External Bottom Bracket Lifespans

[meic]

I bought an external BB crankset without knowing much about them. I have since read all the horror stories but wonder if they are exaggerated or based on a few bad examples.

I have just passed 2,000 miles with mine and no obvious problems yet, my square tapers though have done many times that.

So I would like to gather up some numbers from people who use them.

Apologies to anybody with Truvativ Bottom Brackets but could they be excluded from the results as they are said to be noticeably less durable than the others. (I now expect to be corrected on this ).

I also notice that people can only enter one "vote" in each section which messes things up a bit.

[pherron]

I've just had a Stronglight Isis BB on my Moulton TSR replaced under warranty after just 350 miles. The bike shop thought it may have been fitted incorrectly as it was 'mashed' in their words.

[Colin Jenkins]

Hello Meic.

Not part of your survey I guess, but I have just replaced my old Stronglight 651 sealed square-taper bottom bracket after 25 years and 31,000 miles use in all weathers. It received no maintenance whatsoever. With two new bearings fitted I'm sure it will last another 30,000 miles. It cost £28 in 1986, which seemed a bit expensive then but was remarkably good value I now think. I have no plans to go to outside bearings!

Regards,

Colin Jenkins.

[Big T]

I have a Shimano Tiagra Hollowtech II. Done about 2500 miles and is making annoying knocking noises, which I haven't been able to pin down the cause of. Took to the LBS and they suggested tightening the left side crank, but that hasn't cured it.

My son has them on all bikes and does a lot of miles without too many problems. The ones on his cross race bikes have both needed replacing after about a year, but they do take some hammer , as they are constantly being ridden in filthy, muddy conditions and getting jet-washed. All of his are 105 (winter bike), Ultegra (cross bikes) or Dura-ace (race bike), which may be better quality and longer lasting.

[irc]

I've voted 6-8000. At that point the Deore BB is still going strong. It's on a bike with full mudguards though which isn't used year round. I suspect the BB life might be less for MTBs or year round commuters. By the time I finish my next tour later this year the chainrings might all need replaced. At that point I'll be as cheap buying another Deore crankset with BB included. I'm curious to see what the condition of the old BB is at that point which will be around 10k miles.

[cadseen]

I voted 6-8k as well, that was the tiagra cheaper set on the ribble audax, which gets all the bad weather riding.
I have a durace set on the race bike of 5 years but probably done about 12,000 plus on these so far, with no sign of wearing out.

[Malaconotus]

Bump!

Would be interested in more testimony. Never used one, and I'm finding a very limited choice of square taper cranksets as I need to replace mine soon. (scuffed cranks with worn bolt and pedal threads, and worn chainring(s) more expensive to replace individually than to swap the whole shebang) Do I really need to be wary? I'm heavy, live on hills, and I consume chains and cassettes very quickly already. I don't want to shell out £100 for a Chris King BB just to give peace of mind on a tour.

Thanks.

[ersakus]

Hollowtech II. Started making clicking sounds in less than 1000 miles. Got it to LBS and they had to face/chase the shell and install a new one! The noise is gone and all is OK now. Not too impressed at the moment but I take it as my fault not to face/chase the bb shell when I got the frameset. Still to be seen how the new one will survive.

I have to say that I have same external BB on another bike which did not have any problems for thousand of miles (3K I think). That one has a premium touring frame though, probably with a better, straighter shell.

[John-D]

The BB on my Ridgeback Panorama was replaced after 1900 miles. I don't know what the original BB was; they probably replaced the one in the Ridgeback spec because they fitted a different chainset and cranks for me. The mechanic was initially surprised that it needed replacement after only 10 months but then when he knew it had done 1900 miles seemed to think that was about what should be expected. Amazed me as it didn't seem a very high mileage. Recommended I replaced it with a Hope, which he said would have a longer life and would be simpler (cheaper) to replace bearings. I've done a similar distance on it so I hope he's right.

[Mick F]

I've not voted because I doubt my square taper BB and chainset will ever wear out enough to be replaced.

Rings are available, and so are bearings. Why change?

[meic]

I guess I didnt make myself clear.

This is ONLY for EXTERNAL bottom brackets. To show how real their alleged inferiority is, if people go including the results of long lasting square taper bottom brackets in the survey it will ruin the results.

Why change?

It may not be that everybody already has a bike with a square taper bottom bracket and if they have a bike with an external bottom bracket on, there is plenty of suggestion that THEY should change to square taper.

I would like to have a better picture of what the reality is for people facing that situation.

[Mick F]

Good question.

What is the advantage of Ext bearings?

I understand that the Campag offerings of chainsets is far superior to that of the "old fashioned" square taper, as the set is more rigid. Ultra Torque I think it's called. Maybe these bearings can be replace easily and cheaply too.

[irc]

Good question.

What is the advantage of Ext bearings?

I understand that the Campag offerings of chainsets is far superior to that of the "old fashioned" square taper, as the set is more rigid. Ultra Torque I think it's called. Maybe these bearings can be replace easily and cheaply too.

Ultra Torque.jpg

I find the Shimano Ext BBs more rigid. Standing out the saddle on sq taper I could feel the flex. I'm a heavy rider though. Also I had problems with cranks loosening off on sq tapers on a couple of bikes. It seems to need quite a high torque on the bolts. I find cranks much simpler to remove with the Hollowtech 2 system.

[happyhippo]

Slightly off topic - the Campag chainrings are a little special too...which limit replacement rings. No problems with the bb / chainset in over 2,000 miles although now swapped out for a stronglight triple and square taper bb (gearing issues....)

[Malaconotus]

The BB on my Ridgeback Panorama was replaced after 1900 miles. I don't know what the original BB was; they probably replaced the one in the Ridgeback spec because they fitted a different chainset and cranks for me. The mechanic was initially surprised that it needed replacement after only 10 months but then when he knew it had done 1900 miles seemed to think that was about what should be expected. Amazed me as it didn't seem a very high mileage. Recommended I replaced it with a Hope, which he said would have a longer life and would be simpler (cheaper) to replace bearings. I've done a similar distance on it so I hope he's right.

The Ridgeback is now specced with a UN-54 square taper BB, which has a good reputation and shouldn't fail so soon. I would expect previous models had the same BB (the trend is away from square taper and not towards it)

Oddly it seems to have an Alivio 8-speed crankset (M431) and a 9-speed cassette and rear derailleur. (http://www.ridgeback.co.uk/bike/panorama) Why did you have to swap the crankset? The new one must be Hollowtech 2 to be compatible with the Hope bottom bracket, i.e. you have gone from square taper to external BB and have upgraded to one of the best external BBs for reliability.