Chain Adjustment

[freddered]

I Just reached the end of adjustment on my eccentric B/B and the chain still looked a bit slack.

I removed a link (well, 2 links in order to reveal a new inner-link for my SRAM connector link) and could only get the chain to rejoin by removing the chain from the chainring, re-connecting the connector link and then forcing the chain back on the chainring by turning thre cranks quite hard. 

The chain is now very tight. 

Do you think it will stretch to fit before it snaps or damages anything?

Seems a pity that the B/B doesn't have enough adjustment for link removal (or did I do something very stupid?)

[geocycle]

Hi Fred,
My limited experience suggests that running a slack chain is better than a very tight one.  I find that the shifter stiffens up if the chain is too tight and I worry about damaging something with too much torque.  Maybe you need one of those half-link things discussed elsewhere?

It would be helpful to compile a list of chain ring and sprocket sizes that lead to a lack of adjustment in the EBB.  Mine's a 40 x16 and I've been lucky not to have any problem.

[julk]

It would be helpful to compile a list of chain ring and sprocket sizes that lead to a lack of adjustment in the EBB.  Mine's a 40 x16 and I've been lucky not to have any problem.

I agree that would be most helpful.

Just to make it even more complex, I suspect the frame size with its corresponding chainstay length will also come into play, 3 chainstay lengths for the Raven Tour, 2 for the Raven Sports Tour.

What do you think?

[PH]

I can't figure out what you've done
How much chain have you removed?  You shouldn't have needed to remove more than one full link (one inner, one outer) that should have shortened your chain by 1".  You only need half of that in the EBB adjustment (1/2" in each direction) I haven't measured it but I reckon the Thorn EBB has a lot more than that.
If your adjustment is at one extreme, you should be able to achieve the same tension with another link, before reaching the other extreme.  Unless I've missed something?

experience suggests that running a slack chain is better than a very tight one.

Oh yes, don't run a tight chain.

[neil_p]

That chain sounds far too tight - apart from wearing the chain ring/sprocket, if it snaps when you're up on the pedals could lead to a nasty accident. 

[pdamm]

When I first got my Raven Tour on two occasions I thought the EBB had reached its maximum adjustment and it was time to remove a link.  On both occasions I found I couldn't get the chain on so I put the removed link back in again .  On the second occasion I tried rotating the EBB through a full 360 degrees while feeling the slack in the chain.  It turned out that what looked like the maximum adjustment to my eye was in fact not the maximum, instead it was a bit further round.  I could only tell this by feel.  Have you tried rotating the EBB through a full 360 degrees to find the maximum adjustment?

Peter

[stutho]

Hi freddered,

As others have said, don't run the chain too tight.  Removing one full link removes 1 inch of chain.  The EBB allows just over 1/2 an inch of movement - which equates to just over an inch of chain (moving the EBB forward tightens both the top and the bottom haves of the chain) .  So in theory there shouldn't be a problem.  However...  When I think back to when I first removed a link, I think in the first month, I found that I was left with a chain far too tight.  I replaced the link. 

[davefife]

I've just had to remove a link (or 2 depending on what you classify as a link!) to restore tension.  RST has covered 6,000 miles in 21 months of totally hassle free use.
Based on this experience, if you remove a link and its too tight, its not time to remove a link, run the bb at max adjustment for another say 300 miles and try again. 44x16 chain ring and sprocket. SRAM PC48 chain.

[freddered]

I re-fitted the link and the chain is slack, not worryingly so but it's not possible to get it nicely tight.

So now I know that the BB doesn't provide quite enough adjustment to allow you to keep your chain correctly adjusted up until you can remove a link.

I suppose the moral of this tale is that you really shouldn't be removing links to take up the slack, it's time to throw away the chain maybe.  It's done 5000 miles and been out in every weather for 2 years.

I think I'll buy a new chain plus a half-link.  This should allow for perfect adjustment.

Question - How easy is it to flip the rear sprocket over?

[PH]

Question - How easy is it to flip the rear sprocket over?

It was easy for my LBS with a big vice and a chain whip with a 2 foot handle.
It was impossible for me with mole grips and a cheap chain whip.

I re-fitted the link and the chain is slack, not worryingly so but it's not possible to get it nicely tight.

I'm surprised, I'll have a play with mine next time it needs adjusting.

[freddered]

It was easy for my LBS with a big vice and a chain whip with a 2 foot handle.
It was impossible for me with mole grips and a cheap chain whip.
I'm surprised, I'll have a play with mine next time it needs adjusting.

I spun the BB 360 degrees several times and it never got slack enough to fit the 'magic link'.  With links replaced I spun BB 360 degrees several times and it never went tight.

Now I know this is the case I'm not too bothered.  The half-link will fix it next time.  I may buy a couple so I can remove them one at a time rather than swapping them back in.  I'll report back in 5000 miles.

[stutho]

Hi Freddered,

it never got slack enough to fit the 'magic link'

I might be misinterpreting what you are saying, if so ignore what follows.

Remove the back wheel. Then fit the powerlink.  Finally replace the back wheel.  The power link needs a LOT of slack to fit it.

Stutho

[daviddd55]

I had the chain replace after 6000km as the bike shop said the chain was "just on the limit" of max wear, but in that 6000km I didn't touch the BB adjuster at all, and yes the chain was slack, but it never slipped. I'd rather leave alone unless I hear convincing argument to the contrary?

[stutho]

I had the chain replace after 6000km as the bike shop said the chain was "just on the limit" of max wear, but in that 6000km I didn't touch the BB adjuster at all, and yes the chain was slack, but it never slipped. I'd rather leave alone unless I hear convincing argument to the contrary?

18,000 km on the same chain - thus saving two chains and £30 plus.  Ok I admit it I am cheap!  I currently have about 14,500km on my first chain and I expect it to get to at least 16,000km but hoping for even more (20,000Km sounds like a nice round number).

The thing is that when people talk about the maximum wear of a chain they are talking about a derailer set up. (i.e. 1/16th  extension in 12”)  This does not hold true for a single speed setup. There is no simple rule.  When I do eventually bin my chain, I will swap around the direction of the chain ring and the spur gear. 

Stutho

[Cake]

Hi Stutho,

How do you determine when your chain is due for replacement before it snaps?

Is this a stupid question?!

That is excellent mileage from a chain though!

When my RT was delivered i was quite surprised at how tight the chain was - accepting that it will stretch quite quickly due to being new and was setup (professionally!) with that in mind.