Recently, the off.road.cc team has been very busy converting Chinese XC mountain bikes to gravel bikes and even building our own custom machines from titanium. But I think I’ve taken things one step further here, taking a very good trail hardtail mountain bike and giving it the ‘convertible’ gravel treatment in the best way I possibly could. Here’s how it went!
There’s one reason why I thought this was a good idea. I love hardtail mountain bikes just as much as I like gravel bikes, but I’m not on the kind of salary that allows for a fleet of bikes to pick and choose from when the feeling hits. And with drop-bar mountain bikes becoming more of a thing, whether we like it or not, I wanted to see if I could gravel-ify a trail hardtail and find out if it could quench my thirst for the odd gravel jaunt, but be able to chop and change from gravel mode into MTB mode quickly. Achieve the real best of both worlds that some brands so often talk about.
Now, there’s loads of chat about gravel bikes just being old-school mountain bikes, and there is some truth to that, but I wanted to push that envelope and take a modern mountain bike and make it gravelly. The inspiration came from my time with Rat Bikes’ Dad Rat – a bike that really is a gravel bike, or a mountain bike depending on how you choose to build it. But even then, it sits firmly towards the XC/gravel end of the spectrum, and I wanted a bike that could lean further towards trail mountain biking, but be able to take on a spot of gravel when I felt like it. Plus, my caffeine-riddled brain was telling me that a mountain bike can do gravel better than a gravel bike can do mountain bike things!
The bike I chose was Surly’s Sorceress, a bike I really liked when I tested it earlier this year. But after realising that it’s externally routed, built of steel and remarkably simple, I had my lightbulb moment. This is a bike I’m going to build into a convertible gravel bike.
I’ll admit, I’ve not been particularly clever or fancy with the componentry I chose. I’ll hold my hands up and say that I basically just found lighter and faster mountain bike kit, then threw a drop handlebar into the mix. However, a lot of modern gravel bikes use mountain bike componentry, such as the Maxxis Aspen ST tyres.
Then, the project grew from there, but one thing I wanted above everything else was simplicity. Because I wanted to change the bike from MTB to ‘gravel’, I needed componentry that would make the conversion easy enough to do in five minutes.
With that, hub and caliper adapters weren’t an option. Yes, they’re available, and they work, but more things to change around means more faff… so I had to lean more towards mountain bike kit, like the Zipp wheels I chose. This isn’t looking very gravel so far…
The key component on any gravel bike for me is a drop handlebar. A drop handlebar is defining in more than just its looks, as it opens up more hand positions and can promote a more aerodynamic posture over the bike.
But my desire for simplicity and a drop handlebar wasn’t particularly straightforward (thanks, standards).
Brakes used with drop-style brake levers are typically flat mount. The Surly Sorceress had post-mount brakes, standard for MTB. Aiming not to throw adapters into the mix, I had to get a little clever. I chose to run SRAM Rival AXS levers and shifters with the brand’s Level Ultimate four-piston calipers. Yep, it’s possible by swapping the longer MTB compression nuts with the shorter road-style nuts, and praying that they would actually work.
As I really wanted to make this machine convertible, I went for kit from SRAM’s AXS lineup for shifting, and yes, that’s a 200mm Reverb AXS dropper post. That’s just one thing I wouldn’t have to swap as I go between gravel and MTB.
Going wireless enabled me to use the handlebar as something of a modular system. All it takes is a nip of some bolts and a reconnection of AXS’s wireless wizardry as I change from remote shifter to remote shifter.
Is my heinous blasphemy towards MTB better than a gravel bike? Oh god no. It’s not nearly as efficient or well-handling. But does it quench that gravel thirst? Absolutely. It’s faster than a mountain bike over gravel, and it’s more capable than a gravel bike when the trail gets spicy, exactly as expected. It’s also surprisingly comfortable; I’ve got the hand positions of a drop bar, and it does the job just fine. Really, I reckon this would make an excellent long-distance bikepacking rig owing to its comfort and forgiving ride.
And the fork. Yes, it’s a 140mm suspension fork from Manitou. For gravel… well it’s not for gravel, but it did lend something positive to the overall experience. There’s no lockout on this fork, but winding on all of the compression damping worked nearly as well. It then offered a touch of squish which took the sting out of washboard sections. Then, if I really wanted to, I could open up that compression and let those 140 millimetres do their job. It just blows through all of its travel during heavier compressions owing to the fact I’ve got so much more weight over the front end as a result of the drop handlebar, and it’s just not set up for that kind of weight.
The brakes work too! Not perfectly I admit, but I’ve got most of the power that the Level is known for, but with a squishier and less defined lever feel. Really, that makes sense given that the Rival levers aren’t designed to push and pull four pistons, and all of their seals.
Now, let me address the elephant in the room. Obviously, I never had to go this far to achieve what I did. I could have just slung on the low-profile tyres and been done with it. But where’s the fun in that? Also, this build is no cheaper than an actual gravel bike. The wheels are about £1k, and I doubt that my shifting setup is any cheaper. But the price of the Surly Sorceress and the Whyte Verro gravel bike (for example) is certainly more combined. Plus, I’m saving space in the garage for all of my other crap, so there are still some positives.
Importantly, I knocked my convertible goals right out of the park. All I need to do to change from MTB to gravel and vice versa is swap the wheels and nip up some bolts. It’s a 10-minute job, maximum.
I’ll likely get a lot of questions about this project (some of them not so kind, but that comes with the territory), but what I learned is that the set-up does work, and work rather well. Of course, we’re never going to see this type of build show up in a gravel peloton, but in my eyes, gravel is pretty much anything you want it to be. For me in this case, gravel is a mountain bike but faster, and with a drop handlebar!
