| Author | Message | ||
     Knickers |
So in making the step up from track days to racing this year I've moved from street tires (Michelin Power 2CT) to DOT race tires (Michelin PR1/PR4) and I'm finding I've take a step backward in handling. Specifically my turn in seems much slower and higher effort and I can't change lines with nearly as much ease as I could with the street tires. My first though was that I've upset the ride height so I measured the difference in rolling radius of the two tires. The front race tire is 5mm bigger and the rear 7mm bigger than the street tires. If anything this should steepen my rake and reduce trail which should quicken steering theoretically so I'm puzzled by my observations. Having the stock shock I can't reduce the rear ride height which is ideally what I'd like to try next, but before I fork out for a Penske I thought I'd ask around for advice. Does anyone have experience that 5mm of ride height makes that much of a difference? Should I just try different tires? Slaughter had mentioned that the Bartel's XB race bikes had stock suspension so should I infer that ride height doesn't make that much difference? I love the grip of the DOT race tires but I don't think its worth the trade off in quick steering so I gotta figure a way out of this. Anyway, thanks in advance. Kurt | ||
| Vagelis46 |
I think it is a tire profile issue. The 2CT are very triangular tires that help slow steering bikes like the XB. I also think that the Pirelli race tires are having a triangular profile, that will help the steering. | ||
| M1combat |
Slow steering bikes like the XB??? I think you should hit the gym or something  . Wow... The steering might be a little heavy while you're hard on the brakes but it's certainly not a "slow steering" bike by any means. It just takes a bit more effort to get the same result. That's because it's a "stable" bike. Anyway... Do you run those DOT race tires at a much lower temp than the street tires? If so maybe they just need to heat up to build pressure so the profile works? | ||
| Rocketsprink |
Go with the Michelin front PRC. Trust me. I race on Michelin tires. PR 1 is a rounder profile tire. PRC is very triangular. The difference will be night and day. Don't screw with ride heights. I've been through this already myself. | ||
| Schmitty |
+1 on the PRC front! Lightning fast turn in, great traction and excellent feel. I wouldn't start messing with ride heights or anything like that until you have the suspension dialed in. The stock geometry on the Buell just plain works, so I wouldn't mess with it. Save that for when you're running at the top of the experts! Schmitty | ||
| Knickers |
Thanks, I forgot to point out that I switched from a PR1 to a PRC before the last race weekend. I did notice an improvement, but its still not as quick steering as the 2CT. A few weeks ago I was at a track day where I switched back to the 2CT's on my other wheels. It was dramatic, I was running over curbs at the apex because I was getting the bike to steer so much quicker. It took quite an adjustment. I can deal with just having to muscle the bike over harder on the race tires, but its the ability to change lines mid turn that I miss. I'm using warmers and the tires damn near burn my hands when I come off the track so I don't think its a temperature thing. I'm running 30psi front and 22psi rear cold pressures. My thinking about geometry is that I've modified it by changing to these tires which have a larger rolling radius than the street tires, thus I need to drop ride height to get back to the geometry I had with the 2CTs. | ||
| Buellrcr |
hey i got a penske that i took off of my race bike great shape. 550, took it off to put a tripple clicker on race bike shock retail for about 750 | ||
| Knickers |
PM sent | ||
| Buellrcr |
pm sent | ||
| Sd26 |
The PR1 tire is a very soft carcass tire that feels like a marshmellow being pushed around by a big pencil eraser too. The PR4 is a good tire, but it's pretty much completely inappropriate in temperatures BELOW 90 degrees. There are plenty of these being blown out on the net. There are also about three versions of the PRC out there too. There was an update of the PRC on date code 4206, and there's another one out too, but I don't know the exact date codes. I've used as much as 36psi on the PRC's. You only use 22psi on the PR rear tires. | ||
| Mxer83 |
I would trust rocketsprink & schmitty on this 1. they have alot of laps in on these tires, just make sure you have your sag set right! |
