The Isis Vs Square Taper Debate

[Ashley Smith]

i have personally never had any problems with the square taper interface on cranks, i use middleburns with a hope titanium bottom bracket, but then again im not very heavy, i have never rounded an interface, square taper on my middleburns but have on older model cranks,

isis is o.k. but i have never had the need to move to isis, if i did then i would probably buy the tensiles, they are great value for money, well machined and the looks are great.

regards ash

[iatola says]

The problem with Isis bearings is they have far lower load tolerances as much more pressure is applied through the smaller surface area of the bearings. It's possible to seal a Isis unit just as well as a square taper, so it wouldn't make any difference if we did 100miles or 10 a week,  People also mention the isis bb's being a bit loose. It's not loose, the bearings are f**ked, and when you can run a square taper longer (much cheaper too) and the bearings are still fine, I think I'd go for the hardly noticeable loss in stiffness over changing my bb every two months, which costs more than normal tapered ones, in turn forcing me to run more expensive cranks, and in turn come loose more often.

There's a better range of good quality tapered bb's out there, and if tic's not had a problem with taper so far, why change to isis and spend the extra money? They may be marginally stiffer but I think the cons out weigh the pro's in the bearing department.

James

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Hes is right the square taper uses a smaller axel with larger bearing giving a higher impact capacity but it has less surface area in contact from bb to crank making the taper prone to rounding

I say go with taper if you are tight on cash but if you want to spend lots on isis and replace the regulaly then you get a more direct feel with less flex due to thicker axels

Edited March 21, 2005 by iatola says

[Zordon]

So if isis bb's have lower load tolerances caused by smaller bearings, why not to make bb with isis axel downsized to the size of square tapered axel at places, where it contacts the bearings?