I've just installed my new sram omnium crankset onto my Cinelli mash work frame.Its a Std 68mm BB. I've greased all parts as per normal setup. Once I've tightened the non drive side with the Allen key (not with a tourque wrench as I don't have one ) there still seems to be some lateral play .Ive remove the crank arm and retightened it but there still seems to be the same play. I know I need a torque wrench and will borrow one but I've done up the bolt pretty tight .Am i missing something ? There were no spacers in the crankset kit so I assume I don't need any either ?
Cheers Ja
Have play in my new Sram Omnium crankset
Moderator: robbosmans
1. Wavy washer.
2. The stock bottom bracket that usually comes with the Omnium is pretty crappy. I've found bad tolerances, missing parts, you name it.
3. Is the play in the bottom bracket or in the crank (since you mention being concerned about torquing the cranks)? The Omnium chainring is thicker than standard track chainrings, so if you substituted a ring and used the same chainring bolts, your chainring can sometimes be a little loose on the crank arm spider.
4. I've found the splines not to be consistent in dimension on the bottom bracket. Try refitting it. There's a torque spec, but the crank doesn't have to get forced onto the crankset too hard -- like with Shimano's Octalink, it simply goes on until it stops.
2. The stock bottom bracket that usually comes with the Omnium is pretty crappy. I've found bad tolerances, missing parts, you name it.
3. Is the play in the bottom bracket or in the crank (since you mention being concerned about torquing the cranks)? The Omnium chainring is thicker than standard track chainrings, so if you substituted a ring and used the same chainring bolts, your chainring can sometimes be a little loose on the crank arm spider.
4. I've found the splines not to be consistent in dimension on the bottom bracket. Try refitting it. There's a torque spec, but the crank doesn't have to get forced onto the crankset too hard -- like with Shimano's Octalink, it simply goes on until it stops.
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Hi ,I've got no waves washer but on the sram omnium exploded drawing there isn't one ? I'm using the sram chain ring and the play is up and down but also I can move the crank axle left to right about 1mm .I need to get a torque wrench on it to see if I'm tight enough I guess before panicking as this might eliminate all probs if I'm not up to correct torque .
If the axle is moving then you've isolated the problem to the bottom bracket installation itself. That needs to be done right, and you might need to have the bottom bracket faced properly and then have a shop professionally install the bottom bracket.
There is no "bottom bracket" to install by the sounds of it, just the two external cups (68mm bottom bracket).
If the shell is *actually* 68mm (measure it, i've had under and over size ones) the only adjustment is pulling the crank onto the spline, and it's a lot of torque, if you are only using a standard L shaped allen key, you're unlikely to be able to achieve the required torque.
Also, about half the pictures of unfitted/BNIP omnium GXP cranks i can find have a little bag with what looks like a wavey washer in. But a wavey washer might struggle to take up 1mm. You might have two problems.
If the shell is *actually* 68mm (measure it, i've had under and over size ones) the only adjustment is pulling the crank onto the spline, and it's a lot of torque, if you are only using a standard L shaped allen key, you're unlikely to be able to achieve the required torque.
Also, about half the pictures of unfitted/BNIP omnium GXP cranks i can find have a little bag with what looks like a wavey washer in. But a wavey washer might struggle to take up 1mm. You might have two problems.
The generic SRAM crankset manual says wavy washer only for pressfit GXP BBs, not threaded GXP BBs.
In the event of play in the crankset on threaded GXP it says "If there is play in the crankset, remove the crank arms and apply additional grease to the spindle. Repeat the installation procedure until play is eliminated."
Which kinda sounds like a polite way of saying "Keep forcing it until it works" but it's your crank not mine!
In the event of play in the crankset on threaded GXP it says "If there is play in the crankset, remove the crank arms and apply additional grease to the spindle. Repeat the installation procedure until play is eliminated."
Which kinda sounds like a polite way of saying "Keep forcing it until it works" but it's your crank not mine!
The Omniums are GXP cranks, so you need Sram GXP external bottom bracket cups. The left cup has a 22mm internal diameter, the right one 24mm (Shimano e.g. have 24mm bores on both sides).
GXP cranks clamp the left bearing between the 1mm step in the GXP axle and the left crank arm - this is why you just tighten the bolt and don't have to adjust play.
The axle is not fixed to the right bearing, it just floats there, and all side forces are carried by the left bearing. This is why the left bearing will often wear out 1st.
GXP cranks clamp the left bearing between the 1mm step in the GXP axle and the left crank arm - this is why you just tighten the bolt and don't have to adjust play.
The axle is not fixed to the right bearing, it just floats there, and all side forces are carried by the left bearing. This is why the left bearing will often wear out 1st.
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Marin has it exactly.
On a GXP crankset if there is lateral play you haven't done up the crank bolt tight enough. Once tight enough the non-drive bearing will be captured between the non-drive arm and the 1mm step in the spindle.
On a threaded bottom bracket a wavy washer would achieve nothing.
On a press fit bottom bracket the wavy washer is required to stop the pressfit cup migrating out of the bottom bracket shell.
On a GXP crankset if there is lateral play you haven't done up the crank bolt tight enough. Once tight enough the non-drive bearing will be captured between the non-drive arm and the 1mm step in the spindle.
On a threaded bottom bracket a wavy washer would achieve nothing.
On a press fit bottom bracket the wavy washer is required to stop the pressfit cup migrating out of the bottom bracket shell.
