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| Rev-O |
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 Rev-O L Plate Warrior
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| Mudshark |
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 Mudshark Nearly there...

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| Andy S |
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 Andy S Nova Slayer

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| JoeDougieDoug... |
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 JoeDougieDoug... World Chat Champion

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| Rogerborg |
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 Rogerborg nimbA

Joined: 26 Oct 2010 Karma :    
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 Posted: 14:25 - 09 Jul 2015 Post subject: |
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Have you asked Squishy McRear why he does this? We can only guess. ____________________ Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike |
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| Dcwhite1984 |
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 Dcwhite1984 Nitrous Nuisance

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| MarkJ |
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 MarkJ World Chat Champion

Joined: 11 Apr 2006 Karma :   
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 Posted: 14:49 - 09 Jul 2015 Post subject: |
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Generally it's only when riding on track that you have the rear set to a lower pressure than the front, and even then it's only by a few PSI (28front hot, 26rear hot for example). I assume this is because the rear gets some hammer on track when exiting corners so needs a bit of wiggle room with the pressure in the tyre.
On the road it's always been the other way round, more pressure in the rear tyre (normally 36F 42R is what I've seen). I always imagined this was to keep the rear in a round shape to stop the centre of it squaring off too badly.
Someone will be along with proper scientific evidence soon hopefully, rather than my guesswork
Edit: this is what a tyre guy at some trackdays has on his whiteboard
https://scontent-lhr3-1.xx.fbcdn.net/hphotos-xtp1/v/t1.0-9/11703095_10155886214640165_8034131384431250740_n.jpg?oh=aedbe96ba26ffd77abd96ecadb764c47&oe=56297098 |
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| DrDonnyBrago |
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 DrDonnyBrago World Chat Champion

Joined: 03 Jan 2010 Karma :   
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 Posted: 14:58 - 09 Jul 2015 Post subject: |
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No way I'd pay £1 for two smarties. |
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| MarkJ |
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 MarkJ World Chat Champion

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| Old Git Racing |
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 Old Git Racing World Chat Champion
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| Rev-O |
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 Rev-O L Plate Warrior
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| Slacker24seve... |
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 Slacker24seve... World Chat Champion

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| Wonko The Sane |
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 Wonko The Sane World Chat Champion

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| Teflon-Mike |
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 Teflon-Mike tl;dr

Joined: 01 Jun 2010 Karma :    
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 Posted: 19:27 - 09 Jul 2015 Post subject: |
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| Rev-O wrote: | Bike is an ex-army Harley Davidson MT350 (Rotax single, enduro style bike; smaller brother to the Armstrong 500) |
Off-road.. might make more sense.
In trials, common to back the tyre pressure off enormously; I might run as low as 8-10PSi rear on my old & tubed bike, folks on more contemporary machines with tubless tyres I understand often run zero psi! they rely entirely on the carcass stiffness & the creep-clamps! But on a front, pressures will tend to be higher and more normal;, I would tend to run between 12 & 20 in the front, or the tyre goes where it wants, not where I point it! ____________________ My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?' |
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| barrkel |
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 barrkel World Chat Champion
Joined: 30 Jul 2012 Karma :   
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 Posted: 19:44 - 09 Jul 2015 Post subject: |
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| Slacker24seven wrote: | The front is bigger than the rear, no? That might have something to do with it. |
Rear tyres are usually bigger than front tyres because there's more force applied through the rear; smaller tyres don't last as long. Fat front tyres also affect handling: quickness of steering, and how much braking while leaned causes countersteer.
IMO it's a lot easier to tell when you've got the front too soft than the rear. A soft front won't stay put through a corner without constant steering input. If a bike keeps steering upright from friction (flopping into the corner), then the front needs more air.
Counterintuitively, contact patch has almost no effect on traction; friction is proportional to normal force, so with less contact patch, more weight is squeezed into a smaller area, so it nets out the same. It definitely affects friction from the carcass deforming though, and that friction heats the rubber - and the temperature of the rubber definitely affects traction.
Knobbly tyres on highly uneven terrain, etc., that's a different mechanical story than the simplifying assumptions underlying the concept of friction. ____________________ Bikes: S1000R, SH350; Exes: Vity 125, PS125, YBR125, ER6f, VFR800, Brutale 920, CB600F, SH300x4
Best road ever ridden: www.youtube.com/watch?v=s2MhNxUEYtQ |
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| Rogerborg |
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 Rogerborg nimbA

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| hellkat |
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 hellkat Super Spammer

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| thx1138 |
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 thx1138 World Chat Champion

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| Rogerborg |
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 Rogerborg nimbA

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| bikertomm |
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 bikertomm World Chat Champion

Joined: 03 Jul 2010 Karma :   
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 Posted: 23:14 - 09 Jul 2015 Post subject: |
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Old Thread Alert!
The last post was made 11 years, 60 days ago. Instead of replying here, would creating a new thread be more useful? |
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