Building a Road Plus Gravel Bike

"Roads? Where we’re going we don’t need roads."

Doc was right. If you’re too young to know that quote, stop reading this article immediately and go watch the 1985 classic “Back to the Future”. And feel the mild shame of not knowing such a great moment in cinematic history.

I bring up those words of wisdom because that mentality is the flavor of the year in cycling. Some of us were in to cyclocross, touring, or other kinda-road-but-not a long time ago, but it has officially become mainstream in 2018. Our publisher, Dan Empfield recently wrote about the spanking new idea of gravel triathlons. All I wonder is – how did it take this long for something so cool?

There are lots of ways you can cut this cake – and that’s part of the appeal to me. Do you call it off-road? Road Plus? The easiest catch-all term, to me, is Gravel. If you’re on a budget and have an old mountain bike sitting in your garage, you’ve got a gravel bike. If you bought a cyclocross bike or found one on Craigslist, you’ve got a gravel bike. Touring bike? Gravel bike. Beach cruiser? That’s pushing it, but if you really wanted to, be my guest.

Basically, all you need is something with fatter tires than a road bike, to give you extra grip and safety when the going gets rough. There’s no clear line where road ends and gravel begins (in terms of tire size), but I’ll venture that it’s somewhere around 32mm. Yes, you can ride some gravel roads on tires smaller than that, but I think it’s a fair starting point. For really rough roads, some folks are even using mountain-bike-size tires on 650b diameter wheels (with an outer tire diameter comparable to a standard 700c road tire). When in doubt, err on the larger size for extra safety and monster-truck-factor.

Rather than sit back and watch all this happen, I wanted to get myself a real, modern gravel bike. I’ve had several gravel-ey bikes in the past, but I had never tried 650b wheels nor a true single chainring 1x11 drivetrain (though I’ve done MacGyver systems in the past with 9 or 10 gears out back).

So – I bought myself a new Surly Midnight Special, in hot mayonnaise color. I picked this bike for a few reasons:

1) It fit my budget
2) It fits massive tires (up to 700x42mm or 650b x 60mm (about 2.35”)
3) It fits me
4) As the kids would say, “It’s sick”! In other words, Surly has great marketing and I just had to get on the train.

While Surly says that the bike is a rough road bike (“Road Plus”), I’m lumping it in to the over-arching category of gravel. It just has slightly quicker steering than a true, dedicated gravel bike – which I prefer anyhow.

In this article, I’m going to detail the build, why I chose what I chose, and my initial riding impressions. Cliff’s notes: Very good bike for the price, geometry nails what they set out to do, two technical details bother me as a grumpy mechanic.

Key Drivetrain – Shifters, Crankset, Rear Derailleur, and Cassette

The shifters are a set of Shimano Ultegra 6800’s. Why? They were sitting in my garage, and they have never let me down. I matched them up with an Ultegra 6800 crankset in 175mm length, because they’re being blown out at internet retailers, as Shimano switches to the newer Ultegra 8000 series (translation: they were cheap). For the rear derailleur, I chose the mountain bike-focused XT in a medium cage length. This should handle any cassette size I want to use, and for starters I have an 11-32 Ultegra 11-speed. I also like the fact that it has a clutch mechanism, to avoid chain slap and improve chain retention.

Since Shimano doesn’t officially support single chainring (1x) systems for road use, I needed some help doing the conversion. Shimano road shifters don’t pull the same amount of cable as their mountain bike shifters, so I shouldn’t technically be able to use that XT rear derailleur. However, there is a very slick little converter available from Wolf Tooth Components, called the Tanpan – pictured below. This allows the use of a Shimano road shifter with a Shimano mountain bike derailleur. Combined with a Wolf Tooth 1x-specific, 4-bolt chainring, I have a fully-functional Shimano 1x system.

Wheels and Tires

This is my first time having a 650b wheel (also known as 27.5”). Hed’s tried and true Ardennes Plus SL are available in this smaller size, with a 25mm-wide tubeless-ready rim. They can send you these wheels with any of the modern axle “standards” – Quick release skewers, 12mm front thru axle, 15mm front thru axle, 12mm rear thru axle. More on dropouts and axles later.

For tires, I’m using the outstanding WTB Horizon in 650b x 47mm size. These have become quite popular, seemingly hitting all of the high points – good grip, feel, puncture resistance, and they’re even tubeless-ready. Note that I’m currently running inner tubes with them (gasp!) because I have plans to use some different tires very soon (and swap back and forth), and just didn’t want to mess with sealant yet until I have committed to a tire – at least for a while. Though I haven’t ridden the bike a tremendous amount yet, I’ve been rolling at about 40psi, and it feels smoother than hot mayonnaise.

Brakes – Calipers and Rotors

I’m going to spill the beans, because this is one of the two problems I have with the Surly Midnight Special. It isn’t Surly’s fault alone, but rather the industry’s unwillingness to cooperate. We currently have THREE active standards for attaching a disc brake caliper to the bike: IS, post mount, and flat mount. From a technical standpoint, I really don’t care or have a strong preference between these three. They all work. The problem is that the industry can’t agree or decide on one (or even two), so all three are just dragging along and requiring a lot more inventory in the pipeline of bike shops and suppliers – different calipers, forks, adapters, bolts, spacers, and duct tape.

THIS page has a good primer, which helped me understand and decide what I needed. I used Shimano CX77 brakes, which would normally be used on a post-mount frame, so I needed flat-mount adapters (they don’t make a flat-mount-specific version of this brake). The conversion works. I did have an issue with what I believe is a bad bolt, or bad thread in the frame for the flat-mount. I am 99.9% sure it wasn’t cross threaded, but the bolt just wouldn’t take, and it stripped out. Luckily, I keep a big bin of high quality steel bolts in various sizes, and found a replacement that fixed the issue (perhaps cutting/fixing the frame threads). NOTE: You cannot use a flat-mount caliper on a post-mount frame. No such adapter exists.

At the end of the day, having so many brake standards limits the amount of brakes you can use, and adds complication. Not to mention, the adapters add a bunch of weight and clunkiness to the bike when they’re trying to slim things down with the new standards (I’m getting nightmare-like flashbacks to all of the bottom bracket adapters we still live with). If this all sounds like a foreign language to you – this is why we need bike shops and good mechanics.

If I was in charge, Surly would have used IS-mount or post mount because there are a lot more cable-actuated discs brakes in the world which are compatible with these more established standards (and cable-actuated brakes hit lower price points… which is usually what Surly targets). As a company, Surly normally puts a high value on compatibility and having the freedom to build a “parts bin” bike – with whatever is laying around your garage. To me, flat mount doesn’t fit into this strategy.

As far as the brakes themselves go, I enjoy the CX-77s once they’re set up. They feel good and are on the quiet end of the spectrum for disc brakes. The only issue is that the clearance between the rotor and pads is VERY tight. You’re going to need a rotor truing tool (which you probably already have if you own a disc brake bike). The rotors must be PERFECTLY straight. I’m an experienced mechanic, and the time it took to go from new brake parts in boxes to everything mounted, cabled, and adjusted to being quiet and 100% dialed was at least 90 minutes. Of course, I had to deal with all of the adapters and a bad thread in the front fork, but let’s just say that you may want to let your mechanic handle this one.

Cockpit – Bar, Stem, Seatpost, Headset, Saddle

For the standard controls – I went no-nonsense. Thomson makes outstanding bars, stems, and posts, and I’ve never had a single problem with them. Actually, I’m well-versed in their stems and seatposts, but this was my first foray with their handlebars. I went with the round profile and 72mm reach. So far, so good. The stem is an X4 mountain bike stem (because the Surly has a short head tube for me, and I wanted the 90 degree angle that the X4 offers). The post is a tried-and-true Elite – perhaps the best seatpost of all-time.

The headset is another tried-and-true winner in my book – the Cane Creek 40 Series. I have used these and their predecessors time and time again. They work, replacement bearings are easy to get, and they don’t break the bank. Note that the Surly has a 44mm head tube, meaning that it can accommodate tapered forks (with a 1.5-inch lower bearing, and 1 1/8” upper bearing). However, Surly’s stock fork uses a straight 11/8” steerer tube, requiring the use of a special reducer from Cane Creek.

For the saddle, I used the SMP Avant, which has quickly become my go-to road saddle. It has a 154mm width, wide cutout, and seems to fit me like a glove. As the millennials (or whatever generation we’re on now) would say: 10/10 would recommend.

Finally, I used the Shelter frame protection kit from Effetto Mariposa to protect my investment. This is essentially thick, flexible, clear, adhesive-backed tape that protects your frame from dings, scratches, and cable housing rub.

Thru Axle Woes

This is the second area in which my grumpiness gets the best of me. There are a million and one different axle standards out there. For the layman, these are all different methods for attaching wheels to your bike. The old standard of quick release skewers are by-far the easiest to live with, and arguably one of the most important bicycle-related inventions of all time. The industry has slowly shifted away from these in favor of large-diameter thru axles, which allow marginally better stiffness. In other words, if you’re a large or strong person, the axles will resist bending better when you’re out of the saddle or grinding a big gear. This can translate in to your bike’s steering feeling a little bit more secure – again, if you’re a big fella or gal.

I don’t have an inherent problem with thru axles from an engineering standpoint. It’s the practical implications that get me. For the front of the bike you’ll need to buy an adapter to mount the bike on a fork-mount roof rack or repair stand. For the rear, you’ll need an adapter to mount the bike on an indoor trainer. No big deal, right?

Surly did an interesting thing. They made dropouts that are unique and can fit wheels with either 12mm thru axles, OR regular quick release skewers (pictured below). For this, they get a point for backwards-compatibility. BUT – for use on an indoor trainer, deduct two points because their rear axle doesn’t line up with any of the three existing 12mm thru axle “standards” that I’m aware of.

I have three rear thru axle adapters from Kurt Kinetic. They offer a fine, medium, and coarse threading to work with all of the various frames out there. None of them fit the Surly. So, I got creative and used the medium-thread axle with two washers from the coarse thread axle kit, and voila - it worked.

The result put two large protruding axle ends sticking out – and it just barely fit in to my CycleOps SuperMagneto trainer. My suggestion to you is – if you’re buying this bike and plan to use an indoor trainer, use wheels with good ol’ quick release skewers.

Build It

Brake and axle woes aside, I really like this bike. I can go crazy with any tire I want, and now that it’s dialed in, the bike should be relatively easy to live with (but I’m definitely going to ride a different bike on the indoor trainer).

I’m looking forward to getting to know the bike more, but so far it’s doing everything I expected. The handling is lively, the ride quality is VERY smooth (tire pressure dependent), and I’m excited to see such a strange bike become kind-sorta normal in the eyes of the marketplace. I will definitely keep my fingers crossed for a gravel triathlon to pop up in my region, too!

If you really want to know the proper way to build up a bike with this much attitude, I encourage you to check out the video below. You must begin as I did and open up a can of PBR - using a hammer. I had a lot of fun, but your mileage may vary. Bikes are serious business, right?