What size tyres do the DD bikes use?
 

Was told that alot of the DD bikes use 120/70 fronts instead of the 120/60

Was wondering why?

You get more tyre to use when the bike is on its side.

I ran a 120/60 at the start of last year and ran it off the edge and had a few front end slides. I changed to the 120/70 and the problem was solved.

It was AK who pointed this out to me, I would have just kept going thinking that it was fine!

120/70 creates a rounder profile (taller), so there is a greater contact patch when leaned right over. :D

Indeed, Dominic Clegg's high speed crash at Assen was caused by him riding off the edge of the 120-60 tyre he had fitted.

I use a 70 profile on the road
even with the rear end jacked up
i had to drop the bike on the forks about 5mm
to get the front end feel back, because of the taller tyre.

use the 70 i used the 60 in first half of the season and ran out of tred at assen and had a big crash

Hate to contradict, but I don't suppose anyone in DD has ever ridden off the edge of a warm front tyre! Losing the front end can be caused by many things; too much braking/steering force, cold rubber, cold carcass and hot surface, too little suspension travel, too high tyre pressure, oil/coolant on track, debris on track, change in surface, etc, but the difference between a 60 and a 70 profile front is not going to help you in 9 out 10 instances.

The transition to a 70 profile front is only pretty recent for many racers (in other series) and people have been leaning other race bikes over a looooooong way for many years now without falling off the edge.

If you get the chance, try both. A 60 profile should give you a greater contact patch at the sort of lean angles you'll be riding in the wet, and a 70 should make the bike tip into corners a little easier (better in the dry). Given the state of our climate I wouldn't write one off in favour of the other just yet!

Cheers,

Ali

i was running to the edge of it. Any way when i put the 70 in it also helped the bike turn a lot faster

you can't argue with experience!!

I ran a 70 all last season, then we started this season on a 60 - coz thats what was fitted from the showroom. Did Cadwell, Brands and Assen trackday on it and didn't really notice any difference (forgot it was a 60 actually).

However, I prefer a 70 - even it's psychological.

A racers head is as important, if not more important than anything else on the bike etc.