PSI

Azhar

Hello!

As you may or may not have known I posted a topic a couple weeks ago to make it public that I fell whilst riding my bike in the rain. Since then I have lacked confidence to get back on the bike and ride again cos I just kept feeling I was gonna fall off my bike.

However, I did see somewhere on YouTube that on a wet day that you should let some air out of the tyre to gain better traction on a wet road and get better grip. I tried that today and how good it felt that I could feel the bike grip the road well rather than drifting sideways which sometimes I'm sure that was what was happening. I normally have the tyres at around about 110psi. What psi is usually the best for a wet/rainy day to gain better grip but without comprising performance on the bike too much?

Hope you are well and have a nice day.

Azhar

Torvid

usually about 10 psi but a lot depends on your weight and tyre size and type.

supersonic

10 psi? Surely that would just bottom the tyres on the rim!

corshamjim

If the tyre is marked with both minimum and maximum pressures then it's not a good idea to drop below the minimum otherwise you will risk punctures due to the tyre pinching against the rim when you ride over bumps in the road, potholes etc,. Some tyres have a much wider acceptable range of pressures than others. In general fatter tyres will take lower pressures.

Torvid

supersonic wrote:

10 psi? Surely that would just bottom the tyres on the rim!

I meant drop it by 10psi not run it at 10psi

gosport_commuter

Hi Azhar, if you let us know your tyre size and approximate weight, I'm sure we can offer you some reasonably accurate advice. Also what tyres are you using? I't might be that switching to a better tyre will solve all your problems without too much faffing when it gets wet.

As an example, I use continental 4 seasons in a 700 X 28c, I find I have no problems at all with grip in almost any conditions. I am about 11.5 stone and run the rear at about 90 PSI and the front around 65 - 70 PSI.

Azhar

gosport_commuter wrote:

Hi Azhar, if you let us know your tyre size and approximate weight, I'm sure we can offer you some reasonably accurate advice. Also what tyres are you using? I't might be that switching to a better tyre will solve all your problems without too much faffing when it gets wet.

As an example, I use continental 4 seasons in a 700 X 28c, I find I have no problems at all with grip in almost any conditions. I am about 11.5 stone and run the rear at about 90 PSI and the front around 65 - 70 PSI.

Hello. The tyre size is 700x25c and my weight is, an unfortunate, 100kgs/16st. The tyres I currently have are marathon plus tyres. Excellent puncture resistant tyres. Would be a little reluctant to change tyres, however, saying that marathon plus tyres are incredibly difficult to take off so if the continentals 4 seasons was easier to take off, in the event of a puncture, I might consider changing my tyres. I've heard that the cont4seasons are pretty puncture resistant tyres. Hope this helps to answer my OP

gosport_commuter

Hi,

Whilst I have no personal experience with marathon plus tyres - it seems to be fairly widely accepted that they are very good tyres with the only real downside being that they are a little on the heavy side, and therefore quite slow. I have never heard of them being particulary bad in the wet, so I would say probably best to stick it out with them as they are known for being tough tyres.

Having said that the conti 4 seasons were a breeze to fit for me, and I have yet *touch wood* to get a puncture in mine in the last 2000 odd miles. And they really do grip excellently! (even when compared to the conti gatorskins I have)

On to the PSI, It is generally accepted that about a 15% drop in the tyre(when you load it by sitting on the bike) is about right for comfort vs performance whilst avoiding pinch flats. There is a chart on the web where you take your weight + the bikes weight etc, and then use your tyre size to get a recommended pressure - ideally the heavier you and the bike are the larger tyre you will want to get a usable (tire able to handle it and not bone rattlingly uncomfortable) PSI.

If I assume you are riding an average bike of about 12kg + 100kg for you, 112kg total, then the chart recommends on a 25c tyre that you should be running approx. 130 PSI rear (60% of weight - 65ish KG), and 85PSI front (40% weight - 45KG ish). This will vary depending on your weight distribution, but this assumes a fairly upright riding position of a hybrid type bike.

As you can tell this are quite high PSI - using wider tyres would decrease this, and obviously its not recommended to exceed the max PSI rated on the tire's sidewall.

Hope this helps - follow this link for more information.

http://www.bikequarterly.com/images/TireDrop.pdf

Azhar

Many thanks for your reply and advice. I appreciate that a lot. I am thinking about investing in some conti 4 seasons probably in the new year. Puncture resistant but the fact they are light will help only help me and I can keep my marathon plus tyres as back up.
I never knew that you should put in less air in the front compared to the back. I just assumed the the same air is put in to the front to whatever psi you.ve put on the back tyre. So another lesson learnt. I took another ride in the wet weather today and put the psi at about 90-95 psi compared to the 110psi I usually put in and the handling was a little better. Learning everyday.

Thanks again

nigglenoo

gosport_commuter wrote:

Hi Azhar, if you let us know your tyre size and approximate weight, I'm sure we can offer you some reasonably accurate advice. Also what tyres are you using? I't might be that switching to a better tyre will solve all your problems without too much faffing when it gets wet.

As an example, I use continental 4 seasons in a 700 X 28c, I find I have no problems at all with grip in almost any conditions. I am about 11.5 stone and run the rear at about 90 PSI and the front around 65 - 70 PSI.

That's me as well! 11.5 Stone, 28mm tyres, 65psi front, 90psi rear (but Rubino Pro 28s). We can't both be wrong! (I use the Bicycle Quarterly Chart as well)

nigglenoo

Azhar wrote:

Many thanks for your reply and advice. I appreciate that a lot. I am thinking about investing in some conti 4 seasons probably in the new year. Puncture resistant but the fact they are light will help only help me and I can keep my marathon plus tyres as back up.
I never knew that you should put in less air in the front compared to the back. I just assumed the the same air is put in to the front to whatever psi you.ve put on the back tyre. So another lesson learnt. I took another ride in the wet weather today and put the psi at about 90-95 psi compared to the 110psi I usually put in and the handling was a little better. Learning everyday.

Thanks again

90 front, 110 rear looks about right for you at 100kg plus bike weight with 25mm tyres. Possibly could try lower with the Marathon Plus tyres (they are quite stiff compared to racier tyres, so may ride better at lower pressures). As well as poor ride quality and worse rolling resistance on normal road surfaces, over inflated tyres have less grip and their tendency to skip off bumps makes the situation worse.