Gravel bike tire clearance (OPEN)

I"m selling my first generation checkpoint and looking to get a new gravel bike. It will be 85-90% on smooth gravel or pavement and 10-15% rough unmaintained vermont trails.
I had decided to get an OPEN UP, but then realized that it can take a maximum tire width of 40, which seems very narrow for the way that tires are going. Just wondering if others have the same thoughts.
Other bikes i’m considering that are the new Checkpoint SLR, SC Stigmata and Giant revolt…any advice would be appreciated.

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40mm is too limiting for many gravel rides IMHO. I’d want to be able to run 45mm (or bigger…thats why I got a Cutthroat :rofl:)

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I agree with @FrankTuna that 40mm may be too narrow. Bike Radar voted the Giant Revolt the overall bike of the year in 2022, and it can clear 50mm in the long chip setting.

I’m considering the Fezzari Shafer (nearly identical geometry as the Revolt but with a longer wheel base), the Revolt, and the Lauf Seigla. Just need to explain n+1 to the wife … :roll_eyes:


I would want at least 42


That’s not quite true, the Open UP has plenty of tire clearance: the Open UP accepts up to 2.1" mountain bike tires, provided you use 650b wheels. So you have plenty of tire clearance, it is just that at a certain point you are supposed to use smaller 650b wheels.

Taken from Open’s product page on the UP(PER):

The reason is that if you put on wider tires on 700c wheels, you change the bike’s geometry whereas with 650b wheels the wheel + tire radius is much closer to 700c wheels with 30 mm wide tires.

If you need a lot more tire clearance, you should go for the Open WI.DE instead: it accepts up to 2.4" 650b mountain bike tires and 46 mm 700c tires. Note that the geometry had to be relaxed in order to ensure there is no interference between wide tires and frame as well as chain rings and front derailleur (if you run your bike 2x).


The problem with going for a bike that has room for wider tires is you will likely end up with longer chainstays and perhaps slacker geometry. This will make for a bike that doesn’t handle as much like a road bike (not as snappy, doesn’t descend or corner as well, etc). So while you would be better set for the gravel, you would be compromising on the road which represents the majority of your riding.

I’ve been riding an Open as my N-1 for the past 3 years. I think it’s the ‘perfect’ bike for the type of mix you are talking about in terms of its geometry. It’s climbs, sprints, and descends well on the road for me. I personally find that a 40mm gravel tire is enough for me (though I think it could fit some 42mm tires). If I am regularly needing more rubber than that I’m probably riding on stuff that I’d be happier using a mountain bike for. Though as mentioned above, you could always go with 650b and run fatter tires

Here’s an example of some of the chunkier gravel I ride on (which is probably tame compared to some other people). I find that 40mm is perfectly fine. Sometimes I just have to pick my line or slow downs little bit. Not sure if your gravel will be chunkier than this. I think when it comes down to width a lot of it is personal preference.


Your pictures are beautiful! :heart_eyes:
Want. To. Ride. That.
Can you share where (roughly) that is?

Seems perfect for a gravel bike. I agree with you about tire width: if you go with 2.1" mountain bike tires, you’ll definitely feel that on paved roads. I tried a 3T Exploro with mountain bike tires, and I felt that this bike doesn’t want to spend any time on pavement. Of course, it depends on what and how you ride, but more likely than not, you’ll have to ride some regular roads before arriving at such beautiful double track as pictured here.

IMHO the key is tire choice: you will never have a perfect tire that works in all circumstances. Very often you’ll be over- or underbiked, and as far as I can tell that is part of the appeal of gravel riding.

A few questions I’d ask myself: do you have to deal with rocks? Sand? Wet, goopy mud? Sticky mud that has the consistency of peanut butter and likes to kill bike gear for breakfast? Paved surfaces?

Probably, default gravel tires are something like Schwalbe’s G-One Allround or the equivalent Panaracer Gravelking. On the other hand, you could go for something wider with a file tread like a WTB Byway or HorizonHorizon Road Plus Tire | WTB. Alternatives are Vittoria’s Terreno Dry or Terreno Zero.

Quoted for emphasis: the Open UP has endurance road bike geometry and e. g. its cousin, the 3T Exploro has an even more aggressive geometry. Whether this is good or bad is entirely a matter of taste.

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Buy a bike that will fit the majority of your riding, not the very small minority. For 85-90% of your riding, you are gonna be just fine. For the rest, you may be a little underbiked, but you’ll be able to manage it, IMO.


I wouldn’t put the Revolt in the same category as the Fezzari or the Lauf, geometry-wise. The slack head angles (69/70.5) and long trail figures (80/77) of those two bikes make them very stable at speed and while descending but they feel very far from a road bike: steering is slow and it’s tough to make a quick line change with the Shafer. The Lauf is likely a bit quicker but still very much toward the MTB side of gravel bikes.

The Revolt in ML has a 72* head angle and 65-68mm of trail. Quite a bit closer to road bike handling. Just pointing this out for the OP and you as well, to hopefully make your decision easier. I have the Shafer and I really like it, but it feels nothing like my road bike. For what I bought it for (gravel racing) I do wish the handling was closer to that of a road bike.


I would be fine, but if I could find a bike that could do it all, that would be preferable, that’s why I was wondering about the other bikes I mentioned

Unfortunately, your chunky gravel which looks beautiful , is my smooth gravel


Then how about 2.1" mountain bike tires on a 650b wheelset? You could go for Schwalbe Thunderburt or similar tires.

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The Thesis OB1 is proported to be a “one bike” - good for both road and gravel, albeit with 650b wheels. I don’t have any first hand experience with it but have heard the owner quite a bit on The Gravel Ride podcast. He’s very responsive on The Ridership forum @randall.

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But you would be able to “do it all” on the OPEN….but it may not be “ideal” for 10-15% of your riding.

If you got something that would be “ideal” for that 10-15%, you are likely gonna compromise 85-90% of your riding.

I put on 45’s for Big Sugar…and I was damn glad I did. But for the vast majority of the gravel around me (kitty litter over hard pack), they are slow and sluggish.

You won’t find something ideal for everything…you are gonna need to compromise somewhere, so compromise where it matters the least.


Roughly: in western Montana (a US state for those on the forum not familiar with the US)
Specifically: the lake pictured is Jocko Lake which is in the Seeley-Swan Valley. One of my favorite places. An endless number of dirt and gravel roads and lots of lakes and climbs to fire looks outs. It’s pretty rural so it’s generally you and the wildlife.


Nope, 700’s make more sense for where and how I ride

Why? Tire width determines the ride quality, tire diameter influences geometry.

AFAIK most gravel bikes are not optimized for 29" mountain bike tires, you will run into clearance issues, not just with the frame, but also chain ring and front derailleur (if you run 2x). Plus, it’ll change the geometry. Even gravel bikes with extreme geometry like Evil’s Chamois Hagar only have clearance up to 50 mm in 700c.

You can also see this with tires, e. g. the 47 mm wide version of WTB’s Byway is only available in 650b. The widest 700c tire is 44 mm wide, and they are a rare species. Most companies’ 700c gravel tires stop at 42ish mm.


Echoing others. Nowadays, that’s narrow for a gravel bike. Ideally, get something that can accept up to 50mm tires. Gives you flexibility to add big tires if you need them.

I have a Diverge which officially can fit 47mm tires. But I’d bet I could squeeze bigger in if I needed. Max I’ve run so far has been 45s. My current tires are 38s which is fine for most of my local gravel roads.

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Fair point… I need to do some research and re-think


Gravel bikes come in a spectrum, and a lot of it is a matter of taste. The Open UP is essentially a rugged endurance road bike that supports mountain bike tires without losing its geometry. The Open UP is also designed to be a chameleon, you get the Open UP, two wheelsets, say, one with burlier 32 mm 700c road tires and the other with 700c 40 mm or 650b 2.1" offroad tires.

The Chamois Hagar is much more specialized, I probably wouldn’t want to buy that if I spent a lot of time on the road.

For the chameleon-type bikes like the Open UP, Open WI.DE and other similar bikes, you typically want to change wheel size to make sure that the geometry doesn’t change substantially. It isn’t just Open, Cervelo’s Aspero does the same as well as numerous other bikes. Like some gravel bikes, the Aspero comes with a “flip chip” to change the geometry a little.

What kind of riding do you want to do? You already mentioned that you want to ride some chunky terrain. Why do you want a drop bar bike as opposed to a flat bar bike? (No worries, I don’t want to dissuade you, you do you, I just want to understand better what you are aiming for and what kind of riding you do.)

Here in Japan, most people I know who ride gravel bikes is that they want to get anywhere. We have a lot of mountain passes that are in various states of disrepair, so sometimes your paved road ends and becomes a gravel road. Or you have a few km of gravel until you get to pavement again. This is obviously quite different from your terrain, but it tells you the type of bikes the local gravel scene likes. The frames are essentially road bikes with plenty of tire clearance (like the Open UP or 3T Exploro). The gearing is often road gearing or easy road gearing. About 50 % run 1x, typically with a 40- or 42-tooth chainring and a 11-42 cassette in the rear. And the locals use 38-40 mm 700c wheels with small knobs (Panaracer Gravelkings are very popular).

If you are riding chunkier terrain often, I reckon you might want to look at a mullet setup (mountain bike rear derailleur and cassette in the back, and 38- or 40-tooth chainring in the front). If the terrain is very flat, it might be overkill, though.