted a new square taper BB to my road bike at the weekend, felt like getting re-acquainted with an old friend, and they really do feel smoother when you can flick them round with your finger and they just keep spinning.

Thought they were impossible to over-tighten as they've sat in cups separated from the threaded part. Not sure how you'd apply enough torque with the plastic crank installation tool or find anything with decent enough purchase.

Not sure how you'd apply enough torque with the plastic crank installation tool or find anything with decent enough purchase.

You'd be surprised, the cups aren't supposed to be "throw all your weight on the spanner" tight, and they will deform if over-tightened. And the pre-load tool should be no tension at all, just push the crank on, and take out the play. The proliferation of CNC'd versions with hex heads doesn't help.

Thought they were impossible to over-tighten as they've sat in cups separated from the threaded part

My thoughts too, but you could over-tighten the cranks onto them I guess by goong nuts with the preload.

Are you a bit free and easy with the jetwash, be honest now.

2004 called, they want their rant back.[/quote

For sure but no ones really come up with a viable explanation as to why they don't do something about making them last.

 

Definitely think GXP goes someway to help them last longer with the over tightening issue being eliminated. Hope ones being slightly larger bearings as well mine are lasting well.

For sure but no ones really come up with a viable explanation as to why they don't do something about making them last.

Well they do last, any I've fitted in the last 8 years or so have lasted at least what I'd class as an acceptable time.

There are plenty of reasons they don't last:
1) Frames were out of alignment, which was never an issue before HT2, but suddenly was.
2) Some of the early BB's were rubbish.
3) Over tightened cups deform.
4) Over preloaded bearings wear out
5) Washing; jet washes, bike wash solutions, WD-40/GT-85, etc, all kill the seals and bearings.

174 miles is my record.

At first, I was getting about a year from new.
Went through three in less than 1000 miles a couple of winters ago, almost exclusively in North Manchester/Bury grinding paste.

Switched bike shops after moving, they suggested drilling the bottom bracket or making sure I stored the bike upside down, which hadn't been practical for a few years.

I no longer ride mostly in grinding paste, just a different kind of mud.
Try and dry my bike out a bit more, now getting about 1000 miles, which seems OK.

Wonder if I should get the BB alignment checked?

Going back to square taper on the new bike.

There are loads of long-lasting alternatives.

£25: Gusset ext 24, mine is seemingly indestructible*, and extremely well sealed. uses standard bearings.

£35: Uberbike, similar to the Gusset, just a little bit 'nicer'.

£80: Hope, not as well sealed as the Gusset/Uberbike, but, y'know, it's [i]Hope[/i]...

BB's for every budget, all of them really good.

(*over 15,000 km, on my commuter/off-road tourer. certainly not a dry-weather sunday-best)

I do as above- I take the shields off and pack them with grease. They last me a years riding through all weather- way over 2,500m. Even then some have been saved by repacking them.

Swap to PF30, then you can complain.

Frames were out of alignment, which was never an issue before HT2, but suddenly was.

That's to do with the BB shell face being perfectly square with the threaded shell body. With old, self contained cartridge type BBs this didn't matter so much. Maybe Shimano Hollotech IIs have lower tolerances to compensate for this.

Maybe Shimano Hollotech IIs have lower tolerances to compensate for this.

They have no 'tolerance' for it at all, if the shell isn't perfect the bearings last no time at all.

It's not just the faces of the shell being parallel either, the threads can be cut at an angle too. If you you get the shell faced they have to align the tool in the BB using the threads, and it's never going to to be perfect because (in steel frames at least) the threads are cut into the shell before the frame is made, so the heat of welding distorts the shell. So when facing/chasing the BB the best you can get is an average of the two threads.

Sounds good Fasthaggis. How do you disassemble them, is it something that can be done with readily available tools?

Take a stanley knife or similar very thin tool and insert under the plastic shield ease up gently working your way round. The shield then pops off, you insert a shedload more grease and then press the shield back into place. you can repeat this next December if you like, but I ride 2-3 times per week in all types of slop and since doing this I have not had an HT BB fail.

GXP are definitely better nowaday after they put a 3rd "O" ring seal on the plastic pipe between the cups.

They're one of the few things I've never really had problems with. Currently running a Saint bb on my SLX cranks with no grief.

The plastic PF30 in my Stumpjumper was literally the most infuriating bike part I've ever had.

thisisnotaspoon - Member
Old square taper BB's weren't even threaded, they sat in the frame and two slightly wedge shaped threaded cups went in either side to hold it.

Old square taper BB's were effectively cup and cone, so of course they were threaded. You must be talking about the ones you could get that could be fitted to a BB shell with stripped threads, although I seem to recall Mavic also making a similar item?

the axle pre-load cap is only tightened 1-2nm

very easy to overload, and often overloaded by mechanics both at home and in bike workshop

[img] http://i1.adis.ws/i/washford/544835?$pd_main_v2$ [/img]

especially with companies making metal tools to tighten this cap

this drastically shortens bearing life

Old square taper BB's weren't even threaded, they sat in the frame and two slightly wedge shaped threaded cups went in either side to hold it.

I think he's referring to the original Shimano BB cartridges from the 90s- with the cup centering the cartridge in the frame.

especially with companies making metal tools to tighten this cap

Yeah that's pretty stupid.

*Just for the record, I never pressure wash my bike.

My chuck it in the shed, never clean it, treat it like crap winter bike is still on its original XT bottom bracket. Which i nicked from another bike. Must be 8-10 years old.

Frame was faced when i bought it.

All of them are.

There's an equation somewhere equating bearing life reduction to axial alignment of the bore...... it's not an insignificant effect.

Old square taper BB's were effectively cup and cone, so of course they were threaded. You must be talking about the ones you could get that could be fitted to a BB shell with stripped threads, although I seem to recall Mavic also making a similar item?

Not the cup and cone ones.

UN-72 definitely didn't have any threads on the cartridge itself. It just came with what looked like (from later versions) two none drive side cups, so you threaded the DS one in, inserted the cartridge which was a plain cylinder, then tightened up the NDS one.

Phil wood used a similar system, as did race-face taperlock BB's.

thisisnotaspoon - Member

UN-72 definitely didn't have any threads on the cartridge itself.

I'm going to have to disagree with this - I've got a 68 x113mm UN72 here and the drive side of the cartridge body is threaded and screws directly into the BB shell, the NDS is then supported by a threaded sleeve which screws into the other side of the BB shell and is a close fit over the body of the cartridge - as supplied, they have a non-hardening compound inside the NDS sleeve to prevent fretting.

garlic - Member

Thought they were impossible to over-tighten as they've sat in cups separated from the threaded part. Not sure how you'd apply enough torque with the plastic crank installation tool or find anything with decent enough purchase.

The conical BB's are for use when you've mullered the frame threads, actually quite good IME. Hollowtech are shit because theres no money in BB's that last ten years.

Bottom LH

[img] [/img]

The early ones were DS and NDS loose cups. Later ones had fixed DS, can't remember when they changed though.

I'm going to have to disagree with this - I've got a 68 x113mm UN72 here and the drive side of the cartridge body is threaded and screws directly into the BB shell

Just fit stainless steel bearings in their place, or [url= http://www.chainreactioncycles.com/hope-bottom-bracket-ceramic-bearing/rp-prod36418 ]Hope[/url] ceramic ones from CRC.
Standard size (37 x 24 x 7 if I recall)

Do people not get their threaded bottom brackets faced anymore?
It's not expensive for an LBS to do (although a decent tool can be costly) and along with not overtighteningbthe cranks it pretty much eliminates poor performance of HT2.

Tom KP

I've fitted 2 hollowtechs to my road bike in the past year and there's play in it again, so I'll soon be on number 3. Tempted to go back to internal BB, but I suppose I can live with it given they cost a tenner. It just seems a bit of a flawed design if they need changing every six months. Yes, you can expect some wear, but internal BBs in comparison last years. They could at least make them serviceable.

I've got a few old UN72's in the garage. Some are threaded on the driveside body and some have a push on threaded cap. So you're both right/wrong.

Think I remember the early sealed Shimano BBs being a cart contained and centred by two threaded caps.

I was having to replace Deore ht2 bbs frequently (weeks) sometimes after one wet ride they would be filled with rusty water. The XT bbs different story, getting months, always clean inside. Don't know what makes them better but the bearings are definitely bigger. Sometimes sold cheaper than Deore too.

Some Deore leave the factory with little or no grease in them, had no issues with XT.

We makey shit in third world shacks that not as good as the old shit, sell it to you cheapish, then sell stuff that works like the old stuff for premium price yeah, what don't you get you idiat, now open your wallet and STFU.

Don't forget popular colours and sizes will cost you more demand-n-supply innit 8)

so the heat of welding distorts the shell

(+1 for packing with grease - including between "shield" and top hat thingy and also drilling the BB shell)

I've got 5 bikes with these BBs, all bought as insurance replacements in 2007. Since then I've replaced.. three. And ridden plenty. Once on the road bike, once on the 5 (when I sold that frame and built the Salsa I re-used the old BB and to be fair, one side was a bit grobbly. That was a year ago). The one on the Patriot went quite quickly to be fair, it was replaced with an Acros one.

Can't imagine what you lot are doing wrong. Maybe Kona and Orange are better at facing BB shells?

Not had any real issues with HT2 BBs, never bothered having a BB faced, until my recent London Road purchase, shagged two BBs in quick succession, decided to switch back to square taper due to nostalgic leanings, fitted the NDS cup and noticed where the cack handed welding has apparently distorted the outside couple of threads...

So far the square taper seems fine, more tolerate of cockeyed PX QC and my tubby arse heaving on it, if it gives up though I am probably going to be chasing PX... 🙄 joy...

TBH HT2 needs the BB threads to be nice and concentric and the outside faces parallel to one another and perpendicular to the thread... As well understood as frame manufacturer is now, these things still aren't guaranteed.

The various current press fit standards are intended to address that issue by being [i]easier[/i] to produce geometrically correct, but they've sadly failed by constantly trying to squeeze bigger and bigger axles in. Reducing the bearing section and ballsing it up...

I still see MTBs and cross bikes as more "agricultural" bits of kit personally; bigger bearings are more useful than a fatter, stiffer axle and lower weight... Personal preference I know.

The best BB [i]standard[/i] ever? US / BMX type, big fat bastard 2" OD and 3/4" ID Bearings, weighed a ton, very much an agricultural design, utterly indestructible...

Just be happy you haven't got a push fit BB....

TBH, i dunno what all the love for square taper/pre HT2 is about, mine used to do a season. Pop it in before the first race in March/April, wobbling by November, run it into the ground over the winter. Replace.

The only ones I've had that have lasted longer were either eye wateringly expensive (hope Ti, campag record) or serviceable (M950 or Dura Ace octalink)

I think it's location and bike related. I destroy them on my singlespeed in winter in weeks, can get two years out of an XTR in my geared full sus that avoids the worst of the much.

Based on recommendations from this parish I purchased the a Gusset, took it out yesterday after installation in September. It's totally goosed. I know the bearings are replaceable but I'd still expect them to last longer, the sealing from the plastic top hat is absolutely awful.

Single speed seems to exert more load on them and I ride it pretty exclusively in horrible filth. Never jet wash though.

The Gusset
[URL= http://i1162.photobucket.com/albums/q525/Pictonroad1/AAE02746-67FF-4B2D-994B-E84893027201_zpsdiokmvrq.jp g" target="_blank">http://i1162.photobucket.com/albums/q525/Pictonroad1/AAE02746-67FF-4B2D-994B-E84893027201_zpsdiokmvrq.jp g"/> [/IMG][/URL]

been running an XTR BB most recently and that seems to have lasted really well including about 50 river crossings in Iceland this summer.

used deores before but they sometimes only lasted weeks.

I REALLY dont want to be looking at a man's used gusset before lunchtime!

i go with no washing at all for ht2, the design flaw IMHO is actually the plastic top hat shield and the internal sleeve... the top hats hold the water in against the bearings which then rust and the inner sleeve directs any water in the seat tube to the bearings too. Since I've stopped washing ht2 bearing life has been over 5 years.

shells are way thicker than the yubes welded to them aren't they - why aren't seat-tubes like curly wurlies ?

We're not talking FUBAR, fractions of a mm would be enough. BB shells should be perfect when they're new, they then get distorted during welding and need facing afterwards. The reason the seatube isn't curly-wurly is the frames are put in a straightening jig afterwards to remove the curly-wurly-ness.

And the thicker tube needs more of the heat from the torch, you still need to get both bits of metal up to the same temperature.

Have never had any problems with HTII tbh

Admittedly the old cartridge BBs seemed to last forever but ime HTs are fine. I get bored with them before they wear out

I can't see, given the constraints, that sealing can really get any better for BBs. All my BBs die from corrosion, usually after standing for a week or two.

Rough bearings after they've rusted a bit destroy them selves in record time.

Bikes I use regularly through filth seem to be much better than those I use intermittently in filth. I suspect this is to do with turning wet bearings through grease regularly.

I've just put a hope stainless in to remove the corrosion issue, so I'll see how it goes.

Can't remember the last time I wore out an XT BB...must be well over three years now.

I suppose it depends on conditions, round my way I don't get to immerse my BB in filth often.

pictonroad - Member
...I purchased the a Gusset, took it out yesterday after installation in September. It's totally goosed. I know the bearings are replaceable but I'd still expect them to last longer, the sealing from the plastic top hat is absolutely awful.

that is odd, the plastic top hat on mine wraps around the bearing on 3 sides, creating a very effective labyrinth...

(and then the cartridges have standard seals)

All threaded BBs and ridden and raced in all weathers. North Wales slop makes lovely grinding noises too... nice.

Deore BB50 < 500 miles. Very poor OEM on a bike.
replaced with XT BB70 > 1500 miles with me + still going strong with new owner.
RF DH BB < 600 miles - had play in it OEM on a bike.
Hope BB < lots of play from previous owner who'd only had it on for few months (claimed)

Kept the Hope shells incase I can get the bearings replaced one day but but I've no idea what previous owner did to it to destroy it in such short time unless the RF crank it had on was fitted wrongly somehow. When XT BBs are £10-£15 each I'm not going to worry.

Currently using:
XT BB70 with 300+ miles so far. Installed August.
RF Cinch 30mm with 250 miles so far. Installed July.

I have a lot more confidence in the XT BB than the Cinch one but need it for the 30mm axle on those cranks so stuck with £35 a pop and just hope it lasts ok.

I try not to use hoses but in winter when it's wet and muddy anyway and the bike and I are completely soaked I use a £3 garden sprayer bottle to gently push the worst off as soon as I get home. In the summer I let whatever stuck dry and knock it off with a brush the next day and use a cloth and try not to use water unless everything was soaked anyway from the ride.

So this alignment thing...does it knacker the bearings in itself or does it cause flex/deformation of the seals letting water in and [i]that's[/i] what kills the bearings?

I've had one frame BB faced but not the others, BB life seems pretty hit and miss, some last ages, some only a couple of filthy rides (and the long lifed ones are normally killed by a really wet ride). The faced frame seems no different to the others.

Oh and IME not doing the cups up well bastard tight usually results in creaky bottom brackets. But yeah a light touch with the preload tool.

<edit>xt/xtr [i]seem[/i] to last longer than deore ones but as I said a really wet ride can kill off BBs so I use cheaper ones on my winter bikes, this probably results in cheap BBs consistently being taken out in shitty conditions and dying early reinforcing the [i]cheap BBs = shit[/i] theory.

So this alignment thing...does it knacker the bearings in itself or does it cause flex/deformation of the seals letting water in and that's what kills the bearings?

Oh and IME not doing the cups up well bastard tight usually results in creaky bottom brackets. But yeah a light touch with the preload tool.

IME, and I only noticed this after using a torque wrench, HT2 BB's spin a lot more freely if the cups are torqued up correctly (and the threads are cleaned properly first, and a light smear of grease). I conclude it is possible to significantly deform the BB cups.

Same with a UN-55 I fitted the other day, felt notchy, removed and refitted at the correct torque and it's fine.

It'll be out of alignment bearings, the seals should be flexible enough.

As this thread has expanded somewhat does anyone care to give a numpty (me) an overview of the mechanical principles in your typical Shimano BB/crankset installation. Specifically I'm thinking the purpose of that little preload cap and the groove/shim behind the non-drive-side crank. I change cranks sufficiently infrequently that I always forget the "proper" way to tighten all this and no doubt I've done it wrong a few times.

HTII BB's seem fine to me, tend to get 1000 off road miles out of them,which is approx 1 year of use in all weathers and conditions up in the peak district/north wales. The bike rarely gets washed as well.

And at a tenner per BB, its no big deal to replace yearly.

I'm not normally one for recording the wear life of components but I notice that the Burls frame I'm about to sell has over 1,500 miles on it. It had an XT BB fitted when built. That had come off an El Mariachi that already covered a similar distance and I've removed it for refitting to a new hardtail frame. It's in perfect working order.

The XTR BB on my Blur is the same one fitted from new 5 years ago. At a guess, I'd say that's done over 3,000 miles,probably nearer 4,000.

I did have to replace the Ultegra BB on my Amazon last year but that had done over 6,000 miles, including winter commuting, a LeJOG and various off-road trails.

None of these have had any special attention.

@ rossburton
HT2 BBs work on the same principle as threadless headsets. All you are doing using the preload cap to remove any side to side movement so the axle is held in the same place. Too much preload and you side load the bearings causing premature wear. Too little and the axle moves side to side.
REally there is very little preload required. What I tend to do is puch the driveside crank firmly into the BB and then put the LHS crank arm on and use the preload cap to pull the crank arm in until the rubber seal starts to contact the the outer face of the plastic bearing cover, then perhaps a quarter of a turn more.

i just take out the end float, then check it on the next ride, and if any end float has developed i back the crank off and nip it a smidge. i used to kill the quite routinely but now i do the above they seems to last pretty well. as others have said, if you clamp them down tight, you'll kill them quick.

I was thinking about this thread this morning as I trundled in on my ~1300 mile old 105 HT2 Road BB which is still perfectly fine.
I don't think sealing is really the main issue, its a contributing factor perhaps, but fundamentally it's comes down to "Modern" two piece cranksets using crap bearing [u]for the application[/u]...

The main reason my relatively cheap road BB will keep on going for a fair while is the nature of it's general use, it's going to see a bit of torque (probably not that much in my case), lots of steady revolutions but not a great deal of static loading, and probably not too much in the way of axial loads; I sit in the saddle and turn it over for miles on end, I might stand up for a steep climb now and then and it gets a bit more leverage/side loading but it's still turning, this loading is still dynamic, no drops or jumps, battering across roots, very little levelling of the pedals to stand and rattle over stuff, very seldom dropping the outside pedal, standing and leaning the bike over into a rough blown out turn...

Basically half the things you do to an MTB or cross bike when riding it are rather bad for BB bearings;

Bearings don't like static loads, but that's precisely what they get on offroad bikes. HT2/BB3/PF86/PF92/etc all have tiny cross section bearing, which will have bobbins static load ratings, minor misalignments certainly won't help in this respect either. On top of that most newer BB Standards fail to provide any internal support for the inside bearing race; in any other field you would design an internal support between the two bearing so they could transfer/share axial loads between them, remain better aligned and support the axle, without doing this you can't properly pre-load the bearing assembly (Hence the finger tight-only end caps) and it's easier to induce twist in the bearings, helping wear them out faster, this would probably be OK if your BB only ever saw smooth, constant load purely rotational loading, but it doesn't, road bike usage tends to be closer to the idealised conditions for HT2 BBs so they seem to survive longer...

Hence [i]old fashioned[/i] Square taper cranks, despite the noodly 17mm axles and portly solid construction, still beat HT2 in terms of longevity for MTBs because the bearing assembly was actually designed properly for the application...

My '96 Orange is still on its original square taper Shimano BB

The Hope one on my son's bike came off my Ti HT which came off my steel HT - so started life in 2009; still works fine.

I've also a Hope ceramic sat on the shelf as my Ti HT has 'crumbled' the BB threads on one side so won't tighten anymore - reckon that's had a fair few years use. And the Saint BB which is now on the HT (longer threads) has had two years use.

I reckon it's mainly a maintenance/installation issue.

maintenance?

How should I be maintaining my sealed bearings to get more than 8 weeks of winter use out of them?

As a side note, talking about lifespan in years is entirely misleading,
miles is better, but its still very much conditions related.

FWIW, I've got a BB that was installed in 1995, it still runs perfectly, it's done **** all miles though, and the ones it has done have been mostly dry.

I've also killed a brand new UN55 in a single 24 hour race, but the conditions were horrendous.

But, I've also got a BB that was installed in 1986 (by a previous owner) has done LEJOG twice, toured around France and Spain, been used as commuter through the 90's, winter training bike in the naughties and is now doing duty on a winter SS for me, the reason it's lasted so long? It's a decent old 3(5 really) piece assembly with independent cups, big adjustable ball bearings and properly assembled and maintained and reasonably well sealed with rubber contact and lip seals and a fair helping of marine grade grease, and you know what, if it ever does die, new balls are peanuts, and if it needs total replacement, its a mere £25 for another one.

I have HT2 outboard BBs on a couple of road bikes but stick with Square Taper (and even ISIS/Octalink) on anything that sees a lot of mud and is likely to end up underwater at some point.

Most modern BBs (regardless of flavour) are not built to be serviceable or adjustable, if they were we'd get much longer life out of them with a little bit of occasional maintenance, but the trend for fit and forget and non-serviceable parts currently can't keep up with the use requirements.

pictonroad - Member
maintenance?

How should I be maintaining my sealed bearings to get more than 8 weeks of winter use out of them?

i don't know *what* you did to your gusset (fnar), but there's simply no way that much filth could work it's way into mine.

15,000km out of mine so far, all i've ever done is cover it in mud, and rinse it with road spray/dunk bike in a loch.

I think @cookeaa has it about right: the bearings in BBs are designed to work as an axle bearing around a rotating shaft within an outer shell not as a shock absorption system between the same parts.

Re the pre-load: I lightly finger tighten using the plastic tool then back off 1/4 turn. Maintenance tends to be pre and post winter unless I feel roughness or a clicking the latter usually indicates grit in the threads of the BB shell so a quick clean and re-grease and all is well.

Some things I've learnt on this.

Some frames are worse at getting water into the bb shell. Water can get in from the stays and the seat tube. It's worth bunging these.

I've drilled my bb shells to let water out. Once in water sits against the bearings and does the damage.

The cheap deore bearings are not sealed on the inboard side (where water sits) and do not last in bad weather.

Xt bearings have lasted me better, on one bike that ate bearings after each wet ride I found some ceramic sealed bearings that went into the oe cups and lasted ages.

Preload is key, I killed a hope ceramic last week with too much preload from a crank which would not fully seat (i swear the instructions for no. Of spacers are incorrect).

Don't hang your bike on its side after a wet ride (like I did on the underside of the roof) as water sits on the bb bearings.

I've recently changed a Shimano press fit and standard threaded jobbie, TBF at least it's a lot less faff than square taper! Both looked like the photo posted by pictonroad on page two, both had seized on the non-drive side.

Seems to be a recurring theme, the non-drive side cartridge bearing letting water in, washing away what little grease may have been in there and no I don't go mad with a jet wash either.

I did 4000km in 4 months over the summer/autumn on a drivetrain with an XT BB. At the end of it the BB was shagged - as the was the drivetrain. First time I'd used an external BB, and initially wasn't overly impressed - older square taper setups lasted much longer. On reflection, though, I'll take the ease of installation and the fact you have to carry fewer/less bulky tools on a long, self supported trip. Just consider the BB as a consumable, part of the drivetrain. Nex time I do intend packing out the bearings with marine grease, pre-installation, just out of curiosity.

alexh - Member

The cheap deore bearings are not sealed on the inboard side (where water sits) and do not last in bad weather.

Deore also have softer bearing races and so even if completely clean and dry wear faster (and, er, if you stick one in a dh bike it's worn out after 8 runs at fort william and barely turns after 14. CLONKCLONKCLONK.