Front Eccentric Bottom Bracket going CLUNK

[JamesBradbury]

We've got a Raven Discovery twin tandem and we've had it for about 2 years and done nearly 2000 miles now. We're pretty pleased with it overall, but there are a couple of niggles I'd like to sort out before we go away (which is pretty soon!).

I've found recently the front EBB seems to be going "Clunk" each time my right foot comes over the top or thereabouts. I can feel this most strongly through my right foot and it's audible and more severe when putting a lot of effort in. Is this serious or should I just tighten up the nuts underneath?

The other thing is when I change the Rohloff up to gear 10, it sometimes sticks in a much higher gear, then suddenly drops back to 10 where it should be. Is this just a quirk I've got to watch out for or is it a more serious problem?

Any suggestions appreciated.  

James

[julk]

I hope you find the root cause of the clunk soon.

The best finding would be just what you suggest, tighten the EBB bolts up a bit to stop it. If the EBB can wobble rather than slide sideways in the bottom bracket shell then it may be that a new EBB is in order.

There are quite a few other things which can come loose around that area, any or all of which could be contributing to a clunk - loose crank, loose pedal, loose chainring bolt(s) and a worn bottom bracket.

I still also get the notchy change up into 10 sometimes. I asked SJS about it after the first 300 miles - I was getting the notchy change up into gears 3, 5, 10 and 12 on a repeatable basis. I also had a couple of occasions when the gear slipped before meshing. I was advised to change the oil a couple of times and put some more miles on to let the rohloff bed in.
I changed the oil at 300 and 600 miles and noticed an improvement each time in a reduction in the slips and notchy gear changes.
I am now at 1100 miles and still get the notchy change into 10 and 12 occasionally, but it is not repeatable. I don't change up into 3 and 5 very often to have noticed it there.

Something I noticed for the first time the other day when I was stationary chatting to other cyclists - I rocked back and forwards with some weight on the right pedal at the front I got a noticeable clunk/movement within the gears which felt like a loose crank but wasn't.
I have just checked this and it is noticeable in gears 3, 5, less so in 6 and 7. This repeats in the higher ratio with 10, 12, 13 and 14 but with less effect due to the higher gearing.
Do you have this happening in any gears when you rock back and forward with weight on the pedal?

[JamesBradbury]

Thanks for the reply, I will try tightening the EBB tomorrow, but I'm a bit scared about overdoing it as I don't have a torque wrench.

We just went for a fast hilly ride and had little or no clunking, so it's a bit weird.

I think we may have had a few notchy gear changes at the start, but these days it's only 9-10. It can really throw us sometimes though, when it suddenly drops back down to 10 from whatever it went up to. I guess I should be aware of which gear I'm in and be careful, but I mostly twist without looking.

I've not tried rocking the bike when stationary. As it's a tandem, we're either going or not. I have noticed I can't change when the stoker has their foot pressed down ready to go, but that's not a big deal.

[jawj]

Hi James, I've not owned an EBB (yet!) but it may be that it just needs the Standard Noisy BB Cure™: take it all apart (including removing the internal eccentric shell in this case), clean it all thoroughly (frame, EBB, BB cartridge shell, axle & crank tapers/splines, etc), inspect for damage, regrease (you can never have too much grease!) and put it all back together. 99% of customers go away with a less noisy bike.

When I first got my Rohloff I was accelerating away from some traffic lights and the 9 to 10 gear slip caused me to loose control of the bike as pedalled hard into thin air. Thankfully the suspension forks and knobbly tyres saved me by miraculously mounting the kerb. I was so paranoid I sent the hub back to Germany! They (very promptly) returned it saying they'd changed the oil and fiddles the gears a bit (?). The gear still slips a little when changed under load but more normally jumps into a higher gear, and then comes back down when the pressure is released (as noted above and in 'Living With A Rohloff').

I was very worried about it all, but your accounts above reassure me that it's perhaps normal and I just need to perfect my pressure-release-whilst-shifting technique. I'm at around 500 miles (I don't ride my mountain bike enough...) so maybe I'll change the oil soon and see what happens as it beds in more.

I find the crank drops when shifting (both up and down) in a stationary position too, Julk, but must admit I find it a rather amusing quirk rather than anything to worry about. []

[julk]

jawj,
Thanks for the feedback on the stationary crank 'drops'. I will view it as a feature not a problem.

[Pallium]

Julk,
I seem to have the same problem as you.After engaging certain gears,mainly 14th and 8th,but sometimes other gears as well,the gear engages and then when I put pressure on the pedal a clunk can be heard and the gear engages properly.It annoys the hell out of me but probably does no harm so I haven't contacted Thorn about it.
I've been looking at the forum threads for some time to see if someone else had the problem and then I spotted your comments.Interestingly the problem started on my bike after about 1,200 miles,a similar distance to what you've done.I'll leave things as they are for now and hope that as the mileage increases and the hub beds in, the problem will go away.
I've noticed that little problems tend to crop up with the Rohloff hub as the miles increase, and for no appaerent reason.After about 800 miles the cranks started rotating on my bike when I pushed it,and I noticed that others have suffered from this,hopefully this will go away just as quickly as it arrived with the increase in mileage.
Regards,Pallium.

[julk]

Pallium,
Thanks for the feedback.

I posted a separate item regarding the clunk when stationary and rocking back & forward.
From the responses it looks like it is normal behaviour for the hub.

I get a different problem when riding and changing gear - which is that the hub momentarily engages 14 before dropping into the required gear, this is occasionally happening to me changing up into 10 and 12.
SJS have suggested that this can be caused by over energetic gear changing. I don't think this is my problem as my riding style is quite gentle.
SJS also suggested an oil change or two and I found this did improve matters. It might be worth giving your hub an extra oil change and see if it improves it.

[Pallium]

Julk,
Thanks for your suggestion re changing the oil.I did just that and tightened the cranks and the eccentric bolts but the problem remains,but reading other threads in the same vein suggests that it might be a quirk of the Rohloff hub and hopefully as the hub beds in the problem will go away.Incidentally Thorn recommend a tightening torque of 10-17 nm's for the eccentric bolts,I veered on the side of caution and used 10nm's and found that the bolts went into the eccentric shell quite a way.I think that if I'd used 17nm's I would have penetrated the shell and would use 10nm's as a maximum,assuming that my torque wrench is giving a correct reading of course.
Regards,Pallium.