FSA bottom bracket help, pleeeeease
 

Hey guys,

So I have a brandy new fsa ISIS bb (enough acronyms?) and I have this weird issue. Ok, so I took off the left side 'cup' from the main body of the bb prior to installing. Now, if you look down into the left cup piece there is a little round yellow band that sits in a groove in the inside face of the cup down near the bottom, so in theory the yellow band would be flush with the inside of cup. Sorta like a reversed piston and ring scenario. But my yellow band sticks out just a hair, like it's not quuuuuite big or round enough to press up against the 'wall' and be out of the way. So if I install the drive side, and then tighten this left side on, I will catch that yellow band and kinda rip it out of there and smoosh it. Can anyone picture what in dogs name I'm talkin about? I don't want to just pull the little plastic band out, as I assume it has a function, but I definitely don't want to tighten it on and have it all jammed up and not seated right. Here's hoping someone knows what I'm on about :)

Without pictures I'm more or less guessing but I expect that yellow band is sort of an O-ring that keeps the cartridge from rocking inside the nds cup and keeps everything quiet.

Yes, that makes perfect sense...it would act as a squishy o-ring to snug up against the bb body, and like you say keep metal off metal. I'm thinking either mine is slightly defective or there's a trick to getting it seated, or I'm nuts and it will go on fine. But that seems physically impossible to me, I can't see how to screw it on without catching the edge of the o-ring and deforming it. It's a very thin, insubstantial thing, it wouldn't take much.

Here's a photo- if you look very closely (you may have to squint a little and make like a Popeye face) you can see at about the 11 o'clock position how the yellow o-ring protrudes slightly out of its little groove. The tolerances are super tight,that just looks like it'll get hung up and discombobulated. Lol discombobulated,I love that word. Also,speaking of 'Attached Thumbnails' whats up with that filthy fingernail in the photo? Anyway,anyone seen this ring deal before? Idk what to do with it.


update: not to worry,I HAVE cleaned my thumbnail,it's all sanitary now

It's just a seal. Poke it back into its groove and install the cup.

- Joel

That's just it,it won't poke. It's as if the o-ring is just a hair too small,it won't all lay flush. No amount of poking or prodding will get rid of the small protrusion. Im thinking either A) the yellow ring is defective,not the correct circumference or B) they all look like mine and theres a little technique to get it on without a problem or even C) it looks wrong but its fine and will install fine and Im crazy. Don't get me wrong,I appreciate any kind of help...but you don't really think it hadn't occurred to me to try and seat the ring? Lmao,that'd be like saying "My shoelace has come untied,can anyone help me figure out what to do?" I'm new to bicycle mechanics,not braindead.

If its not working good enough, ISIS was an alternative to Shimano's Octalink . spline.

so you can find the BB's made by more than one source company.

sort of an 'open source' type attempt .. then the trend moved on to external BB..

I'm thinking of just pulling it out. I can't see that it performs any important function, I guess like Hill said that it's just to make a nice cushy contact at the bottom to keep things quiet. I guess. I hate starting off a project with doing something kinda gaffe though. Wish the thing was just nice and flush in there. Maybe I can find a number for FSA and talk to a live person as unlikely as that sounds.