40 front 45 rear would be conservative, no way you'll burp or bottom out. Only reason to go lower would be if it's super bumpy or there's really steep, loose climbing you need a lot of traction for.

A friend podiums Crushar in the Tushar every year, she runs 32/38psi at around 120lbs. I usually run anywhere from 40-50psi, but I weigh 175.

Thanks! I think I'll aim for 35-37 Front, 40-42 rear then.

I run the non tubeless version of that tire (with tubes) on my CX bike. I run them at 50 psi if I'm doing a mix of road and hardpack, and around 43-48 psi when racing CX in a mix of grass and dirt. I weigh 160 pounds. At your weight, with tubeless, I think you could probably go 35-40 psi easily while navigating small rocks and roots, even lower if you know the surfaces will be fairly smooth.

Where you are at now seems high. You are going to lose more speed to vibration on the gravel than a rolling resistance penalty on the asphalt by going lower. Which way you want to err will depend on the course but you describe minimal asphalt sections.

I used the same wheels and the Clement PDX 33C tubeless for CX last year. At 190 lbs I ran 27-28 front, 30-31 rear. I never burped or had any issues. The Clement/DT Swiss combo seemed to work really well together. That was primarily in mud but it gives you an idea how low you can go.

Wow. That is low psi at your weight. I usually don't go that low at my weight!
Although I've never run tubeless in CX before.... maybe I can get down to 24-25psi this year.

I think I'll go with 35-40 for this gravel race though. 50 psi seemed a bit rough, even on harder pack sections.

50 is a lot for that weight on mostly gravel.

I went 40/45 with a 35mm title on 19mm internal rim at Chino, which had the tough combo of nearly equal amounts of tricky gravel and pavement. At DK 40/40 with 35mm tires on 25mm internal rim.

At 155lbs both felt about right.

I ran that tyre in the rear for a mixed surface race earlier this year (pavement, gravel, and trail sectors). I'm around 140 pounds and I ran it tubeless at 38 rear and 38 front ( PDX also tubeless). I felt it was a good pressure where I bottomed out a couple of times in the gnarly stuff - any lower and it would have been a bit riskier. If your course is smooth then 35 ish psi could be better.

---

_______________________________________________

Hi - Jumping in with similar ?'s

Just picked this Spooky up last night to do a 100km or 200km on gravel road event - July 2nd. It's got Michelin Cyclocross Mud2's - the center tread blocks are worn enough & they feel really good/fast. I think this is ready to ride straight-up on the Craigslist's dude's build. I haven't changed a thing except he took his saddle and pedals. Nearly to the mm this matches my road bike frame, no wonder I felt @home soon as I stepped on it.

Are aero clip-ons worth putting on, or is that a dumb question?

The "FTW" Supertouch frame is unreal, but has no bottle mounts. Not sure what I should do - maybe a seat mount, 2 bottles?

170lbs and these are 30's. thks

---

Training Tweets: https://twitter.com/Jagersport_com
FM Sports: http://fluidmotionsports.com

I run Michelin Mud 2 on my gravel bike. Stan's 340 comp wheels run tubeless at about 38 psi front and back for this 162 lb rider. I have run at 35 no issues but when I get down to 30 psi I've experienced some burping.

As a follow up:

I ran 41/44. The course was harder packed than usual and this pressure felt really fast.
There were a few longish sections of baby head cobbles where I was wishing for lower pressure though.
I'm now confident I could run under 40 without issue, and might even be a bit faster.

It depends. If it's an event with few competitors (i.e. - not big groups to ride in), on a flat or very windy course, then you may appreciate them. You'll lose some coolness points slapping them on a nice cx bike like the Spooky though, if you care about such things. You should also check the rules of the event(s) you're planning on, some don't allow them.

The Dirty Kanzaa winner this year used them.


Hydration pack.

I ran the Iconic race yesterday - Port Alberni to Bamfield. I entered that morning, because I wasn't sure about race.

I was WAY under-tired for that road. Insane, even extreme conditions. My gearing was to high as well. Climbs were steep. The first 20K, starting with a climb on pavement. There was a guy on a MTB out front and myself we dropped the main group pretty quickly. The lead guy was behind a race truck and I was not close enough when the road flattened off so I didn't get a chance to draft. I lost touch of the front rider.

So I was on my own when I hit the first logging site on the gravel and OMG I thought I was done for (I sort of was). The road was so rough, loose and very dusty (cars/truck traffic). A few km into tough gravel I got passed by Lee the LBS owner/race sponsor. From there it took all of my concentration to keep the bike from ploughing out. Climbs I had to stay seated for traction. Descents I was on the brakes as much as I could otherwise risk losing control & dangerous. I was swallowed up of course several more MTB riders.

70K of this pure torture :( !!. Lucky some nicer flat sections I could pick speed, but still taking hits.

I lowered my tire pressures twice just by popping the valve a few times to gain some semblance of isolation. Just checked I was down to 30PSI. Finished the 90Km in 4 1/2 hours hanging on to 9th overall. Toughest race experience I have ever done in my short career.

32's came on the bike (~ 1" wide) . I needed something that is a least 2" wide, and with lower bars = not good either.

---

Training Tweets: https://twitter.com/Jagersport_com
FM Sports: http://fluidmotionsports.com

A 32mm tire is about 1.25 inches.

Mud 2 is a great tire. I ran the same pair tubeless for seven years. About 70 cx races and hundreds of gravel miles and training.

After a while they develop a thick latex coating inside and flatting is rarely a problem.

They will expand with time. I think mine went from 33mm to 35 mm. The sidewalls get damaged over time as well and can't support lower pressures. In the first year I could run in low 20s in cx races. Now I can't go below 35 psi. I run about 40-42 psi for gravel. Over 45 psi and the ride gets very bumpy.

I reckon but they felt like I was on velodrome slicks.

---

Training Tweets: https://twitter.com/Jagersport_com
FM Sports: http://fluidmotionsports.com