120 70 17 tyres

[s.j.robson@bt]

Can anybody tell me if they have fitted a 70 profile tyre to the front of their SV.
I have had conflicting advice and want to do a bit more research into this and get as much advice as possible.
Can anyone help ??

Regards Steve

[husky03]

will be ok and make your speedo more accurate-but as the 60 profile is the original factory size if you smash it your insurance company "could" be funny buggers

husky

[tonny006]

I had a 70 in my bike and hated it.
Now got a set of avon storms and love it!

[flymo]

Can anybody tell me if they have fitted a 70 profile tyre to the front of their SV.
I have had conflicting advice and want to do a bit more research into this and get as much advice as possible.
Can anyone help ??

Regards Steve

Yep, this is the usual front tyre size when racing a mini-twin SV650.

Handles just fine provided you keep the tyre pressure as it should be. Compared to the standard fitment 120/60 they are a little taller and may feel a little unusual at first.

[northwind]

I run one, but only to compensate for a shorter front end.

[Bill.Cross]

Why change?

[s.j.robson@bt]

The GSXR runs a "70" front, im assuming this is to improve handling compared to the SV which is obviously set up from the factory to be more of a sports tourer !!

[fizzwheel]

The GSXR runs a "70" front, im assuming this is to improve handling

Yes but theres many variables that effect the handling. Its not just the 70 section tyre that makes the GSXR handle better than the SV does.

The steering geometry is different and it has better front suspension. It also has as wider rear tyre and better rear suspension.

If you think putting a 70 section from tyre on your SV will make it handle like a GSXR does it wont. If you dont understand what it is your trying to do you wont be able to evaluate the changes that the new profile front tyre makes to the way your bike rides.

Whats wrong with the SV your riding now in terms of handling ? You're better off IMHO fixing the problem at source i.e some front suspension work rather than messing about with tyre profiles. It has that 60 on it for a reason and |I never had any issues because of it...

[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.

I replaced my back shock with a GSXR600 K1 from ebay (£50) over Christmas. Not very impressed by the difference. About a month ago I renewed the oil in the front legs with the standard W10. Much better. Then I went to a track day at Cadwell and the man from 100% Suspension fiddled with the rear shock. He increased the rebound damping considerably and added a little to compression. The bike is so much more stable and comfortable now. A BIG improvement.

[kwak zzr]

personaly id stick to what size mr suzuki fits.

[northwind]

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.

[Berlin]

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]

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.

[s.j.robson@bt]

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 !

[s.j.robson@bt]

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

[Bill.Cross]

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.

[stuballs]

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.