[macko]

...the saga continues.

I finally got the bb out (thanks to those who helped) and now I'm trying to slap on the new cranks. Both the cranks and new bb are truvativ and both are isis (duh). I'm not sure everything is fitting together, though.

The cranks don't seem to slide all the way onto the bb spindles. In fact, they (as in both drive & non-drive sides) only go on about 1/2 way. What gives? When I tighten the bolt down will it compress the crank all the way onto the bb?

I looked at the splines on the bb and they all seem to be the same size so I don't think I'm putting the cranks on improperly ... but who knows. Thanks again for any help!

 

[binary visions]

Just tighten the bolt down, it will press them on. IIRC, ISIS splines are still slightly tapered so there's still a little bit of a press fit there.

If it's super hard to crank on the bolt, then don't force them - they should go on with just normal hand torque.

 

[Willy Vanilly]

And as long as you're using both Truvativ BB and cranks you should be fine (which you said you are). I've run into problems with the "taper" between Truvativ and Race Face stuff.

 

[macko]

Okay I think I've determined the problem: I'm using Holzfeller (DH) cranks on an XC bb. The bolt sizes are different. Son of a *****. I figured that ISIS was ISIS was ISIS. This REALLY pisses me off... :redhot:

 

[binary visions]

WTF? Are you sure? That shouldn't be

 

[Willy Vanilly]

I think you might be right. I've had some problems with the Truvativ ISIS stuff before. It was a long time ago though so I'm not sure I remember what they were.

This may be a stupid question but is it possible that one set of the bolts is self extracting and the other not?

 

[Wumpus]

ISIS is a standard. They are all the same.

http://www.sram.com/_media/techdocs/2001-2002_CRANK-E-R2.pdf

 

[macko]

ISIS is a standard. They are all the same.

http://www.sram.com/_media/techdocs/2001-2002_CRANK-E-R2.pdf

Not quite, I do believe that the splines are the same and the cranks just need to be tightened down, but the crank bolts sizes are different. The Holzfeller cranks came with a smaller M8 bolt while the Gigapipe bb requires an M12/M15 sized crank bolt.

That is what I think, anyways. This is my first time dealing with bottom brackets or cranks so I may very well be wrong .. but the crank bolt is most definately too small for the bb (which doesn't make sense seeing as how the cranks are DH and the bb is XC, I'd think it would be the other way around...).

 

[Wumpus]

Not quite, I do believe that the splines are the same and the cranks just need to be tightened down, but the crank bolts sizes are different. The Holzfeller cranks came with a smaller M8 bolt while the Gigapipe bb requires an M12/M15 sized crank bolt.

I thought we were talking about the splines.

but the crank bolt is most definately too small for the bb (which doesn't make sense seeing as how the cranks are DH and the bb is XC, I'd think it would be the other way around...).

Actually, it does kind of make sense. They made the walls thinner(lighter weight) with the bigger hole for XC use and the downhill BB should be a bit beefier with a smaller hole.

 

[Willy Vanilly]

Maybe the holes for the XC BB are meant for a self extracting bolt... which might be bigger?

 

[binary visions]

Maybe the holes for the XC BB are meant for a self extracting bolt... which might be bigger?

Self extracting crank bolts aren't any different, they just have a special collar that threads into the cranks and keeps the bolt from backing out... so when you unscrew the bolt, it pushes the cranks off.

 

[macko]

I thought we were talking about the splines.

Originally, but then we hypothesised that tightening the crank bolt may push the cranks all the way onto the bb.

Oh well...I'm taking it to the shop to see what they say. Thanks for the help guys! AGAIN!

 

[Wumpus]

Originally, but then we hypothesised that tightening the crank bolt may push the cranks all the way onto the bb.

Oh well...I'm taking it to the shop to see what they say. Thanks for the help guys! AGAIN!

Note 3 under "Assembly to BB" says that the "cranks may not bottom out on stops upon first installation."

http://www.sram.com/_media/techdocs/2001-2002_CRANK-E-R2.pdf

 

[Quo Fan]

Didn't the BB come with crank bolts? Every BB I've ever bought has come with bolts.

 

[ioscope]

You all think to much.

Step one. Slide crank onto splines.
Step two. Tighten built until satisfied.
Step three. Ride.

 

[macko]

The bb didn't come with bolts, the cranks did. I think if the bb did come with the bolts then they were the wrong size. I swung by my lbs and picked a couple that were the right size and went for a ride tonight.

Thanks again for helping me think my way through this little "project."

 

[blue]

Yeah...I found out a few weeks ago the same lesson. Different BBs/cranks models/manufacturers use different bolt sizes just to be annoying, even though it's all ISIS. However, most DH-type BBs tend to use the bigger bolts...