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.

i have run both 60/70 profile in the last 2 years...and imho it makes no difference at all...................

as ali points out...there are arguments for both..!.......as for riding of the edge of the tyre.........................LMAO

In theory its contact patch - in reality its mental!!!

Can we go race yet ????

Well all ye non-believers ... when I ran the 60 profile, the tyre was worn all the way to the edge and the I slid the front more easily than on the 70.

When I used the 70 I've never gotten to the edge, there's always been a few mm left, and the tyre has only slid when the tyre was worn.

That was my experience FWIW

Bearing in mind that sliding the front is not necessarily just a result of speed, it can also be a result of how you're riding the bike.

Just my opinion :)

weird innit..i have never had a front slide other than in the wet.?...how come you have and i have not.?

Talk about a 'how long is a piece of string' type question!

Bike geometry, body position all effect how much load is on the front. At as much lean as we carry on these things the 70 has a bigger contact patch and the 60 has less, so if you're already on the edge where the 60 offers you less grip it stands to reason that you can slide it easier.

Phill you're lighter than me, a smoother rider and therefore you could be running your bike with less ride height, different fork internals etc ... lots of reasons why I get slides and you don't.

The list is endless :)

Less ride height??? You can walk under Fil's yellow 583...

Now mine & Chris Woods, you need a feeler gauge..

Andy

I don't bloody know what geometry Phill runs! :lol: The point is that seeing the different styles of riding between Phill and I and our weight differences etc would definitely mean we'd like our setups different.

At the end of the day, it would be impossible to know exactly what is going on with someone's bike without running some sort of telemetry and logging. You can guess all day long and riders can only go from what they feel.

Every rider and every bike is different and both have a big impact.

IMO.

I find the 70 doesn't give me enough grip on the grass, rumble strips and track overbanding hence occasionally losing the front, back and sides of the bike...

Should I try the 60 next season?

I think you should try MT60's - we'll get you special dispensation on safety grounds :D

Sorry Tony, wasnt on a wind-up... just humorous.. :)

Andy

LMAO..............class reply......

No worries mate, I didn't take it that way.

Apparently I'm having a sense of humour bypass this morning ...

TP may make the difference for TP
 

From previous discussions it seems that most people run similar tyre pressures.
It was suggested to me at Snetterton that reducing the TP may allow me to use more of the front tyre.
Seemed to help and give more grip/feel or something. Just got try all things I guess.

Its important for sure, but as long as you know what TP's you're running and what profile tyres, you can try changing them and see if you notice the difference - if you con't - great, one less thing to worry about!!

Tim

I have found TP's to be very important and can actually change the characteristics of your bike. My R1 wasnt turning enough and we had run out of ideas on the suspension, so we lowered the TP on the front and it improved ALOT... we ended up on 26psi on a hot day.

Andy

Hey dom..
When i took the bike to cadwell for the first time(last year) it was running the 60 profile front and found it to be terrible under brake's/turn in.....wallowed like a pony!!!!

I Think it all depends on how you brake/turn/ lean????
If you brake full on into a turn i think a 70 profile is a must....
If you do all your braking before turn in then a 60 should be ok providing youv'e not loaded the front up to much??