On a recent group ride, I was asked a few questions about my fixed gear bike that I was riding, and thought that maybe it make for a good article. So here it is.
After you get over some of the initial technical hurdles of riding a bike that does not freewheel, riding a fixed gear can benefit your riding and racing whether you are a roadie or a mountain bike rider.
A fixed gear bike is pretty much identical to your normal road bike. In fact many times, as is the case with my fixed gear rig, it is an old road bike that you have lying around or hanging from a hook in your basement or garage.
My fixed gear bike
In order to use a frame as a fixed gear, it must have "horizontal dropouts" to allow you to adjust the chain tension. Using chain tensioner, as you might when making a single-speed bike, will not work when making a fixed gear. When you apply back-pressure to the cranks, the tensioner will be bent or possibly torn off the bike. Most bikes made since the mid-to-late 80's have what are called vertical dropouts, and do not allow for any movement of the rear axle forward or backward to adjust the chain tension. You can use a track frame as fixed gear on the road, but this is less than desirable. The geometry of a track frame is different than a road bike and may be very uncomfortable on longer rides. Also putting brakes on a track frame can be difficult. Although, some manufactures do drill their track frames for brakes.
Horizontal drop(L), v. Vertical drops(R)
The Rear Hub
One other aspect of the fixed gear that you'll need to consider is the rear hub. Instead of the common freehub 7, 8, 9, or 10 speed cassette, you'll be using a thread-on track cog in the rear to drive the bike. The easiest way to set your self up to do this is to use an older, screw-on freewheel hub. The threads on a track cog match those on these hubs. Depending on the design of the cogs you get, you'll probably also need to space the cog on the hub to adjust the chain-line. Multi-speed bikes function quite well even when the chain-line is severely angled. Fixed gears, not so much. You can use the lock rings from English thread bottom brackets. They also have the same threads as the freewheel hubs. If you have enough threads showing after you have your chain-line adjusted, you may want to throw another lockring on the outside of the cog just to ensure it does not unthread while you are riding. If you don't have enough threads showing, use LockTite or a similar product on the cog to sure it up.
Rear hub configuration
The Rest of the Parts
The parts list that remains is pretty short, and if you have a complete bike that you are converting, you probably have everything on hand.
SeatSeatpostFront and Rear brake calipersFront and Rear brake levers (you can use STI shifters, and not run the shift cables).HandlebarsStemHeadsetBottom Bracket Road Cranks(1) Chainring(1) Track Cog(1) 7-Speed, or Track ChainRear Wheel w/ Threaded HubFront wheelCables and CasingPedals
As a general rule, I suggest setting your fixed gear up the same as your road or mountain bike with respect to the saddle height and position fore and aft. The set-up of the handlebars should be such that you are comfortable. The time of the training year that you'll be using this bike most often is one when most of us are not in top condition and your body may need a little rest from being in the aggressive position you are in when on your road or mountain bike.
Cranks and Chainrings
Your normal 170 or 172.5 cranks will work on your new fixed gear just fine. I wouldn't suggest going any longer though, as it may get dangerous in tight corners since you can't coast through turns anymore, and the risk of slapping a pedal is now higher. Doing so on a fixed gear could be disastrous. So be careful.
I have two chainrings on my 170 cranks, a 39 and a 42. Having these two rings on the bike at all times, saves me a step when I want to switch gearings for different rides. It also saved me having to seek out shorter chainring bolts.
I run a 42x18 most of the time on my fixed gear. This gear creates enough resistance on hills to get a good workout, but allows me to maintain good leg speed on the flats and pushes me on the descents. I also have a 16 cog and a few extra chains that I can swap in and out for different gear combinations.
In the earliest part of the training year, I'll use a 39x18 to keep the cadence high and the resistance very light. I also try to choose routes that are flat to rolling, avoiding steep hills altogether. The bulk of my fixed gear work is done in the 42x18 though. In the spring, if I really want to push myself, I go on a group ride with the fixed gear and ride a 50x16. I will say that I don't recommend riding a fixed gear group rides on a regular basis. You should be very, very, very, comfortable on the bike first before attempting a group situation. Also, group riding on a fixed gear isn't really the best training. I suggest collecting several chainrings, cogs, and chains and experimenting with different gearings and see what works for you.
When you put the rear wheel into frame, you want the chain tension tight enough that the chain won't hop off the cog or chainring, but not so tight that it binds. When the chain is binding, it sounds like a crunching noise. The sound will often be in consistent around a single revolution of the cranks, as most chainrings are not perfectly round. Continue to make adjustments to the chain tension, moving the wheel forwards and back, until you don't hear any binding of the chain. With practice, you'll get faster and faster at this process.
Why ride a fixed gear?
The thing I like most about riding a fixed gear, is during the "off season", when you are looking for a mental break from regiment, riding a "fixie" is fun but helps you work on very specific abilities without really thinking about it too much. The gear and the terrain will determine the workout. Fixed gear riding works three major aspects of your cycling abilities that are important to both road mountain riders: Endurance, Leg Speed/Efficiency, and Strength.
Depending the length of your ride, you'll get in a solid Endurance workout and work on your Muscular Endurance as well. Face it. You are pedaling every inch of your rides. There is no coasting. Your muscles quickly adapt to constant use.
On the flats and the descents, you'll work on your pedaling mechanics just by trying to keep up with the rolling cadence of the cranks. To get the most out of your fixed gear riding, try to stay ahead of the crank cadence. For example, if the rolling cadence is 120 rpm, then you'll want to try to pedal at 121+ rpm. When you are not pedaling as fast as the cranks are spinning, you'll know it since you'll be bouncing in the saddle quite a bit. The goal is to become a better spinner, so raise your cadence to smooth things out.
Lastly, fixed gear riding is great for leg strength. When you come into a hill, stay seated. Let the bike slow down and the cadence drop in the 50-70 rpm range. Keep your upper body as still and relaxed as possible and pedal from your hips. Concentrate on pedaling circles applying even pressure all the way around the pedal stroke. Your heart rate should stay low, not raising much above the Tempo zone. Be sure that your cadence stays very low. If you force the cadence up hills, you will raise the intensity and start using more power than you want. This comes at a cost and you will quickly fatigue.
I personally don't see a need for heart rate monitors or bike computers when riding a fixed gear, since you won't be using heart rate or speed as a guide for your training.
I hope that this inspires some to try a fixed gear for training. See you on the road.
Have fun and good luck!