Gravel Tire Pressures

Especially for light weight issues concerning cyclocross / touring bikes & parts.

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Mr.Gib
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Joined: Fri Mar 18, 2005 4:12 pm
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by Mr.Gib

I am curious what tire pressures others prefer on their gravel rigs.

My setup:
Tire: Mavic Yksion Allroad XL Tubeless 40 mm
Rider weight: 172 lb (78 kg)
Pressure: 40 psi

I did my first real gravel ride this past weekend (200 km, 2500 meters) and just went with the Mavic minimum recommended pressure of 40 psi. My sense was I would have liked even lower pressure. It was a bit bouncy on some of the rockier sections, but OTOH, I don't live on a gravel road so 20 km on smooth tarmac to the gravel and 20 km on tarmac to get home. I really have no idea what would be optimum. I am curious to know how much I give up in terms of rolling resistance if I drop down to 35 psi.

Not even sure if these tires are any good. I did try out some Donnely MSO 36 mm and thought they were faster but as we know, a rider's "feeling" about speed is rarely accurate. The Mavic's did corner better on Tarmac.

The gravel thing is fun. Gives some new options for those of us that ride silly amounts and are getting a bit bored.

And BTW, the whole Mavic UST thing - incredible. Just like the CGN video. The Allroad wheels are seriously robust as well without being total pigs. The only challenge now is to keep Mrs. Gib from having a complete shit fit every time the trail gets the slightest bit technical. :P Never met anyone so strong and at the same time so useless when the road gets rough. :noidea:
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

by Weenie


NickJHP
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Joined: Wed Feb 14, 2018 2:22 am

by NickJHP

How much you weigh will affect what tyre pressure you should use. I'm 65kg, and with 48mm tyres (Compass Switchback Hill) I use 25psi front and 35psi rear.

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Miller
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Location: Reading, UK

by Miller

Mr.Gib wrote:
Wed Jul 04, 2018 6:07 am
The only challenge now is to keep Mrs. Gib from having a complete shit fit every time the trail gets the slightest bit technical. :P Never met anyone so strong and at the same time so useless when the road gets rough. :noidea:
Lol, I hope she doesn't read this forum!

In my still brief experience of off-road on a CX-style bike, got to admit I was thrown way out of my comfort zone in my first experiences of technical trails. These days I feel more relaxed and confident about those rocky sections while still feeling quite the beginner. The way through this of course is simply to accumulate time on trails. Hopefully she will feel the same and will get to feel more able to negotiate tricky sections.

Mr.Gib
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Location: eh?

by Mr.Gib

NickJHP wrote:
Wed Jul 04, 2018 6:26 am
How much you weigh will affect what tyre pressure you should use. I'm 65kg, and with 48mm tyres (Compass Switchback Hill) I use 25psi front and 35psi rear.
Interesting. So you're running about 30% lower pressure in the front. I have been setting the front just a couple of pounds lower or about 5%. I assume you are doing that to really soak up any surface roughness. Is the tire still stable during cornering on tarmac? Out of the saddle must get a bit squishy no? Granted these are 48 mm tires and you are quite tiny (in a good way).

Those big Compass tires are a whole other world. I would definitely consider them were it not for the inevitable glass encounters to and from the gravel.
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

Multebear
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Joined: Sat May 02, 2015 10:11 pm

by Multebear

Tirepressure offroad is really a can of worms. CX riders discuss that for hours and hours and still don't agree.

The rule of thumb is, that you run as low pressure as possible without hitting the rim/getting snakebites (depending on your kind of setup). If you run tubeless, you'll want to go pretty low, but you dont want the rim to bump directly on the ground.

It's a good idea to bring minipump and tirepressuregauge with you, so that you can adjust the pressure while riding. There's not one pressure, that will be the right pressure all the time. For muddy conditions or for rough roads you want very low pressure for better grip. If the surface is smooth, you can get away with higher pressure for more speed.

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Juanmoretime
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by Juanmoretime

72 kg and I run Michelin Mud 2’s at 38 PSI tubeless on Alpha 340 Comp wheels. Keep in mind Mud 2’s are 30mm and really 32mm according to my calipers.
RESIDENT GRUMPY OLD MAN.

NickJHP
Posts: 105
Joined: Wed Feb 14, 2018 2:22 am

by NickJHP

Mr.Gib wrote:
Wed Jul 04, 2018 3:47 pm
NickJHP wrote:
Wed Jul 04, 2018 6:26 am
How much you weigh will affect what tyre pressure you should use. I'm 65kg, and with 48mm tyres (Compass Switchback Hill) I use 25psi front and 35psi rear.
Interesting. So you're running about 30% lower pressure in the front. I have been setting the front just a couple of pounds lower or about 5%. I assume you are doing that to really soak up any surface roughness. Is the tire still stable during cornering on tarmac? Out of the saddle must get a bit squishy no? Granted these are 48 mm tires and you are quite tiny (in a good way).

Those big Compass tires are a whole other world. I would definitely consider them were it not for the inevitable glass encounters to and from the gravel.
I use the same pressure on both bitumen and gravel, and the 25psi front seems fine when cornering on sealed descents. For longer day rides I usually have a large Carradice saddlebag hung behind the saddle with food, additional water, raincoat, etc, so that increases weight on the rear tyre relative to the front. I would estimate that I've probably ridden more sealed than gravel kilometres on those tyres - most of the gravel riding around here requires me to ride 20-30km on sealed roads to get to the unsealed bits. I'm also running the Compass tyres tubeless, so I don't worry much about glass causing punctures. Last time I cleaned the bike I could see a few places on the tread where sealant had come through, so it looks like it's doing its job of sealing small punctures out on the road without me noticing.

emotive
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Joined: Tue Nov 01, 2016 10:40 am
Location: Melbourne, Australia

by emotive

I'd say for 40mm tyres, and an 80kg rider, and an unloaded bike, go with:
35psi front, 40psi rear for mostly road and hard pack
30psi front, 35psi rear for a mix of road and bumpy gravel
25psi front, 30psi rear for mostly bumpy off road.

Thats what I use for Xplor MSO 40's.

If you have a small hand pump, have the best of both worlds, start with 40psi for the 20km road at the start, drop your pressures for the bumpy stuff, then add some pressure at the end for the 20km road at the end

by Weenie


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MattMay
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Joined: Thu Apr 10, 2014 3:26 pm

by MattMay

Interesting recent article in Velonews in the subject of ideal tire pressure for gravel:

http://www.velonews.com/2018/06/from-th ... vel_468329

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