120 70 17 tyres

[northwind]

Originally Posted by Bill.Cross

I'm with fizzwheel. And what do yo mean by "better" anyway? Faster into turns, more stable at speed? The GSXR's wider rear tyre makes it slower to turn than it need be, for instance, but other things go the other way. Don't know what effect a larger profile front would have, though if it made the front higher, that would increase rake and trail, making it slower to turn in and more stable at speed. It's too complex, as Fizzwheel says, just to guess.

You'd drop the front end to compensate, usually, which will give you equivalent ride height, tighten the head angle back up, but reduce the trail and wheelbase by a few mm. Or alternatively, raise the rear. Or both of course! In theory the 120/70 has better mid-corner grip, I suspect that the historic reason SV racers tend to use 120/70 might be much like the 520 chain thing, it's easier to find race 120/70 rubber, easier to buy and sell takeoffs too.

I used Supercorsa pro. 120/70 on the front, the handling was fabulous, I didn't need to drop the forks or raise the back or do anything else. As there's milimeters in it, you'd have to be superhuman to tell the difference.

The only down side is that the tyre is very close to the mudguard and sticky tyres can pick up stones and grate them against the underside.

... and you do get more rubber at extreme lean angles. Its like having your chicken strips added on again and using the ones you have.


C

[northwind]

Originally Posted by Berlin

As there's milimeters in it, you'd have to be superhuman to tell the difference.

Try doing some a/b testing, slide the forks a little through the yokes- you'll almost certainly notice the difference, it's only mm but I'm no superhuman and I certainly can.

This is all getting a bit complicated !! haha !!
Really appreciate the feed back guys.
I think im gonna go with th 70 profile and see how i get on !
At the very least the front will LOOK more substantial ! lol !

On the subject of lowering the front, what benifit does this give and why ??

Originally Posted by s.j.robson@bt

On the subject of lowering the front, what benifit does this give and why ??

It reduces rake and trail - rake is the angle of the steering axis. Reducing means making steeper. Trail is the distance of the centre of the contact patch behind the point where the line of the steering axis touches the ground. Both of these changes make the bike faster to turn in but potentially less stable. You need to decide for yourself whether this is a benefit.

As has already been said the two advantages are more choices for race rubber and more contact at extreme lean angles.

I did this change on my old R6 and it transformed the handling. the overall radius of the tyre is 12mm taller so you need to lower the yokes on the forks by about 10mm to get the same heaight on the front as with a 120/60. i'd tell you the exact amount but i down know the angle of the steering.

[yorkie_chris]

More of a V shape than a (_) shape so more contact patch area at high lean angle. Wears the middle out a bit quicker.

Sharper profile seems to counteract the raised front end, but then again I had a quite tall shock in the back when I had it on.

So good mod, but I use a 60 profile. I don't push it hard enough to benefit from the bigger contact patch at big lean.