fliplap

Scotch 414h mounting tape. Strong, thin, waterproof, removes cleanly

tiger1964 

...and I suspect you are both correct.

OK, the Shimano SP-18-T arrived. This is interesting, I didn’t see this in the photo online, but I know there were two mounting holes when looked at from the “outside”, but on the “inside” one hole had an inward-projecting boss and the supplied screw goes in and expands the boss — so intended to act like a wall anchor on your drywall. I betcha that would work, but I had other ideas and ground off the boss with a Dremel.

So, first I marked the underside of the shell where the fixed cup would be inserted to fullest, as I did not want interference there; it turns out that from that point to the centerline of the eventual hole is about 17mm so no worries there. Then I center-punched and drilled a 1/8” pilot hole easily enough. I got out the 4.2mm drill that came with the tap, and started to bore out the hole to final diameter and the drill bit snapped at almost zero pressure! Luckily, fitting the stub of the bit to the electric drill, I succeeded in completing the drilling. Tapping the hole was also easy. By the way, the hole in the plastic guide was a somewhat tight fit for an M5 screw so I drilled that out to 3/16” which did help. And I screwed in the screw with the guide in place and it looked fine. i should point out that I measured and the plastic guide is 6mm where the bolt passes through and the BB shell is about 3.4mm; so, from the assortment of bolts I bought, I selected a 10mm long bolt which means you can just feel the tip when reaching inside the shell. But, I decided I did not need one final “tragedy” on this part so I removed it, added a little thread locker to the bolt and re-installed. Now it should stay in place.

And speaking of placement, I am unsure if there are strict guidelines for left-right placement. I ended up with the DS guide channel aimed right down the centerline of the DS chainstay. This means the NDS guide is aimed at the opening between the stays where they meet the BB shell but very close to the NDS chainstay; this should work OK if I were going to use a front derailleur but on this bike I won’t be so not concern to me — other users might want to pay close attention to that.

Well, that was wordy. But I figure someone else might do a search someday and want to know about this part — IF they can find one! (That first one I ordered is still somewhere. in fifteen days scanned by USPS eleven times, six of those today, and no scans mention an actual location).

And as soon as lighting conditions permit, I’ll photograph the part in place and post it here.

UPDATE: The bolt tip stuck perhaps 2mm into the inside of the BB shell. Plenty of room to clear the spindle. But, I decided to upgrade to a sealed BB (in this case, from Velo Orange) and the sealed cartridge is large enough that the bolt tip interfered. My options were a shorter bolt or grind off what was already in place. As I had already put thread locker on the bolt, I decided on the latter. Not much more than one minute of gaining to remove the excess -- but the BB shell for really hot, I wonder how close I got to melting the plastic guide. So, a warning... plan ahead!