Tyre Pressure Effect On Speed – Gravelking SK’s

I’ve only recently bought my 1st gravel bike and am running Panracer Gravel King SK’s 700 x 38, I’ve always kept pressures reasonably high on my 29er as 75% of our rides are on road believing higher pressure meant faster on paved surfaces …. is this so???

The main stretch of gravel we ride over was fine on the 1st few outings on the gavel bike as it was very compact with the odd larger lump and pothole but they’ve just decided to fill the dips and have just put some fairly chunky gravel into the holes which is absolutely horrible to ride over … certainly for the next few months until it gets flattened down again.

My choices are lower the pressure but don’t ideally want to if it’ll have quite an impact on road speed … be interested to hear what PSI others run theirs at for mixed riding with more road than gravel … I’m tubed rather than tubeless.

The other option is maybe get some 43’s and use those which may be better during the winter / mud and give the ground a chance to get trodden in and switch them back again in the summer.

What PSI are we talking when you say high?

I used to have 43mm Gravelking SK’s and I ran them between 25 and 30psi, the front closer to 25psi and the rear closer to 30psi.

That was for roughly 50-50 on-off road stuff.

Now I run the 38mm Gravelking slicks, only just got them but am settling at about 35psi in the rear and a couple of psi lower in the front.

That’s for 80-20 on-off road rides.

I weigh about 75-78kg or something and have always had the above tyres set up tubeless

Edit: my Dad recently got a nice adventure bike with 38mm tyres, but he’s so used to road bike pressures of 100psi+ I could not manage to persuade him to lower the pressure from his current 80psi! He weighs a few stone more than me, but the tyres as so hard it feels like riding on the rims, with a bit more grip

CyclingTips Podcast, Episode 9: Rethinking road bike tire sizes and pressures

I run 45 front, 50 rear. Tubeless, 700*38. I weigh about 85kg. Though I was considering dropping 5 at each end…., But kinda banking in them losing a bit of air over time. Any higher and they get too hard, but around the 40-45psi mark you get a nice supple feeling.
50/50 road/tracks

https://janheine.wordpress.com/2018/01/03/12-myths-in-cycling-1-wider-tires-are-slower/

https://janheine.wordpress.com/2018/07/19/how-wide-a-tire-should-i-ride/

30 front, 40 rear and I’m 95kg. I’ve gone higher but comfort and off road speed is comprised. Unless the road is in very good condition higher pressure isn’t faster.

Seems like I may be running them too high, my 28er was about 55/60 psi and carried the same through to the gravel bike thinking it’d need higher pressure as it was a narrower tyre and knowing people run road bikes at around the 90 psi level … I’m 95kg as well.

I’ll try dropping them both back starting around 40 and see how it feels and adjust from there and cheers for everyone’s help …. have seen the links as well and will have a read and listen to those now!!

Slightly off topic but does anyone know how you get smileys or thumbs p emoji’s on here … or maybe you can’t ???? Even if I try the colon, hyphen close bracket it shows as a square rather than a smiley??

I run about 40 both front and rear with gravelking SK 38s. Seems to work ok for me both on and off road albeit so probably do with going a bit softer if it gets really rough (in gravel terms)

Unless the road is in very good condition higher pressure isn’t faster.

Someone should tell all the pro roadies!

Someone should tell all the pro roadies!

Not really. All depends what speed you ride at and how wide your tyre is. Having a low PSI in a 25c tyre is really not good and is not fast. I use 25c and if they are run soft they are definitely slower and handle dreadfully. Bigger tyres may roll better on rough roads but they are less aerodynamic and they are heavier. For a cyclist riding slowly that is less important than a rider who rides along at 25mph (a roadie)

Experimented with Gravek King SK tubeless on 23mm rims. Settled on 38 rear,36 front.50 50 on / off road. Feel fast on tarmac, grippy and comfy off road. Got me round 200km of Dirty Reiver with no punctures!

Try it and see what you think. Roll-down tests aren’t hard to do and can give you a moderately scientific result. I’d say most of us use tyre pressure to affect the feel / response of the bike with no real basis on its affect on speed and the effect on speed comes down to how rough the roads are and how far you ride ie the effect of cumulative fatigue.
From a reasonable pressure starting point I don’t think you lose average speed by dropping some pressure – you certainly do gain some comfort and smoothness though (which many perceive as ‘feeling slower’). The smoothness (more micro-suspension, efficiency) is where the gain in speed can come from. It’s worth reading Jan Heine’s blog on the topic – much sense in all that and though I’m not sold on the idea of superlight tyres the rest all seems valid and I’d agree from trying similar things.

Interesting thread. I ran 35 mm Gravel King’s tubeless (both tubeless specific and non tubeless tyres) on my GT Grade last year.
I ran the back at 60 psi/front 50 and had 3 rear failures where the centre of the tyre had lots of pin holes that then became an irreparable split. One exploded in the house like this after 2 days of the bike not moving which was a bit of a mess!
The last one went on the Dirty Reiver after 100 k and I needed to tube it after to continue.
It’s kind of put me off Gravel King’s tbh but I know lots of people swear by them and they certainly felt good on the bike.
I’ve been toying with getting a pair of Schwalbe G Ones to try but I’m also thinking I ran the Gravel King’s at too high a pressure off road which compromised them?
I tend to run my 2.6 29er at 18/20 f&r so don’t know why I thought I needed 60 in the GKs other than having the mindset that more pressure is better on a ‘road’ bike.
I can get a pair of GKs considerably cheaper than the G Ones too……

I’m currently running Gravel King SK in 35mm variety and have had them at about 50psi front and back recently but have been mostly on road .

Went offroad this morning and they were “fine” at that pressure, but a bit too hard. Planning a cross/gravel ride tomorrow morning so will drop to about 35 I reckon and see how that feels in comparison. Will be some road sections as well so will be good to see how compares.

@gralnlaw

G-ones are the one other tyre I’d like to try in comparison.
When I ordered the bike I had a choice of tyres and thought the GK’s were the safer option as we do go over some occasional mud and they looked like they had a slightly more aggressive tread then the G-ones. Since then I’ve seen quite a few posts that G-ones are probably more road friendly / faster which is probably 75% of our riding so tempted to get some to try in comparison.

I used these 38mm tubeless flavour on a bikepacking tour probably 70% road. 35psi ish. Would not want that any higher, rolled great on road.

Was thinking about this while riding mine today (50/50 on/off road). My 45/50 psi pressures did feel too hard.

I have some G one all rounds, knobblier than g ones. Run them at around 45psi front and rear for generally riding about, lower for pure offroad.

@granlaw. My 38 GK’s have sidewall markings that say max pressure is 60 for tubeless. Granted they should have plenty of margin but it sounds like you’re running them pretty hard.

I weigh 78kgs and run my 38c GravelKing SK’s at 38 f / 40 r (tubeless)which seems perfect for mixed road and gravel/dirt.

BTW.. I have a spare set in 38c, BNIB, which I don’t need and if anyone wants I will be selling next week for £45 the pair, posted. PM me if interested.

In the dry, I found 29×2.35″ G-One Speed Evos ran great at ~40/45PSI with tubes, for mixed terrain rides with more tarmac than not. I’d expect them to be pretty useless in the wet.

I wouldn’t push the 60psi. I left 65-70 in mine over night on stans grails. Cue the morning with a tyre blown clear from the rim!

Used 43mm SK’s , very impresed at first for touring and commuting at around 40 psi. Recently had a spate of pinch flats but tyres are worn and I try to ride it like a mtb. Overall I reckon 30psi front, 40 rear, good tyres. I weigh 75kg

https://www.schwalbe.com/en/rollwiderstand.html

I’m using a 40mm Nano on the back with a 42mm Resolute on the front on 23.5 internal rims they both blow up to 44mm. I’m running 24psi front and 27psi rear, I weigh 61kg.

I’ve run these pressures over various terrain tubeless with no problems, even rode a rocky Enduro course in France.

I hace 40mm elwood terrene tires on my gravel bike.

Im not really sure about on road, but off road 30psi or lower is loads faster (according to strava results) and is much less bumpy.

I still feel like I want higher pressure it just “feels” faster.

I guess I do about 66% off road 33% on road.