Thorn's EBB vs Bushnell EBB

[Carl]

I'm looking at buying a Rohloff Thorn Sterling for a light offroad touring bike and would like some user experience on Thorn's ecceentric bottom bracket.  Specifically:

1 Is it easy to make small adjustments for chain stretch or does it slip back into a prior indentation?

2. Any creaks due to the 2 screw tensioning method?

3.  Can a Bushnell EBB (http://www.bushnelltandems.com/eccentric.html) fit in a Thorn and is this a better design as it exerts tension over the entire circumfrence of the bb shell instead of just at the two tensioning screws?  (what's the diameter of the thorn sterling bb shell anyway?)

Any thoughts/prior experience of owners would be greatly appreciated.  Carl

[wheezy]

Can't help with any comparison, but my experience of the Bushnell has been entirely positive over three years off-road. No issues to report.

There's at least one more alternative to these two, as well. Can't recall who makes it... possibly Niner, or maybe Salsa.

[JimK]

The instructions make it clean that small adjustments are to be avoided. Separated indentations are required, or the thing won't hold position. The owner's manual, which they have posted on-line, specifies a minimum chain slack to allow before retensioning. Of course, even after retensioning you need to leave a bit of slack because a chain too taut will ruin the bearings!

[julk]

Carl,
Welcome to the forum.

1.No need to make small adjustments, you can run the chain quite slack before adjusting and this allows enough eccentric rotation for the next set of indents.
2. Runs rock solid when tightened to the requisite torque, no creaks.
3. Sorry, can't answer question 3, why not contact SJS and ask them.

I have a Thorn Rohloff, not a Sterling, but very happy with mine.
Buy one and you will have a 100 day 'money back' period, should be long enough to see if you are happy with it...
Julian.

[sbseven]

Hi Carl
(I've replied here rather than my blog!)

1. Just re-tension the chain as little as practicable. This will avoid having the indentations too close. I appreciate that you probably want to make more adjustments on a mountain bike setup over bumpy ground than you would for road riding to avoid chain drop. On the road, I'm retensioning around once every 2000km. That means I'm only go to get a few indentation sets on the EBB before changing the chain. Also, you can try to reuse indentations. You can feel them as you turn the EBB with the screws slightly engaged. Even if you "ruin" your EBB with loads of close indentations, the replacement part is only £30 (see link below), so nothing to worry about. In reality, it really isn't an issue at all.

2. Mine has never creaked (Thorn Raven Nomad) or moved.

3. Will the Bushnell EBB actually fit? I believe the Thorn Sterling (and Tour, STs, Nomad's) has a EBB shell size of 51.2mm...
http://www.sjscycles.co.uk/eccentric-bottom-bracket-insert-fits-raven-mk2-sport-tour-catalyst-enduro-sterling-twin-tandem-prod9053/

Shaun

[Joatamon]

I've always tightened the screws up by feel, I don’t have a torque wrench, and have never had a problem.  It's possible to remove the screws completely and have a look down the hole with a torch so you can tell if the indents are going to be in line.  So if you’re adjusting to a previously unfixed position, you can make sure that you're not about to go too close to an existing indent which might become enlarged and spoiled.  I haven't actually counted how many pairs of indents I've got in 5 years of chain adjustments but I think it's probably five at most.   That'll be one pair at each end, at the extremes of adjustment and 3 pairs in between.   I'd say that's probably all you need but if you want to maintain your chain with less slack you could get a lot more pairs in.

[Carl]

Thanks to all for sharing your experience with the Thorn EBB system.  It's now clear to me that its not necessary to make an adjustment until there's enough slack to move the EBB well beyond the initial indent. Conceptually, I do like the idea of an EBB that compresses against the entire shell as opposed to the dual screw design but it does not appear that I could switch to the Bushnell unit even if I had the inclination and $$ as they fit bb shells of 53.8mm-54 (or up to 57mm with a shim).  The Phil Wood EBB uses the same dual screw design as the Thorn and could not find the dimension requirements for the Niner EBB plus their website seems to emphasize to use it just on their frames.  I think the better part of valor is to stick with the Thorn system and listen to the real world users above who've shared their experience on this thread.  Many thanks to all that answered.

BUT if anyone does find an alternative which compresses against the entire shell might be nice for all users to at least know about it should they need to think replacement (presumably very far down the road).  Carl