am8117

I used to ride gravel before it got its term coined and manufacturers specifically ramp up marketing for it and a lot of it would have been done with robust road tires. I still like to switch between road (slick 32mm eg Conti GrandSport) and not-just-road (touring 37mm eg Schwalbe Land Cruiser) tires seasonally depending on weather with the same CX style frame, but the touring ones come very heavy (often wire bead only) and cheaply made (the carcass develops defects early on).

I see questions about specific tires here from the past, but I hope to get more general answers to the following here:

1) Riding lots on tarmac, is there any point having some other tread than slick centreline?

2) Lots of current gravel-specific tires look a bit like wide tiny-knobbed road tires. What is the benefit of such construction given that on tarmac it is likely to get more rolling resistance, in light mud they would lose traction immediately and on hardpack gravel the wide road slicks with lower pressure would work anyhow?

3) Is there actually benefit of having a wide (40mm+) tire without MTB-like knobs (which make it horrible for road) other than riding comfort (lower pressure)? The wider the contact patch the less it would dive into eg light mud and if there's hard surface underneath it would never reach it to bite into it. In deep mud the tiny knobs of even wide tire would have the wheel slip still.

4) There seems to be a trend to make gravel and CX tires of the same style only differing in the side knobs. Given that the sides wont come in contact with hard sufraces anyhow, what's the benefit of not having them on? Is there dramatic drag / noise on tarmac? Eg Schwalbe G-One Allround and X-One Speed.

5) Does specific tread shape even matter given how shallow it is? Eg Schwalbe G-One Allround and Conti Speed King CX.

6) What's adding most to the tire resistance on tarmac? Large knobs in the centreline, large knobs around the edges, deep grooves overall or the width?

Referencing mentioned tires:
Conti GrandSport: https://i.pinimg.com/736x/9c/7f/c3/9...ba40f97e1a.jpg
Schwalbe Land Cruiser: https://images.immediate.co.uk/produ...ev-c782deb.jpg
Schwalbe G-One Allround: https://cdn.road.cc/sites/default/fi...ing-tyre-2.jpg
Schwalbe X-One Speed: https://cdn.road.cc/sites/default/fi...-tyre-rim9.jpg
Conti SpeedKing CX: https://i.redd.it/6h4kq1fat3l41.jpg

GrainBrain

I used 40mm maxis Velocita least year. I'll probably go gravel king slick in 38mm this year. Maybe 35mm dunno, the riding I do I appreciated the added comfort vs skinnier options (long distances 60+ miles). I'd take them out on our crushed limestone 3/4- gravel for ~33 mile rides almost daily. Had a nasty slide out though so this year I'll have the dedicated tarmac and another gravel option with side lugs (probably Conti terra trail).

Barrettscv 

I've only found knobby tires to be beneficial on round "riverbed" gravel and wet grass and dirt.

On crushed gravel, a wide slick is secure enough as long as turns are given adequate respect.

I'm using slicks on flat routes on gravel. If the route is more technical with faster descents and some turns in the road, I'll put a low profile knobby to keep the front tire from washing out on corners. I'll switch to the Continental Terra Speed TR (Protection) 40 this year when riding more technical routes.

Many factors contribute to bicycle tire rolling resistance. The more material that deforms at the contact point, the greater the rolling resistance. A light tire with a high tpi value and minimum tread or no tread is always fast. Flat-protection belts, large knobs and a thick construction will always increase rolling resistance.

am8117

Thanks a lot for your reply. I've actually seen your earlier edit specifically mentioning different front/rear tire and it captured my attention because I was already thinking it's somewhat odd especially for gravel riding to be putting same tread style (unless it's fully symmetrical) on both. With rear one wants primarily keep traction for the radial/tangential forces, but failing to keep axial forces in check it's always possible to drift a bit, however with the front the axial forces that could cause a washout is something to be actually worried about, while in the radial/tangential direction I could only think of braking making a difference, especially with the front wheel.

I was actually looking at the SpeedKing CX and the Terra Speed for the same reasoning.

Barrettscv 

Yes, I also worry about washout at the front, breakaway at the front can be sudden and difficult to counter. I've been using the Vittoria Terreno Dry on the front, the shoulder knobs offer good bite on moderately loose gravel. At the same time I had the Schwalbe G One on the back. The ping pong paddle tread pattern on that tire was always sufficient on even the most technical descents (when used at the back). Newer tires like the Continental Terra Speed are probably faster with better grip.

chas58

See answers below in red

Just gonna say the german mags tested the G-one Allround as faster than the speed. I'd say its within the margin of error (i.e. they are realistically about the same), but the speed isn't faster just because it is a slick. The UR (OG) allround was a fast tire on my bike (the new one not so much I hear).

msu2001la

On the topic of side treads/center slick (aka file treads), I've never liked these on any terrain. Even for CX racing on dry courses I've always found the cornering traction to be weird.

I have a pair of Schwalbe Sammy Slicks that came stock on a bike I bought a few years ago, they are terrible on pavement.

KJ43

To each their own. I love my Pathfinder Pros and find them very fast and predictable on both pavement and in the dirt.

Yes, on high speed paved corners there is a bit of a weird feeling when you are really leaning, but for me it's never been an issue. In the dirt the center ridge just sinks in and my tires are pretty much like any small knobbed tire.

Rolla

Individual terrains and environments are better suited for some tread patterns than others. I love small knobs, but it's pretty dry around here, and they work well on the loose dirt and hardpack that I ride on a lot. You, however, might not need knobs at all.

I think you should talk to a local shop and/or some local riders who ride where you do and see what they recommend. You're theorizing a lot on how a given tread might behave, and some of your assumptions might not be accurate.

chas58

a nice rounded tire (slick or an SK - something like the terraspeed) allow my bike to handle like a road bike- with road tires on pavement, but...

with side knobs I can drift the bike, and I can ride out of a rut. On dirt, they do hang on a little longer before letting go in a turn.

One good thing about slicks (center or full) as that they have taught me to pedal very smooth and efficiently. I can climb anything (in the dry) with a slick that I can with knobs. Sometimes I hear people talk about spinning out because of the tires, and I think - dude - it's not the tires.

am8117

Thanks the tread pattern looks a bit more original than what I could find around here - it's hard to find slick centreline and knobby sides. I expect them to behave just like you described since this is what touring tires do, just they come all horrible quality and heavy.

am8117

This is exactly what I had experienced before when swapping wide road ones and knobby ones.

I had this nasty experience with Specialized Houffalize CX before - it worn out in the cenreline very quickly and I got a washout with the rear in downtown on polished stone surface once - I believe because of the side knobs, but some might blame my high pressure.

https://products.roadbikereview.com/...falize-cx.html

tFUnK

For tarmac? Get some 27-32mm slicks that are supple. Soma Fab offers some nice ones. I have some Soma Vitesse 33mm (measures out to ~30mm on narrow rims) that are smooth on tarmac and still decent on gravel.

shelbyfv

GP 5000?

cyclezen

Anecdotal info on tires is great - for that particular user...
but in a good comparison of similar use stuff, like tires, a good 'study' is a nice benchmark starting point.
There's more to tires than just 'resistance', especially in gravel/mtb, but if tire resistance is a key consideration, deez days Tom Anhalt is 'the Guy' for that...
from his Blog : Blather About Bikes
Time to share some Gravel Fun
of course how a tire handles, for a rider on their particular riding terrain/surfaces/style/speed is the anecdotal art of deciding...
I'm havin a ton O fun with my converted roadie, using Schwalbe 30mm CX comps (max fitting size); BUT, ragged erosion ditches, sand pits and common sharp rock gardens are a challenge.
Surprisingly fast enough and v-quiet on tarmac. But I only have about 170 mi so far on them (85/15 offroad/tarmac); so not sure how long they will last.
The coming new Poseidon X 'gravel bike' will make the game a new adventure... and will open a much wider window to the tire universe.
Ride On
Yuri