briscoelab

I have been noticing some weird noise coming from my crank area for a while now... and it is starting to drive me insane. It is basically from the chain/chainring rubbing on side of the FD cage.... and then run the other side. It varies depending on which foot is pushing through the pedal stroke at that moment.... This happens most of the time when in my big ring under heavy effort, such as going up a hill or really pounding on the flats. It is worse when out of the saddle. I have looked at the chainring rotation with it on the workstand and it doesn't seem to be coming from a bent chainring. You guys think it's the SLK crankset or the bottom bracket area of the bike flexing?

Some details... the frame is a 2006 Specialized Tarmac Expert, SLK Mega Exo compact crank, Campy Chorus FD (standard double).

The BB area of the Tarmac is pretty beefy... and the test ride I did on it with the stock Ultegra parts (Std double) I don't remember hearing any rub in that area.... But that was several months ago so I cant be sure. I know the SLK isn't the stiffest crank in the world. I'm not a really big guy..... 180 lbs. Think my "twin pillars of pain" are flexing the poor SLK crank too much?

DrPete 

I have an SLK crankset with full Ultegra and I haven't been able to cause that kind of rubbing. I'm 197# and ride a Flyte SRS-3, even race a crit or two here and there.

DrPete

merlinextraligh

I doubt it's the crankset or BB. I have a K Force MEga exo on one bike, and an SLK with isis bb on another, and haven't had a problem with flex, at 200lbs. Have you checked the adjustment/allignment of the front derailleur. If it's a little bit askew, you may not have much margin for error and even a little flex can make it rub.

DLH

I had a clicking noise coming from mine once, it was because the chainring bolts needed tightening. I have had no rubbing on my Le Champion SL full Ultegra, FSA SLK with ISIS and I am 190lb.

briscoelab

That was one of the first things I thought of. It appears to be straight and not out of allignmnet. I need to swing it by the shop and have them take a look at it just to make sure though. Chainring bolts are tight, as is the left crank arm. I can look down and clearly see the thing rub.... driving me nuts

Tommyp

Bent chainring?

Not sure how, but after a crash I had a similar problem. My chainring was bent outwards and was rubbing a bit when in the smaller cogs...weird but easy to fix.

briscoelab

As I mentioned earlier, the chainring appears to be straight.... when up on my work stand and rotating the crank the ring appears to run straight and there is no rubbing. It's only when really hammering on it that the rub happens.

Grasschopper

Is the non drive side crank arm bolt tight? I ask because mine came loose last week.

zensuit

Have you ridden this frame for long? I have had a few bikes that I could cause chain rub in during standing climbing. I'm not Cat 1 type rider but I'm a strong enough rider that I can cause frame flex in frames that are a little more flexible to begin with.

Z

gpelpel

I had the same problem with my SL-K Compact w/ MegaExo. The main bolt got loose and resulted in a clicking noise when I was pushing the pedals hard. Check if the non driveside crank has some shake. The bolt has to be tightened pretty hard.

DrPete 

I'd consider the frame flex possibility too. CF frames are designed with a certain amount of flex, and as a heavier rider you'll be able to flex a frame more than a little skinny guy. I ride an Al frame and it's actually pretty comfortable for me, while still being nice and stiff. I get rid of the buzz with carbon at the contact points (seatpost, Aliante carbon saddle, carbon cranks, carbon fork).

As far as the Tarmac Expert, I've never ridden it and don't know anything about it. Could it be that Specialized manufactures a little more flex into the lower-end frames? I have no idea, but I guess it's possible.

DrPete

Grasschopper

Ok I can't even imagine he is flexing the frame. I ride a Roubaix Comp which has a lower CF spec than his Tarmac and even at my 220 lbs and my bike flexing side to side out of the saddle climbing I don't cause my frame to flex enough to rub the FD. I was really impressed with the Roubaix because of this fact.

fruitless

more likely that you have developed some slack in the cable and the Der is no longer extending to the limit when you make the shift from small to big ring. I hover around 170 lb and none of my FSA cranks flex when I'm out of the saddle. I used to flex the BB on Columbus SLX steel frames all the time, just part of the old steel-is-real BS.

briscoelab

Chopper;
My left crank arm is tight.... I know because it was loose as hell just the other day. I really cranked down on it... just a bit more than the suggested torque this time, and put some locktite on there. I did experience my chainring bolts getting a little loose as well a while back.... a little locktite cured that as well.

My FD is shifting fine... I don't think it is it not moving full stroke. Remember, I have Campy so I have a lot of positions to play with to eliminate chain rub. This is different all together as I can see it happening when I look down.... right at the chainring.

I'll fiddle with it some more tonight, just to make sure it isn't something obvious I've missed and can fix. Then it's gonna go into the shop. I've honestly not been impressed in the least with this crank. I got a good deal on it and decided to try it out on this bike.... Between stuff coming loose and some problems I had with the bearings early on.... I'm about ready to toss it. I'm trying to hold out until 07 Campy stuff comes out.

briscoelab

UGH!!! I think I'm done with this crank. I know some people have had great experiences with it.... but I just about pulled out the sledge hammer on it today. The chainring bolts were a little loose again.... this is after putting locktite on them. I took it to the shop today (after tightening the bolts) They said the chainring isn't bent... and they played with the FD for a bit to make sure that wasn't it. I took it outside and it did the exact same thing... rub.. rub.. rub... with each pedal stroke. One of my buddies form the shop rode along next to me and confired I wasn't making it up They couldn't see anythign wrong with the crank... and said they couldn't imagine that my frame is flexing that much. One of the guys there has a Tarmac Pro (same frame) and is MUCH stronger than I am... he hasn't had any of these issues. I rode his bike and sure enough.. no rubbing. Maybe I just got a bad crank... who knows... But I just can't see keeping this piece of junk.

Arrrr..... what to get then? I wanted oh so bad to hold out until the new 07 Campy stuff comes out. Here is what I currently run; 11-21 for flat races, 11-23 for hilly races/rides, and a 12-25 for centuries. I love the versitility of my compact...... I hardly ever get out of my 50T. I'm thinking of just getting an alloy Record or Chorus crank to put on the bike until new stuff comes out. That would mean putting up with the gearing of a std double.... and giving up my 50T. But, I think I could manage on it for a few months. The alloy cranks are dirt cheap from several vendors in the UK and EU. I have an older FSA gossamer compact that never gave me problems... but I can't stand putting something HEAVIER than what I have back on the bike What to do... what to do....

PedalMasher

Some FSA cranks come with aluminum cranks bolts. I didn't know this until I sheared 2 off in a race and started making that lovely sound. I'm only 180#, so I suggest getting some heavier steel ones if yours are aluminum also.

briscoelab

Mine does have the Alu bolts. What a POS ;-)

Hmmm maybe I can wait until the Zero Gravity crank is out