Eccentric Chain Adjustment

[hux]

Help please.I'm at the point of needing to adjust things for the first time given that the chain is dropping off at annoyingly regular intervals on main roads.
I've read the Thorn Owners Guide and the chain is  past the 60mm slack guide.
Looking at the left crank [as the Thorn photos] their 'minimum throw' setting is 3:15 [clock face anology] adjusting anti-clockwise to a 'maximum throw' of 11:45.
Now here's the rub...SJS supplied my bike with a 11:45 setting so I'm already well on the way to its final setting and I am doubting whether if I move it straight to 11:45 it will not take up the chain slack and it will be a waste of time and alternatively I should take it back to 3:15 and take a link out.
Now you might say just 'have a play' and dont tighthen the bolts up until I'm happy which is fine if this is feasible.
It would help me if there was a photo/diagrams of the internal workings as I can't picture matters clearly.
One final point,if your'e still awake, my chain is a rohloff and I can't see a 'connecting pin' or whatever it's called,do they have a special link to be removed.
Thanks for any comments

[neil_p]

Hi, the Rohloff chain can be broken and joined at any point. There are no special links (unlike some sachs) or special pins (unlike shimano).  Based on the Rohloff hub brochure, once the maximum throw position is reached, you need to remove a link of chain.  Then, return the BB bracket to minimum throw, or somewhere inbetween depending on chain tension.  I hope that helps.

[pdamm]

I can recommend the “have a play” technique.  The first time I tried it I assumed that since my EBB was at the 3:15 position it was at the end of the adjustment so I removed a link and found I couldn’t get the chain to fit.  So I put the link back in and played around some more.  

What worked for me was to rotate the EBB while feeling the tension on the chain with my hand.  This way I found the end position of the adjustment was around the 4:00 mark not the 3:15 that I had assumed.  I found it easy to measure the slack in the chain without putting any of the EBB bolts back in.  When the slack was down to 40 mm I just put the bolts back in and tightened them up.

The other thing to watch is to make sure the EBB doesn’t get pushed sideways partly out of its shell because that would mean the chain ring is not in line with the rear sprocket.

Peter Damm

[stutho]

Hi HUX,

Don’t remove a link until you have tried the EBB set to the maximum setting.  Adjusting the EBB is VERY easy, best advice is just to do ahead and try it! If you still have a loose chain then I need to ask-

Have you ever removed a link from a chain? (Sorry if this sounds condescending)

If not I would say now is not the time to learn. Go to a local bike shop and ask them it will take about 2 minutes and they should let you watch the process.

If you have removed a chain link before then you know what to do!

Best of luck

Stuat

[hux]

Thanks everybody.
Just realised my 'clock' times are a bit confusing,I perhaps should have said that the min.throw point is 15mins,my shop set up position is 55 mins and the max throw point is 45 mins hence my dilemma on whether winding the ebb around 10 mins would be sufficient to take up the chain slack.
Notwithstanding,I will now 'have a play' before I contemplate removing a link.
Stutho...I've only once before removed a link and which took an age [when the pin came right out] so I will go gently this time.

[tynevalleycommuter]

hux,

Have a go at the adjustment - nothing to lose!

If that will not do it, and depending on how many miles youy have done on the chain and in what conditions, before you think about removing links you should perhaps also consider checking the wear on the chain if it is excessively slack. If it is well worn, just taking up the slack on the ebb will take care of the slackness but you could end up prematurely wearing out the chainring/sprocket.

You can buy a chain wear indicator gadget or measure the distance between a fixed number of links. see http://www.sheldonbrown.com/chains.html

Sometimes taking out a pair of links can shorten the chain too much i.e. the chain will be too tight even on the minimum 15 past setting - it all depends on chainstay length and chainring and sprocket sizes on your actual set up. To get around this problem you can buy a stepped "1/2 link". They are quite often used on tandem connecting chains for the same reason.

Good luck,

tvc

[geocycle]

Apologies for being slightly off topic, but what tool are you using for moving the EBB?  Mine is one of these:

http://www.sjscycles.co.uk/product-Thorn-Eccentric-Bottom-Bracket-Insert--fits-Mk1-Raven-Tour-and-Sport-Tour--Adventure--Discovery-11656.htm

and I have the bespoke spanner:

http://www.sjscycles.co.uk/product-Thorn-Thorn-3-in-1-bottom-bracket-eccentric-tool-for-73mm-shell-Raven-bikes-12076.htm

but can't see how to get a grip with it.  Sorry if I am being stupid!

[tynevalleycommuter]

geocycle - I don't own a Raven myself but have worked on a friend's Discovery Twin. It looks like you have a Mk I bottom bracket and a Mk II spanner. If your ebb eccentric has the 5 cut-outs for the spanner rather than 2 holes, it looks like you need the 'C' spanner http://www.sjscycles.co.uk/product-Thorn-Thorn-Double-Ended-Raven-Eccentric-adjusting-Tool--15mm-pedal-spanner-11237.htm rather than the one with 2 pins.

It is probably worth a call to Thorn, they should be able to sort this out for you.

tvc

[geocycle]

TVC,
Thanks so much I thought I'd lost what remains of my technical ability!  The wrong spanner must have been dispatched with the bike -I'll get onto SJSC.

[hux]

Just got around to adjusting things,proved dead simple after all that worrying,surprised how little adjustment took up the chain slack,'clock setting' now at 50 mins so 5 mins took up a lot of slack.
Suprised also how easy it was to release bolts ,they were only hand tight so I've tried to 'pinch'them up the same and added a few drops of Locktite 243.
Not tried it out yet.