aboard

Author Topic: Tire pressures and handling  (Read 1638 times)

0 Members and 1 Guest are viewing this topic.

General_Apathy

  • Neophyte
  • *
  • Posts: 22
  • Karma: 0
on: August 07, 2018, 03:05:41 pm
I am finding the front end very twitchy on my bike. It seems to be overly effected by changes in road surface and particularly by small ruts. My first thought is the tire pressures which seem to be very low in the manual for the front tyre (20). I have upped it to 22 tonight which felt slightly better but still the front isn't very confidence inspiring. I am sure others have experimented and I would be interested to know their conclusions. I am 6 foot and 12 stone for reference. One other thing I noticed was that I am able to turn the rear Springs round by hand very easily, is this normal? Surely it should be under some load?


Richard230

  • Grand Gearhead
  • *****
  • Posts: 2,201
  • Karma: 0
Reply #1 on: August 07, 2018, 04:57:33 pm
Instead of relying on the owner's manual for the recommended air pressures, look for them on your VIN/information sticker which on my B5 is on the down-tube. For my Bullet's skinny tires the specified tire pressure is 24 psi, front and 32 psi rear.
2011 Royal Enfield B5 500, 2018 16.6 kWh Zero S, 2016 BMW R1200RS, 2009 BMW F650GS, 2005 Triumph Bonneville T-100, 2002 Yamaha FZ1


Paul_42

  • Scooter
  • **
  • Posts: 69
  • Karma: 0
Reply #2 on: August 07, 2018, 06:36:18 pm
Hi mate, I'm running 30psi at the front and 32psi on the rear. I had same issues when I first got mine. It would lose the front end forcing me to stand it up mid corners. Check your front tyre for scalloping( humps and bumps). I raised my front forks about 8mm so the the tops are sticking out of top clamp. If you can turn the rear nut on the shock then it's not set up. My rears are turned in about 7 thread counts. I've also gone up a profile front and rear so I can flick the bike in and out of twisty's faster. Also change fork oil. I went 10 weight and it's been great. Other more experienced gents will chime in but the above set up works for me. I'm about 98kg wet to give you an idea.
Cheers
Paul.


General_Apathy

  • Neophyte
  • *
  • Posts: 22
  • Karma: 0
Reply #3 on: August 08, 2018, 02:13:53 am
Thanks fellas. The official figure is definately 20 for the front which feels dangerous to me. Not sure if it's intended for lighter people or maybe Indian roads? @Paul_42 - Glad it's not just me, I have lost the front end twice now. First time I put it down to the smooth tar on the road second time no explanation. I will keep upping the pressures to find my sweet spot.i will be swapping out the fork oil as well at some point. Regarding the rear springs, I am able to turn the actual Spring round by hand on both sides. Usually the spring is under pressure so I am wondering if this is an Enfield thing or my shocks aren't set up right.


gizzo

  • Grand Gearhead
  • *****
  • Posts: 1,736
  • Karma: 0
  • Live slow, die whenever
Reply #4 on: August 08, 2018, 07:38:48 am
I'm with Paul. usually around 30/32, a bit lower at the track. It definitely feels sketchy when the front is down around 24. Would you let us know how you get on after you've tried them pumped up? I can't think of any time I've felt my bike tramline or the front slide, apart from a brand new tyre incident and once or twice at the track, fooling around with pressures. What tyres you have on?
I think you're right about Indian figure vs the Real World. They'd be looking for a comfortable ride as they thud along looking for MPG's. Cornering ability would have very little meaning to them.
I can turn my springs by hand too, when the bike's on the centre stand. I haven't as much preload as Paul, 68kg here.
simon from south Australia
Continental GT
Pantah
Monster
DR250
TRX850
DRZ400SM


Donat Santowiak

  • Neophyte
  • *
  • Posts: 41
  • Karma: 0
Reply #5 on: August 08, 2018, 04:29:51 pm
Not sure if I understand the physics of how the front end works but........ The tyre pressure would affect the tyre flex, like speed and forces in compressing/rebounding of the carcass. Would that not affect the performance of the spring rate and the volume/viscosity of the dampning oil? (And valving). So are the forks be factory matched to a 20psi tyre pressure? Hence not really coping with 30psi.
From Victoria Australia
Honda cbr 600rr Repsol Edition
Moto Guzzi V7
Excelsior Universal 1947


Paul_42

  • Scooter
  • **
  • Posts: 69
  • Karma: 0
Reply #6 on: August 08, 2018, 06:48:55 pm
Well, yeh. We aren't Indian roads or speed limits. Try what myself and gizzo said. Personally with my fat bones the 30/32 psi seems to be the sweet spot. Set the sag. I've given you my settings as a base point to start off with. As you, I had major issues with the front wanting to wash out and having to stand it up mid corner Which getting rid of the sports demons fixed half the problem. Other half was raising front forks and changing fork oil. (Almost 100ml difference between forks). I love the twisty stuff and with the old girl behaving I'm finding I'm backing off from the bigger bikes because it's so much more stable and quicker in the turns. Hope this helps a bit mate.
Paul.


General_Apathy

  • Neophyte
  • *
  • Posts: 22
  • Karma: 0
Reply #7 on: August 09, 2018, 02:14:14 am
Thanks again Paul and Gizzo. I will update on changes to feel as I tweak the pressures. Which tyres did you swap to Paul?
@ Donat - I am not sure that the tyre pressure vs fork oil/Spring works that way, certainly not at this level of fork sophistication. All I can go on is seat of the pants feel and at 20 psi, at my weight and riding style the front feels very loose.
Have to say it has been a long time that I have been this hands on with a new bike, bloody loving it!
« Last Edit: August 09, 2018, 02:16:45 am by General_Apathy »


Donat Santowiak

  • Neophyte
  • *
  • Posts: 41
  • Karma: 0
Reply #8 on: August 09, 2018, 02:40:08 am
Thank you everyone for sharing your experiences regading this topic. Although I wonder if RE India had set front tyre pressure to a low 20psi because of poor road surfaces. Why don't  they recomend 20psi for the rear tyre as well?
From Victoria Australia
Honda cbr 600rr Repsol Edition
Moto Guzzi V7
Excelsior Universal 1947


tooseevee

  • Grand Gearhead
  • *****
  • Posts: 2,679
  • Karma: 0
  • There Are No Truths Outside The Gates Of Eden
Reply #9 on: August 09, 2018, 06:55:38 am
Thank you everyone for sharing your experiences regading this topic. Although I wonder if RE India had set front tyre pressure to a low 20psi because of poor road surfaces. Why don't  they recomend 20psi for the rear tyre as well?

            Because the wife, the mother-in-law and the three kids are on the rear tire.
2008 AVL Classic.Extensive head work by Ace.Ace canister/TM32/Ace manifold.Small open bottle/hot tube removed.Pertronix Coil.Bobber seat.Fed mandates removed.Battery in right side case.Decomp&all doodads removed.'30s Lucas taillight/7" headlight.


gizzo

  • Grand Gearhead
  • *****
  • Posts: 1,736
  • Karma: 0
  • Live slow, die whenever
Reply #10 on: August 09, 2018, 07:16:58 am
Thank you everyone for sharing your experiences regading this topic. Although I wonder if RE India had set front tyre pressure to a low 20psi because of poor road surfaces. Why don't  they recomend 20psi for the rear tyre as well?
Because they don't get performance riding in India? Funny story, I was scolded by an Indian person riding a Bullet in the hills one day. I tore past him, hit the rev limiter a couple times and generally went about my business as is my wont. He caught up at a bike café and tried telling me I shouldn't be riding the Enfield like that. He sure as hell couldn't.
simon from south Australia
Continental GT
Pantah
Monster
DR250
TRX850
DRZ400SM


Guaire

  • Grand Gearhead
  • *****
  • Posts: 1,239
  • Karma: 0
Reply #11 on: August 09, 2018, 08:05:58 am
Well, yeh. We aren't Indian roads or speed limits. Try what myself and gizzo said. Personally with my fat bones the 30/32 psi seems to be the sweet spot. Set the sag. I've given you my settings as a base point to start off with. As you, I had major issues with the front wanting to wash out and having to stand it up mid corner Which getting rid of the sports demons fixed half the problem. Other half was raising front forks and changing fork oil. (Almost 100ml difference between forks). I love the twisty stuff and with the old girl behaving I'm finding I'm backing off from the bigger bikes because it's so much more stable and quicker in the turns. Hope this helps a bit mate.
Paul.

Paul - If not the Pirelli Sport Demons, what tires are you using?
ACE Motors - sales & administration


Richard230

  • Grand Gearhead
  • *****
  • Posts: 2,201
  • Karma: 0
Reply #12 on: August 09, 2018, 08:52:18 am
Speaking of tire wiggles, if you ride on grooved pavement with tires that have a radial tread design, you may experience a handlebar wiggle caused by the tread following the grooves in the pavement, which would not be apparently to a car or truck, or motorcycle tires with a different tread design.
2011 Royal Enfield B5 500, 2018 16.6 kWh Zero S, 2016 BMW R1200RS, 2009 BMW F650GS, 2005 Triumph Bonneville T-100, 2002 Yamaha FZ1


Donat Santowiak

  • Neophyte
  • *
  • Posts: 41
  • Karma: 0
Reply #13 on: August 09, 2018, 04:13:45 pm
If RE India has designed a machine for such poor road and use/abuse. Why are we trying to turn a draught horse into a pretend race horse?. Why not just buy a performance bike in the first place.
From Victoria Australia
Honda cbr 600rr Repsol Edition
Moto Guzzi V7
Excelsior Universal 1947


Arizoni

  • Grand Gearhead
  • *****
  • Posts: 7,032
  • Karma: 2
  • "But it's a dry heat here in Arizona
Reply #14 on: August 09, 2018, 04:20:53 pm
Tire pressures on the middle sized British motorcycles back in the '50's and early '60's were often as low as 18 psi for the front tire and 24 psi for the rear.
This includes Triumph's, BSA's, Velocette's and Matchless's.

In those days the cross bias, tube tires had very stiff sidewalls which didn't need a lot of air pressure to support the motorcycle.

The Avon Speedmaster tires that come on a lot of the new Royal Enfields are basically the same tires that they were back in the '50's with the same ply construction so they don't need a lot of air pressure to work.  About the only real difference in the Avon tires today is they are using better rubber compounds than they did back "in the days".

I don't know what tires the CGT's come with but if they are the newer style, higher air pressure might be more suitable. 

Jim
2011 G5 Deluxe
1999 Miata 10th Anniversary