External Bottom Bracket Lifespans

[naff_monk]

Wish I'd have seen this a couple of years ago before I specc'd two bikes with these. Thought I'd add my experiences even if I'm a bit late on the uptake.

First one, still alive.
Orbit Carroway built late spring 2011 with 105 bb has done approx 3k including a LEJOG and a welsh end to end and still going strong. This is being used by my girlfriend so hasn't had to endure excessive weight/power transfer but also has not been looked after. She never cleans/services her bike, ever.

Second one, dead (nearly).
Bob Jackson audax built early 2012 with tiagra bb (105 chainset). Done a similar amount of miles but in a smaller time frame, same LEJOG and wales but a lot more climbing around the peak district/ribble valley etc and used for city commuting daily since it was built. I am also 90kg so it has received a significant battering in comparison to the first although I don't think that excuses it though, very poor quality kit. It is currently making clunking and loud cracking noises, I've been riding around on it with a 105 replacement in my bag for about a month waiting for it to die, it's still going for the time being but my god those noises are annoying.

It is a shame that the bb's are so unreliable because I really like the format. Being a heavier rider, I can really feel the difference in stiffness, my veloce three piece I had before this didn't feel anywhere near as robust as this setup, I felt like I was constantly having to tighten the crank bolts. I really wanted it to be good for touring as well purely because it meant that I could remove my chainset with a single allen key which would have been great for servicing/cleaning on multi week tours. As it goes, I'll be building my touring bike with a un71 and I'll just have to get over it unless anyone has any suggestions? Maybe the Dura Ace is sealed better? (more likely -> They are the exact same piece with a different paint job)

Ho hum.

[ankaradan]

I'm very interested in this thread, as I am at present looking for a new touring bike, one that is not going to need parts replacing after a few months on the road. As a contrast to peoples experiences here with external BB's, in the late 70's I put together a 531 fast touring bike which I used on a daily commute of 15miles virtually every work day for 6 years, plus regular long day rides and the occasional tour. I don't remember the model of BB, definitely square taper, but on the daily commute alone it covered 18000 miles. I sold the frame on ebay (a stupid, much regretted decision) just before I moved out here, still with a perfectly smoothly running BB.

[[XAP]Bob]

I think we *know* that good old square tapers will last a lifetime.

Externals should be able to last similarly (although I'll be mighty tempted to get a Schlumpf HSD if my BB does fail)

[irc]

There does seem to be a bit of a trend showing here.

Early failure due to either overtightened bearings or water ingress within the first few thousand miles.
Then failure through wear alone centring around 10,000 miles.

Another one here. My Surly Trucker had a Deore HT2 BB which I replaced after about 11000 miles - almost all loaded touring. At that point the o/s was still fine, the N/S was a bit worn but usable. I hadn't noticed any issues in use.

The frame was faced before initial fitting. I had the cranks off once during those 12k miles. When replacing them the tension adjuster was done up snug finger tight only.


Given that in a 3000-4000 mile tour I'll go through around £50 of tyres, and a chain and cassette at maybe £50, the cost of a BB at £15 isn't a big issue every 10'000 miles or so.

My everday rigid MTB has a Deore BB as well. No issues at 3000 miles in all weathers.

[willcee]

HI, i have 2 carbon bikes, equipped with Campagnolo outboard bkts first is ultra torque, good... newest is power torque,and its not getting great reviews and isn't easily worked on.. also 2 FSA mega exo equipped bikes , and another FSA en route, i haven't had any issues on any of these, all under 1500miles to date.. ime as someone who does serious work on racing bikes ,servicing, repairing , the initial fitting is crucial, too many heavy handed sideplay adjustments , how?? i don't know as on Shimano its a plastic bolt and a small plastic handheld ''spanner'' key..perhaps a lack of feel... maybe a lot of affected bikes aren't trued in the shell causing side wear on bearings, lets not forget that the Japs while being good engineers have no real experience of our cold wet damp UK climate and while they are selling lots of bearing kits they are happy... the seal designs are woefully inadequate , i find out recently that Campag super record power torque hasn't any seals at all !!! my own reports from racing men are that some get a season some 2 seasons..on dura ace.. definitely don't have a power wash anywhere near outboard bearings or any other bearing , the seals are challenged keeping atmospheric pressure at bay never mind 1500 psi.. it would be interesting to see what the guys in USA have to say on this matter and perhaps the continent, personally i have drained nearly 1/4 pint of brown water out of a 2 year old well raced Giant TCR advanced while refitting the BB86 set up which are interference fit inboard BRGS using the very same cranks, and 24mm axle as hollowtech shimano.. water and bearings aren't good companions as we all know,.. he got maybe 5000 miles from ultegra stuff.. will

[pliptrot]

Willcee, are Campag now offering power torque on Super Record? I'd suggest the Japanese have plenty of foul weather to contend with, meaning they should know a thing or two about how to deal with it. It's Campag, after all, who tell you that a chain should never be removed from the bike for cleaning....and other hopelessly impractical directions. The cynic would say that external BBs give the manufacturer a steady income from regular replacements, and LBS get steady revenue from fitting them. All good for the industry, all bad for the customer.

[Brucey]

I'd suggest the Japanese have plenty of foul weather to contend with, meaning they should know a thing or two about how to deal with it.

they might, but a lot of their R&D work is done by an indigenous team working in their biggest market, the USA. Specifically in California. And a fat lot of good that is.

It's Campag, after all, who tell you that a chain should never be removed from the bike for cleaning....and other hopelessly impractical directions.

Just like Shimano then. They both have used 'special pin' chains for years, to the exclusion of everything else. They are not designed to be removed for cleaning in either case.

The cynic would say that external BBs give the manufacturer a steady income from regular replacements, and LBS get steady revenue from fitting them. All good for the industry, all bad for the customer.

Maybe. They feel that market competition forces them to innovate; without change they will get left behind. Sometimes the innovations are ones you don't see, in manufacturing technologies, which mean that bikes and parts are better quality and better value. Sometimes it means that the customer is saddled with unproven technologies that don't meet their needs.

As an engineering exercise, external BBs are brilliant; lighter, stiffer, stronger than the alternatives. The fact that they may not be as reliable as alternatives in properly wet weather, and that there is a large market where the rider's don't especially desire or require the lightness, stiffness strength etc is neither here nor there. As long as the primary buyers of new bicycles are leisure riders of various kinds, others (such as tourists and commuters) will just have to make do with variants of whatever is flavour of the month, and the bicycle makers think will sell best to the masses.

BTW some campag BBs don't have seals because they 'don't need them'. Ceramic bearings I think.

cheers

[meic]

I have replaced mine at 7,700 miles. Still working fine but the nearside was very rough from having got wet a time ago and it still had that bit of movement in it. Possibly being a bit too perfectionist
I may knock out the bearing race on that side and replace it and then put it back in service if the Tiagra which replaces it isnt as good as the original FSA.

[RJS]

Just seen this thread, my vote was 3,000 4,000, replaced an XT bb with a hope, probable done 3,000 still OK, the XT wasn't knackered, it was stiff, the grease had dried up, ignored the the do not disassemble notice, repacked it with grease, it's sitting on the shelf , might need it one day
Cheers, Rob.

[[XAP]Bob]

3+ years and four winters of daily commuting... still going fine.

not having a bike wheel in front probably helps, but they're not all obviously short lived - probably 7-8k miles on mine, still running smoothly and no sign of corrosion when I took the cranks off to replace the chainrings recently...

[markjohnobrien]

My Pearson Compass touring bike has a hope stainless BB and it carries heavy loads (I'm 17.5 stone down from 20) with four panniers and has done 6000 miles so far without any problem hauling me about in the Chilterns (commuting and leisure); North Wales, North Yorkshire, Devon - all hilly - without any issues.

Only external BB I've used but I did my research and these, generally, seem to be among the best you can get and seem to last longer than many Shimano external BB. A compromise between a poor Shimano and an uber-expensive Chris King; very pleased so far and it looks nice on the bike - red to match the frame

[gerrymcm]

Hi
Not sure how to vote is it enough to simply post here?
Edit. After posting this I realised after logging there are buttons to vote.


I've had two shimano tiagra ext BBs go at about 3000 miles and I was not impressed as my previous (much cheaper) bike from halfords had a traditional square chin haur make and lasted at least 14k miles. I've gone back to a shimano trad square bb but with a poor quality cranks from the parts bucket. I intend at some point to go back to a new Shimano ext bb but with better cranks and try some of the tricks suggested here I.e. Better and more grease, reversing the black cover plate to waterproof the bearings etc and see if I have more success.

Is it simply the increased exposure to the element that shortens their life ?

Gerry

[LollyKat]

Poor design too, I believe. I think Brucey said (of the Shimano ones) that the ball bearings were small and not many of them. I'm sure he'll be along to give more details.

[Brucey]

Poor design too, I believe. I think Brucey said (of the Shimano ones) that the ball bearings were small and not many of them. I'm sure he'll be along to give more details.

I posted in another thread the exact number and size of balls in external BBs. It isn't as many as you might think and they are not as large as you might expect either; this is double-bad because the load bearing capacity of a ball goes as the square of the size, so one (say) half the size has 1/4 the load capacity. But the bearings are (when lubricated correctly) adequate for the intended service loads. The problem is that they are not adequately lubricated and they don't always see the intended service loads either.

The intended service loads are actually about half those seen by the bearings in a typical ST cartridge unit; the reason for this is that the bearings are almost twice as far apart, which is actually a Good Idea. However the tiny smear of grease they get, the poor seals, the scope for misalignment, and the scope for excessive preload all conspire to reduce their life significantly.

BTW there are a few reports of failed ST cartridges such as the normally reliable BB-UNxx series. These are normally reliable because the installation loads have only a weak effect on the loading seen by the bearings. However if you have a tight-fitting/misaligned BB shell and/or install a BB unit using a mighty torque, the bearings can still see a significant preload. I was recently reminded of this when I reinstalled a well-used UN52 BB unit. It was the only one of the correct length I had to hand at the time, so on it went, despite the fact that it had a little play in the bearings. 'It'll do for a while' I thought to myself as I wound it in. However once it was all the way in (and well torqued to boot) I noticed that the play had gone; clearly the bearings would have seen a considerable preload force had the unit been similarly installed to start with.

Excess preload is almost impossible to detect in new bearings of good quality; it feels almost exactly like seal drag. This has been the downfall of many a good quality component.

cheers

[tim-b]

Hi

Truvativ GXP on my commuter, 8500 miles and three winters so far.
http://www.sram.com/truvativ/technologi ... om-bracket if you want add technologies into the mix. It happened to be fitted to a bargainous bike.

I've got Shimano Hollowtech II on the other bikes, but they're many miles younger

I've not voted because (whisper) they're all still going (oh dear!)

Regards
tim-b