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Discussion Starter #1
Hey all,

I bought some new Pirelli Supercorsas and went with the 180/60 versions instead of the 180/55 I've been using for the last few years. Mounted on wheels, the 180/60 is about 15mm taller than a barely-worn-in-the-center 180/55. So that means the tire is about 7-8 mm closer to the swing arm. I figure rear ride height is about 5-7 mm higher once there is some weight on it. I have stock gearing (16/45) and a stock chain (114 links).

I read here that I can take out the shim between the top of the shock and the frame. So I've done that. That shim (stock I expect - says "up" on one end) is 3mm thick. I measured the axle-to-tail measurements before I removed the shim. I'll compare the measurement without the shim when I finish putting it all back together. I figure that will keep the same geometry I'm used to (even though I could probably be nanoseconds faster with a raised rear ride height!!).

After all that, my question really has to do with the chain. With the 180/60 mounted and stock sprockets/chain, there is no room for my warmers (Woodcraft warmers with the connectors on each end that have to make it through the tight spot at the swing arm). That's with about 50mm of chain slack. I can get the warmers on with the chain at about 30mm slack, which is a bit tight.

So I guess this means a new, longer chain? Will a 116 link chain be too long? Is there enough adjuster room to get it tight enough? And once the chain is tight enough, will the wheelbase increase have any odd effects? I really don't want to loose any nanoseconds (or more importantly, the days associated with an unexpected crash).

BTW, I am a mid intermediate rider. And not in a hurry to go faster - just bought the 180/60s cause I understand they give good contact patch.
 

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Motosylum Racing #132
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The quick answer is yes, you need to go to a 116 chain. The slightly longer wheelbase will not affect anything.
If you are due for sprockets at this time then you might want to go 16/46. That will put you at the same overall gear ratio that you were at with 16/45 on a 180/55 tire. Not only that, but it will shorten the wheelbase up some.
What tracks to you typically ride? That will play a part in gearing as well.
 

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Discussion Starter #3
Re: 180/60 Tire Fit, Chain, and Alignment

Thanks for the verification. I ride Summit Point Main and Shenandoah as well as NCBike. Plan to get to VIR sometime. Stock gearing was OK with the 180/55, though first is a bit low. Not getting anywhere close to top speed (150+), but then my objective is not outright speed. My main concern with the 180/60 is having clearance for tire growth (and warmers) and managing ride height.

Right now, I have the stock 114 link 525 chain with about 40mm of slack and just enough room for the warmers to go on with a little rubbing. Ordered a new 520 chain (116 link) and sprockets and kept the gearing the same (16/45). Figure that will move the wheel back slightly less than 5/8" (one link, top and bottom). That should be enough.

Now just need to figure out a good way to align the rear wheel - thinking of a pair of 1/4" rods, one in the rear axle and one in the swing arm pivot, using various sizes of rubber stoppers to center the rods.

Thanks again for the feedback.
 

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Motosylum Racing #132
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You could go the easy route and use the marks. When people say they are off it makes me :laugh:
Or use a Vernier caliper and measure the distance from the back of the swing arm to the back of the adjusters.
 

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Why yes I don't!!!!!!!!!!
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You could go the easy route and use the marks. When people say they are off it makes me :laugh:
Or use a Vernier caliper and measure the distance from the back of the swing arm to the back of the adjusters.
on my gsxr... the swingarm marks are about 1/4" off on either side. My zx12...5/8". My R6 was an <1/8"
 

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Discussion Starter #7
Re: 180/60 Tire Fit, Chain, and Alignment

something like this??
Yes. Something exactly like that. In fact that seemed to be an excellent solution, with one possible exception: Where do I find one? So I figured I could fab one using a couple of 1/4 rods and various one-hole rubber stoppers popped into the four different hole sizes in the swing arm pivot and axle. Let me know if the pictured one is available somewhere. Would much prefer to have accuracy of metal cones.

Or use a Vernier caliper and measure the distance from the back of the swing arm to the back of the adjusters.
I have a pair of simple inside calipers that I measure the gap between the front of the adjuster and the swing arm cutout. Then I adjust till the gap is the same. Seems pretty good, based on the chain run. But I have a hard enough time steering when its aligned properly and don't need any extra challenge!

 

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Mr. HER6
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I made the same switch from 180/55 to 180/60 Pirellis a couple years ago and I can tell you that if your geometry is set right you do NOT want to lower the rear to compensate for the ride height. The center of the tire is taller, but the sides are not. You will notice a bigger change in the revs as you go from upright to leaned over. I pulled that shim out and raised the front a bit based on the tire size difference. When I did this it was the absolute worst my bike has ever handled. It suffered severe understeer, and the front tire started showing geometry induced tearing. Gave me some real big front end slides, too. I talked to the Pirelli vendor and he said I should have just ridden it as-is and see how it feels. I put the geometry back and all that went away. Just made some minor tweaks from there.

why not just get the right size tire?
It IS the right tire size. 180/55 Pirelli race tires are basically obsolete. They stopped making them in all, but one compound.
 

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Motosylum Racing #132
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on my gsxr... the swingarm marks are about 1/4" off on either side. My zx12...5/8". My R6 was an <1/8"
I'd have gotten the frame checked. Never in my life have I been more than 3mm difference. You are talking 15 mm on the ZX12!
if your geometry is set right you do NOT want to lower the rear to compensate for the ride height. The center of the tire is taller, but the sides are not. You will notice a bigger change in the revs as you go from upright to leaned over. I pulled that shim out and raised the front a bit based on the tire size difference.
It is not the same for all riders. I used to have the shim in. As I got faster, I needed to make more changes. I needed more weight on the rear as well. Pulled the shim, changed the forks by 5mm and dropped nearly 2 seconds in a day.
Front end pushing can also be from a number of front end suspension variables.
 

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Mr. HER6
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True, but in my case it was obviously due to poor geometry. Tire wear was classic geometry tearing, and handling went from good to terrible and back to good over 3 consecutive riding events. Perhaps I was already nearing the limit of not enough weight on the front. But my point is that adjusting geometry to compensate for the upright height difference between these specific tires is going to be an even bigger change for when you're leaned over.
 

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Why yes I don't!!!!!!!!!!
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I'd have gotten the frame checked. Never in my life have I been more than 3mm difference. You are talking 15 mm on the ZX12!
.

yes thats "production" tolerance for ya. None of my bikes have ever been crashed and were mine since new.
also my zx12 is 17 yrs old now. I cant believe its nearly 2 decades since new. :kiss:
 

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Reads the rulez
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Re: 180/60 Tire Fit, Chain, and Alignment

Thanks for the verification. I ride Summit Point Main and Shenandoah as well as NCBike. Plan to get to VIR sometime. Stock gearing was OK with the 180/55, though first is a bit low. Not getting anywhere close to top speed (150+), but then my objective is not outright speed. My main concern with the 180/60 is having clearance for tire growth (and warmers) and managing ride height.

Right now, I have the stock 114 link 525 chain with about 40mm of slack and just enough room for the warmers to go on with a little rubbing. Ordered a new 520 chain (116 link) and sprockets and kept the gearing the same (16/45). Figure that will move the wheel back slightly less than 5/8" (one link, top and bottom). That should be enough.

Now just need to figure out a good way to align the rear wheel - thinking of a pair of 1/4" rods, one in the rear axle and one in the swing arm pivot, using various sizes of rubber stoppers to center the rods.

Thanks again for the feedback.
Multiple ways to skin that cat. Longer chain, like you did, or another popular thing to do is go with smaller sprockets, but the smaller sprockets left handedly extend the wheel base because of the smaller diameters.

16/45 is stock. Going to 15/42 is mathematically the same (ever so slightly shorter, but it's negated with a taller rear tire)

For an intermediate rider, I'd recommend 15/43, or 16/46. You aren't quite up to pace to benefit from taller gearing as you don't have the corner speed required to keep the RPM's up.

For Summit/NCBike, you can most definitely run 17's at Summit and 29's at NCBike with a 15/43 setup as that's what I use. I go back and forth between a 43 and 42, minor differences require slightly different riding style between the two, but honestly I'm splitting hairs for what you're trying to accomplish.
 

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Discussion Starter #16
Re: 180/60 Tire Fit, Chain, and Alignment

For an intermediate rider, I'd recommend 15/43, or 16/46.
I see why now.

With the stock 114 link chain, I was real spooked by how close the 180/60 was to the swing arm. Wanting plenty of clearance, I got new 520 sprockets (16/45 stock gearing) with a 116 link chain. Wasn't too worried about a bit taller gearing with the taller tire - figured I could use a little higher first gear. But, with no additional sprocket teeth, the 116 chain moved the axle further back than I was expecting. Still ok adjustment range, but I'd like to get the 46 rear and pull the axle back into the middle of the range.
 

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Reads the rulez
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Re: 180/60 Tire Fit, Chain, and Alignment

I see why now.

With the stock 114 link chain, I was real spooked by how close the 180/60 was to the swing arm. Wanting plenty of clearance, I got new 520 sprockets (16/45 stock gearing) with a 116 link chain. Wasn't too worried about a bit taller gearing with the taller tire - figured I could use a little higher first gear. But, with no additional sprocket teeth, the 116 chain moved the axle further back than I was expecting. Still ok adjustment range, but I'd like to get the 46 rear and pull the axle back into the middle of the range.
Don't change your gearing for the sake of moving the axle adjusters forward a little bit.
 

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Re: 180/60 Tire Fit, Chain, and Alignment

Yes. Something exactly like that. In fact that seemed to be an excellent solution, with one possible exception: Where do I find one? So I figured I could fab one using a couple of 1/4 rods and various one-hole rubber stoppers popped into the four different hole sizes in the swing arm pivot and axle. Let me know if the pictured one is available somewhere. Would much prefer to have accuracy of metal cones.



I have a pair of simple inside calipers that I measure the gap between the front of the adjuster and the swing arm cutout. Then I adjust till the gap is the same. Seems pretty good, based on the chain run. But I have a hard enough time steering when its aligned properly and don't need any extra challenge!

motion pro makes a chain alignment tool. it's cheap as fu ck.
https://www.motionpro.com/product/08-0048

if you feel like spending money buy some lightech chain adjusters.
 

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Discussion Starter #20
So I went to the track with the bike as above (116 link chain, stock gearing, 180/60, and spacer removed from the top of the shock). Remember, I am just a regular mid pack intermediate. So probably couldn't tell anyway. But the bike felt fine. I didn't notice any change in handling. If anything, it felt better. Of course it always feels good with brand new tires. I did notice I was going through Turn 11 hairpin at NCBike-CW in first and not getting to sixth on the main straight. Maybe I could go one tooth up in the back. I think I am a long, long way from running out of top speed.
 
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