Landracing Forum
Bonneville Motorcycle Speed Trials => Bville Motorcycle Speed Trials General Chat => Topic started by: aching_ass on June 01, 2007, 05:27:16 PM
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Hi,
'bumpy_roads' here. I lost my password and changed emails so had to re-up. I am working on a '97 883 with a 89CI S&S power plant and will test it out this year with hopes of AMA next. I'm thinking about Avon AM26 Roadrider V-Rated 149 MPH Bias. Any suggestions? I have gone through forum topics and Internet looking for info and come up pretty dry? Do I want grip? More or less rubber on salt? Any particular tread design? Or none at all!
Thank you, Bumpy
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The APS/PBF 1650 record holder in 2004 ran on ZR rated Avon Azaro ST tyres. They have an aramid band that precludes the tyre from pulling itself away from the rim due to centrifugal force at speed.
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Password hint!!
Use the same password for every forum, news group, etc. you sign up for.
DW
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very much application specific......but generally speaking...
...less rubber on salt....harder compounds work well.....avoid
prolonged wheel spin......in you application the v-rated would likely
suffice......if you plan on speeds over 160's, consider going to a regular
zr rated radial on rim designed for it.......they have proven very durable on the salt.........
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If it was me, and it's not, I'd consider running an Avon Azaro AV45-ST 110/80 R19 (front) tire on both the front and the rear. It will fit a rim from 2.15 to 3.00 inches, per factory specs. It's 26.10 diameter & 4.30 wide. It's R rated. But (!) I would advise one to turn the rear tire around to roll AGAINST the arrow.
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Splain the lap seam / directional requirement shown with the arrow and the difference in forces between the front and rear tire in German.
Never mind, do it in American, not English and we will translate. :-D
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The Azaro ST has eight layers in the build process: 1. Bead and bead filler (apex) 2. Tubeless lining
3. Radial ply 4. Chafer 5. Radial cut belt 6. Sidewall 7. AVBD wind 8. Tread
AVBD (Advanced Variable Belt Density) offers high stability at all lean angles, including none at all. SBC (Spiral and Belted Carcass) has two extra belts to increase stability and grip under heavy acceleration for speeds of 168+ mph. Spinning reeeaaallly fast (unlikely with a pushrod motor, no offense) may cause the tire tread to rip away from the aramid belt.
Today I am completely unable to translate hard science into simple English regarding front tires on the back. (A cop out. You'll do a better job of 'splainin').
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Pertty good.
The HD is particularly good in the traction department as evidenced by it's long term successes on the mile.
The timing of the power pulses is such that it recovers during the dead pause to hook up again and is ready for more power.
UJM multies are almost electric in their nearly constant power application and once they run away, they don't recover as well.
The point of the arrow:
Wrap your tire with a single length of duct tape in the direction of travel and observe the lap seam at the end.
That is to simulate the wrapping method used to apply the various layers of rubber to the tire.
Now sit, look, and think about it.
Remember what forces are acting on it when in hard use.
The front tire will do a higher percentage of the braking and the rear will drive you down the road.
Now decide which direction you want the free end of the tape / lap seam to go and see if the factory is correct. :wink:
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Well, for the front tire in an A pushrod class (and no front brake) one is probably doing well by running it with the arrow.
For the back tire, traction wheel, in that same A pushrod class, against the arrow oughta' be better.
By the way, I hold the most theoretical land speed records with my fleet of theoretical motorcycles.
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Thanks to everyone for responding. The research continues and all the info helps.
Bumpy
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"Theory becomes fact when the rubber meets the road." (me) :wink:
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Isn't it a requirement to have the same speed rating as the record in the class you are going to run?
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Isn't it a requirement to have the same speed rating as the record in the class you are going to run?
It would make sense. I'll check rules again.
I went with Avon AM26 Roadrider V-Rated 149 MPH Bias. The ZR rated Avon Azaro ST won't fit my wheels. If bike runs faster than I'm anticipating (I hope!!) I'll change wheels for a higher rated tire.
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Isn't it a requirement to have the same speed rating as the record in the class you are going to run?
2.Q. TIRES
It is recommended that tires are rated for the appropriate speeds
and, use is at the sole discretion of the owner/participant. The rider
has the sole responsibility of inspecting the condition of the tire
before and after each run.
Slim should like the comma after the "and".
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Just a hint; best make sure your shoes are rated for the expected performance in your particular class. And if you don't have a steering dampner, get one.
Sam
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Just a hint; best make sure your shoes are rated for the expected performance in your particular class. And if you don't have a steering dampner, get one.
Sam
Yes, steering dampner has been added. Thanks!
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hello all . Is it ok to use a front tyre on the rear? After my mishap last year, fronts cannot be used on the rear down under. I thought it was a good idea. 120/80 18 worked very well on the r1
cheers bones
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After my mishap last year, fronts cannot be used on the rear down under.
Tell us about it. How fast were you going? How much weight on it? Was it mounted reverse rotation?
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I was timed at 130 at the first mile,the bike had a slow weave from the rear[I thought maybe wet salt] but still no problem to adjust steering damper. When it didn't get any better I started to roll off which made it worse. Anyway I ended up on my head,broken collarbone and 3 ribs. I had a rubber valve stem which broke off.The tyre was fitted backwards.This is standard practice with avon tyres on road race sidecars which I have been racing for 20 years.The bike weighs around 210kg 430lb. I weigh 85kg ready to go.Front tyre is a m/t drag front. The bike is very stable at 177.Maybe our rule could be changed,I like the small tyres
cheers bones
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innovation is good, front mounted on rear mmm, I think thought a little weird at first. I think due to course conditions, that you had alot of wheel slip, weave, causing the valve stem (which was rubber) to sheer off and the rest Bones already told you... Metal valve stems are a must, Joe actually had a valve stem sheer off back in 1993 or 1994 right about that same speed, his outcome was better then Bones... Keep at them Bones, like to see you make it work...
Jon
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Hey, Bones....maybe you should be running your sidecar (w/passenger) it might be safer......(just kidding) Back in the "old days" when we were running tube-type tires, we always used a tire-lock
that would keep the tire bead on the rim.........now with tube-less tires and alloy wheels we have been using self tapping screws into the rim and into the tire bead. I have asked in the past why no rules regarding securing tires to the wheel/rim (rear) but was told there have been no problems.
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innovation is good, front mounted on rear mmm, I think thought a little weird at first. I think due to course conditions, that you had alot of wheel slip, weave, causing the valve stem (which was rubber) to sheer off and the rest Bones already told you... Metal valve stems are a must, Joe actually had a valve stem sheer off back in 1993 or 1994 right about that same speed, his outcome was better then Bones... Keep at them Bones, like to see you make it work...
Jon
I feel running a much smaller tire on a standard rear wheel is looking for trouble, if the rear rim that was used (I was there and did not see it) was a narrower rear rim then then I feel it would be better however if it was a standard rear wheel for the R1 or even R6 then it could have assisted the tire in coming loose from the bead much easier at speed causing the accident.
It was great to meet Bones, Evelyn and the rest of the racers from Australia and I hope to race there again.
:mrgreen:
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John is right-on......... IF you are planning on using a smaller tire on a "wide" rim it is safer to use a inner-tube it will keep the tire on the rim-bead...........BUT the rules state "no inner-tubes in tubeless (radial) tires" even though there are inner- tubes made for "radial" tires. Oh,well.............also keep the tire pressure fairly high..........this will help in keeping the tire on the rim-bead......are we having fun, Yet???????????
Reminder.........BUB pre-entry closes on July 3. 07
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The rim size was correct for the tyre 3.00. I showed the tyre to the state Bridgestone manager and he said the damage [like it was attacked with a knife] was classic low pressure delamination.More like no pressure.I think a longer narrow contact area is better.Speedway solo riders go to larger diameter wheels for more traction.Michelin had a 130/80 zr 17, so I setup a wheel for the tyre but when I ordered the tyre it was no longer available. The next size will be 140/70 so another wheel.
Good luck to everyone for your coming season
cheers Bones
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Good luck Bones, hope you and Evelyn go fast this year.
J