With the spring looming, now is a good time to consider gravel tire selection. The seasonal change is going to mean all sorts of things to riders in all sorts of places, and choosing the right gravel tire is much tougher than people might think. I say that as a reviewer who got tired of reviewing road tires because the top-of-the-line clinchers all became so close in performance. It’s similar with mountain bike tires. There are tire combinations out there that are you can run most anyplace.
But gravel tires? No. Here it pays to choose well and wisely.
Prior to a Grasshopper gravel event, I’ll text with friends and look at weather conditions and any other beta we can get to inform a choice.
For starters, in mud you want to go narrower, not wider, because mud, when it’s not being sticky, is slicker than AstroGlide. So, the issue is getting the tire to sink in the mud so that it can bite into the soil beneath. Also, you want big blocks spaced as far apart as possible. If the blocks are too close together, the space between them will simply pack up with mud. I learned this from watching swamp buggy racing. Hey, I’m a Southerner. In swamp buggy racing, the tires are remarkably narrow relative to the wheels’ diameters.
The next thing I’m going to say may be just as surprising. Most of the time, riders don’t need a tire with a lot of tread. I’ve ridden nearly bald 40mm-wide tires on hardpack dirt and not had any problems with losing traction. And in case anyone is wondering, at a certain point a tire can have so much surface area that it’s traction will begin to drop because there’s not enough weight relative to the surface area, but bicycle tires don’t ever get big enough for that to happen, so wider will always mean more traction.
At this point, I’ve developed a kind of logic tree or flow chart for choosing the right gravel tire, and it looks like this:
- What sort of surface will you be riding on? If it’s muddy, or loose, you’re going to need knobs. If it’s firm, you can go with less tread.
- How much rock is there? If there’s a lot of rock, I suggest going wider to prevent pinch flats. The smoother the course, the narrower a rider can go.
- How comfortable do you want to be, or how much comfort are you willing to give up to be fast? If someone wants to try to stay with a group of quick riders, go narrower, as narrow as you dare. You’d be amazed the stuff I’ve ridden on 25s. If, however, you want more comfort or to reduce the chance of a flat, go wider.
Ultimately, this is a question of competing interests: Riders want optimal traction for the surface they are riding on, and they want as few flats as possible. Those two interests line up rather well. However, riders also want to go as fast as possible and as tires drop in width, they lose rolling resistance up to a point. But it’s important to remember that the narrower the tire, the higher the pressure you need to run; And the higher the tire pressure, the more likely something sharp will puncture the tire.
If you’ve got a solid go-to tire, drop it in the comments and let us know what conditions it thrives in.