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Discussion Starter #1
DIABLO ROSSO II 140/70R17 REAR TIRE
DIABLO ROSSO II 110/70ZR17 FRONT TIRE
Sorry for the funky formatting.

I have a 2010 SE. I wanted to get some reasonably sticky rubber. But I could only find Pirelli Sport Demons in stock sizes. I tried a pair. They are ok but they are skittish. They are bias ply and I am sure a better rider could get more out of them. I don't need the cheap thrills.

So digging through the forum I saw that these Rosso's will fit within bounds on our SE rims. Not ideal, but in bounds.

So I got a pair of these.

Here is my problem, the front is 12mm taller. This reduces my effective fork angle. The rear is 15mm less than before. This reduces my rake more. So I lose a good bit of rake from these tires. I am lowering 7.5+6 or 13.5 mm of elevation, rear patch to front patch.

I could put a spacer in the shocks but that really only increases the swing arm rake and more is not better. Besides the suspension is dialed in so if I can just lower the bike I will be good. And with the slightly smaller rear tire diameter it will rev a bit quicker.

I am going to do a bit of measuring and see how much I can lower the front forks. I have the tubes up over the top yoke by 5mm right now. So I have lost a combined 13.5MM, Maybe I can go another 5 mm above the yoke and not have anything hitting. I would be surprised if I could recapture the full loss in rake angle. I will let you know.

I just enjoyed the comfort of the radials and I am hoping I can mitigate the effect of the size changes with these nice sticky tires.

So have you ever run these tires??

How low are you able to move the front tubes up past the top of the yoke without hitting anything on front end compression?
 

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Not sure if you have the correct sizes for your SE. I have a 2013 Thruxton. Owners manual covers the Bonny and Bonny SE specs among others. Manual states Bonny SE as Front - 110/70-17 and rear as 130/80 - R17. Did it change from 2010 to 13? For my Thrux I went with the Pirelli Angel GTs and have been happy with the quality/performance of the ride and their wear to date. These are both Radial tires, although recognize a different size than what you are looking for.

Be careful changing ride height and geometry before researching impact, as well as tire dimensions. I added 10 mm to my Hagon's at the rear (360 mm to 370 mm). Along with the switch to the Pirelli's from the OEM Metzelers, became a different bike to ride/handle. Much more responsive in turn in, almost too much, but I like it after a while getting used to it.
 

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The front tire should be the same as the stock tire height. The rear tire will be a little shorter than the stock rear tire, which would slacken your fork angle a little bit. You can make up for that with preload (aka ride height) adjustment in the rear. If the front tire you installed is 12.5mm taller than the stock tire (radius which is all that matters), then you put the wrong size tire on there. Are you sure it's 110/70? Even a 120/70 (much more common size) would only be 7mm taller.
 

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Discussion Starter #4
Neither tire is the same as stock. But both tires fit in the rim width available and they are sticky tires. Stickier than anything else that will fit at this point.

I bought the 110/70. I am using Tire Size Comparison to compare sizes. The 120/70 is definitely taller than the 110.

I have 14.5 inch shocks on the rear and I have lowered the front tubes 5mm above being flush with the triple tree. That is using stock tire sizes. So I have a little steeper than a 27 degree front fork. It is quick and fun and points and leans very nicely.

I will just have to experiment with the front forks and see how much I can raise the top of the tubes above the triple tree without causing any interference at the limit of compression. If I can recapture all of the loss in rake by lowering the front end then the upside is the bike is lower overall. That combined with better radials and sticky ones at that should equate to a lot of fun. I used to run up and down some canyons in Colorado and the old metzers worked great. I wanted sticky rubber and went to the bias ply Pirellis. In the same canyons I found the bias ply tires to be just a bit skittish, radials spoil you. And the Rosso II's are radials and are even stickier than the sport demons.

I am not a crazy rider who visits 10/10ths or anything remotely close. But sticky tires are always a plus over less sticky. Especially if you need a bit of extra bite at the exact moment you can use it. Repeating myself, radials are better than bias ply.

The stock 3 inch width on the front works great with the 110/70 tire. The 120/70 is optum with a 3.5 inch rim and its even taller. The rear 140/70 is optum with a 4.25 rim but will work with a 3.5. I have a Thruxton hub and may put a 4.25 inch rim on it but it gets so pricey. Then I also have to deal with a tubeless spoked rim and that is another PITA. Or convert a Kawi 650 rim which is also a PITA.

If you have used these tires on your Bonnie let me know. If not I will post back once I get them mounted.
 

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Here is my problem, the front is 12mm taller. This reduces my effective fork angle. The rear is 15mm less than before
I am running these tyres and they are an excellent choice, currently on a Rosso 3 rear and 2 front, same size you have listed, for a mag wheel bike the front is the same profile as stock and the rear is 6mm less profile so I worked on 12mm less rolling, with an 18t front sprocket the smaller diameter but slightly wider tyre is noticable in a good way, longer rear shocks and set your forks in the clamps to get the rake where you like should be good.

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Discussion Starter #6
Thanks for your experience with these Miket100. Are the 3's the same tire with an even stickier compound or a dual compound?? I am really looking forward to getting back on modern radial tires!!! The sticky rubber is the best part. I was out measuring what a full inch lower would do on the fork and I don't think anything hits anything else. So it looks like all I get is a slightly lower over all bike and a slightly higher revving engine for the same speed. I don't see any downside. And it is a heck of a lot cheaper than going to a fatter rear rim!
 

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Neither tire is the same as stock. But both tires fit in the rim width available and they are sticky tires. Stickier than anything else that will fit at this point.

I bought the 110/70. I am using Tire Size Comparison to compare sizes. ...
I'm trying to understand how your front tire is 12mm taller when it's the same size as stock. Did you have a smaller tire on there before? I guess I assumed that for whatever reason Pirelli tells you the Rosso 2 is 12mm taller than the exact same size Sport Demon. I must be misunderstanding the original post. I would expect some slight variation in size from manufacturer to manufacturer, even less between different tires from Pirelli, but nowhere close to a 24mm difference in overall diameter. That's nearly an inch! I am not sure a 12mm taller tire would even fit under my front mudguard/fork brace. I think the mudguard mounting screws would probably rub on it.
 

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Discussion Starter #8
I'm trying to understand how your front tire is 12mm taller....

Sorry for the confusion. Here is what I did:

I had stock Bonneville SE tire sizes in the Sport Demons. Those are 100/70-R17 on the front, and 130/80-R17. I have built the bike suspension around the stock tire sizes.My rear shocks are 14.25 inches if I remember right (eye to eye).

The only thing available in the Rosso II's for a front is 110/70/17 and the rear is 140/70/17. Each of those tires will fit on a 3 inch and a 3.5 inch rim.

When I go to the tire size comparison site: Tire Size Comparison

And compare a 100/70 to a 110 70 I get this: The diameter of the 100 is 22.5 and the diameter of the 110 is 23.1 (inches) So subtracting 22.5 from 23.1 gives me .6 of an inch which converts to 15.24 MM, Divide that in half and the front of the bike comes up 7.62MM. Also that much less clearance on the fender. I think it will clear, we will see.

Same compare for a 130/80 and a 140/70 to get this. The diameter of the 130 is 25.2 and the diameter of the 140 is 24.7 (inches). So subtracting 24.7 from 25.2 gets me .5 inches or 12.7mm. Divide that in half and the rear of the bike drops 6.35mm.

If I add the front rise and the rear drop I get a combined 6.35 + 7.62 lets call it 14MM lower at the rear tire. That, if left un corrected will reduce my front fork rake. I already have the front tubes dropped 5mm. I am going to take my angle finder and get the static fork setting on the stock tires right now. Then I can see if I can lower the front tubes up further into the triple tree and recover my loss.

Make sense?? Your comments welcome. Half of the fun with a bike is experimenting. As it sits right now my SE is a blast to ride. I just don't care for the way the bias ply tires feel.
 

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I had stock Bonneville SE tire sizes in the Sport Demons. Those are 100/70-R17 on the front, and 130/80-R17. I have built the bike suspension around the stock tire
Your bike had the wrong front tyre installed, the SE stock front is a 110/70 so you will now be going back to stock size with the front, the profile difference will exist to what you had on the bike, dropping the front a little should help, to check clearance it's best to support the front then drop the caps off and move the wheel through full stroke to be sure,

Not to sure about differences between Rosso II and III rear as I have only just installed the rear, had been running a Pirelli Angel GT rear and Rosso II front combo on the mag wheels previously.

Your bound to like your new tyres.

SETyres.jpg


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That explains it then, you originally had the wrong size tire up front. 110/70 is the stock front tire size. It's 7mm larger in radius than the 100/70 you had before according to math (and not the actual numbers provided bu manufacturers' charts) ... this is easy math, 70% of the 10mm difference in width is 7mm.

Also, bias ply tires "grow" more than radials at speed, so you might find the taller static radial is similar in size when rolling at 50mph.

As for the rear tire dropping, I also have 140/70 ... it's 6mm smaller than the stock tire size in radius. Again, you can easily make up this difference with preload assuming you didn't already have the preload maxed in the rear. Just put 6mm more ride height in the rear with preload on the shocks. You could do exactly the same thing up front by reducing static preload by 7-8mm, but I'm not sure the SE fork has 7mm of preload with the stock spacer.

Here's the easy way to understand this. Tire sizes in general are +/- a few mm even keeping the same sizes so you can always expect a little variation. Plus changing tires you likely will readjust tire pressure which will have a mm or two of tire height difference. The geometry of the bike is quite dynamic. Ride height is fine tuneable with preload at the rear, and realistically you can usually adjust everything right there without having to mess with the forks. Preload adjusters in the front will give you a little more tuneability up front, and that's a cheap upgrade. You will probably have to get close to a whole degree of fork angle change to really feel it in normal use, and it takes about an inch of height change to give a whole degree.

All of this to say, you fit the new tires in the sizes you suggest, any difference in feel that is not due to changing tire sizes can be fine tuned with preload in the rear alone. If you can feel 6-7mm of ride height difference at one end with all other things being equal, you belong on a MotoGP crew.

Changing from the stock size Avon RoadRiders that came on my SE to my current 140/70 rear (Michelin Pilot Street Radial) and 110/70 front (Pirelli Sport Demon) TRANSFORMED the handling of my SE. Tire changes can make an enormous difference. When changing sizes along with the tire compound/tread/design it will make an even bigger difference. I think you may be overthinking this, just try the new tires and then tune first tire pressure, then learn to ride the new tires, then fine tune ride height at the rear first.

FYI I raised my fork tubes an inch in the triples on my Suzuki and it was just barely noticeable while riding. Mostly what I noticed about this was the riding position change, I'm not sure I can detect any difference in handling. It changed where I sit on the seat and made the bike more comfortable. Point is, don't let the specs tell you what you should feel or prefer. Get out and actually ride it, make objective choices. These changes will have a lot more effect than just minor handling differences.
 

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Discussion Starter #11
Hey Miket100. How easy it is to make a mistake. I could have sworn that the fronts were 100/70's. Lots of google searches for 2010 SE Spec turn this up. I too went to the manual and sure enough saw the page you posted. So I went out to the garage just now and I do indeed have a 110/70/17 sport demon on the front. I had ordered them from bikebandit and installed them last summer. My bike came with the Metzler front bias/rear radial combo as shown in the manual for stock tires. It did not suck at handling with these, I just wanted a stickier compound.

Having the correct front size is good news. I just need to drop the front 6 or 7 mm's and I think I should get back to where I was. I have an angle detector that I am going to put on the front fork to see where it is with the sport demons and then I can work back to that with the Rosso's.

Mr72. I appreciate your input but there is no way I am changing the preload. I have got a lot of time and trouble into getting the front and rear sag perfect and adding preload will hose my rear compression. If you take away the rebound length it will skip over holes or depressions in the road instead riding through them. I used the RaceTech Suspension bible and got static sag and rider sag dialed in on both ends of the bike. So if I just lower the front a bit more I can regain my fork angle.

I do appreciate the input from everyone. There is a lot of experience to tap on this forum. Thanks!
 

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Easily done when all the other 865 Bonnie's are 100/ stock on the front.At least you ordered an ideal front tyre and only have to deal with the rear now.

I have used the Racetech book as well but always end up on the firm side with their spring recommendations unless you have cartridges in the forks and enough damping available to tame them.

What are you using to measure fork angle ? I have been using the built in measure app on the iPhone, it reads in degrees which isn't so bad, move the forks ~5mm at a time, do take care when test riding after geometry changes, I'm sure your well aware of that, at least you have a target setting to chase that you know works for the bike.

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Discussion Starter #13
Easily done when all the other 865 Bonnie's are 100/ stock on the front.At least you ordered an ideal front tyre and only have to deal with the rear now.......

Yeah looking online it shows 100/70 on the front of the bike in many of the "2010 SE Spec" searches.

I have Adreani's in the front and Kawi ZXR shocks with RaceTech springs on the rear. Took a bit of fiddling to get the compression and rebound right and I had to go to a lighter spring on the cartridges to get the correct sag. But it is dialed in and very stable into and out of corners.
 

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Discussion Starter #14
What are you using to measure fork angle ? I have been using the built in measure app on the iPhone, it reads in degrees which isn't so bad.....

I had not thought about using that ability on my iphone. I have a tool that looks like a hinged V with a bubble on one end and a readout on the other side. But it is in storage with the majority of my tools as I just moved. I will have to figure out that angle finder on my iphone.
 

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had a set on my traded 2012 mag wheeler, a less equipped SE, great grippy tyres for about 5 thou! as i say its long wear or great grip or somewhere between.
 

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Hey Pylot7,

Depends on where your iPhone is at with updates but the measure App has been there for as long as I have used them, on mine it's in the Utilities folder and then select Level on the bottom of the screen, play with it for a while and it should make sense, it flips around on the scale as you move it but you can get it to read the degrees laying it along the fork lower on a flat surface, I also use this along the lower frame rail and compare to other bikes when your messing around with the geometry.

I have fitted Andreani cartridges for someone else and found them quite stiff and probably over sprung but the setup was between the owner and the place he bought them from, for myself I have used Matris cartridges and they were outstanding once dialed in.

When you get your measure gadget out of storage be interesting to see how the iPhone stacks up.

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Discussion Starter #17
Hey Pylot7,

Depends on where your iPhone is at with updates but the measure App has been there for as long as I have used......

So first of all thanks for a great tip. I used my iphone to measure the fork angle along the lowers and with me on the bike I get 24 degrees. Its a little steep. I have run it up and down some great twisty canyons with this setting and it does drop in and then wants to keep turning in. So I arrest the turn in about a third in to the arc and throttle out and its perfectly controllable but I always thought I was running a bit steep with the taller rear shocks and the lowered front fork. Now I know.

With the lower rear tire it may be all I need and I have some room to reduce it a bit further by raising the forks if I need to. I am thinking the lower rear will be all I need. I will have to try comparing my angle finder to the iphone.

I measured my Harley FXDC and it comes in at 27 degrees which is what stock is supposed to be. I am thinking the iphone works fine.


Depending on who you order the Andreani's from they are usually a bit stiff. I think its their nod to racing or something. I ordered mine from eBay. They actually came from Italy. I asked for the lighter springs when I ordered them, the Italians ignored that. Had I know that FastBike Industries out of the East Coast was the North American dealer I would have purchased from them. I got mine with, if my faulty memory serves me, .93Kg springs. Way too stiff. Not much sag at all. I spoke with FastBike and based on RaceTech recommendations they sold me a pair of (again I may be a bit off on this) .83Kg springs. Those turned out to be perfect. 3/4 inch static sag, adds another 3/4 inch sag when I get on. The fork ends up in the sweet spot. I had to mess with the compression and rebound settings over several rides up and down the canyon roads but once I got them dialed in the bikes handling is just plain nice. Just a little slow dive and very controlled release on throttle out. Nothing sudden and definitely confidence inspiring.

I just got the tire change tools and a balancer. I am sick of being extorted every time I change a pair of tires. Two tire changes and these tools will pay for themselves. At least that is how I explained it to my wife😁
 
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