Front End Bounce / Hop

Doodlefadd

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Good day fellow riders globally!
Gonna be a long post!

Kindly seeking insight on an issue that's been bothering well over a week.

2015 gen 2 super tenere, first owner, 100k km mileage. Never involved in traffic accident. Dumb dropping the bike at stationary, a few times in past 5 years.
Nothing done to front end of late, prior to issue appearing.

Problem :

FRONT END RHYTHMIC BOUNCE, ESPECIALLY AT LOW SPEED.
  1. bounce occurs most prominent at low speed, at around 40km/h or less, especially felt when clutched in and allowing bike to roll.
  2. It is not a constant bounce. It is rhythmic. When riding at low speed, or when clutching in and rolling the bike at low speed, it will bounce bounce bounce. . . . . Bounce bounce bounce. . . . . . Bounce bounce bounce.
  3. Bounce is only up and down, not side to side.
  4. Nature of bounce follows how soft or hard the comp/rebound settings are. Softer setting, its a plushy bounce, harder setting its a jerking up down bounce.
  5. Intervals between 2 given set of bounces gets closer as the speed gets higher. And vice versa. Slower speed, bigger interval between bounce set.

Attempted solutions (together with my local mechanic)

Things done that did not resolve or made any changes to the issue :

-Riding it on different roads and road conditions
-Played with different tyre pressure readings
-Changed to new set of tyres, inspected tyres no humps, and balanced the wheel on the machine (Mitas terraforce r)
-Pinged all spokes (neither me nor shop owns torque spokes wrench), none were flat toned, all pinging high pitch
-Changed front wheel bearings (as 2 forum members did this and it went away for them)
-Checked both brake discs, not warped.
-Checked front pads, not worn. Brakes functional as normal, nothing out of norm in terms of feel on the front brake lever.
-Changed steering head bearing
-Loosen and retightened all clamps & nuts that holds the front suspension in place
-Did a fork service, used all oem parts. Used 5w oil as per manual and previous fork services.
-removed helibar risers and returned handlebar to stock clamps
-opened up clutch system, worn out parts replaced e.g. friction plate and needle wheel bearing of clutch rod (mechanic thought it was a clutch slippage issue = engine vibrating more, at a rhythm pattern)

Things done that made a difference but did not resolve the issue :

-Adjusted and corrected front fork and rear shocks sag to 30% of travel. Bouncing less prominent.
-played with so many different settings for both compression and rebound. Realized bounce goes close to disappearing when comp and rebound is 1 click away from FULL HARD.

Current causes of concerns
- I was not around during the fork service. Came to shop, collected bike, was told to test it out overnight and return if any issue. On that same night, together with a mate, realized I had high fork stiction. When either compressed down or extended up, fork 'stucked' and refused to return. Heed to dave moss advice on YouTube on greasing the dust cap region, resolves 70% of the stiction (still not within 5-15ml stiction acceptable range) sounds like a shady job yea? But my mechanic is an established Suspensions tuner, and has good relationship with me.
-the current setup where comp and rebound are one click out of full hard, is the best by far. But by setting it up that way, am I actually masking bigger issues that is actually the problem? And I'm sure It will pose a safety concern if I keep the setting this way yea?

Any inputs on the matter?
 

cyclemike4

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I am definitely interested in your resolve to the issues you are having. I have had the same issue as well. I have found only with a new tire that is heavy that I have the bounce issue. Nothing seems to correct it. I have taken new tires off and put my old ones back on and it rides as smooth as silk. I have found for the heavy stiff sidewall tires I have to run very low pressures to keep it soft for a lot of miles. A couple thousand miles sometimes. the bounce will go away after that but you can still hear the cycling hum from the tread though. If I use a light tire i don't have that issue. all other things on the bike are fine and the balance is perfect.
 

~TABASCO~

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I’m guessing fork oil / service as the potential issue. I’ve read you have performed the service, I would like to know more details.
 

jrusell

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I am wondering if possibly there was an issue with the wheel install and possibly brake rub causing the front to drop as the brake rubs causing the bike to slowdown slightly every wheel revolution?
Even oil level being way off should not cause a bounce, and as you know you should be able to run comp and rebound at approx. 8-12clicks out.

My suggestion would be to start by putting the bike on the centerstand and weight the rear or tie it down to get the front tire clear of the ground. Give it a good hard spin and see if there is any excessive brake rub.

After this loosen the pinch bolts on the right fork and check the axle is snug. Then spin the wheel and grab the front brake. If the forks are misaligned the sudden jarring caused by grabbing the brake should realign them if they are off.

Check and make sure the wheel spacers are correctly installed.
Really sounds like a fork, wheel or brake installation problem to me.

Good luck.
 
B

ballisticexchris

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I’m guessing fork oil / service as the potential issue. I’ve read you have performed the service, I would like to know more details.
+1 here. I'm guessing the oil is degraded and the fork bushings are shot. Get the bike up on the stand, remove the front wheel and check forks for bushing play.
 

Doodlefadd

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I am definitely interested in your resolve to the issues you are having. I have had the same issue as well. I have found only with a new tire that is heavy that I have the bounce issue. Nothing seems to correct it. I have taken new tires off and put my old ones back on and it rides as smooth as silk. I have found for the heavy stiff sidewall tires I have to run very low pressures to keep it soft for a lot of miles. A couple thousand miles sometimes. the bounce will go away after that but you can still hear the cycling hum from the tread though. If I use a light tire i don't have that issue. all other things on the bike are fine and the balance is perfect.

This is a simple solution I can do right away.
I used to run my s10 according to what the numbers say on the sticker under the seat for max load. 33psi.while I didn't have any handling issue, all my front tyres squares as wear. Giving me the impression the sticker number suggested a psi too low for my load with aftermarket accessories.
When I checked the forum, noticed many run higher psi for front without issues. Some as high as 40psi.
Currently on 38psi.
At what psi do u run it to solve it? Low 30s?
 
Last edited:

StefanOnHisS10

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Sorry to hear about you’re problems. There is a lot of knowledge on this forum, I’m sure we’ll figure it out. All possible causes mentioned by the members so far are worth checking. Personally I run 36psi in the front and depending on the company I ride with 39 or 42psi in the back. Never had one problem with my 50/50 tire shaking or bouncing.

Stefan
 

Squibb

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Any chance the tires beads didn't seat?
Maybe one side popped but the other didn't?
I agree. There just has to be a slight run-out on that front tyre. Either the bead isn't seating, the tyre was damaged/distorted in transit/storage, or the rim is out of true. The max runout that is acceptable is less than 2mm IIRC. There is some chatter on the KTM forums about the bars oscillating on deceleration & balancing problems, when using the Mitas TR tyre, but not the symptoms the OP describes.

Couple this, with some fork stiction & you have this front end bobble scenario. Stiction normally suggests a full fork overhaul may be due, but a fork service was mentioned previously - what did that involved precisely?

The only other thought is rear tyre condition as Jeff suggests in post #5. A badly worn rear, a distorted rear wheel rim or loose spokes can translate into some strange handling issues up front.
 

holligl

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Has the tire balance been checked? Rim run out?

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Doodlefadd

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..::UPDATE::..

Played around with front PSI again(tho I've done this before) , 32-40psi, issue still present.

With my mechanic now.
We wished to re-do the forks, but fork bushings are not in stock islandwide(that means, nationwide, to us singaporean. Lols) gotta order and wait again.

In the meantime,

Front and rear Tyres are re-beaded. Rims checked, they're true.

Bike on mainstand, front tyre off ground, spun the front wheel with calipers on, and it didn't rotate much (MVP posted a video of his wheels spinning in another thread, and mine spun 3/4 of his total spinning time)

Removed one caliper at a time, rotated the wheel by hand slowly, and noticed when right caliper is on (left removed), at a particular spot on the disc, it has a lot of resistance to rotate.
Aka potentially warped disc.

Both caliper off, spun the wheel, slowly or with one great spin, it spins happily without resistance.
Aka bearings are ok.

Going to change both front brake discs to fresh oem ones today.
Gonna service the both front calipers as per Chris Moritz caliper servicing instructions on another thread (greasing the caliper pins)
Gonna put new sintered brake pads for both calipers.

FYI, caliper seal kits and fresh oem brake discs if any wants as reference for own DIY servicing.
1611893813888545012205631356074.jpg

16118941376637494430922873934762.jpg
FYI, the word 'Designed by Galfer' does not exist on the new OEM brake discs. Not too sure what that would mean. Maybe change of manufacturer? ‍

Let's see if this solves the issue.

Based on this post,
I will eliminate tyre, rims, brakes, wheel bearings.
If it still persist, it HAS to be the forks possibly the bushings.

Will update further.
 
Last edited:

~TABASCO~

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..::UPDATE::..

Played around with front PSI again(tho I've done this before) , 32-40psi, issue still present.

With my mechanic now.
We wished to re-do the forks, but fork bushings are not in stock islandwide(that means, nationwide, to us singaporean. Lols) gotta order and wait again.

In the meantime,

Front and rear Tyres are re-beaded. Rims checked, they're true.

Bike on mainstand, front tyre off ground, spun the front wheel with calipers on, and it didn't rotate much (MVP posted a video of his wheels spinning in another thread, and mine spun 3/4 of his total spinning time)

Removed one caliper at a time, rotated the wheel by hand slowly, and noticed when right caliper is on (left removed), at a particular spot on the disc, it has a lot of resistance to rotate.
Aka potentially warped disc.

Both caliper off, spun the wheel, slowly or with one great spin, it spins happily without resistance.
Aka bearings are ok.

Going to change both front brake discs to fresh oem ones today.
Gonna service the both front calipers as per Chris Moritz caliper servicing instructions on another thread (greasing the caliper pins)
Gonna put new sintered brake pads for both calipers.

FYI, caliper seal kits and fresh oem brake discs if any wants as reference for own DIY servicing.
View attachment 76560

View attachment 76561

Let's see if this solves the issue.

Based on this post,
I will eliminate tyre, rims, brakes, wheel bearings.
If it still persist, it HAS to be the forks possibly the bushings.

Will update further.
If you just changed out the bushings and seals you probably don’t need to replace them again. Just to cross your “T” and don’t your “I”. I would also check all the compression and rebound. Ive seen this bouncing around before. (Not on a Tenere and probably 20+ years ago). If I remember correctly it was a problem with valve stack or rebound. I don’t remember 100% to be honest. It was a “fork issue”.
If it was in front of me I would carefully strip down both forks and start looking for the issue. IMOP, something is “off”

I guess you also have to say this in today’s “world”. I don’t know this is the problem. But this is 35+ years of experience and only my $.02
Keep us filled it. Thanks !!!
 
Last edited:

Doodlefadd

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Location
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..:: Update ::..

Front brake discs and pad changed to oem.
Calipers serviced (new caliper seals, cleaned pistons, reassemble)
Front & rear brakes flushed, abs module cycled.

Issue not solved.
Oem fork bushings are not in stock, takes 2 months to arrive.
I can't say what when down during the fork servicing, as I was not around.
FYI, I fail to mention that the fork servicing was done by another shop, and I'm back at where I usually am to resolve this.
Bad mistake not staying to see the fork servicing done and/or going to another store for a try-out.

Guess I will update this thread in 2 month's time?
 

holligl

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..:: Update ::..

Front brake discs and pad changed to oem.
Calipers serviced (new caliper seals, cleaned pistons, reassemble)
Front & rear brakes flushed, abs module cycled.

Issue not solved.
Oem fork bushings are not in stock, takes 2 months to arrive.
I can't say what when down during the fork servicing, as I was not around.
FYI, I fail to mention that the fork servicing was done by another shop, and I'm back at where I usually am to resolve this.
Bad mistake not staying to see the fork servicing done and/or going to another store for a try-out.

Guess I will update this thread in 2 month's time?
Can you go after market, like All Balls, for fork wear items rather than waiting two months?
"All Balls Fork Bushings - Parts Giant" https://www.partsgiant.com/all-balls/suspension/fork-bushings


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cyclemike4

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This is a simple solution I can do right away.
I used to run my s10 according to what the numbers say on the sticker under the seat for max load. 33psi.while I didn't have any handling issue, all my front tyres squares as wear. Giving me the impression the sticker number suggested a psi too low for my load with aftermarket accessories.
When I checked the forum, noticed many run higher psi for front without issues. Some as high as 40psi.
Currently on 38psi.
At what psi do u run it to solve it? Low 30s?
Yes i do run the tire down around 30 psi. One thing i forgot to mention is my local dealer has closed down and now i am getting tires mail order. I am pretty sure the tires i received were tied up in a bundle too tight and probably sat at the bottom of a pile of tires and deformed them somewhat. I had one unusable. the others i ran at low pressure till the tire had some heat cycles in it and they kind of corrected them selves. I have found that my bike likes the light weight tires better as far as handling goes. I have ran one of them as low as 25 psi for long periods of time till it felt better. I run them that low when it is slick anyway. I am also not a high speed rider.
 

WJBertrand

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FYI, the word 'Designed by Galfer' does not exist on the new OEM brake discs. Not too sure what that would mean. Maybe change of manufacturer? ‍
That's interesting. I had both of my front 'designed by Galfer" rotors replaced under warranty due to warpage/uneven thickness. I only noticed the problem when braking though. The bike was smooth when not on the brakes. Maybe the Galfer brake disks had a problem? My replacement rotors have been fine and still have the designed by Galfer note on them.
 

Cycledude

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Yes i do run the tire down around 30 psi. One thing i forgot to mention is my local dealer has closed down and now i am getting tires mail order. I am pretty sure the tires i received were tied up in a bundle too tight and probably sat at the bottom of a pile of tires and deformed them somewhat. I had one unusable. the others i ran at low pressure till the tire had some heat cycles in it and they kind of corrected them selves. I have found that my bike likes the light weight tires better as far as handling goes. I have ran one of them as low as 25 psi for long periods of time till it felt better. I run them that low when it is slick anyway. I am also not a high speed rider.
I received some Goldwing tires like that many years ago, after I mounted the tire I couldn’t get the bead to seal against the rim good enough to put air in it, wound up dismounting the tire and putting some blocks of wood between the beads to keep them spread them overnight, the next day the the tire mounted and aired up fine.
 

Squibb

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I received some Goldwing tires like that many years ago, after I mounted the tire I couldn’t get the bead to seal against the rim good enough to put air in it, wound up dismounting the tire and putting some blocks of wood between the beads to keep them spread them overnight, the next day the the tire mounted and aired up fine.
Sometimes, if they aren't too distorted, it's possible to use a ratchet strap around the circumference of the tyre. Gently tighten & that's often enough to allow you to get them inflated
 
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