More bottom brackets: Shimano vs Miche

[juliet]

Further to this: Bottom bracket size, I have now taken out the old BB (less painful than I expected, though confused slightly by the lack of collar on the thing).  It says it is a Shimano UN51 1.37 68, and length is about 108mm (investigation reveals that this is probably in fact 107mm).

So, am I best to get, as a replacement, the Shimano UN54 68 x 107?  (http://www.wiggle.co.uk/p/cycle/7/Shimano_UN54_Tapered_Bottom_Bracket/5360027179/
Or there seems to be a Miche track BB available (http://www.wiggle.co.uk/p/cycle/7/Miche_Primato_Track_Bottom_Bracket/5360040672/) which has the right dimensions.  Would that be better?  It is a smidge cheaper...

[Chris N]

Miche = ISO axle tapers
Shimano = JIS axle tapers

They're different.  Not totally un-interchangeable, but the Miche is not a direct replacement for the Shimano

[Biggsy]

The Shimano one may be better sealed as well.

[Greenbank]

Shimano is JIS not ISO square taper aren't they?

I've had no real problems with the Miche BB. Had one in the Tempo since day one and it's done 15,000km.

It occasionally makes a clunking sound but just undoing it and doing it back up (not even regreasing any part of it) fixes that.

I believe Mr O'Tea has had some negative experiences of the Miche BB though.

[Martin109]

Are you dealing with a fixed wheel machine?  If so, the advantage of the Miche is that it can be fine tuned for chainline, which anyway might counteract any problems with mis-matched cranks anyway.

[Biggsy]

Chain Reaction is the best supplier for UN54 107mm @ £15 free post.

Ah, it's only £10 on eBay... Oh, sorry, wrong sort of UN54

[Biggsy]

Are you dealing with a fixed wheel machine?  If so, the advantage of the Miche is that it can be fine tuned for chainline, which anyway might counteract any problems with mis-matched cranks anyway.

Is it adequately sealed for road use?

[Manotea]

I tried a Miche BB because the chainline can be tuned for fixed. It was a bit of an experiment though as (AIUI) the bearing seals are designed for the track not winter audax and they duly gave up inside 9 months. OTOH I've had a similar experience with a Campag Chorus BB so who knows. I'm been running a Veloce BB (111mm) since Christmas (Condor, cost £11). Sorted the chainline by running the chainring on the inner position of my double crankset.

[MSeries]

A tapered crank for JIS will slide about 4.5 mm further onto a ISO tapered BB and there is a danger that it'll bottom out before becoming tight on the taper.  Juliet, get the Shimano 107mm one. UN54 is newer than UN51 and it's replacement. NB I just got one from CRC, not come yet though.

You can of course mix JIS and ISO but why bother when 107mm JIS works

[MSeries]

Further to this: Bottom bracket size, I have now taken out the old BB (less painful than I expected, though confused slightly by the lack of collar on the thing).  It says it is a Shimano UN51 1.37 68, and length is about 108mm (investigation reveals that this is probably in fact 107mm).

I thought so

[juliet]

OK, I'll stick with the shimano rather than messing around with different sorts of tapers.  (The chainring & cranks are perfectly functional still, don't want to replace anything that I don't have to!). 

Thanks for the comments, & Biggsy, thanks for the link!

[Blade]

I'm surprised that no one has posted concerning 'tweaking' bottom bracket tapers.

My elderly Cannondale has a Chorus double chainset, which I converted many years ago to a triple by drilling and tapping the spider to take a granny ring..

When looking to sort out the chain line, the nearest length suitable was a Shimano axle, which didn't quite match up with the taper on the Chorus crankset.

I marked the tapers on the axle with marker pen and then tightened the cranks up on them. On removing the cranks I could see on the axle where they were touching.

Got a power drill with a grinding stick in the chuck and removed some metal from the axle where the cranks had been touching. Marked the axle again and refitted the cranks again. Carried on with the above until I was happy with the chain line and the clearance between cranks and chainstay.

IIRC  the work on the axle was done some 15 years ago and has given no trouble since it's installation.

Finally, I removed some metal from the ends of the axle to ensure that the tightening bolts didn't bottom out on it instead of clamping up the cranks.

The reason that I used a grinding stick is because the axle is hardened and a file won't work on it. Because the axle is tapered, a small amount of material taken from the axle results in quite a bit of 'moving in' of the crank.

[Biggsy]

I'm surprised that no one has posted concerning 'tweaking' bottom bracket tapers.

Because it's extreme hardcore fettling - that would be a terrible idea for anyone less skilled than yourself, Mr Blade.

[Blade]

I'm surprised that no one has posted concerning 'tweaking' bottom bracket tapers.

Because it's extreme hardcore fettling - that would be a terrible idea for anyone less skilled than yourself, Mr Blade.

I suppose, because my job entails a lot of fettling, I didn't consider it anything out of the ordinary.

[juliet]

I can confirm that that would be beyond my skill level

New BB fitted last week & seems to be OK but I went off to a festival straight after & haven't been able to take it for a proper test ride yet!