Gravel Bike Tech: Mixing road & gravel – Setting up 2 wheelsets

A bike like the Exploro performs so well on such a wide range of terrains; it can feel daunting to figure out how to best spec it for both on- and off-road performance.

To a great extent, that’s my job when I create the complete bike specifications, and that’s why I always put a small synopsis at the top of the specification listings so you know what the bike is spec’d for. Some may be more race-oriented, some more for the toughest terrain, etc. But you can also do some further tweaking yourself, based on your riding style and locations.

First you need to ask yourself: Will you often mix on- and off-road within the same ride, or is it more about “off-road on Saturday, on-road on Sunday”? In the first case you’ll need one setup that can do it all, which I write about here. In the second case, setting up two wheel sets as described in this post would be a great solution.

Wheelset 1: Road tires

This one may seem easy, for your road setup you get road tires. I often see people spec 28mm or even 25mm tires on their “road wheels”. Seems logical, after all these are the wheels for the rides where you used to ride a road bike with such tires.

But why did you ride that tire size on your road bike? Because the roads are so smooth where you live? Because you love  punching straight through to the rim when you hit a pothole or crack? Because that’s simply “what a road tire is”? Or because it’s the biggest that would fit?

I would argue that most paved roads are not that smooth and comfortable (they’re often worse than gravel roads). So now that you have all that clearance on your gravel bike, why not use it to give yourself some more paved comfort? Going to a 32mm or 35mm road tire, you will actually DECREASE your rolling resistance.

Aerodynamics will worsen a bit, so that is the trade-off, but unless you’re racing, neither of these changes (which even partially cancel each other out) will make a meaningful difference. And so you’re left with more comfort, more puncture protection, more grip, and a 35mm tire that even gives you some off-road capabilities – should you not be able to control yourself at the sight of that beautiful trail you ride by every morning.

Want better on-road performance than you’ve ever had? Don’t put standard 25/28mm road tires on your bike!

Great “pure road” tires to consider are the Pirelli Cinturato 35mm, the WTB Exposure (in a variety of widths), the Continental GP 5000 (Tubeless) 32mm (it fits big, 34.2mm on our Discus 45 | 32 carbon wheels) or the Schwalbe Durano 32mm. If you value grip and puncture protection even more, then maybe a “one setup for everything” is a better choice for you after all.

Wheelset 2: Off-road tires

There are many choices and I won’t discuss them here in detail. You can match them to the particular area you live in. One general comment is that I would urge you to consider 650b wheels and tires for this setup if you live in an area with tough terrain (or travel to such places regularly). After all, you will already have a 700c wheelset for your road riding, so having 650b as a second set gives you the most options. Maybe you regularly ride a 47mm tire “around the house”, but you now have the option to throw on 2.1″ mountain bike tires for the really crazy rides.

Wheelset 1: road wheels

Again many choices, alloy or carbon, aero or light, some of which are a matter of budget. Zipp, Fulcrum, Hed or WTB, there are plenty of good brands to choose from, some with more road pedigree and some more towards the rougher stuff. Whatever you choose, what I would urge you is to take a close look at the inner width of the rim. As tires get wider, so should the rims.

Some brands lead the way here, while others lag. If you want to be ready for the future, don’t get a 17mm rim. Especially if you go for carbon rims, get at least a 23mm rim, so you can use a 28mm tire but also a 40mm tire if you ever want to.

I may be biased (I am!), but we designed our Discus 45 | 32 carbon wheelset specifically to be aerodynamic with wider road tires (for the Strada) so it is a great option for an Exploro in road set-up too. In alloy, wider rims quickly get very heavy, so there it’s more of a balancing act between rim width and weight.

Wheelset 2: off-road wheels

If you have some budget but not unlimited, put your money in the road wheels, save some money on the off-road wheels. While your off-road wheels are arguably more important, the things that are important here are not necessarily expensive. Expense often equals weight savings, and for your 650b setup you likely want durability more than lightweight. So focus on a bigger rim width (there are still mountain bike wheels with 19mm inner rim width (you don’t want those!!) and focus on the quality of the bearings and seals quality rather than saving a few grams.

Bearing & seal quality

How do you test bearings and seals? That’s tough if you’re not an expert, but for starters inquire if the bearings are stainless. That will increase their durability with the sort of riding an Exploro lets you do.

Don’t waste your money on ceramic bearings. “Oh, but they spin so smoothly in my hands”. Right, so if you are buying a set of wheels to spin in your hands, do that test.

Wheels that spin forever don’t have tight seals. So dirt can enter easily

If you are looking for wheels to spin well even when dirty, do the “opposite spin test”. Spin the wheels and see which wheel stops the quickest. There is no guarantee, but more than likely that’s the wheel you want. First a caveat, if the wheel stops spinning quickly because the bearings feel rough, that’s bad. but if the spinning slows down quickly and uniformly, it means the seals are tight.

And that’s what you want. If the seals are tight when you buy the wheels, they will settle in during the first 100km and seal well for a long time. If the wheels already spin freely in the shop, it means the seals already leave a gap and will let through muck and water from the start. Need I say it: not a good thing. Of course this applies to your road wheels too.

Some common sense is needed here; lousy seals can bind too. But forget about the “oooh this spins so nicely” approach.

Gearing

If you have two wheelset, the gearing you put on each of them can make the process of swapping back and forth easy or difficult. Your minimum climbing speed will be lower on gravel, so you need a “smaller smallest” gear on your off-road wheelset.

You can argue (I usually do) that you can afford a smaller top gear on gravel too, and thus the range you need remains the same off-road and on-road. But the resulting outcome of that complicates your life.

Let’s say the difference you need in gears is 10%, so a 10% smaller lowest gear and a 10% smaller top gear. It is very difficult to find a set of cassettes that achieve this. The only practical solution is to change your chainring, for example by running a 46T on the road and a 42T off-road. But who wants to change their chainring all the time? Plus in all likelihood, you’ll need to adjust your chain length too. Not fun.

Therefore, it is more practical to stick with the same top gear and only change your smallest gear between on- and off-road. The beauty of this solution is that it’s all in the cassette, which is affixed to the wheels you’re changing out anyway (you have two separate wheel sets for this, remember). And with a bit of planning, it won’t require a chain length change either.

For example, you might run a 1x setup with an 11-36T cassette on the road, and then switch to an 11-40 or 11-42T off-road. As long as you set up the chain length for the 11-42T, you won’t have much trouble running the 11-36T cassette using the same length.

What that chain length should be depends on your rear derailleur, as I wrote in a previous post. Even your medium cage derailleur can do a lot if the chain length is adjusted accordingly. Officially this may require an adjustment of the B-gap, but you can get away with one setting if you’re careful.

If you plan to swap wheels regularly, a setup that keeps the same chainring and chain length is preferred

The fact that this works without changing chain length should not be surprising. After all, if that chain length works for the 11-42T cassette, that means it works for that whole range. So of course it also works for a portion of it, say the 11-36T portion. The reverse is not true, if you have set up your chain length for the 11-36, you will notice the chain isn’t long enough to wrap around that 42T cog. Don’t try this at home; you may rip your derailleur off!

Depending on the range you need you may have to experiment a bit, since not every cassette ratio you want exists. And that may also mean that you modify that top gear a little bit after all. Much more on gearing can be found on my post about 1x drivetrains for tough terrain.

Other parts:

The above covers the main points to consider when you ride on-road one day and off-road the next. The only other part you could spend/waste some time fussing over are your handlebars and your pedals. Will you get a standard road bar or a gravel bar? The answer is probably most often a road bar, but if your gravel riding is so tricky that you want a gravel drop bar, then at least make sure the flare starts below the brake/shift levers, so that your hand position on the hoods reflects a true road position and is comfortable. See more about this on the Superghiaia page.

As for pedals, I personally always ride with MTB pedals and light MTB shoes. So much more comfortable if you ever have to walk your bike or stroll across a terrace with your (Italian!) espresso.

Synopsis for a two wheelset solution

As described there are a lot of options, but below is an overview to show the general direction. I also try to include some less-than-standard options here that you may not otherwise think of.

You can finetune it for your specific ride location and strength, and the latter also determines what chainring size you would use with the above cassettes (and cassettes starting with a 9t cog obviously can pair with a smaller chainring to attain the same top gear).

If you run 2x, you can find a similar gear range easily; there are too many options from various manufacturers to list them all concisely.

If you are not sure which cassette works with which derailleur (you would be surprised what works even if the manufacturers say it doesn’t), then I would recommend to check out the other Gravel Bike Tech articles.

One setup for everything

As mentioned, the two wheelset solution is great if each ride you do is clearly compartmentalized. Paved road one day, off-road the next. That said, you can do some pretty impressive gravel rides with a 35mm Cinturato tire despite its road credentials.

However, if you are constantly mixing surfaces within your rides, you may need a different solution: the one setup for everything. I will discuss that in the next installment.