EBB same position for life

[PH]

What is the order of wear ? Or In other words , what will wear out first before it needs replaced between the chain, sprocket and chainring ?

Somewhere in the Thorn literature is the advice to change all three at the same time, not everyone agrees and I'm sure we've done this one 
I don't think I've ever got less than 5,000 miles, a few times over 10,000 and never made it to 15,000. 
I've just looked at my maintenance log, yes I am that sad, on my most used bike the chain is coming up to 4,000 miles and has been adjusted once at around 1,200.  It's wiped and oiled when it needs it, but it never gets a proper clean.  None of the components are even beginning to look worn.

[ourclarioncall]

PH

I just read some of your old comments on an old thread , and i am combining them with your recent comments here and that’s given me a much better picture of what I was trying to understand, Thankyou 👍 👍

You said that you hope to get a good 10,000 ish miles out of a chain , and that you don’t bother to measure for wear, but that you change the chain When you run out of adjustment or the sprocket looks worn

So I now see what you mean by needing to adjust the EBB occasionally over the timeline of those 10,000 ish miles

[ourclarioncall]

PH

so what would happen if you never tightened the chain via the EBB over the course of those 10,000 miles ?

Again, I think I read somewhere that’s it’s ok or even a good thing to have a loose chain on a rohloff ?

[PH]

PH

so what would happen if you never tightened the chain via the EBB over the course of those 10,000 miles ?

Again, I think I read somewhere that’s it’s ok or even a good thing to have a loose chain on a rohloff ?

Yes it's best to run it slack, but obviously not so slack as it's falling off. If you start with it fairly tight it won't get to 2,000 miles without adjustment, if you don't adjust it, it'll fall off.  If you start with it running fairly slack, it won't get to 1,000 miles.  These are just estimates of course, lots of variables, not least the make and model of chain. Neither will you be able to precisely judge when it's slack enough to fall off, well not without more hassle than adjusting. 
If EBB's were a problem, people wouldn't use them.  There's lots of alternatives for tensioning a chain, I never have to adjust the chain on my folder with a Rohloff tensioner and I have a bike with horizontal dropouts which are simple enough, IMO the EBB is still the best and the clamp design the best EBB.

[ourclarioncall]

PH

good info and insight , ok that’s all very helpful, Gives me a bit more confidence now.

So the chain is basically always moving (stretching/wearing) through a set of safe parameters where it will function properly . Not too tight so that it effects the wheel and bearings ? And not too loose so that it falls off.

[JohnR]

Fear not! Adjusting the EBB is one of the easier bike maintenance tasks: Slightly slacken the clamp bolts; carefully rotate the EBB slightly; check chain tension; more rotation if needed, otherwise tighten the clamp bolts. My Mercury came with a pin spanner but I had previously found with another bike that the EBB can be rotated by putting the end of a suitably sized long Allen key into one of the EBB holes and then pushing it round with the crank. It's advised that the EBB should be rotated such that the thin part of the EBB shell is at the top. See the Thorn Bike Owner's Manual http://www.sjscycles.com/thornpdf/ThornBikeOwnerManual2Web.pdf .

[martinf]

Yes it's best to run it slack, but obviously not so slack as it's falling off. If you start with it fairly tight it won't get to 2,000 miles without adjustment, if you don't adjust it, it'll fall off.  If you start with it running fairly slack, it won't get to 1,000 miles.  These are just estimates of course, lots of variables, not least the make and model of chain. Neither will you be able to precisely judge when it's slack enough to fall off, well not without more hassle than adjusting.

I reckon a chain will probably last more than 2,000 miles without adjustment under a Chainglider. And a Chainglider might make it possible to run it slacker without it falling off.

For low chain maintenance without a Chainglider another alternative should be the KMC Rohloff extra thick sprocket combined with the KMC chainring and their e101 EPT chain, guaranteed for 10,000 km. I think there is another manufacturer with a specific long-lasting chain. 

[UKTony]

Fear not! Adjusting the EBB is one of the easier bike maintenance tasks: Slightly slacken the clamp bolts; carefully rotate the EBB slightly; check chain tension; more rotation if needed, otherwise tighten the clamp bolts. My Mercury came with a pin spanner but I had previously found with another bike that the EBB can be rotated by putting the end of a suitably sized long Allen key into one of the EBB holes and then pushing it round with the crank. It's advised that the EBB should be rotated such that the thin part of the EBB shell is at the top. See the Thorn Bike Owner's Manual http://www.sjscycles.com/thornpdf/ThornBikeOwnerManual2Web.pdf .

NOTE this version of the owners manual does not use illustrations of the latest 2 bolt friction type EBB as fitted to the Mk3 Nomad and the latest iteration of the Mercury. The advice for these and the previous 4 bolt mini EBB on the Mercury is that the EBB should be rotated such that the thin part (not the thick part) is at the bottom. This is the opposite to the screw type EBB fitted to the Mk 2 Nomad and Ravens.

[UKTony]

Apologies I must correct myself. According to “living with a Rohloff hub” with the latest two bolt friction type  EBB the thick part should be kept towards the bottom. I’d assumed that as it was a friction type similar to the mini EBB on the earlier Mercury the need to keep the thin part at the bottom would be the same.

[JohnR]

Apologies I must correct myself. According to “living with a Rohloff hub” with the latest two bolt friction type  EBB the thick part should be kept towards the bottom. I’d assumed that as it was a friction type similar to the mini EBB on the earlier Mercury the need to keep the thin part at the bottom would be the same.

Good find! Page 43 of the Living with a Rohloff hub http://www.sjscycles.com/thornpdf/ThornLivingWithARohloff.pdf is more recent than the Owner's Manual.

[ourclarioncall]

Thanks guys , that has been a great help , definitely feeling like I could tackle it when the time comes . The pictures are good too . Visual learner and all that jazz 🙂

Couple things- on how tight to tighten these EBB bolts once you’ve untightened them , spun the EBB and tights the chain - I don’t know nuTTin bout Newton thingys or spanner’s/wrench’s ... but I’d be willing to buy/learn

But would it be possible just to retighten exactly the same amount of turns that I loosened to get it back to a similar place ? As In “ tight , 1, 2, 3, 4, and 3/4 turns lefty Lucy, so il do the exact same in the righty righty direction “

—

The other thing is, I haven’t read I don’t think how to tighten your chain , or in other words , how do you know your chain is tight enough and not too tight once you have rotated the EBB a little to take up the slack ?

Cheers guys

[JohnR]

How to visualise the required torque? Think of a Newton (about 1/10 kg) as being a moderately small apple. 5Nm is thus the torque provided by hanging 5 of those apples on a lever 1m long or 25 apples pushing on a 20cm long spanner. That's not a big force and, in the context of the EBB, the objective is to ensure that the EBB can't rotate when the bicycle is used. It's prudent to tighten anything up using the tools which you will be carrying around so you can be more certain of undoing something when the need arises. If worried about things working loose then a drop of low strength loctite on the threads can be used.

The desirable range of chain tension is shown on page 12 of the owner's manual. However, as long as the chain isn't so slack that it jumps off when you cycle over a bump then it's OK. Thorn bikes are set up with a good chainline which should help reduce the risk of the chain jumping off.

[ourclarioncall]

JohnR

Oh yeah, I remember Isaac and his Apple now

Yeah , I hear folk say it doesn’t take much to tighten the EBB bolts sufficiently

[geocycle]

I find one chain ring does two sprockets, each can be reversed. I use a chain for each side of a sprocket. Perhaps 5000 miles per chain, 10,000 per sprocket, 20,000 per chain ring. Everyone is different though depending on use.

[mickeg]

I can't comment on the Mk III, I have the Mk II.

As noted above by others, the eccentric bolts press a small depression into the aluminum eccentric.  And you should avoid creating too many new depressions or you can end up with a groove and then the eccentric can slip, or at least that is my understanding.

Someone commented years ago that he put his bike upside down, removed one eccentric bolt so he could look inside at the depression, then loosened the other bolt and when he tightened his chain, he could see how far the depression moved as he adjusted it.  I thought that was a really good idea, so that is what I always do now.   

I wait for my chain to get quite loose before I tighten the chain.  The bolts are a fine thread 10mm.  When the depression that was centered in the hole before I adjust the eccentric gets to the edge of the hole, that depression has  moved roughly 4 to 5 mm.  That is far enough, I then tighten the bolts.  If however I can't tighten it that far because the chain gets too tight, I reset the eccentric to where it was before I started and just ride the bike until the chain gets more slack.

I do not use a torque wrench, but if you are not mechanically minded, you could ask SJS for a torque level and use a torque wrench.

After eight years I now have lots of little depressions in my eccentric evenly spaced at about 4 to 5mm apart, no longer need to make new depressions.

On one occasion one of the 10mm screws came loose.  It did not fall out, but next time I ordered something from SJS I ordered a spare.  I also use a couple rubber bands wrapped around the two bolts so that they can't easily turn by themselves to make sure that if one was too loose, it could not fall out.  See photo.

This procedure of flipping the bike upside down may take a bit longer to do, but I find that being able to look at where the depressions in the eccentric are when I adjust it to be an added benefit.

If however you got the Mk III, there are no depressions, the eccentric is infinitely adjustable.  Other than that, since I have not used that eccentric, I can't comment further.

***

A Nomad Mk II is a very heavy bike.  Do you really need a bike with that much weight capacity?  If not, you may decide that you would have been happier with a lighter weight bike.

Chainglider, I do not use one but those that use them are quite happy with them.

I have worn out several chains, but am still on original chainring and sprocket, I have flipped the sprocket to the other side, my sprocket is the old threaded style, not splined.