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Discussion Starter #1 (Edited)
Sorry for a long message, but I want to cover the bases. I have around 2300 miles on my 2018 DL650, running factory tires with proper pressure. I've spent time chasing what feels like an out of balance wheel. I have rebalanced both wheels twice between last fall and this season.

35-45mph speeds give an increasing frequency shudder through the bike, feeling like mainly from the front, I think. Highway speeds make it feel like extra buzz vibrations.

The steering seems okay- no issues with the bearings at the head tube. The tires, visually, look okay.

Each time balancing using the Aerostich balancer, I check the wheel before stripping weights- not perfect but as good as you can get with today's steel stick-on weights. (At least the old lead weights could be cut to custom weights.) I'd then strip the weights and start all over again, working hard to tweak the balance as well as possible. So, this was essentially a static balancing process. I don't know of any local shops that have dynamic balancing capabilities. Maybe a local Harley shop- not too many big 4 Japanese shops left anymore, most are little shops struggling to stay afloat.

Barring static balance issues, what are all the other causes of this speed related shuddering/vibration I'm getting? Bad belt in a tire casing? (Wouldn't show in a static balance.) Throttle body balancing? Steering head bearings? Chain issues? It is lubed and tensioned. The wheels are torqued upon mounting to the bike. Accessories are all properly mounted and remain tight- Givi windshield, SWM crash bars, HB C-Bow hard case side cases. (I'm just throwing stuff out there now...) My first thought is a bad tire belt, but replacing tires would be an expensive diagnostic tool, unless it proved correct.

There is a big recent balancing thread in the +17 DL650 subforum now https://www.stromtrooper.com/dl650a-2017/424621-wheel-balancing.html but I thought this was a unique issue worthy of a fresh thread.

Thoughts? Thanks,
Steve.
 

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Also

For front wheels especially, they also need to be balanced side-to-side, as well as around the axle. If there is a lateral imbalance, it will shake the steering side-to-side. So a simple static balance may not be enough.

Other possible issues are bent wheel, tire out of round or with a high spot, tread worn unevenly, loose head bearings, worn wheel bearings.

That 35-45 speed band seems to be around the point that there is a natural suspension-frame resonance. On my Vee (different bike, I know) even with a new front tire, properly balanced, etc., there's a slight shake at around 40 MPH if you coast down with hands off the bars. So something is feeding into that, most likely.
 

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….2300 miles on my 2018 DL650, running factory tires with proper pressure. I've spent time chasing what feels like an out of balance wheel.

35-45mph speeds give an increasing frequency shudder through the bike, feeling like mainly from the front, I think. Highway speeds make it feel like extra buzz vibrations.
From your description of the high-speed frequency buzz, I would guess it's not a balance issue, especially since you have been rigorous in checking/rechecking your static balance.

With that many miles on your OEM tires, wondering if you have any "feathering" of the tread. Can happen in that many miles (or fewer) depending on how aggressive your riding style.

Only other possibility I can suggest is to check both your wheels and tires for radial and lateral run-out.

Another less common cause of a speed-related buzz is an overly tight chain. Check to make sure you have sufficient slack when the bike is weighted.

Lastly, check to make sure your engine bolts at the frame mounting points are tight. Loose mounting bolts can cause a high-frequency vibe.
 

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1+ to badjuju

Steve, if you have a centerstand, jack up the bike so the front wheel is off the ground and spin it and watch the tire and the rim.

Use any kind of pointer to gradually get close to the rim and the tire to gauge if there is runout. If there is try to estimate how much and if it's just the tire or the rim causing the tire to wobble. My 2004 WEE had that kind of shake and I never managed to get rid of it or even fully establish the cause. But that was a rebuild salvage, so I blamed that as the cause and just rode it.

You can try to use some chalk and try to mark runout on the tire and a marker pen to mark runout on the rim.
 

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Spoke or alloy wheels?
Yup that is what I was wondering, as my 15XT without question has a section on the rim which induces a "HOP" and has been there since day one. With bike on the stand I can visibly see the area on the wheel where the hop occurs, but yet my tire balances without any issues. I am going to give my front wheel to a local mechanic and factory sponsored racer, he is an expert with lacing/truing spoke wheels.
 

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Discussion Starter #7
Thanks everyone. When spinning the wheel on the balancing jig, I did watch for wheel "hop" (think egg shape) and side-to-side runout and noted none. As a long-ago bicycle shop mechanic, that is second nature for me to watch for those issues, but I saw nothing of any concern. I didn't think to mention that in my first message.

My bike does have spoked wheels. Also while spinning I strummed the spokes with the tip of a screwdriver and the sound tone coming off of them was pretty consistent, all pinging fairly the same, not enough of a difference to want to put a wrench to the spoke nipples.

My bike is just a road bike, unpaved surfaces are almost nil. The times I've been off pavement has been on maintained public roads.

In the coming days I'll look though your tips and compare them to my bike to see if anything may apply. Boy, I'm pretty certain somewhere back in my earlier MC life I did have a tire that was doing some of the same things, even when balanced, but I think that tire had more significant wear on it and after replacement all was right with the world once again.

Thanks,
Steve.
 

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So as JimDing suggests check the lateral play. Get wheel off the ground and hold a piece of cardboard/wooden chopstick against the side of the rim then pull away until it just contacts it. Hold or tape the cardboard so it cannot move. Then slowly rotate the wheel and see if it contacts, pulls away for the gap stays consistent. If the runout is off you can adjust by loosing and tightening spokes. You can make rim on a spoke wheel move a lot.

If the runout checks out my next guess would be the chain. Still would not hurt to check the chain for a tight link or a tight section.
 

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In addition to checking the trueness of the outer surface of the tread (run-out) you might also take a look at the tread depth and make sure it is the same all around the tire. If you find one place that has a much shallower tread depth than the rest that could indicate a possible tread separation/bubble between the tire casing and the tread portion. I had a car tire like that once. Les Schwab said the balance was good, and it was, but that tire shook like crazy while driving, until I noticed the bulge one day.
 

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It is interesting that this is happening to more than just myself. As I stated in the other thread, I balanced my tires and hit a stretch of brand-new pavement on my nearest highway. All seemed well.
But as I venture out to less-than-perfect stretches of asphalt and chip-seal, I can still feel it. My instinct was to put the bike up on the centerstand, raise the front and check the run-out. I did just that yesterday. I can't find anything wrong.
Now it could be a bad tire, it could be a bad tire on two 2018 DL650 XT's. Odds are not. So what is it?
I'm starting to suspect the suspension set up. I've noticed that when I dismount the bike, the front suspension will unload to its extreme. It's almost as if there's a catch or bit of resistance that wants it to stay there. When you mount the bike and add your weight, there is a sudden compression off the high spot of the forks. It's almost as if the spring rate and dampening are encouraging the bounce when you're on any surface less than perfectly smooth.
If I had the money, I'd throw some of it and the springs and dampening - just to see. But that's going to have to wait. I may drop the forks a tad in the tree and see if the slight variance of geometry makes any difference.

edit:
For comparison and information compilation-
I have 2018 DL650 XT
Spoke wheels
Tires are Bridgestone Battlax Adventure A40
 

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Recheck

I've noticed that when I dismount the bike, the front suspension will unload to its extreme. It's almost as if there's a catch or bit of resistance that wants it to stay there. When you mount the bike and add your weight, there is a sudden compression off the high spot of the forks.
Might loosen the front axle fasteners, bounce the bike a couple of times against a walll or other immovable object, and retighten, following the manual instructions. Maybe 'squeezing' the forks, causing the excess friction. Maybe pop off the fork caps to assure that there is oil in the forks, too.

Under oddball problems, was reading a tech forum for Porsches, one guy was having front-end vibration, and the advisor said that sometimes tires will develop hard spots. No explanation of how or why.

If you lived by someone else with a similar bike, I'd say swap front tires and see if it helps, or transfers the problem.
 

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Just a wild-ass guess... Do you have crash bars on the bike, or a rear rack for side cases, with no cases mounted at the moment? Both of these are also well-known to cause vibrations, as they act as tuning forks. You might try removing them and see what happens. My DL1000 was noticeably less "buzzy" when I had to remove the crash bars. (Due to a broken bolt which took a few days to source.)
 

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Check chain tension. Try loosening it up 1/3 turn and retighten everything and ride it again to see if that could have an effect. A bad chain or out of round rear sprocket could have a similar effect on the bike as an out of balance wheel. Also, it could be the REAR wheel causing the problem. YOu need to check that out too.
 

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Is I still under warranty being a 2018 chances are fairly good it is. If so why not take it to the dealer for them to track down the culprit?
 

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Just a wild-ass guess... Do you have crash bars on the bike, or a rear rack for side cases, with no cases mounted at the moment? Both of these are also well-known to cause vibrations, as they act as tuning forks. You might try removing them and see what happens. My DL1000 was noticeably less "buzzy" when I had to remove the crash bars. (Due to a broken bolt which took a few days to source.)
I do have Givi crash bars. Mine is less buzz or vibration and more like a bounce.



Check chain tension. Try loosening it up 1/3 turn and retighten everything and ride it again to see if that could have an effect. A bad chain or out of round rear sprocket could have a similar effect on the bike as an out of balance wheel. Also, it could be the REAR wheel causing the problem. YOu need to check that out too.
I've not adjusted the chain since I bought it. I keep an eye on it, but it's staying in good shape.



Is I still under warranty being a 2018 chances are fairly good it is. If so why not take it to the dealer for them to track down the culprit?
What? I'd have to quit riding it then! JK, it may come to that but I'm not sure I have confidence that they'd sort it out.
 

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Discussion Starter #16
Update- just gave everything a onve-over. Chain is good in all aspects, slacked at the max. rec. in the book. Steering bearing feel okay. Checked everything that bolts on, even took some bolts off and added locktite. Front tire is looking good, very minor scalloping of the tread. The rear tire, though, is developing more pronounced scallop edge on the tread blocks, but consistent around the tire, it doesn't have a particular bad spot. I'll keep riding and head scratching and messing around, see what happens.

And yes, both tires had been rebalanced each time.

Thanks,
Steve.
 

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Discussion Starter #17
Enough is enough, I booked an appointment with the dealer for Thursday this week to sort out this issue.

I rode to work today and my route has a stretch of fresh asphalt, and taking away rough pavement sure lets the shimmy shake shine through. It really feels front end related, hopefully it is something easy to diagnose and repair.

Steve.
 

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Discussion Starter #19
But if it is consistent around the tire, why would it produce a rhythmic pulsing through the bike around 45-50mph instead of just a speed-varying buzz vibe? I guess anything is possible with vibrations... I've had worse scalloped tread before on other tires/bikes without this sensation. And with only 2400 miles on the tire. Pressures are always watched carefully.

But yours is a legit idea, that I share, that we'll check out. Thanks.

Steve.
 

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Tire(s). Sounds like you've done everything else. Myself, I don't usually go cheap when it comes to tires. Especially when I'm chasing a problem.
 
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