ISO v JIS square taper BB's

[redraleigh]

I hope someone may be able to help me out. I have a cross bike with a Nervar crankset ( 50.4bcd ) that has a single 45T chainring and runs on an old Campag Record cup & cone BB. I would like to fit it with some TA 50/40 chainrings that I have and in doing some research on Velobase & Sheldon Brown find that I need a 117mm axle for a double and that the Nervar cranks are ISO, not JIS. I was hoping to find a sealed bearing BB that fit these criteria, but have not had much success and am not keen to mix ISO with JIS unless I really have to. Any help and suggestions welcome. Thanks.

 

[MartinC]

Try Spa Cycles http://www.spacycles.co.uk/ They sell Stronglight SBB BB's that might fit your needs.

 

[kyuss]

I thought Stronglight BB's were JIS.

Loads of Campag BB's around in 115.5mm. I'm not convinced 0.75mm either side would make a huge difference.

Or how about a Miche? No 117mm but they do have adjustable axles so a 119mm might do and just bump the driveside over a mm or so. And they're definitely ISO.

 

[redraleigh]

Thanks for the suggestions. I didn't know about the Miche. I'll check it out.

 

[MartinC]

I thought Stronglight BB's were JIS.

Stronglight do both, ISO for the Speedlight cranksets that are original French design and JIS for the Sugino ones (Impact) that they make under licence.

 

[MacB]

Stronglight do both, ISO for the Speedlight cranksets that are original French design and JIS for the Sugino ones (Impact) that they make under licence.

Yep, and also worth ringing Spa, they are very helpful on the phone, even with my stupid questions

 

[jpembroke]

Ambrosio make ISO BBs, too but, again, they'll be 115.5mm.

 

[Paul_Smith SRCC]

...Nervar cranks are ISO, not JIS. I was hoping to find a sealed bearing BB that fit these criteria, but have not had much success and am not keen to mix ISO with JIS unless I really have to. Any help and suggestions welcome. Thanks.

If you try and put a crank designed for a JIS BB onto an ISO shorter tapered BB which would happen if you use a Shimano Chainset onto a Campagnolo BB, then the crank may go to far up to the end of the taper, so you will be tightening the axle bolt against the axle, as apposed to the crank onto the axle taper, not such a problem vice versa of course as the crank depth will not reach the end of the taper; still not to be recommended.

Paul_Smith
www.corridori.co.uk