Adjusting EBB

[in4]

Just adjusted my EBB as per Thorn instructions. It was quite stiff to move, doesn’t surprise me when considering the conditions I cycled in on my recent Scottish tour. My question is: Should I lubricate/grease the EBB and if so, is there an access hole/ point I should use? TIA

[WorldTourer]

I always lubricated the shells of my Thorn Nomad Mk2 and Mk3 EBBs when I was building the bike or replacing the BB, i.e. when the cranks were not attached. It was easy then to slide the shell out and rub grease on it. But when your cranks are attached, there is no real way to get grease around the shell.

[Danneaux]

Should I lubricate/grease the EBB

Yes. Without periodic lubrication, they can seize in place making future adjustments difficult or impossible until freed with some effort. Remember, the frame's BB shell is steel, while the eccentric insert is anodized aluminum. Galvanic corrosion can form between these two dissimilar metals over time without some sort of grease a an isolator. I believe Thorn has recommended using CopperSlip. I have had good luck using Phil Waterproof grease.

if so, is there an access hole/ point I should use?

Like WT, I remove one crankarm (the off-side/left side) and then loosen the grub screws and slide the eccentric and BB with right arm attached, pulling the unit out the right side. I then clean and grease the interior of the frame shell and the exterior of the eccentric and then reinsert and reattach the left crankarm. It is a pretty quick operation and keeps adjustments smooth (or restores easy adjustability if it is sticky to start with).

As for lateral (left/right) adjustments of the eccentric, I've found my Nomad one is perfectly centered when it is midway in the frame's BB shell. I just use my fingers as a crude caliper to check my eyes and...done. If yours is purposely offset for some reason (i.e. to achieve the needed chainline with the crankset you're using), be sure to note and measure any offset before removing the eccentric so you can restore it After.

Best, Dan.

[Matt2matt2002]

I'll second Phil waterproof grease.

One of my many squeaks disappeared after applying the grease. Don't need much at all. Now it's a regular part of my PPM.

Unlike Dan, I'm unable to remove a crank arm.
( What should I buy?). I undo the 2 bolts holding the EBB and slide it to the left, grease and then slide to the right. Appears to work.

Best
Matt

[Danneaux]

Unlike Dan, I'm unable to remove a crank arm.
( What should I buy?).

A standard crankarm puller for 3-piece cranks should cover the bulk of current cranksets intended to work with internal bottom brackets. Something like this...
https://www.sjscycles.co.uk/tools/cyclo-14mm-cotterless-crank-puller/?geoc=US
Of course, you'll need a socket wrench to remove and replace the crankarm bolt as well; you get that by flipping the above tool over to the socket end. Yours may not even require that, as many more recent cranksets of this sort are supplied with a center bolt that incorporates a duct cap and is tightened/loosened using an 8mm allen head wrench.

If your crankset is a 2-piece design with external/outboard bottom bracket, then you can remove the left crankarm by loosening allen-head machine screws and flipping the safety catch up before sliding the left arm leftward, off the spindle.

I undo the 2 bolts holding the EBB and slide it to the left, grease and then slide to the right. Appears to work.

If you can get enough grease in there to do good, then you should be fine. Thorn's eccentrics are sort of hollowed out in the middle, leaving only a ring on each side and part of the middle to deal with. Other designs (like the one on my tandem) are solid with no reliefs.

Best, Dan.

[Matt2matt2002]

Thanks Dan. It's on my Xmas list.

[mickeg]

I have never lubricated my bottom bracket eccentric.  It is anodized aluminum, the shell (Nomad Mk II) is painted (or is it powder coated?) steel, so the paint isolates the steel from the aluminum eccentric.  Thus, no dissimilar metal corrosion. 

I was not aware that some of the eccentric shells were bare steel inside.  I suppose that the Mk III Nomad would probably need a tighter fitting shell than the Mk II because of the bolts that hold the shell tight around the eccentric.

Someone on this forum years ago said that he removed one eccentric bolt when he adjusts it on a Mk II Nomad so that he could see where the depressions were from the pointy end on that bolt that presses into the eccentric, so that when he adjusted it he could make sure that the depressions (I call them divots) are far enough apart to prevent the eccentric from forming a groove.  That sounded like a brilliant idea to me, that is what I do.  And that also means that my chain has to get quite loose before I adjust it because I want the divots to be at least a couple mm apart on my eccentric.

I have now adjusted my chain enough times with replacement chains that I almost never create a new divot, reuse old ones.

I bought a XLC brand crank puller for my Nomad Mk II square taper cranks.  It uses the 15mm open end wrench that is the on eccentric wrench that comes with the Nomad Mk II frame.  And there also is an 8mm socket on the part of that puller that you turn.  I have to remove both crank arms to pack my frame into the S&S case, thus the wrench goes with me on a tour.  I want to minimize the size and number of tools I need when I travel with that bike.  I also cut a straight stub of 8mm allen wrench that fits into the 8mm socket hex hole in the eccentric wrench, so I can use that on both the crank arm bolts and XLC crank puller.
https://www.xlc-parts.com/gb-en/xlc-crank-puller-to-s07-for-square-bb/

The XLC tool, the eccentric tool and a multi-tool are in the photo.  The stub of 8mm allen wrench is attached to the eccentric tool with a rubber band so it does not get lost.

[Danneaux]

One useful thread on seized eccentrics can be found here...
http://thorncyclesforum.co.uk/index.php?topic=1738.0

Best, Dan.

[PH]

Up till now* my annual service has included removing those items that have a tendency to seize - seatpost, EBB shell, cranks**, pedals - it's a chance to air the frame out, clean and examine the components, spray some ACF-50 inside and apply copperslip before refitting. It isn't a huge task, the entire service, including a hub oil change, will be done in two sessions over a weekend, leaving the frame to air, and the flush oil to drain, overnight.
I do sometimes wonder if I overdo it, but I've never had a roadside repair that I've thought could have been avoided.  I can't remember the last time I did any maintenance on the bikes, other than adjusting brakes and lubricating chains, outside of that annual service. 

*My riding has reduced, grandkids do that for you, I may start servicing my bikes bi-annually. 

** There is an argument that the crank/spindle interface shouldn't be lubricated and are best left undisturbed. I've seen several wrecked by becoming impossible to remove, I don't know of anyone who'd wrecked one by lubrication!

[PH]

One useful thread on seized eccentrics can be found here...
http://thorncyclesforum.co.uk/index.php?topic=1738.0

Best, Dan.

Thanks for that trip down memory lane Dan.  Interesting the discussion of split shells. I always thought them a superior design, I spec'd it on my custom bike before Thorn adopted it, though Thorn have made a much neater job of it with only  partial splits.

[PH]

...and a reminder of why it's a good idea!
http://thorncyclesforum.co.uk/index.php?topic=14338.0

[mickeg]

...
** There is an argument that the crank/spindle interface shouldn't be lubricated and are best left undisturbed. I've seen several wrecked by becoming impossible to remove, I don't know of anyone who'd wrecked one by lubrication!

What was the cause, dissimilar metal corrosion?

I have never had such a problem, maybe I need to start worrying about it.

If my memory is correct, Campy recommends against it.  I have Campy square taper cranks on four bikes.

[PH]

...
** There is an argument that the crank/spindle interface shouldn't be lubricated and are best left undisturbed. I've seen several wrecked by becoming impossible to remove, I don't know of anyone who'd wrecked one by lubrication!

What was the cause, dissimilar metal corrosion?

I think probably corrosion of some sort, it doesn't have to be galvanic to cause seizure.
The problem is usually stripping the threads trying to remove, I've done it once, it's difficult to judge how hard to go, tool was fully inserted and I didn't think I was using excessive force... I've considered self extractors a couple of times, but some reports suggest these can be equally troublesome.  Thankfully, apart from that once, mine come off reasonably easily if removed when servicing.

[Danneaux]

I've had good luck over the years by lightly greasing my square-taper BB spindles and then torquing them to spec ONCE. I don't re-torque nor do I lubricate the underside of the bolt heads. My general approach is summed up nicely here...
https://www.renehersecycles.com/to-grease-or-not-to-grease/#:~:text=They%20advised%3A%20%E2%80%9CGrease%20the%20tapers,press%2Dfit%20between%20the%20parts.

Best, Dan.

[mickeg]

...
** There is an argument that the crank/spindle interface shouldn't be lubricated and are best left undisturbed. I've seen several wrecked by becoming impossible to remove, I don't know of anyone who'd wrecked one by lubrication!

What was the cause, dissimilar metal corrosion?

I think probably corrosion of some sort, it doesn't have to be galvanic to cause seizure.
The problem is usually stripping the threads trying to remove, I've done it once, it's difficult to judge how hard to go, tool was fully inserted and I didn't think I was using excessive force... I've considered self extractors a couple of times, but some reports suggest these can be equally troublesome.  Thankfully, apart from that once, mine come off reasonably easily if removed when servicing.

Since I have to remove my crank arms on my Nomad Mk II to fit it into an S&S case, I installed self extractors.  They might have worked better if I used a thread locker like Loctite, but I did not.  Somewhere in the middle of Iceland, one of my self extractors self extracted.  (See photo.)  Thus, when I went to pack up the bike to go home, had no extractor on that side.  Had to transfer self extractor from one side to the other to remove the crank arm and did not have the proper tools to do so.  That is when I bought the small XLC crank puller I described in a previous post in this thread.  That stays in my tool back and won't fall out at an inopportune time.  With the stub of an 8mm allen wrench that I cut to fit in the Thorn eccentric tool, that does all I need. 

No more self extractors for me.  I had crank pullers before that, but they were larger or my Sugino puller used different tools that I could avoid bringing with the XLC one.  Since whatever tools I used had to be carried on the tour, I wanted to minimize that as much as possible.

A friend of mine had to cut a crankarm off of a bike.  He got the bike used and the crank was on there really tight, so tight that the square end of the spindle was flush with the square hole in the crank arm.  I had never seen a crank on a spindle that far.  I am not sure why he ended up cutting it off.  I loaned him my Sugino puller, he might have worried that he would break my tool if he forced it too much, that would not surprise me?

Crank arm bolts are the only bolts on a bike that I more often then not use a torque wrench when I install them.  But, I do not carry a torque wrench on tour, so they often are not torqued properly on my Nomad Mk II.  I previously mentioned that most of my cranks are Campy, but my Nomad Mk II uses low budget Vuelta crank arms.