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!
17 thoughts on “I took a perfectly good mountain bike and built into a convertible gravel bike… and it was great!”
Thois has no place on ROAD CC. Please remove it. Padding out content with irrelevant partner guff isn’t a good look and you’ll pay for it in the long run.
I think it could be a bit clearer what this article is about exactly.
There is this talk about ‘making a convertible mtb/gravel bike’, and I don’t think I am the only one who thought you were trying to make a bike that can easily switch from a gravel (drop bar) to a mtb (flat bar) setup.
So I was curious what solutions you came up with for the various problems that brings with it (especially the cables). And then, almost at the end, it turned out that you have basically turned it into a gravel setup fulltime, except that you can change out the wheels to make it more mtb-ish.
Who’s Thois, and what have they done to upset you?
@mdavidford – He’s a cousin of Thanos, but he just has kidney stones.
It was a simple typo – they were referring to Thoir; thundering their disapproval and suggesting road.cc’s ratings will get hammered.
@chrisonabike – it’s a common mistake if you’re typing in Norse code
My convertible mtb uses a Chinese carbon version of the Surley corner bars. Needed a different stem to adjust the position (a smaller frame size would have worked better) converted to 2x from 1x to give a better range for the road. Using the same brakes and shifters makes it a quick simple swap.
Have put drop bars on a 2001 B1 mtb, a 2007 stumpy hardtail and a 2010 stumpy full suss. In all cases fairly basic conversións leaving gearing and wheels broadly the same and concentrating on correct positioning of bars and fit. Oddly, with all 3 I was happy with the result when recently done, but after a few months found that the extra speed on easy trails was more than offset by the lack of ability (probably mine) on tougher routes and finally preferred flat bar with slammed and inverted stem as best overall compromise. Good fun playing around, though.
That’s where the convertible aspect comes in. I’ve got a gravel bike but the canal I sometimes commute on has roots under the tarmac and barriers. The mtb with ‘drops’ is more comfortable for this and fits through the barriers. If I want to do something more technical I can put the flat bars on.
I did this a couple years ago with my Saracen Mantra Trail Elite 650b Hard tail MTB. All my mates were spending 1000s on new Gravel bikes. I decided to spend about £400 and convert the Saracen. It’s perfect, it’s so so comfortable to ride. I put rigid forks and 700c wheels on. I ride it regularly.
@Sredlums The main convertible component is just the handlebar. By using SRAM’s AXS kit and modifying the drop-lever brakes very, very slightly, I can run flat-mount brakes without adapters on the drop bar, and just throw the flat bar in place and nip up the caliper bolts to bring it back to a full MTB.
Wait, you put the AXS drop bar brakes on flat bars? And here I am with my Canyon Exceed actually swapping AXS to flat bar brakes and rebleeding each time. Though there are solutions for that too these days
I mean, there’s nothing stopping you from putting drop levers on a flat bar, it’ll just be quite weird. Here I’ve got two sets of brakes, the SRAM DB8 that came with the Sorceress that stay on the bar that also came with the bike. I’ve then got Rival AXS levers hooked up to Level Ultimate calipers that stay on the drop bar.
There are quick hose links around; I’ve just found them harder to come by.
@Liam Mercer: But that’s my point…
If you chop off the roof off a car, you didn’t turn it into a convertible. You converted it into a roofless car.
Same with your bike.
You did not make a ‘convertible gravel bike’.
You converted your mtb into a gravel bike.
A convertible (car) can, easily and because it is designed to do so, *convert* from open mode to closed mode.
For your bike to be a convertible bike it should be able to, easily and because you altered it for it, *convert* from gravel mode to another mode.
@Sredlums But it can easily be *converted* between modes. Five-minute job. Just pop the flat bar on, which has the necessary brakes and hoses still attached, and bolt on the correct wheels? Nothing I’ve done here is permanent.
For gravel, take the drop bar with necessary brakes and hoses still fitted and bolt that on, with the correct wheels.
@Liam Mercer What is it like to ride? In particular how is the steering with the very short stem? What would the bike be like to ride with a smaller frame with a lower stack height and deeper drops?
@Pub bike It was surprisingly natural and much more comfortable and ‘right’ than I anticipated. The steering was a little more laboured than what you would get with a purpose-built gravel bike, but it worked well enough.
A smaller frame with a longer stem would make it feel much more like a regular gravel bike, but then I would lose the performance that I would want from the mountain bike with a flat bar.