Off-Road Fixed Gear Setup, Revisited -- Part I
by Matt Chester
Well, here we go again. I'm here to revisit my thoughts on setting up a fixed gear bicycle for off-road usage. It's been a while since I last wrote on this topic, and now I have a few more years of experience (and hopefully of wisdom as well).
This is a two-parter: this first part will cover some basics regarding your frame, fit issues, gearing choices, and crank length. The second part, appearing in the next issue of 63xc.com, will concentrate on the more empirical, nuts-and-bolts territory of component selection.
Fixed gear off-road is gaining converts, mostly from the singlespeed MTB world. Its growing popularity shows, albeit in a small way, how everything is cyclic (no pun intended). You see the same cycles in politics, music, design, and other areas. Everything is impermanent. As cyclists, we are just following trails that were opened up long ago by other riders, riders who didn't have access to the myriad of component choices that we do now.
Before getting started, I thought I might say a few words about the fixed gear 'attitude'.
While exploring earlier, simpler forms of cycling, you should always remember the Fixer's Mantra: 'Calm down.' Really. Riding a fixie off-road is pretty daunting at first, and you'll need a new set of skills to ride successfully. (By 'successfully' I mean: 'without hurting yourself'.) Stripping things to the bare essentials certainly makes them 'simpler'. It doesn't necessarily make them 'easier' or even 'better'. It takes patience and repetitive practice to bring an ethos of 'doing more with less' to fruition.
So why bother to acquire those new skills?
Fixers will tell you that a fix is more efficient than a geared bike. Well, that's true--up to a point. The fix certainly scores high in foul weather or icy conditions. As an everyday offroad machine, however, its simple setup often works out less than ideal from a performance perspective.
So what? I'm not worried about performance. My own love of fixing comes from the fact that I like to cycle, and a quiet, basic machine appeals to me. My good memories of cycling have little to do with equipment and everything to do with experience.
Ride your bike to ride your bike. Do it because you want to. If you approach riding with a relaxed, light disposition rather than with an aggressive mindset, you'll really enjoy yourself. If you enjoy yourself, you'll stick with it. Sticking with it is good.
I assume that readers of this site are already familiar with the basic points of singlespeed and fixed gear setup, in particular the ways that the need to tension the chain impacts on frame choice. (If not, you can find a nice primer in the sidebar.) I'll take the opportunity to repeat, however, that no fixer can use chain tensioners like the Surly Singleator, Soulcraft Convert, Paul Melvin, or dummy derailleurs which are common in the singlespeed world. If you set up an external tensioner on your fix and try to apply backpressure to the pedals, tension in the bottom run of chain will force the thing out of the chainline. The result will be a broken tensioner and often a bent derailleur hanger... or worse. So, no tensioners! OK? You can still use track ends/horizontal dropouts, eccentric bottom brackets (EBBs), or eccentric hubs.
Now, let's discuss fixed-gear specific aspects of frame design.
1. Seat tube angle and saddle position
I built my freewheeled singlespeed 'cross bike with a steep seat tube--75 degrees, believe it or not. I really enjoyed riding it. I loved the quick transition between seated and standing climbing and, once my hamstrings were used to the position, I thought I'd never ride a slacker seat tube angle.
But when I made the full-time change to fixed off-road, I found that my 'cross bike made descending hard. Since there was no way to get behind the saddle, I had to stay seated, putting my weight as far back as possible and pedalling all the way. Descents on gnarly terrain made me feel like a ski jumper, making panicky stabs at my front brake as I hung over the front wheel and tried to keep the whole flailing mess together. High speed fireroad descents, where clipping out and 'coasting' were impossible, would find me bunched forward on the bike, weighting my hands excessively while trying to maintain a non-freakish-looking level of blurry high-RPM spinning.
When I built myself a new frame, I utilized a more traditional 73 degree seat angle. The difference was marked. I'm no star on a bike, but I was much more comfortable with more weight on my rear end and a lower center of gravity. Nor did I notice any ill effects on climbing, leg speed, or whatever. The new position was different, but suited to a broader range of situations.
Now, seat tube angle is one of the grayer aspects of frame dimensioning, as many external variables can affect the relationship between your saddle and your pedals--seatpost layback, saddle position, position of foot on pedal... My advice is to err on the side of slack. Keep your seat back and set the bars a bit higher than on your coasting bike. I'll return to this point when I talk about fit later on.
2. Bottom bracket height
Bottom bracket height is more of an issue for fixers than coasties. This has less to do with handling characteristics than with pedal clearance, a quality which is also affected by crank length, pedal choice, and tire choice. However, while these last three are easily changeable according to the rider's preference, BB height relates to the frame design and can't easily be changed.
In practice, it's hard to reach a fair measure of BB height, because it can be affected by tire choice. Most framebuilders prefer to talk about 'drop'. This term denotes the vertical distance between the bottom bracket center and a line passing between the hub centers. A traditional real world 700c road bike (a Rivendell, say, or a classic British tourer) would have a drop of around 80mm. A real roughstuff 700c cyclocross bike would have much less drop, say 60-65mm. Since the 'cross bike will likely be set up with larger, taller, knobblier tires, the bottom bracket will gain even more height. A higher BB gives more pedaling clearance, which is advantageous in a cyclocross race where aggressive cornering and rough terrain are all part of the hour's worth of extreme effort.
Fixers ride off-road without being able to 'ratchet' the cranks or to hold our feet in the '3 and 9' position when coasting through rough bits, so lots of pedal clearance seems like a good idea. But, guess what? Even on a frame with an insanely small drop--perhaps even a negative one, like on a 26" wheeler with a BB above the hub center--you'll still strike a pedal sometimes. That's just reality.
The point is: don't give in to fear. Just get out and ride a lot! The real trick to getting through obstacles on a fixie is your own ability. Practice. That's it. The standard ranges of drop on existing off-road bikes are more than adequate.
I myself ride a bike with 70mm of drop and a 700 x 35c tire. (70mm is pretty normal--for a road-specific machine.) Of course, I use 165mm cranks despite my 6'2 height. But we'll talk more about cranks later.
3. Chainstay length
Chainstay length is subjected to incessant analysis. 'Shorter chainstays are better for climbing!' crows the internet discussion forum sage. Utter nonsense! No single aspect of frame design will enable you to predict a bike's handling characteristics. (If that were really the case, my job would be much easier.) In the real world, all aspects of frame design work in concert with one another. Adjust one, and the others are affected.
Why am I wailing on the oft-repeated myth of the 'short chainstay?' Because there's more to building a good off-road fix than lopping the chainstays wicked short. Here are the things that I've learned from experience.
The first is that you are seated on a fixed gear. A lot. On rough terrain. Any frame design which tucks the rear wheel underneath you is likely to produce an uncomfortable ride.
The second is even more important--to me, at least. You will find that the shorter the chainstay, more difficult it is to keep the rear of the bike tracking straight while pedaling at some ungodly RPM down a mountain pass.
It is possible to combine a longish rear end with good climbing. The old guys knew this already. I have learned, too.
4. Frame overview
So, let's review. Based on points 1-3, it seems that a stable, conservative, somewhat traditional, commonsense frame design is best. It's no longer the 1980s! There's no reason to take things to the extreme and then declare 'it's better because--' Nope. If you look back to the days when almost everyone rode the dirt on a fixed gear, or even just back to the early days of mountain biking when adventure, self-sufficiency, and fun were the order of the day--well, that's the way it was. Keep it basic and simple! We've been locked into our own 'it's better because--' phase for too long. Turn off the computer, put down the magazine, and go ride. It's your only hope!
If you continue riding fixed gear both on and off-road, you will soon discover that many bike industry's innovations have been well-meaning and indirect attempts to sidestep the crucial issue of fit.
A low ratio fixed gear--especially a rigid one--gives you nowhere to hide. If you take a freewheeled bike on a long ride and your back/hamstrings/neck/whatever start stiffening, no problem! Stand up on the pedals and stretch when descending, right? That moment just doesn't occur on a fixie. Technical descending? You're seated or hovering (depending on the grade) the whole way as you pedal. High speed descending? You're usually weighting your hands while sitting forward on your saddle and spinning like crazy. Twisty quick singletrack? Keep that body low while, yes, pedaling! I could go on. The simple fact is: a fix denies you opportunities to unweight your backside, legs, or hands. Suspension forks, rear suspension, suspension seatposts, squishy gloves, gel saddles, inline top mount brake levers, etc. have all been developed for the comfort of the gearie off-road crowd. We're riding fixiess in the dirt! What chance in hell do we have?
Plenty, actually. Just deal with the basics.
Fit is important, and dialing in your cockpit length and bar height is crucial. I don't want to generalize too much about what works, because everyone is different--but there is a general goal for all to reach. It starts with a relatively high bar position, higher than you might use on a gearie XC MTB or cyclocross bike.
But be careful how you set those bars. Jacking your bars up blindly does little good. Since the headtube angle on bicycle frames is more acute than 90 degrees, raising the bars brings them closer to you, effectively shortening your cockpit. A too-short cockpit can be just as uncomfortable over long distances as a saddle that is set excessively higher than your handlebars.
Optimize your cockpit length in concert with your handlebar height. You should aim to ride very 'light' on the bike, yet still be able to climb with power and descend with confidence. When I talk about being 'light on the bike' I mean: very little pressure on your hands when riding the flats, no undue pressure on your backside and sensitive bits, very little shrugging or bunching in your shoulders, and no undue strain on your neck. Your position should be as relaxed as possible, so that you are draping yourself over the bike like a piece of cloth. If you are relaxed, you will experience less fatigue over the course of a ride, and be better able to react to the situations that arise. Smooth steering input and finite adjustments in position are much easier when you aren't operating in a state of tension.
Having worked with a lot of setups over the last few years, I've come to feel that very, very few people are sitting as comfortably as they could be. Achieving a good riding position, especially on a stock frame, involves time, patience, a little trial and error--and an open mind!
When setting bikes up for customers, I've often specced longer-than-usual effective top tubes and unusual stem dimensions. This is especially true when working with non-standard handlebar configurations--moustache bars, North Road bars, Jones bars, drops especially. Sometimes the resulting machine is far from the customer's idea of 'normal', but my experience has been that functional setups of this kind pay huge dividends in reduced fatigue and improved concentration.
I'm aware that my advice may sound hopelessly general. The truth is, we're adaptable creatures! We can get used to anything over time--check the Mike Ferrentino anecdote in the sidebar. We humans differ so much dimensionally--even before we factor in our preconceived 'preferences'--that there's just no plug-n-chug way to express good bike fit.
Shut up and ride, right?
No aspect of riding a fixed gear, on- or off-road, has been argued over as much as gear selection. Except for maybe crank length. So here are my thoughts on both topics. I don't expect them to quell the discussion.
What's best? 'It depends.' Always. If you feel the need to ask for a definite answer--don't. Ever. Just like bike fit, we're all different, and the external variables are numerous. They include topography, surface, windiness (of the terrain, not your internals) and on and on...
So let's talk about gearing. If you are not already familiar with the measurement of 'gear inches,' read about them in the sidebar. Let's also simplify things by looking solely at steep, hilly terrain with little flat. Think of Southern California, or the Cascades.
Most singlespeeders run a gear in the 42-55" range. Freewheel gears at the low end of that range are great in our theoretical terrain, since they allow the singlespeeder to coast the downhills. But as soon as you change over to a fixed cog, a low-40s gear really isn't great at all. It will make any extended descent into a miserable experience.
Singlespeeders have always pondered one question: 'What gear will get me over these hills without grenading myself?' Fixers have a second question to worry about: 'What gear will get me over this hill and down the other side without grenading myself?' The fact is that the downhills can be just as challenging as the uphills.
There are two possible responses to these contradictory demands. The first is to wear your lockring wrench down to nubs and round off all your 5mm allen keys by incessantly changing chainrings and cog looking for that one angelic gear, the one that is 'right' all the time!
The other approach is to bolt on what you've got, ride it, and deal with the consequences.
Like I said earlier, 'simple' doesn't necessarily mean 'easy.' There is no 'right' gear. There are 'acceptable' gears... and that's about it. Singlespeeders are either incredibly overgeared or laughably undergeared depending on their spot on the map at a particular moment. The same goes for fixers. The fact that you have to pedal speedily on the way down means you should try and be a little more optimistic on what sort of gear you can push going up. Get stronger!
Folks coming from a singlespeed MTB background will usually go for a bigger gear than they have ridden before. A good example is my pal Rudi (also a contributor to 63xc.com), who rides a great deal of hilly terrain in southern Arizona including lots of 100 mile and 24hr races. He's usually on the podium of the singlespeed class and often times on the overall classification podium as well. Rudi generally ran 'normal' ratios in his freewheeling days but opted for a 38x18 gear on his fixed gear sled--resulting in a ~54" gear depending on the tires he was running. The Team Hugh Jass guys in Virginia have been running bigger ratios on their fixies than most johnny-come-lately single speeders for the better part of a decade.
Rudi and I have talked a lot about gearing over the years and the conclusion we've come to is that you definitely want to gear up a little for the sake of downhilling, but not so much so that you make it difficult to accelerate on the way up. You're certain to find yourself grossly undergeared for the flats or downhills, so learn to spin, don't be in such a damn hurry, and be happy about it. The XC ski superstar of yore Gunde Svan had a great quote when talking about classic skiing (kicking and gliding rather than skating). He said: 'You must hurry slowly.' If you want to go faster when riding a 50-something-inch gear on 10 miles of flat pavement--calm down, relax your body, pick up your knees, and smile. You'll go faster, but try not to think about it!
I ride a slightly higher gear myself, a 36x16. With my skinny tires, that puts me on about 61". Why? Well, I ride one bike for everything and I find this to be the best compromise. Do I have to walk sometimes? Yep. Remember, even if you're riding one gear you always have another gear. Your 24" gear. Two feet. Remember the mantra: 'Calm down.' There's no harm in walking sometimes. Pushing doesn't make you a wuss or weakling, and your ego shouldn't depend on getting up Hill X without putting a foot down. Have fun!
So, what gear should you run? 'It depends.' Yeah, I'm helpful.
Crank length 'depends' too. Freewheeling singlespeeders have often opted for longer cranks, usually 180mm ones, in order to gain a little more leverage when reefing up the steeps. That's fine, especially when you're coasting through the techy terrain and down the hills. Fixed gear riding is a bit more complex, since you're pedaling everywhere.
Along with many other off-road fixers, I favor shorter cranks. They seem to be advantageous in a broad range of situations. Wes Williams (of Willits Brand fame) got me started on this years ago, even when I was riding a freewheel. For my formative years of onespeeding off-road, I rode and recommended 180mm or longer cranks for reasons of mechanical advantage. Wes scoffed at that and gave me a quick lesson distilling what he'd learned from riding fixed gears off-road for the better part of twenty years. Steep, difficult climbing is definitely part of the single gear experience--but why not get that little bit stronger and push shorter cranks that will serve your needs much better for high RPM pedalling on the flats and downhill? I find it less of a challenge to climb with short cranks than to spin at 150+ RPM with 180mm cranks. Short cranks also give you additional pedal clearance and reduce the likelihood of toe overlap, which may be important to shorter riders on 700c/29" wheeled bikes.
After talking to Wes, I sold off my 180mm Ritcheys and bolted on some 170mm Mavics. I've never gone back. These days I ride 165mm Sugino XD cranks, despite being a gangly 6'2". (Not really a traditional setup, as I mentioned before.) Sure, I lose some leverage, no question. But I can get round that with a more aggressive approach to climbing. You want to stay on top of the gear as best you can with leg speed. Gears and crank length don't result in speed--leg speed results in speed. In a tight spot where you lose all your momentum, well, you've got to toughen up and turn that gear over with a shorter lever. There's no free lunch.
You are still the most important component on the bike and it is up to you to decide what choice will provide the best usage over a broad range of circumstances. For me, shorter cranks are the ticket. Others I'm sure will raise a chorus of disagreement. Again, helpful huh?
One aside: Sheldon Brown has developed a method for describing gears which he calls 'gain ratio'. It incorporates both gear ratio and crank length. By introducing crank length as a variable, leverage is now incorporated in comparing how 'easy' or 'hard' a gear is--a quality omitted from the standard gear inch measure. Sheldon's system is simple and smart! There's a link in the sidebar.
So that concludes Part I, in all its anecdotal vagueness. In Part II, I'll get a little more in depth about mechanical setup, with notes about cranks, bottom brackets, chainrings, cogs, lockrings (or not), chains, rear hubs, pedals, brakes, saddles, and tire choice.
Thanks for reading and I'll talk to you next issue!