Minimum Tyre Pressure

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Rhodrich
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Re: Minimum Tyre Pressure

Postby Rhodrich » 20 Jan 2015, 1:25pm

niggle wrote:
*BTW how did you get to the 45/55% weight distribution figure?


My understanding is that with drop handlebars, this is about the weight distribution you'd expect. With a more upright style of bike, you'd expect more weight on the back.

Not having ever weighed my bike on a pair of scales however, I wouldn't really know! I guess having a saddlebag almost permanently fitted to the back, with my commuting kit in does increase the rear wheel weight.


reohn2 wrote:Well there's always one of these:- http://salsacycles.com/bikes/vaya/2015_vaya_2/overview/ :D


I'd love one! Sadly though, finances couldn't stretch that far, and I'm already at D-1 in terms of number of bikes. I'm already getting stick for having bought a Jack Taylor tourer that I very rarely use.....

Bicycler
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Re: Minimum Tyre Pressure

Postby Bicycler » 20 Jan 2015, 1:28pm

Rhodrich wrote:
reohn2 wrote:Well there's always one of these:- http://salsacycles.com/bikes/vaya/2015_vaya_2/overview/ :D


I'd love one! Sadly though, finances couldn't stretch that far, and I'm already at D-1 in terms of number of bikes.

Divorce - 1? :lol:

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al_yrpal
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Re: Minimum Tyre Pressure

Postby al_yrpal » 20 Jan 2015, 3:21pm

Rhodrich wrote:
niggle wrote:
*BTW how did you get to the 45/55% weight distribution figure?


My understanding is that with drop handlebars, this is about the weight distribution you'd expect. With a more upright style of bike, you'd expect more weight on the back.

Not having ever weighed my bike on a pair of scales however, I wouldn't really know! I guess having a saddlebag almost permanently fitted to the back, with my commuting kit in does increase the rear wheel weight.


Easy to test. Just put the front wheel on your bathroom scales when you and your gear are on it, then the rear wheel on the scales. That will give you a pretty good idea. I always run the 37mm tyre pressures on my Vaya at about 50 and 60 which gives a comfortable ride with very low possibility of p***s on Oxfordshires flint and pothole strewn roads.

Al
Touring on a bicycle is a great way to explore and appreciate the countryside and towns you pass through. CTC gone but not forgotten!

reohn2
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Re: Minimum Tyre Pressure

Postby reohn2 » 20 Jan 2015, 3:40pm

al_yrpal wrote:
Easy to test. Just put the front wheel on your bathroom scales when you and your gear are on it, then the rear wheel on the scales. That will give you a pretty good idea.....
Al


But make sure the other wheel is chocked up to the same height as the scales with a book of block of wood,etc,otherwise you'll get a false reading of weight distribution.

Rhodrich
Weight distribution with drops depends how far stretched the rider is or how low the h/bars are in relation to the saddle.
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Mick F
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Re: Minimum Tyre Pressure

Postby Mick F » 20 Jan 2015, 3:58pm

Using the bathroom scales method - plus a chock for the other wheel - my dropped handlebar bike came at 60% 40%
It made little difference if I was on the drops or the tops. It was ages ago when I did the test, so I can't remember specifics other than the ratio.

I think the weight distribution has a lot to do with frame geometry and your personal physicality.
Mick F. Cornwall

reohn2
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Re: Minimum Tyre Pressure

Postby reohn2 » 20 Jan 2015, 4:09pm

Mick F wrote:Using the bathroom scales method - plus a chock for the other wheel - my dropped handlebar bike came at 60% 40%
It made little difference if I was on the drops or the tops. It was ages ago when I did the test, so I can't remember specifics other than the ratio.

I think the weight distribution has a lot to do with frame geometry and your personal physicality.


IIRC your h/bars are lower than your saddle and you don't ride particularly upright on the bike.
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Vantage
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Re: Minimum Tyre Pressure

Postby Vantage » 20 Jan 2015, 4:33pm

I can neither find nor remember the weight figures for my bike, but unloaded (nothing but me on it) it was front heavy, and loaded (it varied a lot by how much loaded) it was rear heavy.
However, I read and this does make sense to me, weight distribution on a bike constantly changes according to whichever gradient you're cycling on and so the load on your tyres are forever changing.
I also have to wonder how pressures are affected on tyres with differing 'suppleness'. My Landcruisers and Voyagers which are almost identical in size feel sooooooooo different when run at the same pressure.
Bill


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nirakaro
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Re: Minimum Tyre Pressure

Postby nirakaro » 20 Jan 2015, 4:41pm

Bear in mind that probably the majority of cyclists throughout the world have never thought of measuring their tyre pressure. They just pump the tyres up until they feel reasonably hard, and repeat the operation when they feel soggy again. And mostly it doesn’t cause any problem.

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Mick F
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Re: Minimum Tyre Pressure

Postby Mick F » 20 Jan 2015, 5:52pm

reohn2 wrote:
Mick F wrote:Using the bathroom scales method - plus a chock for the other wheel - my dropped handlebar bike came at 60% 40%
It made little difference if I was on the drops or the tops. It was ages ago when I did the test, so I can't remember specifics other than the ratio.

I think the weight distribution has a lot to do with frame geometry and your personal physicality.


IIRC your h/bars are lower than your saddle and you don't ride particularly upright on the bike.
Yep.
Correct.
Just like I said.
Weight distribution has to do with frame geometry and your own physicality.

I suppose I meant that "frame" included saddle position and handlebar height and reach.
Mick F. Cornwall

sreten
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Re: Minimum Tyre Pressure

Postby sreten » 21 Jan 2015, 12:29am

Rhodrich wrote:
I'm currently riding at the minimum recommended pressure of 70psi, both front and rear, and the ride on the bike is a bit bouncy, which also suggests that this is too high.

What would be the consequences of reducing the pressures to 52psi front, 64psi rear, which are below the minimum recommended pressures as stated by Continental? I don't want to destroy my tyres, or get pinch flats......

Thanks


Hi,

The front is too high, drop it to say 55 psi, keep the rear 70psi. Ride your bike. Pump
up the tyres when they are too low, which should be quite a while, say a week or so.

There is no chance of damaging your tyres or pinch flats. Imagine you weigh 100Kg ....

It won't take long to work out the lazy attitude to tyre pumping,
do it when needed, and go a bit over what seems to be the best.

rgds, sreten.

Personally I reckon about 55psi rear and 45psi front minimum for your weight.