I don't consider myself an expert, but I've done a fair amount of gravel riding. I'm currently on Conti Speed Ride 42's (measure at 40 on WTB I-19 rims), and my next build (90% complete) will be on 50's... Washington Cascade foothills and mountains.

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Ha, it most certainly depends!

Depending on where I ride, I use: 35mm and 38mm 700s, and 42mm and 48mm 650bs. Traction is generally a non-issue for me, so most of my tire choices are slicks - though I do have some treaded options for dirt and mud if required on some courses/routes.

What drives the volume factor mostly in my opinion, is how smooth your route is and how fast you will be going on the descents. Most of the double track and fire roads in my area require 650bx48mm tires if I want to ride fast "no brakes". Nothing worse than scrubbing off tonnes of speed on the descents due to inadequate tire volume - total waste of potential fun!

Edit: If I HAD to pick a tire size, then I'd say 650bx42mm should be the least offensive if your route involves: pavement, gravel, fire road and a bit of trail.

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A non-expert from the Midwest checking in. It depends (lol). I've done many gravel rides on 23s, which is sketchy but not as bad as you'd think on typical fire roads. 32 or 36 is perfect the vast majority of the time. I'm currently running 44s (Compass) or 50s (MSO) because I'm not racing, they fit on my bike and why not: the hovercraft ride at 28 PSI rules.

I am not an expert, but I run Panaracer Gravelkings that are 43c's. I use them for commuting on path/road as well as gravel. Are they overkill for what you describe? Probably. However I will say I am surprised how fast they are on pavement and have enjoyed the extra volume. Tradeoffs I guess, enjoy the ride.

Where in Socal?

My riding in Socal has been done on 34's or smaller. Either WTB Exposure's or WTB Cross Bosses. I do think I'll find my happy medium in a 32.

I can ride pretty much anything on the Cross Bosses in a 34, but there is not a lot I won't ride on a 30 or bigger in a slick or gravelish tire.

Running tubeless really helps and just watch the big rocks.

jake

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Get outside!

I ride a lot of gravel.
It's very conditions dependent. Most of my gravel this year has been fresh and deep, making a wider tire better.
However, on hardpack my 40C tires feel slow and heavy. I much prefer my 33C CX tires.


Given your needs, I'd say you could go 32-36. Even less if you don't mind a rougher ride.

However, I was wrenching my wife's gravel bike with 40C Maxxis Ramblers and took it out for a test ride to run through the gears.
WOW. For a wide tire they feel blazing fast and light. I might switch to them next year, they seem the best of both worlds.

For Gravel like this:

You're looking for the largest you can fit.

For This:

You can ride anything.

If you rides are "B" + Pavement, you probably want something 33 or smaller and fairly smooth, with perhaps some smallish side-knobs.
(I run 30c Schwalbe G-One Speeds on the above).

36 is a good "all around", not the fastest on hardpack, not the surest footed on deep and loose.
I run 37c WTB Riddlers on gravel paths and low-tech singletrack.

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If mostly asphalt, what about Schwalbe G-One; come in 35 or 40mm.

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29 years and counting

man, that looks glorious



$0.02 - I do our regional spring classic rides. its miles of asphalt leading to fire roads or farm roads, then back to asphalt. then repeat. there's no single-track, you can drive a car on all of it. its a faux Paris Roubaix

I used 25s, then 28s, and now 31s. I got happier and happier.

socal can mean a lot of different things. if you ride in the mountains - the san gabriels, the san bernardinos - even on fire roads you're going to get a lot of steep and sandy. my buddy and i just rode up a fairly well traveled dirt road that is 8.2 percent average for the first 3mi and sandy in spots, so the 11 and 12 percent sections were a little dicey, required a little grip. further, if you race and you get stuck behind guys going up hills that are slower, then you need a tire with enough grab at the pace they're riding, rather than the pace you'd ride.

right now i'm riding 38mm specialized tubeless trigger pros and they seem to be a pretty good all-round tire. but i have some challenges coming to try out.

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Dan Empfield
aka Slowman

I like 38's as an all-purpose, whatever-you-encounter size. Challenge Gravel Grinder Race. For a couple years, I held an 8-mile paved road KOM using them on my gravel bike. (A roadie has since claimed the KOM on 25's.) Fast, smooth, reliable. And at 50/55 psi, I never pinch flatted on Dirty Kanza.

to Slowman and Jakers: I hate to reveal my whereabouts, but I'm talking Santa Monica mountains. Dirt Mulholland, Westridge, Sullivan, etc. Hard packed dirt with small rocks. Not soft gravel. Also occasionally the trails around Griffith and Elysian parks.

I too am in SoCal with similar conditions. My opinion is that 36-44mm measured tire widths are the "sweetspot" for this type of riding you describe.

I actually don't look at it as a tire width selection problem though, but more of a pressure and tread texture selection problem. For less challenging routes, or ones with a good amount of pavement, I'll be choosing a fairly smooth treaded tire (i.e. Challenge Strada Bianca, or Compass Snoqualmie Pass). For rougher routes, all the way up to playing on single-track, I'll then go with something that has at least a significant center file tread, with some small side not for cornering "bite". I REALLY like Challenge Gravel Grinder Race or Pros for that purpose.

Going narrower on tires for the more pavement oriented rides doesn't really gain you much speed, but adds to the discomfort over the rougher sections. By contrast, a smooth treaded, wide tire will have you traveling just as fast on pavement as a narrower tire, but will be way more capable off road, mostly due to the extra "suspension" and lower tire pressures allowable.

Just my 2 centavos.

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I like those too...but, I like the 42s even more :-) I found that the 38 measures quite a bit undersize BTW, at more like 36mm wide, even on a wide internal width rim (~21mm). The 42s measure out at ~44mm on the wide rims.

Are you running latex tubes in them? If not...you should give them a try.

I'm looking forward to the TLR versions of these. Although they added a bit of sidewall rubber for air retention, they also eliminated the puncture strip. I suspect they'll actually be as fast, if not faster than the Gravel Grinder Pro versions due to that omission :-)

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What are your thoughts on this tire assuming one could fit it in their frame?

https://www.continental-tires.com/...tires/speed-king-2-2

I was referring to the 27.5 version. FWIW, BRR pegs the rolling resistance of this tire as being lower than a GP4000SII. With a Center section that’s basically a slick, I’d imagine it would behave quite well on the road.

I ride 35 clements xplorer ush and have no issues on typical midwest gravel.

I like the ush because i have to ride 2-3 miles on pavement before i hit gravel.

Ha, I guarantee you if you were to do a timed road loop with your gravel bike using a 700x25mm GP4000 and this 27.5 conti, you would notice a big difference. I've done quite similar comparisons with 23mm 4000s and 650x48mm compass switchback hills (one of my favourite tires) on the same bike.

I know that's not really the point of this tire though. I just think you'd be disappointed if you thought it would be just as fast on the road when riding or smooth gravel compared to a fast slick in the 36-38mm range. I bet it's an awesome tire for adventure riding!

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This. Wide with low rolling resistance.

If you're new to gravel, and your bike handling skills / athleticism is middle-of-the-road, I'd suggest erring on the larger size. As in, the biggest that'll fit in your frame, while still having at least 5mm clearance on all sides. This can really depend on the year/make/model of your bike - we went through a phase 10-20 ish years ago during which some cyclocross frames couldn't do anything beyond a 35 -38mm tire (and road bikes had you stuck at 23-25mm). The Surly Cross Check was an early lone wolf, and it became a favorite for "monster cross"... with tires in the 42-45mm ish range.

Big tires + low pressure... it'll ride nicely and allow you to gain confidence when you do hit the rough stuff, and have more grip in case you screw up.

If you want something fast, my best setup so far was the Michelin Mud and Jet on wide Stan's rims setup tubeless. They are labeled as 700x30, but run wide, especially on wide rims... mine were about 35mm inflated. Very comfortable and they always felt like fast rollers. They did feel narrow, though, for the rough trails when I lived in Colorado. I always wanted those same tires in a 40-42mm size.

You’ll lose on aero as you get up above 20mph for sure but you should know that Compass’ compound is inferior. Check out how their new “road race” tire stacks up against the usual suspects in that category (same compound used in all their other tires fyi). Pretty abysmal and that difference will only be amplified as you add more material to the tread.

I wouldn't definitively say the Compass compound is "inferior" or "abysmal". There does appear to be some inconsistency though between tires in their line-up. Take a look at Tom's findings for the Compass 700x44mm - pretty fast to me! What puzzled me though is how much slower the 35mm Bon Jons were though - both sharing the same EL casing.

https://forum.slowtwitch.com/...ost=6471664#p6471664

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If it would fit, I'd give it a shot! :-)

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