External bottom brackets are rubbish?

My XTR960 one has just given up the ghost, I bought it 2nd hand and it's done a year of being ridden nearly every day. It's the only one I've ever had that has failed.

I think the early Shimano external BBs (LX580, XT760 etc.) didn't last very long but the newer ones despite looking exactly the same last much better. My modern Tange square taper only lasted 2 years before developing a bit of play. My UN54 has done over 10,000 road commuting miles though and is still perfect.

slimjoe":2zd428ql said:

If you think external bottom brackets are bad the new generation of bb-30 etc push in brackets are utter plop :roll:

Some people are only getting a few rides out of these.....Another bike industy bloomer!

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I thought the whole point of the BB30 format was to increase stifness beyond the 24mm HTIIs and alike but also allow large internal bearings like square taper so also improving reliability.

I wonder how many times can you press those bearings in and out before things get a little loose. I wouldnt want to press my headset cups in and out every few rides especially with an ally frame.

Excessive preload, hosepipe washing and non-faced BB shells are the main bugbears with external BBs.

Experience of Truvativ BBs is generally poor. Later Shimano ones are very tight and and like earlier units have loads of resistance but seem to last OK. FSA seem to be a mixed bag.

Am very happy with my Pace unit as seem to be the 2 punters who own winter bikes I have fitted them on. Only Hope unit I have fitted to an MTB was only the other week - but have 4 or 5 road bike customers out there that are happy with them.

I've never had any problems but I've always had the BB shell faced on new frames before I've fitted an external BB and I don't jetwash my bikes.

Some units will fail, its impossible to produce the numbers that Shimano do and maintain 100% quality. Most people will be OK, some people will get the Friday afternon specials!

I've always had my BB shells faced and am careful about how much preload is applied so they last ok.

I guess things like BB's will always wear out at some point. I sometimes wonder if the Shimano ones are that well sealed because when I tried to revive a seized one it didn't take much to get behind the seals. The SK bearing upgrade is supposed to be worthwhile and easy enough to do.

Russell":1rk5u9mk said:

ISome units will fail, its impossible to produce the numbers that Shimano do and maintain 100% quality. Most people will be OK, some people will get the Friday afternon specials!

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hmm, I find it hard to believe that quality is the issue - they are made by machine so should come of the production line identical.

failure is due to the reasons mentioned above..... or maybe they are not as well sealed or as robust as the cartrdge type in whcihn case it is a design fault not quality.

Time for me to fess up...I think I over pre-loaded the bearings
Home mechanics are rubbish!

You live and learn. He who doesn't make mistakes doesn't make anything!!!

You only need to adjust the plastic do da thing until the side to side play is gone, it will be less than finger tight, then do up the pinch bolts.

JamesM":1507pvkd said:

You live and learn. He who doesn't make mistakes doesn't make anything!!!

You only need to adjust the plastic do da thing until the side to side play is gone, it will be less than finger tight, then do up the pinch bolts.

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Ha ha...true, everyday is a schoolday.
Have ordered a Hope BB tool...I am going to clean up the bearings first, might just be a bit of grit somewhere

Got a set of M960's that have been on various bikes over the last 6-7 years I've had them. On the third BB so far. Just bought a new XTR one from CRC. Never had problems. Did have a set of Raceface on a different bike which went after 2 and a half months.