60kmh front wheel wobbling

[Fedeskiff]

I am experiencing some serious wobble at 60kmh. I’ll upload a video to see if anyone can give me a hint.
Bike is 2019 with 7000km on it.
I checked tire pressure already and front it’s 28psi.

IMG_8682.MOV

drive.google.com

Thanks

Fede

 

[mzflorida]

Hi Fede. That sure as heck looks like either a worn or loose steering head bearing, which would be unusual, but not out of the question, for that low of mileage. If you have ever heard of the "tank slapper", the steering head bearing is typically the cause of that issue, which can be very dangerous.

 

[wspollack]

I dunno. What @mzflorida may be correct, of course.

However, I seem to recall noticing that around 37mph (60kph) my first ('22) C 400 GT did the same sort of thing ... if I took my hands off the bars. And so, after discovering that, I never took my hands off the bars at around that speed. At higher speeds, yep, on occasion, when I need to criss-cross andd swing my arms to stretch on a long ride.

(Note: I had a that '22 for about a year -- June '22 until May '23 -- and put more than 5,000 miles on it, and then had an engine problem. So that was a while ago. I got my '23 C 400 GT in Oct. '23, and only managed to put about 400 miles on it before winter. So I didn't get to do that experiment on the new scoot.)

So, a question, because it's not clear to me: was that video made with your hands off the bars?

Second, note that, from my personal experience and also my reading, pretty much all bikes do that, i.e., have some resonant frequency at some particular slow-ish speed, with hands off the bars (typically manifesting itself when not under load, i.e., at a constant speed or decelerating). And thus there may not be anything wrong with the bike, just don't take your hands off the bars at approximately that speed.

Edit Addition: Oh, by the way, your 28PSI seems a little low to me, unless you've decided for some reason that that's the pressure you want to go with. The owner's manual says this:



I run with 33/36 F/R, as a sort of just-leave-it-alone compromise, because I mostly ride solo, but occasionally my wife rides out back. In my opinion, that works well, the bike seems very planted and stable, at speed and in the twisty bits.

 

[Fedeskiff]

Thanks for all the messages, I've been running 28psi because i did not check it before, manual suggests 32, I don't think 4psi will make a lot of difference, however I'll check anyway. In the video I am not holding the handlebars at all.
Thanks,
Fede

 

[wspollack]

Thanks for all the messages, I've been running 28psi because i did not check it before, manual suggests 32, I don't think 4psi will make a lot of difference, however I'll check anyway. In the video I am not holding the handlebars at all.
Thanks,
Fede

Right. I don't think there's anything wrong with your bike. And if you can wait a couple of months, I will try the same experiment -- sort of coasting down, hands off the bars, around 40mph -- with my '23 C 400 GT, and I expect to find the same thing happen as you discovered, which is the same thing that I discovered with my '22 C 400 GT.

 

[mzflorida]

@wspollack you may be correct. However, comparing two of the same generation bikes with the same issue does not indicate the bikes are performing as designed or intended. TO the contrary it could indicate a manufacturing run on steering head bearings that were out of spec, undetected, and installed. My 23 has none of this wobble that you are both experiencing, which is what I think most would accept as the bike performing as designed or intended. Tire pressure may have something to do with it, but 4 PSI is unlikely. @Fedeskiff Bill and I are both guessing as we are not able to observe your bike. You're the one who is going to get hurt if there is a catastrophic failure. I would test for play, and retorque everything on the front suspension. It could also be an item with a runout parameter like your rotors or rim. I am not a worry wart by any means. But there is no way that I would leave that undiagnosed.

Bill, I am not being contrary or argumentative by any means. I might be in agreement with you if it were ~1 degree of wobble; but @Fedeskiff video is showing at least 5 degrees of play if my observations are correct. That is neither safe nor normal.

 

[Fedeskiff]

I was wondering if could be some miss balance of the front wheel that could be providing some vibration to it with resonance at 60kmh.
Since the bike it's under warranty, I am planning taking it to the shop.

 

[wspollack]

@wspollack you may be correct. However, comparing two of the same generation bikes with the same issue does not indicate the bikes are performing as designed or intended. TO the contrary it could indicate a manufacturing run on steering head bearings that were out of spec, undetected, and installed. My 23 has none of this wobble that you are both experiencing, which is what I think most would accept as the bike performing as designed or intended. Tire pressure may have something to do with it, but 4 PSI is unlikely. @Fedeskiff Bill and I are both guessing as we are not able to observe your bike. You're the one who is going to get hurt if there is a catastrophic failure. I would test for play, and retorque everything on the front suspension. It could also be an item with a runout parameter like your rotors or rim. I am not a worry wart by any means. But there is no way that I would leave that undiagnosed.

Bill, I am not being contrary or argumentative by any means. I might be in agreement with you if it were ~1 degree of wobble; but @Fedeskiff video is showing at least 5 degrees of play if my observations are correct. That is neither safe nor normal.

No offense taken, no contrariness assumed, etc.

1) As I say, in a couple of months, when the salt clears and my riding season starts again, I will perform this experiment ... with my hands nearby, at the ready, prepared to take over in a split second.

I am assuming that my two different-model-year, delivered about a year and a half apart, C 400 GTs were manufactured at vastly different times. My money is also on the newer bike's behaving like the older bike.

2) Have you tried that experiment yourself? Not trying to be a smartass or snarky here, just really wondering.

Just slowly coast down from, oh, about 40+mph, with your hands off the grips, but, obviously, very close, ready to pounce.

3) As I say, this happened to me, early on in my '22 C 400 GT ownership. I was just stretching or something, at about that coasting-down speed, and, whoa!, the bars started flip-flopping just like in the video that @Fedeskiff posted.

I was a little startled, of course -- who wouldn't be -- but I was not really surprised. I have read about this same no-hands-wobble issue, over the decades and regarding vastly different bikes -- standards, huge baggers, etc. -- on assorted bike forums, as well as experiencing this myself (usually at around 30mph or so) on them. Eventually this very issue becomes a topic on all the bike forums I've been on (not as prevalent as which is the best oil, of course).

So all I said to myself, a few seconds later, was: "Okay, so that's the harmonic no-hands wobble speed of this scoot -- don't do that again." And I haven't (but, as I said, I still take my hands off, but at higher speeds, when I've been sitting in the saddle for a couple of hours, and the road is straight, and there's no traffic around, and I can see that there are no deer around, etc. etc., and my shoulder blades are starting to tighten up a bit).

You can get a taste of this prevalence pretty easily: google something such as motorcycle handlebar wobble hands off while riding, and stand back. I just did that (1.8m hits), and did some random skimming. Here are a couple of snippets.

From a Yamaha Tenere forum:

The wobble while decelerating with NO HANDS is very common on most motorcycles but most folks never notice it because they keep their hands on the handlebars, tightening the bearings will take away the wobble but tightening them to much will cause wondering issues that you definitely won’t like so be very careful .

From a Vespa forum:

"Doctor, Doctor, it hurts when I do this.
Don't do that."
Nothing to worry about unless you have wobbles with your hands on the bars.
Most motorbikes (scoots and cycles) exhibit a bit of deceleration wobble, usually through 30mph. It's not important.
If you notice funny steering characteristics when holding the bars, notchiness, vibration, that's another story.
BMWs do it, Yamahas do it, let's do it too.

Of course, as you indicate, there are also loads of suggestions that the steering-head bearings are shot or misadjusted. Or the tires, or frame, or something else, are out of balance.

And I imagine that there are many bikes that are misadjusted in some way or other. But, as I say, I keep coming across this no matter what bike I have, on that bike's respective forum(s), and when dealing with low-mileage variants of whatever make and model. So, as I say, I wasn't surprised at all. A tiny bit startled maybe, but not surprised.

 

[mzflorida]

I was wondering if could be some miss balance of the front wheel that could be providing some vibration to it with resonance at 60kmh.
Since the bike it's under warranty, I am planning taking it to the shop.

Unlikely that an unbalanced tire would produce that wobble.

 

[mzflorida]

2) Have you tried that experiment yourself? Not trying to be a smartass or snarky here, just really wondering.

Just slowly coast down from, oh, about 40+mph, with your hands off the grips, but, obviously, very close, ready to pounce.

Yes. Just did it today while testing out the new shocks. Did it at least ten times and smooth as silk.

The wobble while decelerating with NO HANDS is very common on most motorcycles but most folks never notice it because they keep their hands on the handlebars, tightening the bearings will take away the wobble but tightening them to much will cause wondering issues that you definitely won’t like so be very careful . Calling BS on this one.

From a Vespa forum:

"Doctor, Doctor, it hurts when I do this.
Don't do that."
Nothing to worry about unless you have wobbles with your hands on the bars. This is categorically incorrect. scholar.goole.com for additional academic support of this. At the very least trajectory is changed and center of gravity are impacted.

Most motorbikes (scoots and cycles) exhibit a bit of deceleration wobble, usually through 30mph. It's not important.
If you notice funny steering characteristics when holding the bars, notchiness, vibration, that's another story.
BMWs do it, Yamahas do it, let's do it too. Like you, I've been on over a hundred motorcycles. I have had oscilating wobble on only one and that was caused by a steering head bearing.

Of course, as you indicate, there are also loads of suggestions that the steering-head bearings are shot or misadjusted. Or the tires, or frame, or something else, are out of balance.

And I imagine that there are many bikes that are misadjusted in some way or other. But, as I say, I keep coming across this no matter what bike I have, on that bike's respective forum(s), and when dealing with low-mileage variants of whatever make and model. So, as I say, I wasn't surprised at all. A tiny bit startled maybe, but not surprised.

I think we'll have to agree to disagree on this one.

@Fedeskiff I would get a competent mechanic to check it out, but that is my perspective. Bill is very experienced and knowledgeable and could be spot on. But, both of us are guys on the internet who could be totally full of crap.

 

[mzflorida]

I am not trying to belabor this, prove a point, or say "I'm right." My only intention is to be helpful and informative. I was at the dealer today and brought this up to a mechanic who I trust very much. He said, without a doubt, that there is a problem with the bike. It could be minor, like wheel weights or cupping, or something that will get progressively worse, like a steering head bearing. Interestingly he said a bent rim could be the worst of all as it will almost certainly lead to a rapid deflation, while parked or underway. He also said it is important to understand something. A commonly reported "issue" does not make it normal or something to be expected, it only means that it has a high rate of observation across brands. Wobbling, on either the front end or the rear, needs to be diagnosed by a mechanic. Again, good intentions only.

 

[Fedeskiff]

So, after a little while I took my bike to the Motorrad Service in Valencia, Spain.
They replied to me the following:
-They noticed wobble at same speed that I tested when you have no hands in the handlebar. As soon as you are holding the handlebar, this diminishes.
-They tested another bike in the same shop and noticed same effect.
-They asked Mr. Bmw (according to them) so they replied that if while holding the bars there's no shake, then it's okay.
-Also they replaced my brake calipers due a Corrosion Recall.

Would be nice if anyone with a similar bike 400x or GT could check if there's same effect or not.

Thanks

Fed

 

[wspollack]

So, after a little while I took my bike to the Motorrad Service in Valencia, Spain.
They replied to me the following:
-They noticed wobble at same speed that I tested when you have no hands in the handlebar. As soon as you are holding the handlebar, this diminishes.
-They tested another bike in the same shop and noticed same effect.
-They asked Mr. Bmw (according to them) so they replied that if while holding the bars there's no shake, then it's okay.
-Also they replaced my brake calipers due a Corrosion Recall.

Would be nice if anyone with a similar bike 400x or GT could check if there's same effect or not.

Thanks

Fed

Nag, nag, nag.

You're in luck, because it turned out that it got up to about 65°F today -- we're still below freezing at night -- and we haven't had any significant snow for a few weeks, and the town has salted or brined the road in a month or so, and we've had some rain to wash away the dust and crud.

So I went for my first C 400 GT ride in three and a half months.

And in addition to my normal ride recording via my windshield-mounted camera, I added a chest-strap-mounted one, just for you, for the start of the ride. And quite easily duplicated your situation on my '23 C 400 GT. As I mentioned earlier, this is the same situation that I noticed early on, doing some double-arm, criss-cross, stretching, shortly after I started riding my (former) '22 C 400 GT.

Only this time I documented it:

Yep, same as you: c. 37 mph / 60 kph, both times. My '23 C 400 GT had 439 miles on it when I filmed this, and had its initial service at my local BMW dealership back in December (after which it just sat in the garage, until today).

(By the way, if you go to the video on YouTube itself, I have a fairly long write-up in the Description field there. Click "More.")

I'm not an engineer, or even a trained bike mechanic, but I still maintain that:

- I've experienced this hands-off handlebar shake on, I think, every bike I've owned, from baggers to scooters. Go searching through assorted bike forums and you're bound to find discussions on this.

- This is not a high-speed wobble, tank-slapper, head-shake type of situation, because you have to purposely take your hands off. And you have to look for it, e.g., slowly coasting down at the right speed for a given bike.

- So this is a normal situation for a bike ... again, if you look for it this way .. and so does not represent some improper adjustment of steering-head bearings. I'm sure that many bikes out there are in need of steering-head-bearing adjustment -- it's an eventual wear-item maintenance task, just like replacing, or repacking, or tightening swing-arm bearings or wheel bearings -- and I also assume that misadjusted or worn-out steering-head bearing can cause all sorts of problems. But what we're talking about here is a hands-off phenomenon of brand new bikes, not a case of hands-on steering with worn-out stuff.

And Mike -- you're reading this, too, right? -- have you given this a shot? As you can see from my video, it's not that hard to duplicate.

 

[Fedeskiff]

Nag, nag, nag.

You're in luck, because it turned out that it got up to about 65°F today -- we're still below freezing at night -- and we haven't had any significant snow for a few weeks, and the town has salted or brined the road in a month or so, and we've had some rain to wash away the dust and crud.

So I went for my first C 400 GT ride in three and a half months.

And in addition to my normal ride recording via my windshield-mounted camera, I added a chest-strap-mounted one, just for you, for the start of the ride. And quite easily duplicated your situation on my '23 C 400 GT. As I mentioned earlier, this is the same situation that I noticed early on, doing some double-arm, criss-cross, stretching, shortly after I started riding my (former) '22 C 400 GT.

Only this time I documented it:

Yep, same as you: c. 37 mph / 60 kph, both times. My '23 C 400 GT had 439 miles on it when I filmed this, and had its initial service at my local BMW dealership back in December (after which it just sat in the garage, until today).

(By the way, if you go to the video on YouTube itself, I have a fairly long write-up in the Description field there. Click "More.")

I'm not an engineer, or even a trained bike mechanic, but I still maintain that:

- I've experienced this hands-off handlebar shake on, I think, every bike I've owned, from baggers to scooters. Go searching through assorted bike forums and you're bound to find discussions on this.

- This is not a high-speed wobble, tank-slapper, head-shake type of situation, because you have to purposely take your hands off. And you have to look for it, e.g., slowly coasting down at the right speed for a given bike.

- So this is a normal situation for a bike ... again, if you look for it this way .. and so does not represent some improper adjustment of steering-head bearings. I'm sure that many bikes out there are in need of steering-head-bearing adjustment -- it's an eventual wear-item maintenance task, just like replacing, or repacking, or tightening swing-arm bearings or wheel bearings -- and I also assume that misadjusted or worn-out steering-head bearing can cause all sorts of problems. But what we're talking about here is a hands-off phenomenon of brand new bikes, not a case of hands-on steering with worn-out stuff.

And Mike -- you're reading this, too, right? -- have you given this a shot? As you can see from my video, it's not that hard to duplicate.

Wow!! Thanks a lot for the reply, exactly same behaviour as mine.
Regards

Fede

 

[mzflorida]

Nag, nag, nag.

You're in luck, because it turned out that it got up to about 65°F today -- we're still below freezing at night -- and we haven't had any significant snow for a few weeks, and the town has salted or brined the road in a month or so, and we've had some rain to wash away the dust and crud.

So I went for my first C 400 GT ride in three and a half months.

And in addition to my normal ride recording via my windshield-mounted camera, I added a chest-strap-mounted one, just for you, for the start of the ride. And quite easily duplicated your situation on my '23 C 400 GT. As I mentioned earlier, this is the same situation that I noticed early on, doing some double-arm, criss-cross, stretching, shortly after I started riding my (former) '22 C 400 GT.

Only this time I documented it:

Yep, same as you: c. 37 mph / 60 kph, both times. My '23 C 400 GT had 439 miles on it when I filmed this, and had its initial service at my local BMW dealership back in December (after which it just sat in the garage, until today).

(By the way, if you go to the video on YouTube itself, I have a fairly long write-up in the Description field there. Click "More.")

I'm not an engineer, or even a trained bike mechanic, but I still maintain that:

- I've experienced this hands-off handlebar shake on, I think, every bike I've owned, from baggers to scooters. Go searching through assorted bike forums and you're bound to find discussions on this.

- This is not a high-speed wobble, tank-slapper, head-shake type of situation, because you have to purposely take your hands off. And you have to look for it, e.g., slowly coasting down at the right speed for a given bike.

- So this is a normal situation for a bike ... again, if you look for it this way .. and so does not represent some improper adjustment of steering-head bearings. I'm sure that many bikes out there are in need of steering-head-bearing adjustment -- it's an eventual wear-item maintenance task, just like replacing, or repacking, or tightening swing-arm bearings or wheel bearings -- and I also assume that misadjusted or worn-out steering-head bearing can cause all sorts of problems. But what we're talking about here is a hands-off phenomenon of brand new bikes, not a case of hands-on steering with worn-out stuff.

And Mike -- you're reading this, too, right? -- have you given this a shot? As you can see from my video, it's not that hard to duplicate.

Yup. Since this post first started many times, and zero wobble. I did it on my NC too and zero wobble. Just differing opinions on this is all. Frequently observed and performing as designed are two different things.

Glad riding weather is back with you Bill!

 

[wspollack]

Glad riding weather is back with you Bill!