George

But I don't think it is. I shift down from the big ring to the small and the cassette in still on the center cog. That's why I don't think it's an adjustment of the front derailleur. I can push the chain over about 3mm, before it hits the cage. Everything is working fine when I'm pedaling, but when I stand, it starts making noise, that I cant figure out. The BB has 4000 miles on it and I have one on order. If it's not the BB, what do you think it could be?

Thanks for any replies.

Al1943

That's not many miles for a bottom bracket, I doubt that is the problem. It might be frame flex causing the chain to rub the FD, but if it is you should be able to tune it out with the cable barrel adjusters.

Hinge

So are you pedaling while standing or are your feet stationary while standing?

Is this a recent development?

If the chain absolutely is not hitting the FD, here are some things to consider that I have encountered before:

How well lubed is your chain? Could be lack of lube.

Or it could just be the sound of the chain links engaging with your chainring.

Chainring bolts tight?

Are you sure the noise is coming from the front? Could it actually be the rear derailleur?

George

Yes I'm standing and pedaling and it is well lubed. It's not the links on the chain ring and I did try and move the chain rings while on the bike rack. I will check that out further though. I did try and adjust the front derailleur and I think it shifts better than it ever did. I'm in the middle on the rear so it's really not hitting anything. I got 7 K on the BB that I replaced, so I was wondering about that as well. I even looked for cracks on the frame, but didn't find any. It's a Specialized Roubaix and it's a fact 8 and I'm 200#.

I also checked out the rear derailleur hanger and it looks ok, but I don't have the tool they use to check it. The bike has never been down though.

Retro Grouch 

Is it possible the chain is rubbing the inside of the big chainring? I've encountered that before. I helped the problem by installing a 2mm spacer to move the BB over and sweeten the chainline.

George

I just went and turned the bolts a touch on the chain ring and I'm going to check it out right now.
Thanks for the replies everybody.

Andrew R Stewart 

Is the chain and/or cassette worn out? Are the ring teeth also worn? Next time you service the crank/BB take apart each ring bolt and grease then when reassembling them. Have you checked the crank arm/spindle tightness? Andy

Al1943

I had a noise like chain rub that didn't make sense. The inside ring looked worn so I replaced it and the noise went away. The chainring set had about 25,000 miles, the inside ring probably had 15,000.

George

Well I just got back from tightening just about the whole bike. I put new pedals on it and went over the handlebars, saddle tightened the brake calipers. I'll pull the BB when my new one comes. I did grease it about 6 months ago though and I haven't been riding in the rain. I did check the rings and they look good as well. I only have about 12k on the bike. New chain, but not cassette.

FBinNY 

It's not all that rare for a chain to rub the FD cage when standing or sprinting. The high loads deflect the frame at the BB rocking it side to side with the shifting load. Many bikes built for sprinters and climbers have heavily stiffened seat and down tubes to resist this. Some builders even use gussets for extra stiffness there.

You can confirm, by putting your bike in a corner, with the front wheel against the wall. Holding yourself up against the parallel wall, stand on the pedal as if trying to ride through the wall up front, while looking at your chainring through the FD cage. You should see the horizontal movement of the top of the ring.

In most cases you can manage the rub in some combinations with careful trimming, but I've known riders who can make the chain rub on then outer plate with the right foot, and then on the inside with the left. Fortunately, nobody makes a steady diet of sprinting and power climbing so the incidental rubbing isn't a real issue (if that's what it is).

George

I just went through all the gears riding and the noise is in the first 2 strokes and that's it. That's from a standing start. If I try and sprint while rolling it's ok. I know not to ride in the small ring and the small cog, but just to try it, it worked fine except for some chain rub. Then I did small ring to large cog and that was fine as well. I should say the 2 largest cogs. Once againm that's from a standing start, not while riding.

Thanks again everybody.

FBinNY 

OK it sounds like deflection rub which is only happening at the max pedal pressure. Something you can live with if trim and shifting are spot on. Next time you're laying on heavy power, glance down and confirm the relative movement of the top of the ring vs. the FD cage.

George

Ok, I'll give it try tomorrow. I just can't understand why now and not before. I'll try another cassette as well.
Thanks again.

FBinNY 

Eiter you've gotten stronger or heavier, or far more likely, there's a slight change in trim so what was a silent very close pass at the closest is now an intermittent rub.

Of course, it might not be this at all, which is why I suggested eyeballing it.

George

That's exactly what I thought last night, before going to bed. I'm going to go play with it right now. I really appreciate the help, thanks again.

Now I have to figure out if I should tighten it, or loosen it.

George

Will after adjusting the trim, putting on a new cassette and readjusting the derailleur, I still have the same problem. I guess I'll swing by the shop, to see if they can figure it out.

tbo

Had to read that twice. First time, .

kwcahart

It sounds like your big chainring might be bent just a tiny bit, and just in one place. Check that.

George

Well I did everything, but check the BB and that's what it was. It wasn't worn, but was loose. MY bad. Thanks everybody for all the help.

Hinge

... I put new pedals on it and went over the handlebars, ...

I thought the exact same thing! Hilarious.

Hinge

I'm going to go out on a limb and suggest that you tighten your bottom bracket. Let us know if that works.