Eccentric BB/crank problem on new Raven Tour

[gregmacc]

Hi all ... My BB/crankset has developed some slack. It can be felt as a slight "knock" through the pedals when riding. If the end of a crank arm is pushed and pulled laterally with one hand whilst holding the seat tube firmly with the other hand a slight amount of movement can be felt. The eccentric bolts are secure and the crank bolts are tight. The bike has only 1600 Km on it. Any ideas?

[richie thornger]

Mine made the knocking noise and I wondered what it was. Later that day the chain fell off because the bolts holding the BB in were not tight enough. The BB had worked loose and the chain slackened and off it came up a hill.
My Raven Tour uses the Plastic BB holder if that is of any use.
Perhaps the bolts do need tightening ??

[il padrone]

Yep, I'd reckon try giving those EBB bolts another quarter turn or so and see what happens.

I was touring Tassie in January and developed a click.... once every pedal rotation. I thought it was a loose crank - tightened it. Then thought it was a loose chainring bolt (one is loose and can't get it tighter).... tried that again. Still clicking. I rode for about 700-800kms with this click, blaming it on the loose chainring bolt.

Back home I checked the crank again and noticed a small amount of play in the EBB. Took out the tool and tightened the bolts. No more clicking  

My EBB bolts are rather tight to adjust - none of this "do them up finger tight" that I've heard others talk about. Don't know whether it's corrosion, dirt in the thread or some metal obstruction in the thread, but I have to use the spanner to do them up and to undo them. This has tricked me out a few times when resetting the bolts to secure the EBB.

[wildrover]

Yes, my Royce BB was that way, from the start.  My hubby pulled the crank arms, and tightened it with the Royce tool we bought with the bike.  Been OK since.

[geocycle]

I do my EBB bolts up tight using the spanner and do not get any lateral movement.  Having inspected it afterward I think you would really have to provide some serious torque to damage the shell.  You should always avoid the thin side anyway.  I had a bit of a noise at one point from some slipping where two holes had joined.  Other noises from that department were from a pedal on two occasions and a crank on one occasion.  This is a 2006 set-up.

[JimK]

I use a torque wrench to get this right. The Thorn User Manual says 10-17 Newton-meter. That causes the pointy bolts to make a good sized impression in the shell!

[triaesthete]

"If the end of a crank arm is pushed and pulled laterally with one hand whilst holding the seat tube firmly with the other hand a slight amount of movement can be felt. The eccentric bolts are secure and the crank bolts are tight. The bike has only 1600 Km on it. Any ideas?"

If you are using a Shimano hollowtech 2 crankset with outboard bearings they may be clapped out at 1600km

To see if this is the case put one finger across the gap between bottom bracket shell and eccentric and wiggle crank end as above. If you can't feel movement between shell and eccentric then the eccentric is mounted securely and the play is probably in the bearings. The right hand one normally fails first. It's a good job they are cheap and easy to fit.

I hope this helps diagnosis
Ian

[gregmacc]

Hi again all and thanks for responding ... Today I whipped off the crank arms and double checked the eccentric bolts which were well secured (I used some medium strength Locktight last time I adjusted the chain). Whilst having a bit of a poke around in the general area I noticed that the drive side bearing cup on the BB was loose. This proved to be the problem because once the cup was tightened and crank arms re-installed all was well again.
Cheers,
Greg