Painful Learning Curve Part 1 - Tyre pressure

felix.london

Just came in from my daily hack. Lost the front wheel again on the corner of a very dry gravel track (3rd time in 2 months of riding - different corners of different tracks). And the penny has finally dropped that maybe I'm running the front tyre with too much air in it.

Now I don't have a pump with a pressure gauge - yeah, yeah I know - it's on the never ending shopping list. But my theory was run the back tyre pretty soft as I'm riding a HT and could do with the extra cushioning and pump the front tyre right up because the forks will sort that out - wrong I guess.

The other thing is there's about 2km (out of a 14km XC trail) on tarmac but my grazed, bruised & swollen shoulders are telling me it's better to lose some speed on the road home than keep this abuse up.

Should I be running a lower pressure in the front tyre and is there any benefit of having the front tyre pumped up more than the back on a hardtail?

Thanks

(shoulder is stiffening up nicely, as I type this )

TuckerUK

I'm certainly no expert on MTB tyres, but I run my tyres between the recommended pressures, with the tyre pressures higher at the rear to counteract the higher loading the rear wheel takes when I'm seated, and because I would rather have slightly less drag and slightly less grip there. I'm just playing around with some Sport Alberts on my HT at the mo. and my 16 stone seems to like 45psi rear 30psi front.

geebee2

Should I be running a lower pressure in the front tyre and is there any benefit of having the front tyre pumped up more than the back on a hardtail?

Sounds wrong to me - you generally want to run as low a pressure as possible while avoiding pinch flats, which implies a bit more pressure in the rear tyre if anything, since the front suspension lessens the likelihood of a front tyre pinch flat.

I'd go with near-equal pressure in each tyre though.

But since you don't have a gauge, we have no idea what pressure you are actually riding.

I'd say it's likely too high though.

[ PS I'm a beginner, so don't take my advice too seriously ]

TuckerUK

Also worth checking you've got your fork dialled in exactly regarding spring rate and rebound. I'm still playing with my MXs to get them exactly where I want them.

felix.london

Right - yeah that makes perfect sense. If there is a difference in pressure it should be the other way round - doh!

How the hell do change the rebound adjust on these forks? - tbh I haven't really looked into it and haven't started fiddling around with forks at all. Probably should get my tyre pressure sorted first

Do I need to buy a low pressure pump to adjust the forks?

cooldad

Shock pump is high pressure, low volume.
Tyre pump is low pressure high volume.

So get a shock pump and a track pump for the tyres, much easier. With pressure gauges.

I run my rear slightly higher, as it takes most of my weight.

supertwisted

What tyres do you have? Pressure is only part of the equation, some tyres really struggle on dry loose surfaces.

felix.london

@ cooldad - There's 2 Marzocchi shock pumps - high & low pressure. I've got MX Comps.


http://www.chainreactioncycles.com/Mode ... elID=22256


@ supertwisted - I'm running 2.0" Specialized Pro Resolutions



Cheers guys

nicklouse

they are the same. they just have different gauges so you can see the pressure you want.

So low pressure for a fork.

felix.london

Cool. And could I use that pump for my tyres too? - the pump I use now is really cheap and about to give up the ghost

Thanks

cooldad

You could but it will take a week to pump them up. You need a tyre pump. A track pump is worth having as it takes a minute of minimal effort, plus a small pump to carry.

sharky1029

The rear tyre should be harder than the front tyre as the front needs more grip nd you can save rolling resistance on the rear. I run 20-35 psi on the front and 25-40 out back.
A track pump with a gauge should really be fairly near the top of you shopping list as tyre pressure is the most common adjustment made to a bike.
Also that infinitly long list gets longer the more you read about bikes

RobJ20

Yeah i run around 38psi at the back 32 at the front, i like my back to go if anything much easier to control than the front sliding first.

diy

I actually run my tyres quite hard, I like them to feel precise. If I want more grip I put different tyres on. Generally I put the grip up front. Obviously it depends on the tyre, load etc. as some tyres respond well to low pressures, while others don't.

Generally for control you want the grip up front. Its important to get a pressure gauge , so that you work out what pressure feels right for different situations.

felix.london

Right. Gonna go & buy a track pump today!

Thanks for all the advice 8)

Big Question

i havent got a gauge either(need to get one) but for now running the front softer than the back with a grippier tyre up front should shift the bias towards losing the rear first.
im using a nic front/ralph rear and the arse end was going first yesterday on loose gravel just make sure you trust the front and put your weight over it into tuns, if you shy away from the corner and keep your weight back you will lighten the front end and probably lose it first regardless of tyre set up

Daz555

felix.london wrote:

Just came in from my daily hack. Lost the front wheel again on the corner of a very dry gravel track (3rd time in 2 months of riding - different corners of different tracks). And the penny has finally dropped that maybe I'm running the front tyre with too much air in it.

...or your riding position is not ideal when cornering is such conditions. Perhaps your are not getting enough weight onto the front end. If you are too far back the front will be light and have no grip no matter what you do with tyres and pressures.

felix.london

Think you guys might be right there too. Think I feel myself easing off the front end on big, fast, loose corners. Going out later so will see what I can change.

Cheers

felix.london

hahaha - let out some air from the front tyre. 10km in I get a puncture in the front tyre. Valve broke off.

Feeling more of the ground from the back with more pressure in that tyre but the bike did seem to handle better at speed. Kept messing up the fast corners because now I've gotta also think about keeping my weight forward as well as my outside pedal down and keeping off the brakes..

Seem to be clanging more things with my pedals too but presume that's because I'm getting more confident on the bike, going faster and picking tighter lines - I hope so or else it means I'm regressing! Good fun though - as always!

felix.london

Just found out first hand why I need a pump with a pressure gauge. The Specialized Resolutions are rated at 35-80 psi. After reading advice from you guys that possibly my front tyre had too much air in it I let some (random amount) out - obviously too much as the next two rides I got exactly the same puncture on each ride. The valve was nearly cut off the tube as it must have been rubbing against the valve opening in the rim. I'm presuming this was because there was not enough air in the tube causing it to move. Track pump should be here next week...

theshrew

I just use a digital tyre guage from Halfords cost about £3.99. Its only small ( its a key ring one ) very light so you could take it in your bag with you if you want.

At least its digital so you no exactly what you have in the tyre.

felix.london

Good idea. Gotta track pump with pressure gauge on the way but also a little Topeak pump to put in my pack - that doesn't have a pressure gauge. No halfords round these parts but will check out the local auto shop.

Cheers

lastwords

felix.london wrote:

hahaha - let out some air from the front tyre. 10km in I get a puncture in the front tyre. Valve broke off.

Feeling more of the ground from the back with more pressure in that tyre but the bike did seem to handle better at speed. Kept messing up the fast corners because now I've gotta also think about keeping my weight forward as well as my outside pedal down and keeping off the brakes..

Seem to be clanging more things with my pedals too but presume that's because I'm getting more confident on the bike, going faster and picking tighter lines - I hope so or else it means I'm regressing! Good fun though - as always!

The pedal on the outside down doesnt apply to every corner for instance if its burmed i believe you keep you pedals level.
I find in order to ride fast with lots of grip you have to attack and ride with confidence i find that at trail centres which are built to be ridden fast if i take it easy there is less grip and i make more mistakes.

skullthaw

hardtails best to run front softer for grip and rear harder for efficency i find any way

felix.london

yeah - also realised that running the tyre pressures that way round you're kinda 'persuading' the back wheel to lose it before the front does - a good thing!