[biker]

I noticed the large chainring is starting to hit the FD while pedaling on the 50/12.
It appears to be during the down stroke on the drive train side. I rode in this config
for 3 weeks on a fix trainer with no problems (very true). Did some mountain riding out west for about a week came back and put bike back on fix trainer and started noticing this out of true
situation. I have since tighten all chainring bolts,checked tightness of clamping bolts that secure crankarm. Problem still remains. Removed crankarm/spindle and checked tightness of bearing cups. Reassembled. Problem still remains. No play when grabbing
arms and checking for side play.

Is this a normal characteristic of these cranksets and use ? I have only been using it for about a month with maybe 600 miles on it. The spindle still has a tight fit into bearing cup holes.

Any ideas ?

Thanks

 

[Kerry Irons]

It appears to be during the down stroke on the drive train side. I rode in this config for 3 weeks on a fix trainer with no problems (very true). Did some mountain riding out west for about a week came back and put bike back on fix trainer and started noticing this out of true situation. I have since tighten all chainring bolts,checked tightness of clamping bolts that secure crankarm. Problem still remains. Removed crankarm/spindle and checked tightness of bearing cups. Reassembled. Problem still remains. No play when grabbing arms and checking for side play.

Is this a normal characteristic of these cranksets and use ? I have only been using it for about a month with maybe 600 miles on it. The spindle still has a tight fit into bearing cup holes.

Your wobble is likely either a slightly off spider arm, or a slightly off chainring. Either/both is a very common thing (I won't say problem, because in most cases, it has no effect on performance). It sounds like you either bent something when riding out west or during transport.

You have to straighten your spider arm/chain rings. Hold a small screwdriver or other short, pointed object against the seat tube so that the tip just grazes the crank spiders as they pass. If the spiders are bent (most likely problem), you can even them out as follows:

Place the bike on its side with the crank supported on a block of wood at the axle. With another block of wood or a stout dowel placed at the end of the offending spider(s) give it a whack with a hammer. Check for change in alignment. If you got no change, hit it harder next time. Repeat until all the spiders are even. You may need to bend them away from the frame (brace the right crank on the block of wood) or toward the frame (brace the left crank).

Once the spiders are even, check the chain rings with the same technique except put the point of your screwdriver at the teeth of the rings (most likely the big ring only if the spiders are even). Straighten the chain ring by placing a large adjustable wrench over the ring with the jaws adjusted for a slip fit over the ring. Bend gently, and check alignment. Repeat until you've got it right.

Even with the chain rings dead straight, you still will get some deflection due to pedaling forces, but that should greatly improve your situation.

 

[JimP]

The issue can be caused by the FD not moving far enough over the 50 ring. The MegaEXO BB causes the chainrings to be moved out a little and the FD has a little protrusion that binds on the frame/mount. If you have binding, you can take the FD off, hold it in the big ring position, and file the little protrusion enough to clear the front DR mount.