BB removal newbie questions

[Shut Up Legs]

I've just removed my BB, a Shimano Hollowtech II, model number SM-BB5700. At least, I think it is. I can't see any model number on the BB I just removed, but I bought a replacement with this model number, and it looks identical. Here's the removed BB:

My questions are:

1. Is there any way to check it for wear, other than putting the cranks back on, rotating them, and checking for the unevenness/grinding feeling?
2. When I put them back on, I know the left and right hand adapters need to be tightened to 35-50Nm torque (which if I understand correctly, is "very tight"? ). But how tight should the star nut attaching the left crank to the axle be? It seemed fairly easy to remove after I removed the two allen bolts from the crank. Is there a recommended torque for this star nut?

My plan now is to thoroughly grease all the BB parts, the axle and BB frame shell, then reassemble, and see how it is on my next few commutes. I'll also do a short test ride once it's reassembed, to check I haven't stuffed anything up.

Thanks,

--- Victor.

 

[Manonabike]

These BB have sealed bearings and you replace the whole thing so I doubt there is anyway to check for wear. If it wasn't noisy before you removed it then I'd put it back on.

The star nut doesn't need much tightening as a guess I'd say a little bit more than finger tight.

Your plan sounds OK to me. Make sure the BB shell has some grease.

 

[Shut Up Legs]

OK, thanks for that, finger-tight it is!
And yes, I had planned to grease just about everything in sight . I made a note when removing the parts of which parts had traces of grease still on them.

 

[Manonabike]

youtube is a good source for videos on bike maintenance.

 

[Shut Up Legs]

I know, I watched a few before doing this (and previously for other jobs). I've just reinstalled the BB and cranks, and I just took it for a short test ride which included some uphill riding. It's very smooth, so I'll see how it goes for now. I still have the BB I bought a few months ago, if this one ends up needing replacing . Thanks for the advice.

 

[smokeysmoo]

Do up the 'star nut' first, do not tighten the pinch bolts until you've done this. It is actually a pre-load cap and is designed to, obviously, pre-load the bearings without exerting too much force, which would of course cause rotational problems and premature wear.

The correct tool for the job is designed to only be used by hand and is a TL-FC16, you only need to tighten it until you have eliminated any play from the cranks. Shimano do quote a torque setting on their TECH DOC of 0.7 - 1.5 Nm, but how you are supposed to gauge this with the TL-FC16 is beyond me, but also a non-issue in my opinion if you do just eliminate play.

When doing up the pinch bolts make sure you alternate side to side, don't wrench one side up tight then the other as you could cause damage, nip one up, then the other, then the first again until it's tightened

[EDIT] FWIW all Shimano HTII BB's are also interchangeable, ie: you could fit a Tiagra, 105, Ultegra or Dura-Ace one if the mood took you.

 

[Shut Up Legs]

Thanks, I did just that, put the 2 bolts on, but only did them up loosely, then tightened the star nut finger-tight, then finished tightening the 2 bolts, alternating them side-by-side as you mentioned.

 

[simmi]

Be very careful not to over tighten, I shot mine in 1200 miles and can only put it down to over tightening the pre-load cap.
See this thread.

 

[Shut Up Legs]

I just replaced my bottom bracket, and found it's a lot easier when you've previously removed the old one for cleaning , because the whole procedure, and the required tools, are more familiar.

Today while riding home, the BB was making an awful racket, nasty loud clicking and rattling noises (especially on the climbs, and there's plenty of those on my commute), plus I found after a quick check that I could wobble the axle, a sure sign that something was loose in there. So it wasn't the seat creaking, as I suspected late last week. For some reason, the BB noise is a lot less when I was standing up pedaling, compared to sitting on the seat while pedaling - don't know how that works, but that was why I incorrectly thought it might be the seat, last week. So the rest of my 33.5km commute home was a lot noisier than usual. I was a bit self-conscious, thinking that passing-by cyclists were probably thinking "poor newbie, can't even maintain his bike properly" . Once I got home, I remained in my cycling clothes, and immediately started replacing the BB with a new one I'd bought months ago.

This time, it took exactly 35 minutes for me to replace the BB, take the bike down then up a nearby hill to check how smooth it was, get home, put the bike and tools away, then clean my hands . It might have been quicker, but I tried adjusting the star nut on the left pedal then re-tightening the 2 fixing bolts, but still the axle wobbled. When I checked the 2 outer sections of the old BB, I found that their inner rings wobbled inside the outer ring, the source of my axle wobbling. The bearings must have been fairly worn? No such wobbling in the new BB, though!

Should be a nice, smooth and quiet commute to work tomorrow.

 

[smokeysmoo]

Should be a nice, smooth and quiet commute to work tomorrow.

Nice one

Just looking at your location and I certainly wish I had your commute instead of mine

 

[Shut Up Legs]

Nice one

Just looking at your location and I certainly wish I had your commute instead of mine

Here's what it looks like, although the route has changed slightly since I created this video. It's a 90 minute ride compressed into just over 10.5 minutes of video.


I think anything different is nice, though. I'd like to do some cycling in the UK, Western Europe or even Canada, one day, but first I have to get enough time off work .