Posted by: lazywheels | November 28, 2010

Bottom Bracket!

What a pig. However for those who don’t know changing a bottom bracket from an old loose caged bearing bracket to a nice shiny Shimano cartridge is not difficult. However having the tools helps and also using a bit of nous half way through also helps. Why change it? Once more

The commuter machine

Falcon millenium flyer

in the interests of wolf in sheeps clothing biking thebike actually runs quite well! Used to have 10 gears. The old bracket has been on since the “birth” of the bike. Getting off the adjustable side was not difficult. The bearings were really grating. There was no oil in them either.  Getting off the other side was a different proposition, the bearing race appeared to be completely locked in. It hadn’t helped that I was turning

the nut the wrong way.  I managed to hammer something into the hole and then twist it off. They cleaned up quite

well and the new cartridge fitted

like a dream. Although I measured it accurately, it did seem quite long, however pedalling it did seem a real improvement. I really don’t see how these really expensive bottom bracket cartridges can help a lot. Going to have a go at the chain n

ext week.

Removing an old splined bottom bracket can also be a problem. The Halfords tool is a good fit as is the park Tool. However as soon as the tool starts to twist in the splines you e stuffed Apart from hammering and hacking it out, which may wreck the threads an alternative way of clamping in the tool has to be found.

Adjustable Clamp on bottom bracket

Stanley sliding clamp with Halfords tool on Bottom Bracket

Apart from hammering and hacking it out, which may wreck the threads an alternative way of clamping in the tool has to be found. By using a fairly thick piece of MDF on the left hand side of the bearing with a hole in it and protecting the shaft with anoth piece of mdf. You have to make sure that the MDF sits square. The tool is placed in the splines and the adjustable clamp locks the tool hard in place.  Using a buddy to hold everything whilest you clamp everything in place can be useful. There are 2 sets of flats on the tool. Using the flats, the larger ones are better because the turning motion does not try to twist the tool out of the splines.  Obviously the turning motion is almost self defeating because you are by default increasing the pressure on the tool from the inside. However gentle easing of the clamp without it falling off helps you slowly free the brackets threads. Once the threads free off, the clamp can be dispensed. Clean and grease the bottom brackets before using the new bracket. It could be possible to tighten up the new bracket with a torque wrench without resorting to the clamp again. Please don’t cross the threads, if it does not screw in easily.

Shimano bottom bracket


I have a UN54 on both the hardtail mountain bike and the commuter machine. Changed both and they are both showing no signs of wear, unlike the earlier brackets. Needless to say this is only advice that may help you remove the BB. Should you wreck your threads or damage your bike, or even youself, I do not take responsibility. If in doubt take your bike to your LBS. However this works.





  1. hi I was luck to discover your subject in digg
    your subject is outstanding
    I get a lot in your theme really thank your very much
    btw the theme of you website is really exceptional
    where can find it

    • Thanks very much. This is about keeping a commuting bike on the road, being no hassle, largely unstealable , but still a pleasure to ride. My next serios article will be about clippless pedals and wear.

    • The blog is a standard blog. The picture can be altered. It actually comes from a walk that I did last spring. The top and the bottom were cropped to fit. It has to be a specific size.
      Thanks for you kind words. If you wish to use the picture it is fine by me. I think I should change it.

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