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Idea About Crank Conversion.


Mike Winton.

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My odd idea.

This may seem strange and maybe slightly pointless but could be good for some people.

A small adaptor that fits into an isis crank arm making it square taper, so if you broke your bb or couldnt afford and isis bb you could tempoarilly use a square taper one

post-16048-1200431370_thumb.jpg

this would allow you to use cranks like echo cnc and other isis only cranks with a square taper bb, maybe save weight?

anyway its just a random idea what do you think?

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I dunno about that. How would the adaptor be held on the crank? Plus bolt sizes vary, you'd need some kind of crazy insert in the ISIS bb and an extra long bolt on the cranks. It's a nice idea, but way too dangerous IMO.

Shit I just realised you're talking about doing it the other way round...

Errm could work, but still could be dodge because of bolt sizes and stuff. Nice concept though!

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Nice try but its a problem that isn't really there for most people. If you can't afford ISIS cranks and bb just buy square taper.

Thats exactly what i thought,

but when i first started i couldn`t afford combinations of things so just bought one or the other, so if you wanted to get an Isis crankset for your bike, and couldn`t afford cranks and bb at the same time these would be for you. these adapters could be made very cheaply so you could get new cranks and use them with your old BB until you could afford an Isis one.

i suppose the target market would be people on a budget and beginners really.

crank puller would get the adapter out too.

Edited by ToXiN-BoY
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Given how few people would be interested in buying this adaptor it would probably cost a hell of a lot since there's no mass production economy of scale to be had. It would have to include a washer so that a square taper sized threaded bolt would be able to apply pressure to the splines in the crank arm and hold the crank on.

The next question is what material to make it from. If you use aluminium you get a good interface with the square taper BB and lower manufacturing costs. There is a danger the part will bulge due to the taper on the BB axle and possibly damage the ISIS splines on the crank as ISIS cranks are not designed to deal with forces trying to bulge the crank spline in the same way as square taper cranks (This is probably not a big issue though). If it's made well from steel it'll interface well with the crank and the BB but cost more to make (Steel is just plain harder to machine). Steel is the material I'd choose though.

I'm guessing the cost of this interface plus the cost of a square taper BB would buy you an ISIS BB. The main reason people stay away from square taper BB's is that they snap a lot more easily than ISIS so I can't see anyone being willing to run one long term as square taper BB's aren't strong enough. Just save your money for a bit longer and change over completely.

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