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external BBs - how long do yours last?

Im getting frustrated with my external BBs, I dont seem to be able to get more than 6 months riding out of them. Ive checked all the usual stuff, bb shell is parallel, clean, well greased, correct torque etc, even after getting a new bike Im still not getting much life out of them.

So far Ive used all shimano ones - Tiagra, 105 and ultegra, not much difference in them either really.

So whats going wrong? should I just accept theyre weak and get a Hope SS one?

If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.

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21 comments

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Jack Osbourne snr | 7 years ago
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Update on my "get shot of PF30" saga... Have now fitted the BSA adaptor, Shimano cups and the required new chainset. So far so good.

There is one huge difference... The cranks actually spin now. The drag is so low that with the chain off the crank will happily make several revolutions before it starts to pendulum. NEVER got close to that with any of the PF30 assemblies/bearings I've tried up to now.

Wish me luck as this is my last attempt at a fully functional bottom bracket with this frame.

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Judge dreadful | 7 years ago
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One of my bikes ( the hell and high water one ) has external Sora cups. I keep them clean and lubed, and so far they are at 20000 miles (including some horrific winter conditions) and still as good as gold. My internal BB bike, has yet to get past 3000 miles ( mostly good weather ) without the BB failing. I hate internal BB's.

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Fish_n_Chips | 7 years ago
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Just pulled out a GXP BB after 2 years of turbo training (3x30 minute sprints) , it had a bit of play but still functioned.

A year ago I took off the seals and injected some grease and it was good to go.

Manufacturers use cheap grease IMO.

 

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Crashboy | 7 years ago
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The parts themsleves might be cheap, but without the tools / knowhow fitting it is going to be more than the example £12 mentioned in the thread and repeated breakdowns soon add up I suppose.  If the Hope option is more likely to be a one time fit & forget solution, then surely for high milage and peace of mind it's better to shell out (no "bottom bracket shell" pun intended) for that? I don't know enough about the topic, but  that sounds like a wise investment - Although obviously I appreciate it's a complicated combination of factors that affect the wear.  

 

FWIW I've have an external BB30 MegaExo (I think!)/ FSA combo on my Boardman MTB which has gone through 2 BB's in 4 yrs (not ridden all the time, cleaned relatively well, not dipped in gloop TOO often - so probably 1500-2000km between each one)...my new Marin Four corners seems to have a similar looking BB (haven't looked up what it is yet)with Sora cranks, so hoping to get a bit longer out of that...but if it goes as regularly as the Boardman, I was looking at something like the Hope bling....(if it's good enough for Guy Martin etc etc.)

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mike the bike | 7 years ago
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Can't say I've ever had trouble with external BBs, at least not those from Shimano.  In fact, apart from bike lights, I can't think of a component that has improved so much over the last fifty years.

Maybe one reason for my good fortune is that all my bikes, whatever they have been made from, have had a three-sixteenths drain hole drilled in the BB shell.  It takes all of five minutes and prevents too much water build-up around the bearings. 

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Chris James | 7 years ago
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I'd echo the comment about checking whether the frame has been faced. On the other hand, the sealing on external BBs isn't great, they certainly can't withstand a cyclocross washing regime for long, even a hosepipe can flush all the grease out and kill the bearings.

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1tal | 7 years ago
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I rode 31,000 miles in 2012 uesing Ultegra external BB without haveing to replase one ,  granted it was on 4 difrent bikes, so I would say you should get your L B S to have a look at the frame to see if the threds are in line, or try Rotors self centering BB to see if that helps.

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Mungecrundle | 7 years ago
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For some data from a source that has applied some rigor to the testing method:

http://www.bikeradar.com/road/gear/article/friction-facts-measuring-bott...

Take home message. The difference between the best and worst bottom brackets in terms of 'draginess' are minimal and even then offset by other real life factors such as wear rate, sealing, lubricant other elements of the drivetrain etc. Often the cheaper BBs are as good as or better than expensive ceramic bearing types and the type of bracket is pretty much irrelevant. The regular cyclist is neither going to benefit or notice the difference.

Doesn't tell you what you wanted to know re wear, but for what it's worth I don't seem to have any issues with the external BB on my everyday bike, and they're pretty cheap and easy to replace anyway.

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TypeVertigo | 7 years ago
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Will chime in with my experience.

The cross bike (2014 Giant TCX SLR 2) came stock with a FSA Omega crank and a MegaExo BB86 bottom bracket, but the crank was a strange animal in that it had a 19 mm spindle, not the 24 mm that Shimano or SRAM GXP (24 mm -> 22 mm) use.

I waited about a year and a half, slightly longer, before I swapped the FSA crank for a 105 FC-5750 unit and an SM-BB91-41B bottom bracket. In all that time and the 7500 km I had ridden, I never heard a peep out of it. I've heard horror stories both about FSA and press-fit bottom brackets, but my experience so far has been favorable with both - at least with BB86 frame shells that is.

My only real complaint with FSA and its Omega cranks is the ridiculous spindle diameter and poor BB parts availability. As best as I could search around the Internet, replacement BB-AL86 parts were nowhere to be found. Good, heavy-ish crank, but disposable because of the lack of BB support unfortunately.

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Jack Osbourne snr | 7 years ago
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On my old commuter, I have had no issues with Ultegra HTII external bearings having installed them as replacements for some FSA Megaexo trash.

I have PF30 on my new commuter and it's been a fucking nightmare. I have now found an adaptor to convert to BSA and once fitted will plug in some Ultegra cups... Sadly I need to change chainset too.

I should add that my "best" bikes all run Campag square taper, none of which have I ever had a problem with...

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Stef Marazzi | 7 years ago
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Ultegra ones seem to do about 3000 miles. You could buy a hope one, but they are like £70 quid, whereas a Ultegra one is £13. its so cheap, who cares?

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DaveE128 | 7 years ago
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FSA cheapy that came on my bike has lasted 5500 miles in mixed conditions (including a fair amount of off road) so far with no problems.

The facing on the BB shell is absolutely critical for external BBs as this is the reference face that ensures the bearings are aligned. On old style BBs this face was unimportant as the bearings were aligned inside the BB unit.

See this page for more details:

http://www.parktool.com/blog/repair-help/bottom-bracket-tapping-threadin...

I'd suggest you get your BB shell chased and faced by your local shop. If you strip it down yourself it won't cost much.

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Chris James | 7 years ago
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I think it depends on what use youput your bike to. I think the hollowtech bottom bracket on my summer bike will last almost forever. My winter / commuter only lasts a year or so. On my cyclocross bike my last bottom bracket only lasted half a race season.

I like that they are cheap and easy to replace though.

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matthewn5 | 7 years ago
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In my experience BB386 push fit bearings have been flawless for both Shimano and campag for several thousands of km of all-weather commuting. BB386 is different from the other press fit standards, as the whole bearing is inside the frame structure. I can readily see why PF outboard bearings are a bad idea, but PF inboard bearings seem fine, from an admittedly limited experience.

Traditional square taper bottom brackets are great too, but they are a bit of a mare to get in and out, and to get the cranks off, not that you have to remove them often.

I'm old enough to remember cotter pin cranks, which were a total piece of crap, though the bearings did seemto last a long time, even if they were never particularly smooth.

For my 2d, external BBs have the edge because they are so easy to remove and replace.

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dottigirl | 7 years ago
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Could depend on the frame structure too.

One of my bikes needs upending every time I ride in the wet/slightly damp, as the BB gets flooded down the seat tube/seat stays. All that water has one way out - through the BB. Had to replace it twice in a year. When I removed the BB, there would be either water, or silt, or a combination built up encasing it. It couldn't seem to find its way around to draining out the bottom.

Whereas another of my bikes with a square taper never seems to have the same problem.

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fukawitribe | 7 years ago
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Well I suppose Bank Holiday Monday is as good a day as any for over-generalised nonsense about external BBs....

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bechdan replied to fukawitribe | 7 years ago
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fukawitribe wrote:

<p>Well I suppose Bank Holiday Monday is as good a day as any for over-generalised nonsense about external BBs....</p>

What useful input. What's your problem

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fukawitribe replied to bechdan | 7 years ago
1 like

bechdan wrote:
fukawitribe wrote:

<p>Well I suppose Bank Holiday Monday is as good a day as any for over-generalised nonsense about external BBs....</p>

What useful input. What's your problem

My problem was SP59 unequivocally condemning external BBs without any real nod to reality.

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medic_ollie | 7 years ago
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I got around 18 months out of Tiagra BB (approx. 5000 miles), probably left it a bit longer than I should have but just didn't have the time to swap it out. 

The new, slightly smaller, black Ultegra one looks great though 

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Simon E | 7 years ago
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External means that the bearings are outside the bottom bracket shell, as opposed to the sealed unit type such as square taper. Nearly all chainsets are external now - see this article:

http://www.bikeradar.com/gear/article/complete-guide-to-bottom-brackets-...

My second Tiagra Hollowtech BB died after just over 12 months, though the previous one had done 4 years with the same kind of treatment. Neither can hope to get near the reliability of the cheap S/T BB in my old Kona. Personally I'd avoid the press-fit type if at all possible, they seem a real PITA.

Here is a still from a Youtube video explaining the differences:

 

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sergius | 7 years ago
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Am I missing something here?  Is an external BB different to the normal Shimano BB's I've got on both my bikes?

 

It sounds a little strange, my winter bike has around 4500km on it over 3 winters now and the Tiagra BB is absolutely fine - I've never done a thing to it since buying the bike.

My new best bike has about 3500km on it so far, again never touched the Ultegra BB and it's just fine.

 

Are you riding hundreds of miles a week?  Do you take everything apart all the time to clean/oil it?

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