Tramlining !!!! - Avon Road Riders

Yesterday we were out for a ride that included about 20 miles of newly laid grooved concrete road. I had new Avon Road Riders installed last week and this was their first outing. They replaced the old Road Riders. Wheels are the standard 4.10/19s. Pressure was 32F 34R.

At 60-70 MPH the bike was so squiggly that I thought some suspension component had broken or the swingarm bushings had suddenly gone missing! It was really bad - even a bit scary. I ride extensively on rough cobblestone and gravel so I'm quite comfortable with the "hunting" feel that is typical of those surfaces. This was different and got worse as speed increased - the opposite of what happens on cobblestones/gravel where the faster I go, the more it smooths out. I actually had to slow down to the point that the other two riders (one was my wife) were disappearing into the distance. When we got back on ungrooved road, the bike was back to normal and I was able to catch up with no issue. When we got back home I asked my wife how her bike ('19 Africa Twin) reacted on the grooved road. Her response was, "The what?" She hadn't noticed that the road was grooved. The other rider, a friend who rode his souped up KLR also didn't have any issues.

I checked (partially) the front fork oil (different post) this morning as a result of that experience but don't think the front suspension had anything to do with it. Checked the swingarm with the bike on the center stand and bushings are fine.

So what's the deal here?

My only experience of grooves in the road affecting a Commando was when I just bought my 74 and it has Dunlop TT100's on it. Swapped them a week later for Avon roadrunners and no longer had issues with grooves and never since either on roadriders.

They are directional, so check they are fitted the right way round.

Kevin Cameron had a really nice explanation of tire resonance and chassis frequency matching in his excellent “Superbike Performance Handbook”. The short version is it’s your tires. I would suspect the new road riders that you fitted have just enough of a change in their construction to alter their natural resonance and this was matching up with the natural frequency of the chassis when riding on that surface.

You can change their natural resonance tires resonance a bit by altering tire pressure, so that’s the first thing I’d try. If that doesn’t solve the issue then the tire should be replaced. Generally only the front needs to be replaced.

Back when I owned a KTM 950 Adventure there was a lot of fuss and bother over some of them having a disturbing transient wobble and others not. One bike would weave and hunt and another would be rock steady. On the forums there was endless discussion over loading, suspension damping, bearing preload, steering dampers, and so on- but the answer was to change the front tire to another of the exact same manufacture and size. It seems the Pirellis used were made in two different factories- and QC was such that some of the tires made the bikes wobble and others didn’t.

I once bought a R100GS at a rock bottom price because it had an “incurable wobble” that had appeared with a tire change. The local dealer had rebuilt the forks, changed the head bearings, changed the swingarm bearings, rebuilt the paralever suspension, replaced all the wheel bearings, fiddled with suspension set up, and given up. I looked at the then still very new tires and noted that one was a radial and the other a bias ply. I bought the bike, swapped out one of the tires so the pair was matched (I forget which one) and it tracked and rode perfectly.

The lesson is to go back to the last thing you changed- and that even new tires of the same manufacturer can sometimes cause a problem. I’ve had a number of bikes that didn’t “like” a particular tire brand or size.

MexicoMike said:

Yesterday we were out for a ride that included about 20 miles of newly laid grooved concrete road. I had new Avon Road Riders installed last week and this was their first outing. They replaced the old Road Riders. Wheels are the standard 4.10/19s. Pressure was 32F 34R.

At 60-70 MPH the bike was so squiggly that I thought some suspension component had broken or the swingarm bushings had suddenly gone missing! It was really bad - even a bit scary. I ride extensively on rough cobblestone and gravel so I'm quite comfortable with the "hunting" feel that is typical of those surfaces. This was different and got worse as speed increased - the opposite of what happens on cobblestones/gravel where the faster I go, the more it smooths out. I actually had to slow down to the point that the other two riders (one was my wife) were disappearing into the distance. When we got back on ungrooved road, the bike was back to normal and I was able to catch up with no issue. When we got back home I asked my wife how her bike ('19 Africa Twin) reacted on the grooved road. Her response was, "The what?" She hadn't noticed that the road was grooved. The other rider, a friend who rode his souped up KLR also didn't have any issues.

I checked (partially) the front fork oil (different post) this morning as a result of that experience but don't think the front suspension had anything to do with it. Checked the swingarm with the bike on the center stand and bushings are fine.

So what's the deal here?

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Where did you find "new" Avon RR? What is the date code?

My experience is any new tire with central line groove can tend to tramline on surfaces with "rain grooves" like overpasses in my area. When I drove off the lot with a brand new modern Mini Cooper in Southern California, it felt like a wheel was about to come off on the first highway I got it on. Those tires had a deep grooved centerline. After 500 odd miles the issue seemed to resolve. My Commando with first K70, now K81/TT100's does tend to wiggle on our overpasses...which has tended to lessen after many miles. My Velocette with Avon RoadRiders, looking pretty new, show very little tendency to tramline on these same grooved overpasses.
Perhaps a bit more "break in" on the rubber is needed on your bike? Assuming SA spindle, bushes, and isolastics are in good shape? I have the Dave Taylor type headsteady on the Commando if that makes any difference.

I've only had problems with tracking on grooved roads with tt100s
I have a 90/90/19 roadrider on the front and I think a 410/19 roadrider rear (I'm not near the bike and I can't remember)
I put 35psi in the front and 42 psi in the rear and I have no problems at all

baz said:

I've only had problems with tracking on grooved roads with tt100s
I have a 90/90/19 roadrider on the front and I think a 410/19 roadrider rear (I'm not near the bike and I can't remember)
I put 35psi in the front and 42 psi in the rear and I have no problems at all

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42 psi in a Roadrider ??

"Where did you find "new" Avon RR? What is the date code"

They are not "new." I bought them 4 years ago and they've been sealed up/stored in the dark since then. Despite being 4 years old they feel nice and supple, not like the 10+ year old tires they replaced!!!


"They are directional, so check they are fitted the right way round."

I just checked and discovered that the shop mounted the rear tire in the wrong direction. Didn't occur to me to check when I picked them up. I'll pull the wheel and take it back to the tire shop tomorrow. Not being a tire guy I don't really understand why the same tire would be mounted in one direction on the front and the opposite direction on the back but I know it's supposed to be that way.

I checked the swing arm, Iso clearance, head steady bearings and all are OK. If it's not the tire direction thing I'll start futzing with tire pressure. My gut feeling is to reduce it from the 32/34 though I see Baz's 35/42 comment.

Fast Eddie said:

42 psi in a Roadrider ??

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Likewise.

36F
42-45R in the RR's. (Depending on load)

Fast Eddie said:

42 psi in a Roadrider ??

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Yep
I did this after reading the recommendations for modern triumphs etc
It made a good difference to the handling on my BMW r100 that's fitted roadriders when I went up on the tyre pressure
And I now do the same on the commando

Wow, that’s a good 10psi more than I use!

I feel a day of experimenting coming on …

I use Avon Road Riders , love them , but not on grooved surfaces . Yes a higher pressure helps a bit . Less flex sideways . Oddly enough they track a bit better on the grooved surfaces when approaching the end of their life . Here in the G.T.A. there are constant HWY. resurfacings on highways going on . This involves removing asphalt , cutting wavy grooves into concrete underlay to hold the new softer ashphalt to be spread and rolled at night .
We wrote a letter to the M.O.T. about this , asking for more temporary roadsignage to warn us about impending resurfacing ahead . The reply was disappointing , sometimes signs or not . We do our best .
If we got notification a bit before the next exit that would be best .
Enjoy .

MexicoMike said:

"Where did you find "new" Avon RR? What is the date code"

They are not "new." I bought them 4 years ago and they've been sealed up/stored in the dark since then. Despite being 4 years old they feel nice and supple, not like the 10+ year old tires they replaced!!!


"They are directional, so check they are fitted the right way round."

I just checked and discovered that the shop mounted the rear tire in the wrong direction. Didn't occur to me to check when I picked them up. I'll pull the wheel and take it back to the tire shop tomorrow. Not being a tire guy I don't really understand why the same tire would be mounted in one direction on the front and the opposite direction on the back but I know it's supposed to be that way.

I checked the swing arm, Iso clearance, head steady bearings and all are OK. If it's not the tire direction thing I'll start futzing with tire pressure. My gut feeling is to reduce it from the 32/34 though I see Baz's 35/42 comment.

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I always put an arrow on the tyre in chalk and on the rim in big black marker pen (sharpie) and TELL them and still check them afterwards.

You have to remove all necessity to think before getting people to do anything for you these days it seems.

Modern tyres need more air, back in the days 28f/30r but new design in tyres now that be way to low i run my Avons on my Norton at 36f and 38 to 40 on the rear and works great, on my modern Triumphs Thruxtons i run 38f and 42r no matter what brand new tyres i use (Avons or Metlzers any less it feel the tyre a losing grip in the corners, so you need to experment with you tyre pressures ti workout best for your riding style after you get the rear tyre fitted in the right direction.
It was my local motorcycle tyre shop who told me modern tyres run higher pressures, 3psi more makes a big difference in handling and smooth running.

Ashley

"I always put an arrow on the tyre in chalk and on the rim in big black marker pen (sharpie) and TELL them and still check them afterwards."

Yep, I should have done that and will definitely do it from now on. I ASSumed that since they were the same tires and the shop does a LOT of motorcycle tire changing, they would of course (!) know to mount the new Avons the same way as the old Avons. But I ASSumed wrong...

MexicoMike said:

"I always put an arrow on the tyre in chalk and on the rim in big black marker pen (sharpie) and TELL them and still check them afterwards."

Yep, I should have done that and will definitely do it from now on. I ASSumed that since they were the same tires and the shop does a LOT of motorcycle tire changing, they would of course (!) know to mount the new Avons the same way as the old Avons. But I ASSumed wrong...

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not a hundred percent sure as I'm an 18" rim man for dedicated rear tires, but I thought you were supposed to mount a universal or front use backwards on a rear rim? Here's a quote from the legendary comnoz on this forum some years ago

"I use the Avon Cobra AV71 front tire for both front and back on my bike. I mount the rear tire backwards from the directional arrow.
A little more expensive than the Roadrider but they are nice and sticky and I get nearly twice the mileage out of them"

Do the tires spin true with no" high spots" up and down or "run out" side to side? Are they balanced properly?

In the Norton Rider's Manuals for Avon GP or Dunlop TT 100 tires nominal tire pressures are :

Front 24 psi rear 26 psi

It is lower than I used to think would be Norton's recommended psi.

Grooved roads or harmonics caused by road work and pavement irregularities can be killers.

Carl H said:

Do the tires spin true with no" high spots" up and down or "run out" side to side? Are they balanced properly?

In the Norton Rider's Manuals for Avon GP or Dunlop TT 100 tires nominal tire pressures are :

Front 24 psi rear 26 psi

It is lower than I used to think would be Norton's recommended psi.

Grooved roads or harmonics caused by road work and pavement irregularities can be killers.

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You got to remeber the riders manuals were wrote 50 years a go, new modern tyres are better made and the old tyre pressures from 50 years ago is way too low for modern tyre and even back in the days ex0eramenting with psi was also needed as each bike is different with set ups and weight of the rider, all plays a part in handling and smooth running, so important to get the tyre pressures right for your set up and riding style.

Ashley

I've been running 30psi front and rear on my RR2's since I got the bike with no problems whatsoever. (100/90 x 19 and 4.00 x 18)
What's to be gained by upping the pressure? Harder tyres would have to be harder on the rolling chassis.
I got about 8000 miles out of the last rear - I think it was about 11,500 miles from the front.
It'll stand on the front wheel under severe braking (one emergency - whew!)
Not sure what else to ask of them?
Cheers

robs ss said:

I've been running 30psi front and rear on my RR2's since I got the bike with no problems whatsoever. (100/90 x 19 and 4.00 x 18)
What's to be gained by upping the pressure? Harder tyres would have to be harder on the rolling chassis.
I got about 8000 miles out of the last rear - I think it was about 11,500 miles from the front.
It'll stand on the front wheel under severe braking (one emergency - whew!)
Not sure what else to ask of them?
Cheers

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Higher pressures will make a harder tyre and a harder tyre will deform less under weight, braking, turning etc. This should therefore allow it to turn easier. That would most likely be the most noticeable difference that you would feel I think.

However, tyres are meant to deform to a degree in order to create a bigger, grippier, contact patch. So the downside is most likely a smaller contact patch with correspondingly reduced outright grip, especially at extreme lean angles and under hard braking.

It’s the contact patch topic that’s forefront of my mind. We run narrow tyres on our old bikes and the contact patch is freakin’ small at the best of times. Making it smaller goes against the grain somewhat in my mind !

I guess it’s a ‘different horses for different courses’ kinda thing.