Replacing bottom brackets and chainsets: spindle sizes!!

[rattle]

Hi guys,

I'm in the process of replacing my old vintage steel chainset for something more modern.

I've got these chainset and cranks coming (Truvativ Isoflow Road Double Chainset Cranks)http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=290489794408

And my bike is a vintage Estelle Clipper (White and green v.) which currently has solid steel cotter pin cranks. I'm also looking to replace the BB or maybe just the spindle but I'm stuck as to what spindle length to go for!

The cotter pin spindle is something like 140mm long but with a different chainset will I need different spindle length??
Both are double ring chainsets..

Any help would very much be appreciated!!

P.S. Any reasons for and against just replacing the spindle or replacing the whole BB would also be appreciated!
(My existing bearings look in pretty good condition!)
(either way the cotter pins are out of here!)




Regards,Martin

 

[Gerry Attrick]

Most of the knowledge you need is here.

Should you replace the cottered spindle? IMHO yes. Cotters are fiddly, prone to seizure and in unskilled hands (no offence intended), stripping the thread.

You could go down the line of changing to a square taper spindle. That is probably the cheapest option. If it was my bike, I'd look to changing to a cartridge BB. That option will probably be easier to achieve the correct chain line and it is a fit and forget system which requires no lubrication or cleaning.

 

[rattle]

Thanks for your advice!

Yeh I'm more set on a nice and easy cartridge/internal BB setup.


Was just wondering if generally, changing from a cottered chainset to a normal square tapered one would require a different length spindle!
I don't have my new chainset yet so I feel like I can't measure for chainline in order to buy a new bottom bracket..

 

[Gerry Attrick]

A decent lbs should allow you to return a BB that is not the correct length. Alternatively, allow the lbs to fit the bb and cranks.

 

[PpPete]

A square taper won't be 140mm, that's for sure. Do you have any other square taper BBs ? Even old non-cartridge type, that you can offer up to the new cranks to try and get a rough idea of what you need?

By the way - Have you checked it it's 68 mm shell / English threaded?

If you are ultimately going to replace whole drivetrain it might be worth just trying to standardise around Shimano's standard chainline. (43.5 mm IIRC) - but beware you could find issues with the 39T fouling the chainstay.

Or you could ask LBS or local club if anyone has old spindles that you could combine with existing cups & bearings?