120/70 on the front?

I've got 120/70's on the front of mine, and have been running them for well over a month or so now:

1) The turning issues is hardly noticeable unless you're literally throwing the bike underneath you from almost full lean one side, to full lean the other side, it does it 'slightly' quicker, but not much. Also not had any problem with it trying to tip in at low speeds.

2) It does alter your speedo, but by hardly anything. At 5.5k rpm, it used to read 75mph, and it now reads 73mph. Probably a little bit closer to the actual speed, but will still be over-reading the same as every speedo always does.

3) The only problem you may find is if you have fitted a 'Fenda Extenda', as the end catches on the tyre unless you adjust the front mudguard slightly, but after adjusting it, no problems

I am surprised no one else has detected it, I consider the slow speed drop-in most notable and really really irritating!!! I’d actually say verging on the slightly dangerous …

Sure when you get above say 30mph it really makes no odds what tyre you have on, but round town I find it very irritating!!

Originally Posted by andyharding

I think i am right in saying this, but i think race bikes do this to liven the steering up abit so it turns in quicker.

Doesn't turn in any quicker but does have a larger contact patch when over and more tyre before you reach the edge.

C

In the March edition of TWO they did a guide to the SV650. Regarding tyres they said:

"Many find the OE 120/60-17 front feels like it's about to tuck in and prefer a 120/70."

I'm not saying it's true - please don't shoot the messenger.

Originally Posted by Blue_SV650S

I am surprised no one else has detected it, I consider the slow speed drop-in most notable and really really irritating!!! I’d actually say verging on the slightly dangerous …

I agree that it requires a tiny fraction more control at slow speed, but as long as you have full control over the bike, it will be no more dangerous than quickly dropping it in on 60 profile tyres at low speed.

[northwind]

Originally Posted by Blue_SV650S

I am surprised no one else has detected it, I consider the slow speed drop-in most notable and really really irritating!!! I’d actually say verging on the slightly dangerous …

Could be choice of tyres? Are you comparing like with like?

Originally Posted by northwind

Could be choice of tyres? Are you comparing like with like?

That is true, not ALL 70s are the same ..

To expand on what I HAVE done:-

Used 70 on trackbike (Pirelli Supercorsa pro) then when I decide it has done enough service, use same tyre on my roadbike to get more miles out of it (middle bit used on road, not so much on track, therefore- I take old track tyres and use them on my road bike, front and rear so I use up the middle bit too ).

I currently have a 60 Pirelli Evo on there and the back to back test (70 Pro, 60 Evo) is pretty significant to be honest!!

Bearing in mind it is a full on race type tyre, the Pro might indeed be a bit more severe than say a more traditional road tyre ... also where my Pros have served a previous life on track, it might have worn into an even sharper profile still ...

I do have a 70 profile 020 that I will put on at some point .. I am open to the suggestion that I might change my opinion of the severity of a 70 after trying that as a 70 section ...

I used the 70 on the bike, one of ^Blue's supercorsa pro's, and the front never let me down. I was happy doing u-turns etc on it, and, I have nothing to compare it to, but I liked the feel. I'd say go for it.

I do agree. The explanation was pooy, but I am still a firm beleaver that 120/70 is the better tire for an sv650s/n.

Tehcnically, a 120/70 should slow the steering as it raises the front spindle affecting rake and trail. But it's be a very good rider who could tell the difference. like those above, I'd say the feelingw as die to tyre differences and not profile. Playing with the front pressures makes a big difference too.

The SC Pro has a very rounded profile back and front so it tends to be a very neutral turn in. Quick, but neutral. The Conti Road 120/60 falls in quickly at higher pressures but feels like the SCPro at lower pressures. The Z4 was slower than both of them.

The rears suspension can also make a difference to turn in rate. The stiffer it is, the more eager it *should* be to turn in (steeper head angle) but the more it'll want to run wide mid turn and especially in the exit as the rear suspension can't squat to turn the bike.

The SV is probably the most susceptible bike I've been on for this. Three extra clicks of Preload on the rear changes the bike completely and it just doesn't like holding it's line. Leave the bike set up for a pilion with extra preload and it's no fun at all.

Like any system, changing one thing (tyre profile, tyre pressure, tyre make, suspension, etc) changes everything else so you may have to tweak the other settings to get the same feel. A stiffer carcase tyre may require a lower pressure to get the same feel. Even as a tyre wears you may have to change settings to keep the feel the same.

Cheers,
Carl