'Theoria'

How to Choose a Gravel Bike: Part 1 – Key Questions and Materials

I’ve been meaning to do a piece for a while on gravel bikes, and how to think through one’s needs. When I say ‘needs,’ I mean the word in the pragmatic sense, not as a proxy for ‘wants.’ I don’t want to come across as a pusher of stuff; I don’t believe in that. I believe in taking a good, hard look at what we need to achieve our goals and aspirations, and choosing our tools wisely. I believe in tools that are driven by function, not fashion. Buy once, enjoy for life. This is a ‘materialism’ that focuses on the quality, usefulness, and durability of things rather than the acquisition of wealth and material possessions.

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But there’s a problem. Nothing lasts forever. I’ll never forget the day I was at BikeWay with my older brother sometime around 1994, as he shopped for a new mountain bike, his first from a bike shop instead of a department store. “What’s this one?” he asked, pointing at a titanium bike on a pedestal. “Oh, that’s titanium; it’s BOMB-PROOF!” said the salesman. “Whoa, bomb-proof!” We figured that justified its massive sticker price; the bike would never break! My brother walked out with an entry-level Cannondale M400, which he enjoyed for a few years before upgrading to a Catamount full suspension bike, possibly one of the worst riding bikes of the 1990s.

Anyhow, titanium bikes break, just like bikes made out of every material known to humankind. I’ve personally seen plenty of reputable titanium bikes crack. If bike companies built bikes that didn’t break with today’s (affordable) materials, nobody would want to ride them; they would feel horrible. So bikes, and virtually every component that comprise them, have finite lifespans, or ‘life-cycles.’ It’s really good to know how long your bike parts were designed to last, and retire them before they fail. I can tell you from experience, this is wise.

I say all this to point to the fact that riding bikes, and riding bikes a lot in particular, means that bringing more bike stuff into our lives is necessary in order to keep riding. Unlike coffee tables, watches and cutlery, there is no ‘this bike part/frame will last me for LIFE!’ Instead, there are life-cycles, and decisions to be made about when to retire equipment (if anyone can point me to the life-cycle chart one of the component brands put out a while ago to inform these decisions, please let me know; can’t find it!), and what to replace it with.

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Enter ‘gravel riding.’ For some, a new gravel bike will fall into the N+1 stream, ‘N’ being the current number of bikes owned, ‘1’ the next new bike. “Oh, there’s a new kind of bike I can add to my stable? Cool, what should I get?” If you want to buy a ‘gravel bike’ for the sake of having a gravel bike, what follows probably won’t be relevant to you. It might. I mean, read it and see. But my target audience here is the rider who wants to make an informed decision about what sort of bike to get to meet their actual or intended riding needs. I am going to talk about what matters in a ‘gravel bike’ for people who are going to ride them, either sometimes, a lot, or somewhere in the middle. Spoiler, paint doesn’t matter.

Before we jump in, one last insight worth mentioning: ‘gravel’ events and plain ol’ riding is evolving, in part because the technology being made available is changing, and riders are asking for more from producers putting equipment onto the market. While 10 years ago a ‘dirt road’ bike could easily have set up with 30mm tires for events like D2R2. However, as riders have pushed their bikes harder and further on unpaved surfaces, they’ve, we’ve asked for more tire volume. Does this sound like a familiar story? See ‘mountain bike evolution’ and ‘fat bike evolution.’ More volume is l’ordre du jour in most categories, from road (23mm to 25mm), MTB (2.3″ to 3″), fat bike (4″ to 5″), and ‘gravel’ (28mm to 40mm). Where does it end? I’ll provide my view in the final installment of this three-part series.

In this initial post, we’ll look at how to start the thought process of selecting a gravel bike. In Socratic fashion, we’ll use key questions to orient the process.

Asking the right questions

I get a regular influx of emails and messages about gravel and cyclocross bikes, wheels, and tires, and I always take time to respond thoroughly. In this case, when Paul de Swart emailed, I figured I might as well save my response and use if for a post. So, here we go:

Paul: ‎Hi – I would consider your club the authority on hard core gravel riding.   As experienced experts, I would appreciate any recommendations you have have for a great gravel bike. I already have a cross bike, but I am looking for a new ride suited for long days of riding gravel, trails and races like the D2R2.    A bike which could handle wider tires than most cross bikes would be also be great.   

I have looked into the Niner RLT in steel but at an estimated $5200 it is very expensive due to very limited CDN distribution.   

If you have any strong recommendations for bikes which are comfortable in the long haul and great value builds ‎I would be very grateful for any advice you could offer.  

Have you had a chance to ride the Salsa Warbird in carbon?  

I liked Paul’s question. It was targeted, and showed that he’d done a lot of research and thinking about his needs and the value proposition of different models on the market. I will address the key questions Paul raised, and build on them.

What is ‘gravel,’ anyhow, and why can’t I ride what I already own?
For years we called the unpaved roads we rode ‘dirt roads.’ We still do, but the bike industry decided to call all unpaved roads ‘gravel,’ probably because ‘gravel bike’ is easier to say than ‘all-terrain bike,’ or ‘all-road bike’ (which had traction for a while), or whatever. Slicing bikes into ever narrower sub-genres always ends up being pretty silly, as we’ve seen with the proliferation of categories within mountain biking. For example, ‘trail bike’ is actually a mountain bike category, despite the fact that all mountain bikes are designed for trail riding.

Gravel bikes are drop-bar bikes that fill in the gap between cyclocross bikes and drop-bar mountain bikes. If you’re asking what the hell a drop-bar mountain bike is, just picture a regular hardtail mountain bike, whatever that is, with drop bars and a rigid fork. I’ve written about my experience with adapting a 29er into drop-bar mode, and that experience has heavily influenced my perspective on what makes a good gravel bike for me. Another rider might not land in the same conclusions, but I’ll elaborate mine, and try to help you understand how to think about your needs.

Basically, gravel bikes are primarily about tire clearance; this is the most obvious difference between them – or at least ‘proper’ examples – and cyclocross bikes. In my view, road bikes with clearance for 30mm tires are not legitimate ‘gravel bikes.’ Being able to ride on a smooth dirt or packed gravel road doesn’t make a bike a dedicated platform for ‘gravel.’ Why not?

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‘Gravel’ covers a broad swath of terrain. For some, it’s packed dirt roads that can be ridden on 28mm tires, no problem. For others, it’s crushed rock up to baby-head sized. Then there’s trails. The adventurous approach of taking routes off pavement is that one can link up roads with trails, or vice versa! Some regions have miles upon miles of mellow trails that are a joy to ride on a drop-bar bike, but boring on a mountain bike.

Recommendation: When moving through the process of selecting a gravel bike, work through the following questions, which will help you determine which are better suited to you an your needs. You might find that you can use what you already own for most of the gravel riding you’ll want to do. Or not, it comes down to whether you’ll be selective about the rides you do, or will be open to take on just about any route an event or your buddies throw at you.

1) Where will I ride the bike, and what is the terrain like?

  • If you expect to use the bike for mostly local riding, what is that riding like? Buff dirt roads? Chunky gravel? Trails, no trails? Fast descents? If you don’t expect to stray from pretty hard-packed dirt roads, you can have a great time on a bike with clearance for 30-32mm tires. As long as it has good geometry, it’ll be fun.
  • If you expect to use the bike for all manner of surfaces, you’ll want more tire clearance for rubber up to 40-42mm, perhaps even bigger, 50mm. If you’re a mountain biker who loves the trails, forego the slim clearance bikes and go for one with big clearance to keep your options open.

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2) Will I stick to flattish terrain, or seek out hilly routes?

  • Some of the gravel bikes on the market are being optimized for single chainrings. If you will ride mostly in an area without big climbs, that’ll work. If you have big hills, and/or like to travel with your bike, you’ll benefit from using a compact double crank with a wide-range cassette in the back, like an 11-36. This is the recipe or a true ‘go anywhere’ drop bar bike.
  • Disc brakes dominate the gravel category, and have lots of advantages. However, it you ride flattish terrain in mostly good weather, they could be overkill for you. For hilly terrain, I would always lean toward them, and if your flattish terrain has pointy rocks, disc brakes will be better too, as you will likely dent your rims if they’re alloy.
  • Overall bike weight will matter more the longer and steeper your climbs are. If you really don’t have much of that, or you have terrain that allows you to carry momentum well, you really don’t need to fret about bike weight. The most important aspect of your system in terms of performance will be your fit on the bike (including aerodynamics) and your tire performance.

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3) Is this bike for ‘just riding,’ ‘racing,’ something in between, or both?

  • The ‘how’ part of the riding matters. If you don’t intend to ride this bike at your limit, don’t worry too much about aerodynamics and bike weight. Look at a set-up that will excite you about riding – whatever that it – and run with it. For some, this will be a pretty gnarly set-up that allows them to ride fairly techinical trails in a way that is different from the MTB experience. For others, the bike will need to be optimized for racing, and thus replicate their road bike position, but with larger tires, and perhaps different gearing.
  • For lots of trail riding, a more upright position will work best, and some frames are built for this, while others emulate road bike positions.

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4) What’s my budget?

  • This is going to be vital for most. Remember that the most important aspects of a bike set-up at the time of purchase is the frame and fork design and construction, and how they fit you, the rider. Next most important is wheels, which will essentially determine the character of the bike. Next in line is compoments, which are easily changed as they wear out or are found ill-fitting to one’s needs. Some, however, like single chainrings, are not necessarily easily changed. Like the custom MTB below, Rob English can make you a custom ride optimized for your riding, or you can pick one off the rack; different strokes for different folks.

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Ok, with these probing questions out of the way, how can we tell the ‘real deal’ gravel bikes from the pretenders? We’ll start with frame and fork materials.

What makes a bike suitable for ‘gravel?’

This is a question about a whole slew of elements, but when considering a whole gravel bike it’s key to consider the core aspects that comprise the ‘essence’ of the bike: the frame and fork. Everything else is interchangeable, and should be considered secondary when assessing complete bike options.
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Frames and forks are of course made out of different materials, and manufactured in different ways, from robot-built to hand-built, all of which drives their pricing. Given marketing points to carbon as the holy grail of frame materials, it is forgivable that most riders believe it is their only option for a high quality frame. The truth of the matter is that every material has a host of properties that count as benefits and detriments. For example, steel is rather ductile, so it tends to bend before breaking. That’s great in a crash! But to get steel light enough to feel ‘fast,’ the tubing has to be quite thin, making it not exactly hard to dent. It’s also ferrous, so one has to protect it from rust.

Carbon fibre, in contrast, tends to fail more, ummm, dramatically, particularly when used for the lightest road race bikes, but it doesn’t fatigue through load cycling unless there are imperfections in its construction (this is the tough part to ascertain as a buyer). It is very amenable to shaping for aerodynamics and ride quality (i.e., to absorb vibration), making it a highly tuneable frame material. It also requires a lot of labour, and that little of that is done at North American or western European living wages, so when it is, the price ratchets up proportionally (see Parlee’s $9k frame/fork). Or it’s simply high because R&D and marketing budgets need to be accounted for in profit margins. Not to mention the costs accrued by companies associated with conterfeits of their products….

On the aluminum front, as my friend south of the border, Jeff Roberts, reminds me, hydroforming is enabling companies to produce high-performing frames that surpass the ride quality previously possible, especially when deployed in the rear end of the bike (i.e., flattened seat-stays). A few companies are producing great aluminum race-level bikes across categories these days, which is great news for those looking for a stellar return on investment. The caveat here is that aluminum has a finite fatigue life significantly shorter than steel or carbon, so one must monitor these frames and retire them before they get to the end of their life-cycles. The good news is they are not expensive to replace, and can be recycled.

Let’s not leave out titanium (I actually did, have added this in)! I have yet to own a ti bike, despite lusting after them for years. Why not? Great titanium frames are expensive, and since they do tend to last a long time, I’d like to make sure I nail my format and geometry when I finally get one. By that, I mean, I want my first ti frame to be fairly ‘future proof.’ Back to matter, ti is really ‘hard,’ meaning it’s hard to cut, and it’s quite dent resistant. The hard to cut part combines with the hard-to-weld nature of the material, which both conspire to make manufacture more challenging and costly than with the other metals. When built well, however, ti is the strongest, most durable metal option for bikes, and is generally though of as a life-long investment. In terms of ride quality – ‘stiffness, compliance, vibration damping’ – ti will ride effectively the same as other metals when built with the same diameter tubes in the same thicknesses. While ti has a reputation for being ‘whippy’ compared to steel or aluminum, I firmly believe that this all comes down to tubing diameter and thickness. If a builder wants their bike to ride ‘whippy’ in ti, small diameter tubes reasonably thin will ge them there. If a ‘stiff’ ride is desired, larger diameter tubes, thin, will get them there.

Regardless of the material, each builder – mass production or custom – will have their own ideas about what amount of flex is ideal in a frame. This is a subject I could go deep into, but in general, it’s should suffice to say that large diameter tubes will generally ride ‘stiff’ and small diameter tubes will generally ride ‘comfortable.’ Carbon is the frame material that allows builders to use large, perhaps aerodynamic tubes AND maintain comfortable ride characteristics. This isn’t possible out of the other materials at present.

Gravel bikes are clearly for riding on rough terrain, so one has to consider what feel is desired, and how to get there. That is, a stiff frame like the Prologue below will benefit from a compliant seatpost, perhaps shallow-ish carbon wheels, and high volume tires on rough roads, while a bike like my Truffle Pig can use deeper wheels and smaller tires for the same road and wind up feeling similar (yet perhaps be faster, thanks to aerodynamic gains).

To further complicate things, one must consider how the bike will be ridden, i.e., what sort of power will go into the bike most of the time. If the riding will be long(ish) and steady, a more flexible seat-tube will allow for an efficient pedalling rhythm. The same bike won’t feel as good in a sprint or a steep, out of the saddle climb as one with a stiffer seat-tube. These are trade-offs. Cyclocross bikes are often optimized for accellerations, and thus use larger diameter, stiffer tubes than we commonly see used in steel road bikes (and steel CX bikes).

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Forks come in carbon, steel, and aluminum, and carbon is now well established as the gold-standard for ride quality and durability. Thank god the durability part has been figured out! Steel forks tend to be either low-end or custom, the latter affording builders the freedom to tune ride quality and geometry for the rider, whereas most carbon forks off the shelf come in one rake (more on that later). Some companies use different rakes for different frame sizes, many don’t. Steel forks are heavier than the other two, but can also be very strong. Aluminum forks are not very common anymore, and are best avoided, in my opinion. They tend to be overly stiff, and not terribly durable.

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That’s key questions and materials in a blink. From a riding perspective, if we could put costing and everything else associated with materials to the side, geometry matters far more than frame material. One could construct the lightest, strongest frame imaginable in any frame material, but if its geometry was wacky, the bike would be horrible, perhaps dangerous to ride. How wacky is wacky? A head angle as little as two degrees steeper than usual on a 55cm bike (say, 75 degrees) would be downright scary to ride on a loose gravel descent with a typical fork. Subtle differences in geometry are what make frames and forks feel ‘right’ in different conditions versus ‘nervous,’ ‘squirrely,’ or, on the other end of the spectrum, sluggish.

In Part 2 I’ll delve deeper into geometry, setting the stage for Part 3, which will focus on wheels and tires.

Please feel free to fire off questions you’d like addressed either here, or in the following parts, and I’ll do my best to answer! You can submit questions below, on FaceBook, or via email: teknecycling@gmail.com

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How to clean your bike in ten easy steps

Archive: Vermont Overland Grand Prix: Crush and/or be Crushed

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