Tuesday, April 22, 2008


In the back of my mind there is a vague notion to try and utilise bigger bottom bracket bearings. I dont think there is much need to go into why, as there are clear and obvious benefits. In addition, an internal system would be nice in terms of longevity (the outboards are ok, but not the most moisture resistant). Coupled with light weight and high stiffness and bobs your uncle.

Here is a thought...

Look closely. That is an ebb equipped cannondale 29 er frame built for commuting...with a cannondale si crank and bb30. The ebb was machined to accept the press in bearings. Not bad eh? read about it here...which is where i lifted the pic from. The only downside i can find to trying it out is the cost of those cranks - around £500. But, with fsa, truvativ and others bringing bb30 cranks to the market (including it is rumoured shimano dura ace ones) there should be more choice soon.

Some interesting threads have also surfaced looking at fitting bb30 cranks to normal shelled bikes. Seems like a lot of fuss, and some of the benefits are lost, but interesting nonetheless.

mtbr thread

weight weeneis thread


Anonymous said...


all rest is just marketing tosh to make you buy new expensive stuff.

krs said...

Hmm... I'm not so sure that bottom brackets are so fundamentally poor that we need another standard [Cotter pins and ISIS excepted].

A quite lovely bike although I think a lefty and Rohloff are overkill for around town.

What you want is one of these puppies: http://www.trekbikes.com/uk/en/bikes/2008/urban/soho/soho40/

GBP700 for shimano alfine - surely the most refined shifting hub gear plus big rubber bump strips along the top tube so you don't have to pretend to not care when the bike scrapes down a lamp post. Thought is given to cleanliness - disk brakes so no filthy rim brake pad dust, a chain guard [of dubious quality, but the thought is there] and the promise of very little maintenance required - Just add mudguards...

Oh and I just noticed that the fork is ready for a low-rider rack.

And its a nice colour.

Who cares what bb its got - it will probably last 6 months and be replaced with a UN72 which will last for ages. Then be replaced.

Want to buy Clyde?

dRjON said...

i used to very much like un72s. the un73s were less good, as the plastic side lock ring would tend to loosen. still have some saved metal ones. ive only ever had one that lasted longer than 6 months tho.
the issue is not the bb, which is good. the issue w square taper is having to stop and tighten on most rides the cranks. not only this, but you have to carry an 8mm allen key to do so. also most of the cranks you can get for square taper are crap,,, middleburn, and poss WI excepted. the rest are generally poor quality...bring back suntour xc pro and id be happy!

so: the newer styles are a good idea for me...stiffer and a bigger interface so avoid the loosening from being mashed by my ugly pedal stroke. Here, there is no doubt some improvement is needed, and i think bb30 is it. the bearing surface contact is truly massive cf isis and even most externals..that if done even halfwell makes the bearings much more robust...cubed!

I'm not really gay said...

Phil Wood and White Inds/Middleburn

and of course old school Race Face, been a set on my Retrotec for 6 years now and still perfect

Nick said...

I really think that external BBs have so many problems of their own that they are trying to solve that they have forgotten the original reason they were developed.

Square taper bottom brackets have very few issues with stiffness, as you say j0n, it was usually cranks that failed. Though that was usually only on those bikes were I didn't leave well alone so the taper insude the crank wore out, leading to play, which meanth they had to be tightened up even more which knackered the taper in a vicious spiral towards self-destruct.

Shimano cranks were OK, and so were Roox (though they did skin your ankles), and so far Race Face Turbines have proved trouble free.

For me the real problems for square taper only started once throwaway society came up with the cartridge BB which placed the bearings closer together - making them less able to resist the assymetrical forces on them from pedalling.

Since then my square-taper cranks have been fine, but all my cartridge BBs have failed by developing side play. My cartridge bearing but widely spaced Royce goes on and on and on...

Marty Savalas said...

the issue w square taper is having to stop and tighten on most rides the cranks
you know the answer to that don't you...

would you like to borrow my custom allen key aka THE BIG SNUGGER? you have roof bars on the passat, yes? :)

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