Sur-ron creaks when breaking front - Stem bearing??

TS81

1 mW
Joined
Jul 27, 2021
Messages
17
Hi,

my Sur-Ron creaks when breaking strongly with the front brake. The creaking noise comes NOT from the brake. It comes somewhere from the handlebar bearing or next to it. I already checked the stem bearings but found nothing wrong (see pictures in video). Also set the bearing clearance but not change. Have the Sur-Ron about 6 month and have 2000 KM. There are no visible cracks in the frame or any clearance. I don't known where the sound comes from. It's also noticable riding in heavy terrain. It works fine but the sound is annoying and also a little bit frightening.

Any ideas?

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regards
Timo
 
Even the best of best and the priciest of priciest main stream bicycles leave the factory out of spec, the sur-ron is a different story vs the biggies but the biggies qc rate I'd assume would be much higher then the stand-alone niche market bicycles/ebikes.
 
@amberwolf:
But how can the tube itself creak? The clamps to the stanchions? Where do I find them? How to they look like? I am not this familiar with this part of the bike. Do you have a picture or anythink that helps?
Thanks
Timo
 
@calab: So you think it's simply "normal"? Any Ideas how to fix it anyway? Maybe I can finetune the out of specs, if it's something adjustable.
 
Just found this video https://www.youtube.com/watch?v=_FsYV9Q03uc by searching for "clamps stanchions mtb"? This really could be the issue. I will try this. @amberwolf: Is that what you meant?
 
A couple of diagrams with labels to show part names:
index.jpg
index.png

You can get creaking in metal as it bends and flexes, like in the steerer itself or the stanchion tubes, this can be a precursor to actual fatigue failure.

If the bolts that tightne the clamps or crown to either the steerer tube or the stanchions are not completely tightened, or are stripped and unable to tighten, you can get creaking as metal shifts.

You can also get creaking if there are cracks (which you may not be able to see, they can be completely internal to the metal with cast parts, which the clamps or crown could be, though they could be machined billet I think that costs significantly more than cast).

Bearings can also creak if they are damaged or worn, it's usually not the actual bearings but the races, if the race cracked then it can creak as it spreads open and closes during stress that flexes it. Cartridge bearings have integral races, but open bearings can have separate races that are pressfit to the frame and steerer / crown. I dont' know which kind your fork has. Cracks in races are typically fairly visible if you have good light, might need magnification but usually not if you're in direct sunlight. It's usually the outer race that cracks, but sometimes it's the inner.


If there is a mismatch in size (whcih can be very very small, in thousandths of an inch) between parts, you can get movement between them that can cause creaking, and over time this movement will wear the parts and if the wear is great enough it can cut thru them enough to cause failure during a high stress moment; this typically takes a long time. My experiences with creaks in various metal structures that later fail is that they stop creaking for no apparent reason and then a while later they fail. :( I don't know why the sound stops first, though I have theories in my head that are probably wrong. ;)

Preventing the movement would prevent the creaking (and preventing failure by preventing the wear), which is probably why the loctite thing works (sometimes, as he says) in that video.
 
I've had bikes click in the front end for a couple non-steer-bearing reasons.

Sand and debris in my handlebar clamps.

Sand and debris in my triple clamps.

Non-uniform torque on triple clamps.

Cracked aluminum structural parts, like frame weldments.

If you don't track down the noise with cleaning all the clamped front end joints up and re-torquing with a torque pattern to a tube-crush safe value, I would spray all the stressed areas of the headtube with UV penetrating dye and follow instructions for locating cracks. You probably don't have a crack, but it's better to play it safe than sorry on frames.
 
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