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Square Taper Bb Vs Isis Bb


ogre

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An ISIS bb will take a lot more complicated machining to make I imagine.

I think this mans got it.

Also, I can imagine ISIS bb's being using better materials. Whats the point in producing a bb with such tolerances, and making it out of shit material? Whereas a taper bb, aslong as its square and the right length, its fine.

Are'nt the bearings in an ISIS unit alot smaller and alot smoother then square tapers?

Tom

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Smaller yes to cope with the bigger axle, but I doubt they are smoother.

No-one really makes a cheapo reliable ISIS bb like the UN53 is for square, they are all high end units.

Also, think about the amount of UN53's sold, or that come stock on bikes, compared to the amount of a certain ISIS bb, this is another reason why they are more expensive.

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Theoretically, the Echo Isis External BB kinda seems to solve all the problems encountered with normal Isis BBs. So I guess... :turned:

Anyway, both are decent designs... I'd choose taper or Isis over shit like Profile 48 spline or the other 36 spline BMX garbage you find. If the Echo Isis External BB really is as strong as its designed to be, what with its big bearings and chunky axle... could it be a possible option for serious BMXers out there? Seeing as the Echo BBs look pimp and plus they are 10x easier to install an isis crankset than a stupid 36/48 spline 3 piece bollock.

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Theoretically, the Echo Isis External BB kinda seems to solve all the problems encountered with normal Isis BBs. So I guess... :turned:

Anyway, both are decent designs... I'd choose taper or Isis over shit like Profile 48 spline or the other 36 spline BMX garbage you find. If the Echo Isis External BB really is as strong as its designed to be, what with its big bearings and chunky axle... could it be a possible option for serious BMXers out there? Seeing as the Echo BBs look pimp and plus they are 10x easier to install an isis crankset than a stupid 36/48 spline 3 piece bollock.

What problems do BMXer's have with bottom brackets anyway that an Echo bb would solve?

Fitting them is a lot easier than you make out, they are stronger and its much easier to replace individual parts when they break axles and such.

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I can see Euro 3 piece BBs being relatively easy to fit, but for stuff like Profile BBs doesn't the axle move side to side according to how many spacers on each side and how tight you do the crankbolt? If that's true then its gonna be a bit of a pain compared to how easy Isis and taper are.

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  • 5 months later...

(sorry for bumping an old topic, but better than starting a new one (Y) )

I find that Square taper is just as good as long as its all good quality stuff, as the cranks have to be made of a better alloy to cope with the stress without rounding. There fine if you tighten them every ride.

Also 36/48 spline BMX BBs are awsome, they are really easy to fit if you know how. The cranks spacing can be a bit of a pain, but after fitting 2 or 3 sets you find it really easy, and the cross compatability makes eveything worth wile in the long run!

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The ISIS interface is inherently stiffer, and allows for the use of a larger diameter axle to increase strength. Unfortunately however, the larger axle means there is less room for bearings, so in most situations the load capacity of the BBs are reduced, or they don't last as long, or both. Various methods have been devised to prevent this, such as the external bearing BBs, although the mentioned SKFs seem the best on the market at the moment.

You are right about the actual taper causing problems over time. Square taper cranks work on a fully tapered interface, you can just keep going if the crank becomes slightly loose, wheres the ISIS taper has a much shallower angle, and actually has a stop, so unlike square tapers which you can keep forcing when the taper wears a little, the isis cranks push on and stop at a set point. If any play develops, which it can after a lot of use (accelerated by multiple removal of cranks) then there is no way of getting rid of it, the taper is permanently damaged. I've seen this happen to a few cranks, including middleburns. you undo the crank bolt and you can just slide the crank off, no need for an extractor.

Square has been around almost forever, and i think it will have its place for a long time to come yet, its simple, cheap, universally known and easy to maintain.

ISIS is a great solution for the more extreme ends of biking nowadays, which inherently have shorter lifespans on high stress parts such as cranks any way, so you may be able to justify the reduced longevity for the extra strength.

They are more expensive as the Tapers profile is harder to manufacture, it is a more complicated shape and has to be made to a higher tolerance than square taper cranks.

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i have rounded 2 square tapper cranks, fully trashed a shimano lx bb :-

still waiting for my isis bb and my try-all freeewheel :D for a month now :( (romanian shitty shops, i have to wait for someone to go to hungary to get a try-all fw for me and this pisses me off X( )

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