Plainsman

Hello Smart folks out there! I have a 2014 Scott CR1 road bike, and for the first time I feel a sort of "clunk" when I stop hard. Even though I can't find any play in the headset, I'm wondering if I have a bad bearing. I've never tried to service the bearings on a headset before (though I'm comfortable enough taking my bike apart). I looked at the original spec, and the bike has a Ritchey integrated headset with cartridge bearings. How do I know what size/spec I need for replacement, and are any unique tools required to replace the bearings? TIA!

cyccommute 

Before you go tearing anything apart, stand over the bike and hold the front brake closed. Rock the bike back and forth to feel if there is any knock when you do this. You may want to grasp the front wheel behind the fork as well. If you feel any movement, you likely have a loose headset. Loosen the stem bolts and tighten the bolt on the top cap (slightly). Check for knock again. Tighten the top cap as needed but don’t get it so tight that the headset won’t turn.

What you are describing is most likely a loose headset than a bad bearing. If it is a bad bearing, you are going to need to replace the bearing. It should just lift out and should be marked with the size. There are probably 3 dimensions that you’ll need. Two are in mm and one will be in degrees.

Crankycrank

Also, before taking anything apart take a photo of how the spacers are stacked and how the cables are routed. This will save you some headaches putting it back together again without having to rely on memory and having to guess.

Plainsman

Thanks. Funny thing is, the headset seems rock solid otherwise. I've replaced plenty of stems and pre-loaded plenty of headsets, so I feel good about checking that out. I don't have any play when performing any of the rocking back and forth tricks. That was actually the first thing I checked for when it happened on a ride. I first thought that clunk feeling might be the bottom bracket going out (I'm familiar with that feeling), but that tends to be more regular and happens when pedaling, not braking. I was going through the process of elimination which brought me to the headset, but I'm not a mechanic. I was also wondering if in a cartridge type system I could have a bad spot that could result in that "clunk" only under sufficient load and just the right angle?

Plainsman

Thanks for the heads up, always good advice. This is thankfully a non-internally routed setup, so thankfully not much to unpack. Full spacer stack under the stem of identical traditional round spacers, and nice external cables.

maddog34

sounds like the lower bearing may be bad... the standard "grab the brake and rock" test may not detect a bad lower bearing since the action of braking and rocking Increases Pressure on that lower bearing... I've also seen where a lower bearing, or bearing cup,is moving in the Frame or in relation to the Steerer tube/crown seat.

time for a tear down and inspection.

also... are you certain that the Quick Release is properly adjusted?

Is your bike a Disc Brake model? Disc brake loads can cause the Axle to torque around in the Dropouts.... Aluminum/plastic QRs and Aluminum Dropouts are more susceptible to this issue...

i'm assuming that you've already checked the brake mounting for loose fasteners....

zandoval 

Don't be afraid stud... You are going ta be fine... You know this...

cyccommute 

It’s easy enough to pull the bearing. Like I said above, it should just slip right out and you can rotate it by hand to see if there is any play.

That said, I still doubt that it is the bearing. That’s not how a failing bearing usually presents and a “klunk” under braking is indicative of a loose headset. Have you checked your caliper for play?

Plainsman

This is a 2014 Scott CR1, so before the major advent of road disc. The QRs are always locked tight, but it honestly didn't occur to me to check the calipers? I just replaced both the front and rear pads though, and everything seemed solid when I did. Hadn't thought about the lower bearing getting locked in during the standard test so that's a thought for sure.

Plainsman

Been under the weather and didn't ride this weekend, but to your point, when I pull the bike back down I'm going to pull it all apart. I'll remove the stem and spacers, re-install, load the headset, and then go for a ride. I can't seem to get the "clunk" to happen during any type of static test. It only seems to present during rides, and randomly during only select stops at that.

Plainsman

So as I’m tearing this down, and it does have cartridge bearings, what am I looking for on those cartridge bearings when inspect them to tell if they are bad? I thought I had this fixed with a headset adjustment, but I still get a clunk at a hard stop. Interestingly, when I adjusted the headset and tightened the loading bolt minimally (2-2.5 NM), the bars seem to want to return themselves to a certain position when turned.

grumpus

Press them together as hard as you can and rotate - you're feeling for grittiness or notchiness.
That's "Brinelling" (named after the hardness test that makes dents in metal) otherwise known as "indexed steering". It could just be annoying but it could cause stability issues - you'll be wanting a new bearing. But that might not be the cause of your clunk - have you checked your wheel bearings?

cyccommute 

To check the bearings, remove them and see if they turn freely. If they are in a cup and won’t come out, just twist them in the cup. They should be smooth and turn easily. If not, you may need to replace them or service them.

While you have the bearings out, inspect the frame on both the top and bottom for any signs of wear. I’d suggest using a caliper and measuring the width of the cups both side to side and front to back. It should be the same in all directions. If it isn’t, you may have wear of the frame. I’m not sure how you can address that if it has happened.

Plainsman

Thanks. I did narrow it down to the headset. I can now replicate the issue when the bike is static. It’s almost 10 years old, and I’ve never touched the headset. Turning the bars it does have that “indexed” feeling. These are the caged type bearings. I don’t own a headset press or the like, and have decided that after ten years, it’s time to just treat myself to a new headset. Going to have my trusted local shop help me, I think the full headset replacement may be just a bit beyond my DIY skills. I appreciate all of the advice!!!