[Obi-Wan is lost...]

Trying to fix a creaky BB on my Kona. It's got an 'old style' square taper Truvativ. Not wanting to replace the full chainset I'm trying to work out which one I need. I've removed the cranks and measured the axle length as 115mm, 113mm seems to be the standard so I'm guessing that's the right length, however there is two widths, 66mm and 68E/73mm?? see here:
http://www.cyclesportsuk.co.uk/product_info.php?products_id=3525&cPath=291
I haven't taken out the existing one yet (see next question) so what should I be measuring? On the 68e/73 is one end bigger than the other?

Also does anyone know if I need an ISIS or Shimano removal tool for Truvativ?

http://www.cyclesportsuk.co.uk/product_info.php?products_id=6538&cPath=208
or
http://www.cyclesportsuk.co.uk/product_info.php?products_id=6533&cPath=208

[scratchy head smiley]

[northerngreg]

There are basically two different shell widths - 68 and 73mm. Simply measure the part of the frame that the bottom bracket is housed in from one side to the other, most bikes are 68mm. The 68E is for a bottom bracket mounted front mech. Both of those tools you listed do exactly the same job. As for the axle length, if you measured 115mm then you need a 115mm axle! They generally come in 107, 110, 113, 115, 118, 122.5 and 127 mm lengths. A couple of mm either way usually works though. Do yourself a favour, buy a Shimano UN54 and not a Truvativ b/b. They last for a lot longer!

http://www.cyclesportsuk.co.uk/product_info.php?products_id=3314&cPath=291

[Obi-Wan is lost...]

Cheers Greg, would that be compatible? I was told that Truvativ chainsets had on go on Truvativ axles as the tapers are different on Shimano ones?   

With the removal tools are you saying both fit both? If so why are there two available?

[bigd942]

take care putting in the new one, I screwed up a frame crossing threads not that long ago and it's an easy done thing. People either go with grease, anti sease grease or a loctite type solution, I've used them all and never had a problem either way. I hate creaks, do your head in, not sure if it really did the job or not but the last few mystery creaks I had were sorted by 40+ miles in the rain. Check your pedals and chainring bolts as well just to be sure, nothing worse than buying new parts and the creak hasn't gone.

[northerngreg]

Cheers Greg, would that be compatible? I was told that Truvativ chainsets had on go on Truvativ axles as the tapers are different on Shimano ones?   

With the removal tools are you saying both fit both? If so why are there two available?

The tapers are exactly the same. You might be thinking of if it was a Truvativ Powerspline - they have to use a Truvativ Powerspline b/b. The tools in the pictures do the same job.

Just remember, the right hand side is left hand threaded and the left hand side is right hand threaded!

Trust me - I run a bike workshop.

[Obi-Wan is lost...]

Trust me - I run a bike workshop.

and that's why I love this forum, we've got experts in almost every field! Thanks again.

[Mark Lloyd]

As a supplementary question is it ok to fit an external bottom bracket to a road bike that has previously had square taper bb as long a s I get the chainline correct ?

[peewee]

As a supplementary question is it ok to fit an external bottom bracket to a road bike that has previously had square taper bb as long a s I get the chainline correct ?

yes, though external BB's require a different crankset as the axel is attached to the crank and goes through the BB instead of the cranks bolting directley to the BB splines.

[clm]

dims often written on it when you take it out. Took my old one to the shop with me when i did mine.

[Obi-Wan is lost...]

I'm hoping that's the case, just ordered a removal tool before I order the BB to check. I think it's 115mm x 68mm. I'll go for the Shim, sounds like it fits according Northern 'Bicycle Repair Man' Greg.

[northerngreg]

As a supplementary question is it ok to fit an external bottom bracket to a road bike that has previously had square taper bb as long a s I get the chainline correct ?

Yes, absolutely - providing that you face the bottom bracket shell. This makes sure the two surfaces are absolutely parallel to ensure the bearings aren't misaligned. With most external road b/b's (esp. Shimano) it is impossible to get the chainline wrong. You can't get different length axles.

[fatdoc]

 

external BBs are the best hardware change `mtb ever gave to roadies.. and the best thing MTbers had in yesrs.. ISIS.. christ - how shit??

4 weeks for one to fail...

[northerngreg]

external BBs are the best hardware change `mtb ever gave to roadies.. and the best thing MTbers had in yesrs.. ISIS.. christ - how shit??

4 weeks for one to fail...

External MTB BBs are great in that they are very stiff and strong. However, the bearing life is terrible compared to square taper. EG, I am running an 8 year old UN91 square taper that is still silky smooth. I have destroyed 3 XT external BBs in the last year. It is always the non driveside that goes first, the sealing is terrible. They seem to respond worst to being left unridden after a wet ride for a few weeks allowing the bearings to rust up nicely. I cannot vouch for the likes of Chris King or Hope etc as I haven't tried them.

On road however, they are great as they are never exposed to the shitty conditions that MTBs are!

The best thing MTBers had in years must be lock on grips.

Yes, ISIS is a joke. If your cranks don't creak or fall off within a month, the bearings are destroyed soon after anyway!

[Norton Sharley]

Try a Hope BB Greg, they last for ages longer than XT and you can replace the bearings without replacing the whole shell.  XT BB bearings are made of putty imho.

So where is your bike workshop - cyclesport?

[fatdoc]

 


also the lock ons are indeed... ace