Fitting bottom Bracket

[chillyuk]

Hi all. I am looking at fitting a sealed bottom bracket onto a mountain bike to replace the cup and cone job on there now. I have never performed this job before, and when I had my hybrid done it was done in the LBS. i have watched a number of videos on the job but some seem to contradict each other. Taking the measurements as read, and cleaning the threads etc and having the correct cartridge. the first stage is to fit the non drive side ring first. Some people seem to say screw it all the way in tight, others to leave it loose. Then to screw the cartridge in and to torque it up. What do the cartridge threads actually screw up against. Once the drive side is torqued up then the non drive side ring is tightened. It is actually the tightening sequence I am finding a little confusing. I do have the Shimano tool to tighten the cartridge and ring. can someone give me a definitive sequence please.

 

[GrasB]

You're actually asking the impossible, there is no definitive answer! The reason they contradict each other is there are various schools of thought which deliver conflicting but crucially not incorrect methods of installing a bottom bracket. What I would do is read the manual supplied with the bottom bracket & follow that tightening regime.

 

[jpembroke]

First, install the left hand (non-drive side) cup but don't tighten it right up; screw it in until just a few threads are visible. Next, install drive side (the main bit) and tighten it up. Finally tighten up the non-drive side cup.

Oh, and make sure you clean and lightly grease the BB shell and threads before installation.

 

[fido]

I fitteba cartridge bottom bracket for the first time this morning. I just bunged it in and tightened it up; It seems absolutely fine.

 

[chillyuk]

I fitteba cartridge bottom bracket for the first time this morning. I just bunged it in and tightened it up; It seems absolutely fine.

now that's my sort of mechaniking

Seriously, thanks for the advice from all. I have never even seen a sealed unit in real life, but am sure it will all make sense when I actually do the job!

 

[Sheffield_Tiger]

Easier than pratting about with grease and bearings (never liked using bearing cages)

 

[Big John]

And you'll need a tool for tightening it, don't forget. They're not overly expensive.

 

[Alien8]

Personally I'd fit the removable ring last. Unless you're fitting like-for-like you may find that a few threads in the removable ring are left exposed (that's fine) so you want to make sure that the drive side is in nice and tight first. Whatever you do take it easy and don't cross-thread it!

 

[chillyuk]

Thanks for the advice all.

I have just done the job. Very easy, as someone said, easier than messing about with bearings cups and grease etc. Only problem I had was that the cartridge wouldn't pass through the frame. Once I stopped panicking and used my eyes I saw that the screw that secures the gear cable guide to the frame was protruding in too far. A couple of washers under the head soon sorted that out.

Because it is a rubbish BSO mountain bike I have only fitted an economy unit, but it will probably outlive the bike knowing the average life of a BSO. At least now I have the tools and the know how if I have to do it on any of my better bikes. Sorry LBS, another job you have lost.