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stinkwheel |
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stinkwheel Bovine Proctologist
Joined: 12 Jul 2004 Karma :
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Posted: 13:38 - 13 Feb 2020 Post subject: Tyre pressures? |
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People are very cagey about this, maybe trade secrets?
I have trials tyres fitted to my Royal Enfield 350 bullet. Specifically a 3.00x19 Cheng Shin C-186 on the front and a 3.50x19 Heidenau K67 on the rear. These aren't full-on trials tyres, they are harder and road legal, the really sticky sort won't last the distances involved in the event I'm doing (and wouldn't pass scrutineering anyway).
Both wheels have rimlocks.
I'm doing a long distance trial event next weekend which will be a mix of rough roads, green lanes and very steep, very muddy tracks. Maybe a couple of special tests on wet, muddy grass. Roughly 100 miles in total.
I'm prepared to go to the effort of adding/removing air at the start and end of observed sections.
I'm planning on setting them to 14/15psi initially but will letting more air out give me a worthwhile advantage? Especially on the soft, muddy stuff?
I'm not really sure how low is "low pressure". You hear of people riding full-on trials bikes with 4 or 5psi in them but I think this may be asking for a snakebite on my bullet? ____________________ “Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles. |
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MarJay |
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MarJay But it's British!
Joined: 15 Sep 2003 Karma :
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Riejufixing |
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Riejufixing World Chat Champion
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doggone |
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doggone World Chat Champion
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Fizzer Thou |
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Fizzer Thou World Chat Champion
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Easy-X |
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Easy-X Super Spammer
Joined: 08 Mar 2019 Karma :
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Posted: 03:08 - 14 Feb 2020 Post subject: |
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I think you'll have to do some test rides. That's a relatively heavy bike versus the "standard" lightweight dirt bikes so I don't know you can apply the same "do this PSI" formula they do... less air in the back than the front is about the only certainty ____________________ Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter |
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steve the grease |
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steve the grease Crazy Courier
Joined: 26 Jan 2018 Karma :
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Posted: 18:58 - 06 Apr 2020 Post subject: |
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The advantage of letting tyres down is that increases quite dramatically the footprint of the tyre , this therefore gives a considerable improvement in grip. Without grip in soft going, you ain't going anywhere.* The downsides are increased noise, tyrewear, somewhat unpredictable handling and the risk of pinching the tube.
Personally I run the most expensive Michelin motocross 4mm thick Michelin UHD ( ultra heavy duty)innertube that money can buy , they are twenty odd quid , but make other 'heavy duty' inner tubes look like condoms. The other thing I do ( this is on the rear, yes) is run 2 tyre security bolts. My tyre is not moving on the rim. Nor it seems is it puncturing , no matter what low pressure I run. I did a run over to Lampeter, a windy road about 50 miles each way . I thought Bike feels good I'll check the tyre pressure so I know what to run. Ahem , 6 psi!
*At a festival I once saw a rock stars wife (or similar) in some 4x4 BMW all four low profile tyres spinning in the mud Screaming out of the window " I paid nearly £100k for this pile of shit , why won't it move?" Funny. ____________________ All the above is my personal opinion, you can see my lips move, but I'm talking out of my arse.
I've been riding, and fixing , bikes for 50 years, in that time the more I learn, the less I am absolutely sure of..... |
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stinkwheel |
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stinkwheel Bovine Proctologist
Joined: 12 Jul 2004 Karma :
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Posted: 22:15 - 06 Apr 2020 Post subject: |
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It later turned out 6psi was about right. About as much grip as I was likely to get and no pinch flats, even when riding over boulders.
It also turns out the tyre has slipped on the rim, despite the rim-lock. Not doing up the nut on the valve stem means it didn't rip the tube, just sitting at a funny angle now. I'll have to break it down off the rim and move it back round again. ____________________ “Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles. |
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Easy-X |
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Easy-X Super Spammer
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stinkwheel |
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stinkwheel Bovine Proctologist
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trevor saxe-coburg-gotha |
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trevor saxe-coburg-gotha World Chat Champion
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stinkwheel |
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stinkwheel Bovine Proctologist
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trevor saxe-coburg-gotha |
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trevor saxe-coburg-gotha World Chat Champion
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stinkwheel |
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stinkwheel Bovine Proctologist
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Old Thread Alert!
The last post was made 4 years, 59 days ago. Instead of replying here, would creating a new thread be more useful? |
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