Dirt gurus - a question?

[Imonster]

Tomorrow I'll be laning on my lady's bike - as it has been chucking it down I want to be running low pressures. On mine I'd probably run 8 in the back and 10 in the front, but I've got rimlocks, hers doesn't.

What do you reckon the lowest pressures I can get away with are? Having ripped the valve off her bikes front tube last week, I'm keen to avoid a repeat performance.

It's a light bike (Serow), if that makes a difference.

Ta muchly...
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Those who make peaceful revolution impossible will make violent revolution inevitable.

[yen_powell]

I used to run 15psi on my DR350 with no rimlocks with no problem, probably could've gone a little lower. That was on MT21s.
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Blackmail is a nasty word........but not as nasty as phlegm!
XT1200Z and a DR350 in bits

[colin1]

I've got a ttr250, which is basically a slightly bigger serow.

I've ridden it with flat tyres for a few miles without problems. Running with low pressures, defintely gives better traction for off road. Particularly the back wheel, on terrain where you would otherwise be spinning the back wheel, it just bites in.

I'm not knowledgable about these things, just talking about my experience.

I don't know what a rim lock is, so please tell me.
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colin1 is officially faster than god

[Imonster]

Cool, cheers. Maybe go conservative option to avoid breaking her bike again tomorrow, and run at 16 rear, 18 front?
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Those who make peaceful revolution impossible will make violent revolution inevitable.

[Imonster]

[G]

Yes, wouldn't really go much below 15psi or so without rimlocks, especially if it's got fairly knobbly tyres. Obviously can get away with a bit less on tyres that are quite road-biased, as they'll tend not to grip so much anyway.

As above, the rimlock basically clamps the tyre onto the wheel. Worth having if you're serious about off-roading.
Without them, the tyre can grip, but with little pressure in the tube holding the tyre onto the wheel, the wheel can spin inside it, ripping the valve off the innertube.

Running a very low pressure tyre (under 8psi) can cause pinch flats. Rockier terrain and more pressure needed. There's various ways to convery rims to tubless, but they're all a bit of hassle. The tubliss system I've got is quite good that it also acts as a big rimlock too.

[Tonka]

I've been running 15/18 on my little Honda, if that's at all relelvant to your situation.

I will be reducing this as it gets wetter, but was looking at 10/12 minimum.
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'The core of a man's spirit comes from new experiences'
Suzuki SV650S (Clean); Yamaha XT250 Serow (Dirty)

[.....]

What would you go down to with rimlocks? Just out of interest.

[Tonka]

Not actually ridden a winter but have been advised that at a push go to 8 but staying in double figures is preferable.

I guess it's going to be a case of trial and error as the bike size, rider size and conditons all have such a big bearing.

EDIT: On extra thick tubes now
____________________
'The core of a man's spirit comes from new experiences'
Suzuki SV650S (Clean); Yamaha XT250 Serow (Dirty)

[G]

I reckon my rear must have been about 5psi on the 690 in a particularly 'gnarly' rocky section in spain at one point - but this is with the tubliss that means no tube and uber-rimlock. Pretty sure it would have caused some pinch flats if I didn't have it. 8psi is about the minimum with a heavy duty tube.

Wouldn't go much below 15 without rimlocks - if you remember my first dirt ride on the 690, that 'puncture' was due to the valve getting pulled because the (pretty road biased) tyre was at too low pressure without a rimlock. Luckily it only just stretched the rubber too much, rather than ripping it off.

[S]