Monday 9 December 2013

When is a Single Speed bike most suitable and how to make the most of one

Summary: A single speed bike can be the most suitable, flexible and low maintenance bicycle for many people to get around cities. This post lists the circumstances and cyclists that single speed bikes are most suited to. These include a lack of hills, wanting to minimise maintenance and ongoing costs, short to medium trip distances, and preferred speeds of 20-35km/hr.

For those who are suited to everything about single speed bikes except being limited to only 1 gear, there are two options:

(a) Get a flip-flop hub and put a larger sprocket on one side for the trips when the hills, wind or load requires an easier gear. (Typically flip-flop hubs have a fixed sprocket on the other side but you can fit a second freewheel there will just be a little less thread)

(b) Get a single speed bike with an internal gear hub. These can often be had on sale for ~$400 and usually offer either 3 gears (175% range) or 5 gears (~250% range) - which compares favourably to the ~400% gear range of a 20 speed road bike. I own a XDS Adult Street bike which is identical to a single speed except it comes with a 5 speed Sturmey Archer internal gear hub.
See: Are internal gear hub bikes the secret to low maintenance commuting?

cc licensed ( BY ) flickr photo shared by Mikael Leppä

Related Posts:
What type of bike should I buy?

1. Best if you can avoid hills or can handle the climbs with one gear
- Single speeds are best suited to few steep hills or strong legs or a suitable longer way round. Flat, smooth terrain is always better for single speed bikes and they can be just as quick and effective as geared bikes in these circumstances.

- Try climbing hills of various gradients before purchasing a single speed. You'll know your limit and if hills beyond your limit are going to be a necessary part of your cycling. Gradients below 5% are no problems for most single speed cyclists. Above 10% are challenging for most.

- Often hilly cities (e.g. San Francisco) have cycling routes that avoid hills, so research likely routes and options.

- You'll build up the strength and stamina for climbing on a single speed with regular practice. However, it's important to identify if you will genuinely enjoy this type of riding. E.g. Climbing on a single speed often requires standing not sitting.

2. Well-suited to cyclists that don't currently use many gears
- If you currently use a geared bike (3 to 24 gears) but only use 1-3 adjacent gears the majority of the time then you may be well-suited to switching to a single speed. Most cyclists do not need more than 8 gears and many are already only using 1-3 gears most of the time as the standard gear setup their bikes have makes changing the front gear cumbersome and inefficient.

- Single speeds are also suited to cyclists who prefer to pedal slower and harder when necessary rather than mess around with changing gears.

3. Remember you can choose your single speed gear ratio; Don't settle for the default and err on the side of easier to pedal
- The most important decision to make when opting to switch to a single speed bike is the gear ratio to use. Most single speed bikes are built with a default of a 46 tooth chain ring at the front and either a 16 or 17 tooth cog at the back. However, the size of the back cog can readily be changed to make it easier to climb hills.

- Changing the gear ratio is easiest when buying a "custom single speed/fixie" - where you choose from a range of parts and colours and the bike is then assembled. But even if buying a pre-assembled single speed and you're told that changing the back cog is not allowed, just insist on it if necessary - you will find a retailer willing to do so as these cogs are always readily available and easy to change.

- Note that making the bike easier to pedal up hills by using a larger back cog will also reduce your top speed (as you will "spin out" at a lower max speed), so you need to get the balance right. My girlfriend's single speed bike was changed from a 16 tooth cog to an 18 tooth cog and this allows her to climb almost all hills in inner Melbourne but reduces the top speed on a flat road from 40km/hr to 35km/hr. This isn't an issue for my girlfriend as she has no interest in riding over 35km/hr.

- For generally flat cycling with a few hills, I recommend a 46 / 18 setup. And as cycling conditions get harder - hills, wind, weight of bike (including adding puncture proof tyres like Schwalbe Durano Plus or Marathon Plus) - switch the 18 to a 19 or 20 tooth rear cog.

- If you stick to even numbered gears at front at back (e.g. 46 /18 or 46 / 20 or 48 / 16) there will be less wear and tear and you can extend the life of the chain, rear cog and front chain ring. See: Extending Bicycle Chain and Sprocket Life

4. Your trips and preferences are suited to speeds of 20-35km/hr and you don't desire to pedal above 40km/hr
- My Fuji Declaration single speed bike now has a 46-20 ratio and on a flat, smooth road with no wind, tops out the pedalling speed at around 30km/hr. Your top pedalling speed on a single speed bike is limited by your gear ratio so if you commonly wish to pedal faster than 40km/hr (like you can on road bikes) you may not be best suited.

- Personally, I use my single speed bike predominantly to get around the city and I consider pedalling over 40km/kr to generally be too dangerous. Though I am still able to hit higher speeds when the gradient and wind contribute, such as when riding out of the city.

5. Prepared to make the most of momentum when riding and don't mind standing to take off
- Riding a single speed comfortably and enjoyably is all about getting up to speed, keeping momentum (not accelerating and braking/stopping unnecessarily) and accelerating before you climb hills. If you are prepared to push yourself to accelerate as much as necessary before you hit the bottom of a hill you'll find climbing most hills on a single speed is enjoyable.

- Similarly, single speed bikes best suit riders who proactively maintain momentum rather than brake or stop as they are more difficult to get going from a standstill. It helps if you are prepared to put in extra effort to make the green light and are willing to stand to get up to speed from a stop.

6. Prefer upright riding positions with flat, bullhorn or track handlebars
- Single speeds typically have flat handlebars (or bullhorns which can be held on the flat part) and are suited to upright riding positions. Upright riding positions are desirable for safe, comfortable urban riding. If you have very long, regular trips (over 20km) you may find a road bike with drop handlebars allows for a more aerodynamic, faster ride.

7. Common trips are short to medium distances
- Up to 20km without stops is a comfortable range on single speeds for most people in normal clothes. However, with decent stops breaking up the ride, it's feasible to cover much more km in a day (~80km). However, if you'll regularly be riding longer trips than 20km, you may find cycling-specific clothes and road bicycles are better suited.

8. Have a limited budget for buying a bike and maintaining it
- If you have a limited initial budget you can save significant money not buying gears and derailleurs. However, the real savings are annual as you can much more easily maintain the bike yourself without paying for regular services. Also, the chain and gears will last much longer as you can tighten them as they wear. I estimate mine will comfortably last at least 8,000km. See: Actual cycling expenditures prove how cheap cycling can be

9. Desire a very low maintenance bike
- Regular riders (e.g. daily commuters) can benefit greatly from a bike with only one gear as they can easily clean and maintain their bike themselves. As there are no derailleurs you never need to adjust them. My single speed bike bought in 2012 has never required any paid maintenance and likely never will.

- Single speed gears/chains also can be ridden much longer without requiring replacement as the gears and chain take longer to wear and the chain can also be tightened as it wears by simply moving the rear wheel backward in the dropouts.

10. Do not need to use a rack or affix too many things to the frame or handlebars
- Some single speed bikes do not come with rack mounts and if you've switched to a single speed to make your bike light and stripped down you may not wish to add a rack even if it is possible. Hence, think about how you can minimise what you carry and whether you can rely only on your pockets, a saddle bag, frame attachments and, when necessary, a backpack.

- Single speed bikes with bullhorn or track handlebars also typically use handlebar tape and this may make it more difficult to attach lights, speedometers and other handlebar mounts.

- Unlike some utility bikes, most single speed bikes do not come with full fenders. Most single speed riders prefer this and choose to use light, plastic mudguards (often only at the back) which they keep on only during the rainy season.

11. Desire a light, strong, bullet-proof and ultra-reliable bike. Also one less likely to be damaged or stolen
- Single speed bikes are typically made from steel alloyed with Chromium and Molybdenum ("Chromoly" or Cr-Mo steel). This makes them very strong and durable compared to carbon fibre and aluminium. While not the lightest material, the fact you are carrying a minimalist drivetrain means your bike will be quite light compared to a typical geared commuter, city or comfort bike. See: Understanding Bike Frame Materials

- As they don't have multiple gears and derailleurs, single speed bikes are resistant to accidental damage and vandalism from passersby. Derailleurs are particularly susceptible to damage when bikes are locked together closely and moved without care (e.g. on trains, in public areas).

- Since single speed bikes cost less, have less components, and their wheels are locked with axle nuts not quick release skewers, they are less likely to suffer from opportunistic theft. You still need to lock them correctly with a quality U lock or chain lock, but they are ideal bikes for being able to leave locked up in most places.
See: How to prevent your bike being stolen

- Single speed bikes do have one slight reliability weakness - they typically have horizontal dropouts allowing the rear wheel to be moved forward or back. A couple of times, when the rear axle nuts haven't been super tight, I've had the chain side of my rear wheel knocked forward and jammed against the frame and haven't had a 15mm spanner with me to adjust it. You can eliminate this issue by buying a single speed with a chain tensioner or fitting one afterwards. Or as a simple workaround, just find an object the right size and you can put it between the axle and front of the chain side dropout. I used a Schrader valve cap with a bit of tape to make a tight fit and there is now no lateral shift possible.

12. Get 2 gear options with a flip-flop hub. Or 3-5 gears by buying a single speed-style bike with an internal gear hub
For those who are suited to everything about single speed bikes except being limited to only 1 gear, there are two useful options:

(a) Get a single speed bike with a flip-flop hub - these are quite common with one side being a fixed gear and the other being a freewheel, as some riders prefer fixed and others don't. When you buy these bikes the size of the rear sprockets is usually the same on both sides or the freewheel side has just 1 tooth more.

But, in practice, almost all cyclists prefer riding either fixed or freewheel (I prefer freewheel). While there is slightly less thread available than optimal on the fixed side, you can replace the fixed sprocket with a larger freewheel. This then can give you a much easier gear option for trips where the hills, wind or load are challenging. In my case, I had a 17 tooth sprocket on one side and first added a 18 tooth sprocket to the other. As my bike became a bit heavier and slower (with Schwalbe Marathon Plus tyres and general wear) and I also wished to ride with less exertion, I changed the 17 tooth sprocket to a 20 tooth sprocket. So my two options are now 18 or 20 teeth sprockets.

Note: I use Schwalbe Durano Plus tyres on my bikes and Schwalbe tyres are nominally directional. Obviously, you don't want to have to change the tyre direction everytime you flip the rear wheel. However, unless you are pushing directional tyres to their limits (e.g. cornering fast) and the tread profile is significant (not worn away) it doesn't really matter if the tyres are used opposite to the direction indicated.

(b) Get a single speed bike with an internal gear hub. These can often be had on sale for ~$400 and usually offer either 3 gears (175% range) or 5 gears (~250% range) - which compares favourably to the ~400% gear range of a 20 speed road bike. I also own a XDS Adult Street bike which is identical to a single speed except it comes with a 5 speed Sturmey Archer internal gear hub.

See: > Are internal gear hub bikes the secret to low maintenance commuting?

My XDS Adult Street - Single speed syle but with 5 speed Sturmey Archer internal gear hub

13. How do I find the sweet spot for the gear ratio so I can climb hills but not spin out on the flat at my maximum cadence?
As noted above in Section #3 the most critical decision in choosing a single speed bike is customising the gear ratio to your circumstances and preferences. As chainrings are much more costly to change than rear freewheels or sprockets this tends to mean carefully choosing the rear gear size.

Bear in mind that a new bike with a brand new freewheel and light, speedy tyres will run fast. But if you aren't running a top quality freewheel that stays fast, put on heavier puncture-resistant tyres, or add other things (rack, load, accessories) the bike will be a bit harder to pedal in actual use. So err on the side of making pedalling easier.

My Fuji Declaration started with 46-17 but has slowed down as the stock freewheel has worn, with heavier Schwalbe Marathon Plus tyres on, and I am often carrying a load in a backpack. I have put an 18 tooth freewheel on the fixed side of the flip-flop hub and a 20 tooth freewheel on the freewheel side.

You use the Bike Calc website to estimate the sweet spot for your rear freewheel/sprocket size choices. Below you can see I am running standard large 622mm rims, 28mm tyres and keeping the 46 tooth chainring. A comfortable near-top cadence of 90 (default) is a reasonable number to use.

On the flat at a cadence of 90, I can hit 29.45km/hr on the 18 tooth freewheel and 26.45km/hr on the 20 tooth freewheel. At a max cadence of say 100 I can hit 32.72km/hr on the 18 tooth and 29.39km/hr on the 20 tooth.

This is fine for me. I'll mostly be using the 20 tooth sprocket for regular trips (including shopping, cruising up hills) and would only rarely switch to the 18 tooth spocket for long, mostly-flat trips with no load where I didn't want to take my road bike . Generally, though, I use my road bike for the long, higher-speed trips.

So I can live with the lower top pedalling speed on my single speed bike. For most urban cycling I am happy to top out at 30km/hr on the flat. It's safer, reduces unnecessary sweat and enables me to get better at spinning. Of course, with tailwinds or downhill gradients I will be able to easily go up to 40km/hr.

Fixed Gear Calculator

14. Where to buy affordable, quality 16 - 22 tooth single speed freewheels and sprockets?
This is actually quite challenging, especially once the freewheel you got on your new bike has worn out or you decide it is not the right size for you.

The best quality, single speed freewheels are by White Industries but they are expensive (over $100) and most cyclists prefer to give up some efficiency to save money and keep their bikes a low theft risk.

The lowest quality single speed freewheels have no manufacturer brand and are often missing notches to allow for a freewheel removal tool to be used. You have to take them apart to remove them. They cost $5 to $10. They do work if you need a super cheap freewheel but won't last a long time and probably shouldn't be pushed to the limits (attacking big hills in high gear ratios).

Dicta freewheels are the next level up at about $15. They are reliable enough but not hugely efficient and won't last a very long time.

Shimano freewheels only come in 16, 17 and 18 tooth sizes and cost about $30-40. They are considered to be reliable and good enough for utility cycling.

ACS freewheels have a few quality grades. The grade considered one level up from Shimano is the Crossfire and these are considered to be good, long-lasting freewheels. The Crossfire costs $50-60.

 The above are typical options for Australians. Given my focus on finding the best value-for-money I ultimately have chosen to try out Sturmey Archer freewheels as it is a known, decent quality brand and I can get between 16 and 22 tooth freewheels for $17 at Evans Cycles.

Please note that flip-flop hubs (fixed / freewheel) may use compact (smaller) hub sizes compared to hubs that are designed for a single freewheel or fixed sprocket so check the sizes or compatibility before purchasing freewheels and sprockets.

Further Info:

Sheldon Brown
Articles about Fixed Gear and Singlespeed Cycling and Equipment
Singlespeed Bicycle Conversions

Bike Calc
> Fixed Gear Calculator

Park Tool
> Cassette and Freewheel Removal and Installation
> Freewheel Destructive Removal

Ride More Bikes
> Single Speed Wheelsets and Hubs

How to Rebuild Your Singlespeed Freewheel

> Single Speed Freewheel Overhaul - Disassembly/Assembly

Sturmey Archer
> Single Speed Freewheel Specifications (pdf) (SFS30 thread is 1.37in x 24TPI)

Stack Exchange - Bicycles
How many freewheel thread sizes are there?
How do I change my single-speed to a fixed gear?

Charlie The Bike Monger
> Threaded Single Speed/Fixie Freewheels with comments

Flip-flop hub

Evans Cycles
> Cassettes and Freewheels

SJS Cycles
> Sturmey Archer Single Freewheel Remover Tool