Landracing Forum
Bonneville Motorcycle Speed Trials => Bville Motorcycle Speed Trials General Chat => Topic started by: gschuld on October 21, 2018, 06:03:44 PM
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So for a roughly 400-425lb 58” wheelbase 1000cc classic gas bike capable of the 150s plus, what’s the story with tire wear? I’ve read reports that some of the high HP crowd can chew up a rear tire very fast if they knowingly or unknowingly had a little more rpm than their rear tire had traction down the track. I imagine the front tire doesn’t see much wear.
Is it common practice to bring a spare drop in rear wheel/tire? Several?
George
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You might chunk some rubber out of a drive tire and need a spare, you might spin it up and hurt it, and you might decide that using your spare - which you conveniently purchased in a slightly-different size from your other rear so that you broaden the spectrum of possible gearing - is a good idea. See where I'm going?
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Yes, I get the alternate advantages. I can (plan to) get rear sprockets made up in one tooth increments so combined with the 16 and 17 tooth primaries, I should have a good selection of sprocket for fine tuning.
I’m more thinking about rookie with little experience noticing the fine points of minimal traction lows burning up a rear tire or two. I understand the shaving/truing tires thing helps with this. It’s common to intentionally shave a bit of a flatter spot mid tire to increase tire contact patch some as well?
George
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George, we ran the same front and rear tires on our 1000 GSXR from our record in production, then Modified, all the way through to Special Construction when we got my son in the 2 Club at 208.959... Never burned or chunked one. When we needed to change the front because it timed out we were running open and I went as small as available....
Yea... we run Bikes and Cars with the same motors...... that 1000 motor held Production, Modified and Special construction records in bikes and then Gas Lakester and Mini Pickup records...
Go out the first year and be safe, have fun and go fast :cheers:
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Great.
Did you do anything special to the tires? Shaving just enough to finely balance them like vintage road racers often do? Actively remove tread thickness to reduce the chance of chunking? Cutting in a mosest flat section to increase the contact patch? Perhaps I’m reading into this too much with the mid to upper 200s guys...🤔
Stone stock speed rated off the shelf tires?
George
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Bridgestone Battlax was the tire of choice back then... rule changes for over 200 now require a "for racing purposes only" tire. We did nothing but put 50 lbs of air and a little lead elsewhere to keep traction. We did not shave, or do anything special... that tire was well suited for Bonneville.
A lot of Busa's and turbo bikes can easily overpower a tire if the rider is not paying attention to rpm and slip... you will have slip at Bonneville, the traction is about 60% of pavement, but you do have the ability to control and limit slip with your right hand.
Like I said before, get your bike within the rules (safe), Enjoy the ride, WFO throttle is exhilarating, and go as fast as you can... if you set a record... cool... no feeling like knowing you have the fasted bike 8-)
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Funny, the Battlax BT-45s are my favorite tire, but I’m sure you ran a different model of Battlex with a higher speed rating.
Things to chew on. I’d just assume do all the homework that I can to be as prepared as I can. It’s a 6 day driving round trip for me to get there and back with thousands in expenses, 2 weeks of time, and tons of hours to prepare a bike for a grand total of perhaps 30 minutes of TOTAL on track time over several days. When putting it like that, it sounds a little crazy😬. I’d prefer to reduce the chances of disssapointment as much as possible😉
That’s why I’m asking so many questions😁
Something about proper planning and practice prevents Pi$$ poor performance.
A secondary benefit to all this is to help inspire a few speed junkie friends with similar bikes to also go out this year. The more answers I have and the more I understand about how it all works(in theory) the better my sales pitch will be.😉
Let me know if I start wearing out my welcome😎.
George
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Look at the timing.... you could do BMST, 700 back to CO for the Mile, then back to Bonneville for WoS....
take the month off and have fun... :cheers:
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Look at the timing.... you could do BMST, 700 back to CO for the Mile, then back to Bonneville for WoS....
take the month off and have fun... :cheers:
Baby Jesus, are you trying to get me divorced😳? 😎. Seriously, I’d love that but I’m having a hard enough time trying to get away for 2 weeks since I will then be right in the middle of the construction of my new house, of which I am the acting general contractor(like last time)
Perhaps it’s something that could be done in 2020 though😉
Is there much of a turnout for bikes at WOS?
George
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Look at the timing.... you could do BMST, 700 back to CO for the Mile, then back to Bonneville for WoS....
take the month off and have fun... :cheers:
Not to mention your closest venue - Loring, Maine in mid July, and again Labor Day weekend.
I've run tires until their 10 year max life expired with no apparent tread wear.
Tom
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My guess is about 1/3 of the entries are bikes...
Just like SpeedWeek, the number varies year to year.... Lots of cool bikes and cars at both
Different rules than the BMST in some classes and different record book than the BMST in all classes
Raced at both... its all racing on Hallowed Ground :cheers:
Added Tom has a good point.... Look at all venues to get your racing fix....
but for your Bonneville experience..... well you know :cheers:
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Yes, I’ve looked at the Loring event. A good option to consider. Pavement is not as appealing to me, but less intimidating and less complicated(travel/altitude/traction)
George
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George, don't get me wrong... Loring in July is a weekend distraction for practice and bike checkout in preparation to go to Bonneville. If you find weak spots in your program you still have time to straighten things out before the "Big Dance".
Start working on your tuck and riding position.... the smallest frontal area is to your advantage.
Hope to see you on the salt 8-) :cheers:
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Veering off topic a bit, but you mentioned reducing frontal area to a minimum. I’m with you there, but one area that is challenging is dropping the ride height to the minimum allowed in the rules. It would require either major frame mods, 17” wheels with low profile tires, or both.
I’ve got the bottom of the frame rails/engine down to 4.5” from ground level before running into clearance issues. This leaves me with nice underslung clean exhaust options. Must lower and I’ll need to put exhaust out the sides. The frontal area of the center mass is pretty good and compact. I’m wondering if it’s worth considering more severe and unattractive alterations to drop the bike another 2” or so.
George
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Try what you have. I always try to get my bikes lower, but just lowering the bike 2" doesn't change the frontal area by more than the tire width by 2". But it might make the bike more stable in crosswinds due to lowering of center of wind pressure.
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I was thinking the same. Very little actual frontal area increase, so the return is pretty low for a lot of mods/compromises.
The rest of the mass is petty low overall. So it’s seems to be a good place to be satisfied and concentrate on he finer points of the envelope I have now.
Is 1.5” of suspension travel front and back with rider on board sufficient?
George
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Start working on your tuck and riding position.... the smallest frontal area is to your advantage.
Hope to see you on the salt 8-) :cheers:
Your tuck and riding position is your biggest band for the buck when it comes to lowering your frontal area.
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Start working on your tuck and riding position.... the smallest frontal area is to your advantage.
Hope to see you on the salt 8-) :cheers:
Your tuck and riding position is your biggest band for the buck when it comes to lowering your frontal area.
Well sure. I’ve been experimenting with riding position, and it’s one of those times when I wish I wasn’t 6’3” 220lbs. Trying to get low and keeping my back fairly flat for reduced frontal area and decent flow over my backside is a bit of work. It seems that more than a few riders set up their bikes so they effectively lay fwd on the bike itself to take pressure off holding that position and reduce the turbulence inducing gap between rider and bike on top? Sounds smart to me.
George
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George, I had Kent Riches cut the seat portion of my Charlie Toy body so that I had about 4" more room. I use the room to allow me to sit far forward during hard acceleration on paved tracks - and then slide back a third of a foot so I can get down flatter on the tank when the wheelie threat is diminished.