Tyres for The RC - Wrist Twisters
 
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post #1 of 16 Old 03-09-2006, 08:16 AM Thread Starter
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Tyres for The RC

Okay... I need as much feedback, and data as I can get.

Here is the background:

I used to run 180/55 tyres on my rear all the time. I have used mainly the Pirelle Corsa (SuperCorsas at the track), and also at one time, I had the Metzlers on the bike.

I recently went to a 190/55 Pirelli Corsa just to try it out. On my first couple of rides, the bike started sliding the front end a bit, in fact, I almost low sided on a real tight right hander because the front end almost washed out. Took me by surprise.

Initially, I thought the front tyre might be losing traction / threading, etc. However, I then started to figure that the front end might be raised a little from a shorter profile rear tire.

Here are the conclusions;

The 180/55 tyre has a sidewall aspect of 99 millimetres (180x.55)
The 190/55 tyre has a sidewall aspect of 95 millimetres (190x.50)

This essentially means front end invariably was raised about 5 millimetres, since the rear has now dropped by that much. This seems to make more sense to me as to why the front end would slip in turn. Also, with a 190 profile tyre, this would make it wider and thus the bike will not fall into a lean with the same ease as it did with a 180 profile.

So, the questions are:

Am I right in my thoughts? Is the 190/50 the culprit? Should I change to a 190/55? Or back to a 180/55?

My thoughts at the moment are to raise / lengthen my shock by 5 millimetres to compensate for the new tyre.

Any and all feedback would be appreciated.

wim.

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post #2 of 16 Old 03-09-2006, 08:24 AM
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I would go 190/55

And I think your conclusion is right

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post #3 of 16 Old 03-09-2006, 08:33 AM Thread Starter
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Quote:
Originally Posted by turn_1
I would go 190/55

And I think your conclusion is right

Thanks!

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post #4 of 16 Old 03-09-2006, 08:55 AM
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Quote:
Originally Posted by WIM-RC51
The 180/55 tyre has a sidewall aspect of 99 millimetres (180x.55)
The 190/55 tyre has a sidewall aspect of 95 millimetres (190x.50)

This essentially means front end invariably was raised about 5 millimetres, since the rear has now dropped by that much.
wim.
So math isn't your strong point?



Is it possible that you are just going faster since you now have more rubber to the ground with a 190/55 vs a 180/55? So you have more grip on back and not more on front. Or maybe you're thinking too much and doing it to yourself? I know I know, I sound like Keith Code now, but I'm just curious if you factored that in.

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post #5 of 16 Old 03-09-2006, 09:11 AM Thread Starter
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Quote:
Originally Posted by ragdoll
So math isn't your strong point?
DANG! My bad!

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post #6 of 16 Old 03-09-2006, 09:13 AM Thread Starter
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Quote:
Originally Posted by ragdoll

Is it possible that you are just going faster since you now have more rubber to the ground with a 190/55 vs a 180/55? So you have more grip on back and not more on front. Or maybe you're thinking too much and doing it to yourself? I know I know, I sound like Keith Code now, but I'm just curious if you factored that in.

Sorry for my mis-calculation and statement, I actually have a 190/50 on the rear, not a 190/55.

I am not going any faster than I usually do, and I was never a big thinker - can't you tell ? I really do think it is just the tyre and subsequent loss in height.

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post #7 of 16 Old 03-09-2006, 09:18 AM
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Oh. if you are running a 190/50, which is what the bike is set up for in the first place, then why would you need to adjust anything? It should be set up for that size already. Or am I missing something more?

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post #8 of 16 Old 03-09-2006, 09:33 AM Thread Starter
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Quote:
Originally Posted by ragdoll
Oh. if you are running a 190/50, which is what the bike is set up for in the first place, then why would you need to adjust anything? It should be set up for that size already. Or am I missing something more?

Yep.. there is more to tha story. When I built this particular bike, I lowered the front end - in other words, I raised the forks in the triple clamps. Also, when I installed the shock, I extended the length by 5 mm. This gave the bike a front-end bias, as far as weight distribution. I was running a 180/55 tyre on the rear and loved the handling like this. It fell nicely into turns and would hold it's line very well.

My rear eventually wore out - completely and almost low sided me. My dealer was out of 180/55 and I did not want anything but a Pirelli Dragon Corsa to match the front - so I agreed to try out the 190/50 - which is on the bike right now.

So, with the loss of 5mm on the rear, the front is invariable raised that same amount.

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post #9 of 16 Old 03-09-2006, 09:51 AM
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I think you need to ride more and take a Code class...or 10.

post #10 of 16 Old 03-09-2006, 10:00 AM
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Whoh, you monkeyed with a lot there. Put everything back to stock heights and then lower the front a hair and you should handle and flick nicely. Or just leave it stock and muscle that brute into the corners. It'll hold the line better than it did before you went back to a 190/50 I bet.

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post #11 of 16 Old 03-09-2006, 10:12 AM Thread Starter
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Quote:
Originally Posted by Clear-a-Path
I think you need to ride more and take a Code class...or 10.

LOL!!!

Doode! Aren't y ou proud that I can even talk this semi-intelligently about a bike's set up. That I seem to actually grasp some kinda concept of what might be going on and not panicking all over the place and ordering a new Ohlins front end or something ?

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post #12 of 16 Old 03-09-2006, 10:19 AM Thread Starter
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Quote:
Originally Posted by ragdoll
Whoh, you monkeyed with a lot there. Put everything back to stock heights and then lower the front a hair and you should handle and flick nicely. Or just leave it stock and muscle that brute into the corners. It'll hold the line better than it did before you went back to a 190/50 I bet.

LOL!!! Monkeyed aye? Well, they do call em grease monkeys right?!?

Funny, I did not remember the stock tyre was a 190/50 from the factory. It will be kinda tough to figure out stock setting now - I have an aftermarket upper triple clamp and so, the whole "only have X lines showing on the forks" does not work for me.

Then again, considering I am concerned because of the loss of tyre height in the rear, I would either have to drop the front further or raise the rear to compensate.

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post #13 of 16 Old 03-09-2006, 10:22 AM
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Quote:
Originally Posted by WIM-RC51
LOL!!! Monkeyed aye? Well, they do call em grease monkeys right?!?

Funny, I did remember the stock tyre was a 190/50 from the factory. It will be kinda tough to figure out stock setting now - I have an aftermarket upper triple clamp and so, the whole "only have X lines showing on the forks" does not work for me.

Then again, considering I am concerned because of the loss of tyre height in the rear, I would either have to drop the front further or raise the rear to compensate.
Dude, just sell the bike and get a new one... that one is hopeless...

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post #14 of 16 Old 03-09-2006, 10:35 AM Thread Starter
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Quote:
Originally Posted by ragdoll
Dude, just sell the bike and get a new one... that one is hopeless...
I thought about it, but I have too much work / money, etc. Into it. And... no one will pay all that back for me, so I might as well enjoy it.

Shockingly, I am looking at the CBR1000RR as a second bike... or a GSXR 750!

OY!

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post #15 of 16 Old 03-09-2006, 10:49 AM
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Quote:
Originally Posted by WIM-RC51
I thought about it, but I have too much work / money, etc. Into it. And... no one will pay all that back for me, so I might as well enjoy it.

Shockingly, I am looking at the CBR1000RR as a second bike... or a GSXR 750!

OY!
Well, I was joking, but I'm glad you're not selling it either. Dem dar GSXR 750's are supposed to be nice. I can't see myself on a Suzuki sportbike though. SV650, that's a different story. (I love that hammer head)

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post #16 of 16 Old 03-09-2006, 11:19 AM Thread Starter
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Quote:
Originally Posted by ragdoll
Well, I was joking, but I'm glad you're not selling it either. Dem dar GSXR 750's are supposed to be nice. I can't see myself on a Suzuki sportbike though. SV650, that's a different story. (I love that hammer head)

I don't know man - if I was to go with an I-4 again, I would certainly consider the Gixxer 750. It is a beautiful bike, and I am digging that whole new shortie pipe. I saw a 650 over the weekend and loved the darn thing!

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