Square Taper Crank Maintenance Question

[cnighbor1]

BB Axle tapers there is two standards for tapers Europe and Asian and best not to mix them has different degrees of slope
Has in reality your just contacting on the edges and not the full length
Sort of works for a while

[marciero]

Originally Posted by cnighbor1

BB Axle tapers there is two standards for tapers Europe and Asian and best not to mix them has different degrees of slope
Has in reality your just contacting on the edges and not the full length
Sort of works for a while

If you are talking about ISO vs JIS I think they have the same taper-angle is the same (4 degrees if I recall) - but different lengths. You can mix and match as long as you are mindful of the possibility of bottoming out the "short" crank on the longer taper, and also caveats about chainline. Could check Sheldon.

[marciero]

Originally Posted by Mark McM

So, I looked at the crank installation instructions on the Rene Herse web site. What a mish-mash of both good and bad advice!



They're right to recommend lubricating the spindle tapers, but they fail to give a bolt torque specification. They shouldn't recommend re-tightening the bolts (and if they gave a good initial torque specification, the bolts would never loosen, anyway.)

I'm thinking the rationale is that these cranks are forged, so stronger than cast or milled. So they will be less susceptible to damage from re-tightening. That could be the reason for the recommendation of re-tightening. Odd not to have an indication of when to expect it to finally settle in, or a torque spec. On the other hand, if the cranks are strong enough it could be that it is simply not that critical, as is the case with most non-carbon components not designed at the absolute limits of safety. He indicates that "you need strength".

[oldpotatoe]

Originally Posted by Mark McM

So, I looked at the crank installation instructions on the Rene Herse web site. What a mish-mash of both good and bad advice!



They're right to recommend lubricating the spindle tapers, but they fail to give a bolt torque specification. They shouldn't recommend re-tightening the bolts (and if they gave a good initial torque specification, the bolts would never loosen, anyway.)

So..that are 'kinda' right? Or maybe 'kinda' wrong?

[oldpotatoe]

Originally Posted by cnighbor1

BB Axle tapers there is two standards for tapers Europe and Asian and best not to mix them has different degrees of slope
Has in reality your just contacting on the edges and not the full length
Sort of works for a while

Actually the 'slope' of both is the same(2% I believe) but actual measurements of the width of the spindle taper is smaller for ISO.

[El Chaba]

I’m in the camp believing that the iso vs jis thing is a relatively recent creation. Before these standards were thought of , each manufacturer made a matching bb for their cranks. As time and bankruptcies wore on, it was primarily Campy and Shimano remaining. This was a convenient point to divide the spindle world into two camps. Things get more complicated when you start considering other brands.... I said start... For example, both Stronglight and TA have made cranks that more closely followed either jis or iso depending on the timeframe. I think the best situation is to match the crankset to the bottom bracket from the same manufacturer and era. It is just not as simple as two standards. Remember that the bike industry has always hated standards.

[oldpotatoe]

Originally Posted by El Chaba

I’m in the camp believing that the iso vs jis thing is a relatively recent creation. Before these standards were thought of , each manufacturer made a matching bb for their cranks. As time and bankruptcies wore on, it was primarily Campy and Shimano remaining. This was a convenient point to divide the spindle world into two camps. Things get more complicated when you start considering other brands.... I said start... For example, both Stronglight and TA have made cranks that more closely followed either jis or iso depending on the timeframe. I think the best situation is to match the crankset to the bottom bracket from the same manufacturer and era. It is just not as simple as two standards. Remember that the bike industry has always hated standards.

Not really recent and match crank brand to BB unless that 'brand' makes both ISO and JIS, like Suntour did..Superbe Pro BBs/cranks were ISO..pretty sure..been a while.