bampilot06

2019 Cervelo C2 shimano 105 with superteam wheels. 8,000 on the bike 3,000 on the wheels. Chain is new, and cassette is around 2000 miles.


Today riding around Dallas, I started to hear a knocking noise. It wasn’t consistent but I could only hear it when I pedal. Dallas roads are pretty rough, but when this started I was on a bike trail that resembled a side walk. Each segment of concrete was uneven so I was riding over constant bumps.

The knocking started small, not consistent, and at times I thought it might just be the bumps. I stopped multiple times to check items but nothing appeared to be lose and nothing appeared to be hitting the wheels or crank arms.

Near the end of the ride the noise got progressively louder, and by the end it was constant. As far as I can tell it’s only when I pedal. My freehub is loud however so when I coast it’s possible that it is droning out the noise. Gearing did not change the noise or consistency.


Since I have finished the ride I have checked, seat, seat post, pedals, cassette, chain rings, crank arms, headset and derailer cables. Nothing appears lose.
I did not check torque on front chain rings but there is absolutely no play in them.


I can’t think of anything else, so any ideas would be greatly appreciated.

Mad Honk 

Since I am sure it is not your ankles making the noise and since it only occurs with pedaling it could be as simple as a shoe string clicking on the crank, or the shoe rubbing against the crank arm. Check those items and see if they may out of specification. Smiles, MH

Rolla

Loose bottom bracket cup or worn BB bearings?

bampilot06

Just threw my bike on the trainer. No noise.

Iride01 

Wheel off or wheel on trainer?

How hard a knock? I still use the old Garmin GSC-10 speed cadence sensor and the other day the magnet was turned askew on the spoke. It made a tick tick tick every now and then till it annoyed me too much.

bampilot06

wheel off trainer. Did 20 miles and never heard anything. So I dont this it’s the bottom bracket.


Could riding over repeated bumps loosen tension in my spokes? Didn’t know if my rear wheel could be flexing and that’s the noise I am hearing.

Tension does not feel off, and wheel is tru but it was just a thought I had.

Other theory, the valve washer wasn’t lose when I took the wheel off, maybe that was rattling? Noise seemed too loud for that to be the case.

Iride01 

Wheels will flex. If you've never had your wheels spoke tensions checked, then I'd recommend you do so. Spokes can all feel the same when you wiggle or squeeze them but tensions can be wrong even when the wheel appears somewhat true.

I take all my new wheels to the shop after their first 300 to 600 miles and let them check them out. It's actually surprising how the one wheel that seems visually and tactilely the better of the two can be the worst when checked with a tension meter. After only that one inspection they may be good till your next bike.

How 'bout your tire size? If you put big tires on it that have minimal clearance to the frame or components, then wheel flex might be the thing to let them rub intermittently. Or maybe you had a spot of mud on them or picked up a piece of bubble gum that that bumped the frame.

Is this repeatable on different rides or just one ride?

I've never in 50 plus years had a bad bottom bracket so I always look at any claims of BB issues as dubious.

bampilot06

32mm tires. Have been on it for 4000 miles or so. Nothing was sticking to the tire.

This just started Yesterday, 30 miles into a 60 mile ride.

It def sound like carbon on carbon, the only other thing I could think of is the bearings in my rear wheel going out.

I took the wheel off and it spins fine, nothing is loose, no noises came from it.

I never had the tension checked so maybe that is it, and I am hearing the rear wheel flexing. So far that is the only thing that makes sense to me, and as I said before the hub is so loud when I coast that might be why I didn’t hear it.

ThermionicScott 

A repetitive sound from the back could be the rear derailleur. If the RD is not well-aligned, the pulleys will run at an angle, and the jockey pulley can make clicking noises as it is pulled from side to side. If you have a proper stand or another trainer that can let you leave the wheel on, that would help see what's going on.

bampilot06

That would be a clicking correct? Not a carbon on carbon knocking?

Would it do it when I have the bike on the wahoo kickr? If so it did not continue once I put the bike on the trainer.

ThermionicScott 

I can't hear your noise, just throwing out possibilities.

masi61

You mention that the freehub sound is loud while coasting. I'm wondering did your freehub mechanism somehow lose some of its lube? Did you ride in the rain at all? With the wheel removed from the bike when you ratchet the cassette then apply torque does it act like it wants to clunk? If so, is it possible to drizzle some thick oil into the freehub body to see if this does anything? What brand of rear hub is it and what type of service have you asked of the wheel during its first 3,000 miles - has it been ridden in the rain much?

bampilot06

with the wheel off It appears to ratchet fine. It’s a superteam wheel and free hub was always just loud. I guess they wanted it to sound like a chris king hub.

I do ride this bike in the rain, it’s my work horse. I have not had the wheel serviced once since I through it on the bike in Jan. I’ll play around with it some more tomorrow, I only checked the cassette for a short time yesterday when I took the wheel off.

I originally thought that it might have to do with my cadence, where I was pedaling faster than the hub was engaging and I was hearing the knocking when the hub engaged. I can simulate that with the wheel on the bike and spinning the crank. Near the end of my ride however I was cranking slow and it was happening over and over.

My rear disc had a slight rub that day, I don’t know if constant rubbing can eventually lead to a sound like that, but I doubt it.

Plan is to take the wheel to the trek store near me and have them check the tension. Ill bring my bike and see if I can get them to get the noise to start again.

Only other thought is my head set might be warped. The play is not significant, but if I hold the brake and rock the bike significantly I can hear it pop. I’ve torn the head set a apart and repacked it, preloaded and torqued it and it’s still there. But under normal load I do not think this would be causing the noise, and again the noise was coming from the rear, also not hearing the noise now the bike is on the trainer.

If I sprint on the wahoo I can feel the play.

Iride01 

If it only happened that one ride, I'd not even worry about it much till it happened again. Might have been some trash that got kicked up and caught in something. Then by rides end it was gone leaving you puzzling about your bike.