left-hand and right-hand drives

You might have heard the term "left hand-" or "right hand drive" thrown around on many BMX websites. This is simply a description of the side of the bike that has the chain, rear cog, and sprocket. Many bmx hubs come with the option of a right- or left-hand drive. Some are on side-specific while others are ambidextrous- the can be used for let- or right-hand drive.

The standard on bmx bikes and every other kind of bike has always been right-hand drive, so one might ask why anyone would want to put their sprocket on the left side of their bike. The reason is simple: grinding. If you ride ramps or street on your bmx bike, you very likely have pegs on it and use them to stall or grind on ledges, ramps, or rails. If your preferred grinding side is the right side (this is a personal preference just like writing with one hand or the other), your sprocket, chain, and driver are in jeopardy of being mangled. You can get a tank-ish chain, a guard on your sprocket, and a guard on your rear wheel, but a much easier and more reliable solution is to just move your drivetrain to the other side of your bike.

This is easier said than done.

Most hubs are made by default to be used with the chain on the right side of your bike, commonly called RHD for right-hand drive. A LHD hub is made as a mirror-image of a RHD hub. A regular hub has teeth inside the hub or freewheel such that, when the driver rotates clockwise, the hub engages, driving the wheel forward. An LHD hub must be made so that the driver engages when the driver spins anti-clockwise, so the pawls on the driver (or in the hub, if you have a hub with the q-lite system, which subverts the dominant pawl/ring paradigm) engages the hub when turning anti-clockwise.

To move your drivetrain from right to left, you need to start by getting a new hub, or a whole new wheel, that is LHD-compatible. Buying an individual hub might prove to be cost-prohibitive because you will likely need a whole new set of spokes and pay a mechanic to lace up the new hub to the old rim. There are a few hubs on the market that can be easily switched from RHD to LHD and back easily such as the G-Sport Ratchet, but most hubs only swing one way. There are also LHD freewheels for those of you still stuck in the Stone Age, but those also require a LHD, reverse-threaded freewheel hub. Those are very hard to find these days.

The part about this switch that has the most people hung up is getting one's sprocket on the left side of the bike. With traditional bmx cranks, there is a drive hole and bolt only on the right crank arm and nothing on the left. This would leave one to believe that the sprocket can only be used on the right side of the bike, but that would make one WRONG. I will get to that in a moment.

Thank heavens for LHD-compatible cranks! Most modern cranks are now being made with drive holes in both crank arms so that the sprocket can be run on either side without much hassle. Take your crank arms off, swap the sprocket to the opposite arm, re-install your cranks and Bob's yer uncle, you have a LHD drivetrain. If you don't have the luxury of this novel application of technology on your bike, don't fear the structural integrity of the piggy bank, there's hope for you yet!

Conventional wisdom would tell you that swapping your crank arms is a bad idea because your pedals will work themselves as you pedal. In case you were unaware, left-side pedals are "reverse"-threaded tighten anti-clockwise) and right-side pedals have normal (tighten clockwise) threads. I have been told that the Wright Brothers are credited with this invention, but I can't verify that. Anyway, it is possible that reversing that system will result in wobbily pedals that will work themselves loose (due to a mechanical process called precession, which I still do not fully understand) but this is unlikely if you take a few basic precautions like tightening your pedals really, really hard. A little thread-locking substance like Loc-Tite 242 will help too, but that might be overboard. Always grease your pedal threads and torque them down tight. If you check them occasionally and keep your pedals snug in your cranks, they will not cause any sort of catastrophic accident. Just a little mechanical vigilance is all that's needed to avert a pedal/ crank separation disaster.

If you go this route to swapping your drive-side, you will encounter one other obstacle: your left pedal will now be on the right and the right pedal on the left. You may never have noticed, but most flat pedals are designed with a parallelogram profile so that the top platform is always nudged a little farther forward than the one on the bottom.

(mad MS Paint skillz!)

Left and right are mirror images of each other, so swapping your pedals is going to make them feel awkward under your feet. Awkward is a word with appropriate spelling, because typing or writing that word is, for lack of a better word, awkward. I can't do anything with that latter linguistic problem but the former mechanical conundrum has an easy fix: disassemble your pedals, swap the pedal spindles with their respective pedal bodies, and reassemble. This might be more difficult that it sounds. Disemboweling a pedal of it's bearings and putting it back together so that it spins smoothly takes some finesse. Take care and don't loose all those darn tiny bearings!

Regarding grind-sides, many bmx riders run pegs on only one side of their bike because that is their preferred grind side. Doing this limits one to grinding only certain objects and doing it only one way. If you roll up to a perfect handrail and it's on one side of your bike and your pegs on on the other, you might find a creative way to grind that rail by hoping over it, doing a 180 and grinding it backwards, or grinding up the rail. If none of those options are in your bag of tricks, you are going to just have to move on. The other option is to run four pegs and learn to grind in an ambidextrous manner. There is something ethereal and yin-yang about "completing the circle" and learning to spin both directions, bar spins and tailwhips both ways, opposite wall rides, etc that is worth exploring. Ask Dan Price about that.

Nevertheless, you are most likely going to have a preferred grind side and your chain should be on whatever side is going to see the least amount of abuse from grinding.

BMX in skateparks!

Be kind to you two-wheel-ed friends

Some of you live in towns where there are no public skateparks. Others have a local public skatepark but the "no bikes" rule is enforced leaving you with no fun, legal, safe place to ride. Below are my thoughts and experiences with skateparks and how to get one built or get access to the one that already exists.

The first thing to do is to stop whining about it and moaning incoherent comments about skateboarders and go do something about it. Things are not going to change by them. Gandhi did not ask the British nicely to leave India and then step back. He acted.

Do some research and be ready to articulate your argument for why the local authorities should build a public skatepark or let bikes in the one you already have. Most of the reasons why bikes are not allowed in skateparks are bogus, so refute those claims. Write it all down.

When you have some idea what you want to say, call your local city government and ask to talk to someone in the Parks and Recreation Department, or whatever department you have that handles stuff like that. Ask them if you can set up an appointment to sit down and talk with him/her in person. Talking over the phone will not get you anywhere most of the time. Give them copies of any information about the advantages of public skateparks, reasons why bikes should be allowed, statistics on how many people are into skating/bmx, etc.

Next, get a coalition of skaters, inliners, bmx riders, local bike- and skateshop owners, PARENTS, teachers, etc interested in helping you with the effort to support, design and build the thing or get your bikes allowed in the park. Getting adults, especially parents, will help the cause a LOT. Depending on your age, most of you probably don’t pay taxes and you don't vote, but your parents do. There is tons of information on the Internet about public skateparks. Start here: http://bmxriders.org/ (lots of links from there too.)

A note about petitions: get LOCAL people to sign a petition if you want to go that route or gathering support. Online petitions are easy to create but they are worthless. Do not bother getting all of your buddies on Myspace to sign your petition. No civic official is going to care if Joe Blow from Australia signed your petition if you are trying to get a park built in Springfield, USA. Joe doesn’t pay taxes, work, or vote in your town, so why would city officials care what he thinks they should do with other people's taxes? Getting a broad coalition of individuals from different walks of life (age, education, sex, occupation, location in town, etc) is going to mean a lot more than sheer numbers.

Next, go to any public parks department or City Council meeting, or whatever equivalent you have in your town. The city council may be a good idea, but the parks department would be the place to start because they are the ones who have to bring the idea of a skatepark before city council before anything else can happen, so go to the parks department first. They should allow a time for public comments, so you can stand up before the Council and state your case for a publicly funded skatepark for skating and BMX riding, or a change to the rules at the skatepark(s) you have to allow bikes. They will be 1) ecstatic about the idea, 2) confused and hesitant or 3) totally opposed to the idea. Don’t get discouraged if they aren't immediately stoked on the idea. It takes some cities more than a decade to be convinced to build a public skatepark. If some nearby towns have public skateparks already, invite the folks from your town to use those skateparks as examples.

If you're lucky, the local newspaper will catch on and write about it. Find out who the reporters in the audience and talk to them. If you can't find a reporter (they are a dying breed, I know this from personal experience!), call one on the phone. They may be itching for a good story and want to write about your plight. Free publicity! Make sure you find someone articulate to talk to the newspaper.

Once city leaders realize there is a demand for a public skatepark that allows bikes, just like there is a demand for walking trails, playgrounds and athletic facilities like baseball, soccer, tennis, etc, they will want to get started. The best thing to do, in case they don’t think of this, is to have a public meeting, inviting all interested locals to share their ideas for skatepark design, location, features, etc. publicize that meeting big! 

Once the ball gets rolling, make sure the local skaters and BMX riders stay involved in the process the whole way through! If the city thinks they can do it on their own, they will screw it up and make a crappy skatepark that no one will ride, wasting a ton of taxpayer money. Make sure they get an actual skatepark designer to design the park. Old guys who have never stepped on a skateboard might know a lot about designing libraries and sidewalks, but a skatepark needs a skater/rider to design it or it will be a big waste of money.

Keep in mind that this is a long process. You are dealing with government bureaucracy and taxpayers' money. They will probably have to wait until the next bond election for the voters to have a referendum on how they want their tax dollars spent. It may be easier and faster, in the meantime, to go to a local civic organization to get something temporary built. A local church, YMCA, Boys and Girls Club, etc might be able to get something built faster, so try those too.

If you are writing a letter and you are not a seasoned writer, ask an English/composition or government/civics teacher from school to help you. If you are a student, maybe they will give you extra credit! If you really get involved in this, you will be A) writing a formal letter (writing skills), B) delivering a speech in public (English/speech skills) and C) engaging democracy in a concrete way (government/civics skills). A teacher might also help you articulate your argument and make sure the letter looks good so they will pay more attention.

I have seen this process in action more than once. Do not hesitate to ask me more questions about public skateparks.

compendium of bmx hub types and gear ratios

One of the most common questions about BMX bikes that I hear is "I want a smaller sprocket, what should I buy?"

The first question you must ask yourself is: why do I want a small sprocket so badly? The answer probably has a lot to do with peer pressure. Peer pressure is not a phenomenon relegated to kids, we are all subject to social conformity. So when one peruses a magazine and see that every single rider in there has a sprocket that is no larger than a compact disc, one assumes that a tiny sprocket it necessary to riding bmx.

The truth is that most bmx riders have small sprockets because they can. Either it came with their bike or the spent some money doing a conversion. These days, it's hard to find a bike that comes with a larger sprocket, but if you have an older BMX bike or a cheap-ish bike, you might have a dinner plate, as it is known in the parlance of our times.

Smaller sprockets are lighter and stronger due to their size, and who does not want a lighter and stronger bike? They also make certain grinds and riding ramps a little easier because they are out of the way. Back in the dinosaur days of 16t freewheels and 45t sprockets, we old dudes bashed a lot of chains on ledges, driving us to insanities such as the KMC 415 garage-door type chain (another great image here) and sprockets with 3/16" teeth. (Normal road bike sprockets are known to have a 3/32" chain and bmx/single-speed bikes have 1/8" chains) Also popular were the dinner plate-esque full sprocket guards.

If you think you need a tiny sprocket, give it up. You don't. If your bike is too heavy, do some pushups. Take a dump before you go out riding. If your big ol' sprocket hits the coping when you drop in, un-weight the back end of your bike as you go over. That's how Mirra and Hoffman did it for many years.

When you are ready and have the money to upgrade to a smaller drivetrain for the reasons above, there are a few things to consider: component compatibility, gear ratio, and durability.

Component compatibility:

This is the most complicated part of upgrading any part on a bicycle. Thankfully, compatibility issues on a bmx bike are not nearly as complicated as components on a road or mountain bike. Here as some things to assess:

What kind of hub do I have now?

• If you have a standard freewheel hub, your choices are very limited. A standard bmx freewheel hub works by accepting a thread-on freewheel of various sizes 16-tooth and larger. The hub itself has no drive mechanism inside it but instead the freewheel has a series of ratcheting pawls and teeth which allow it engage when rolling forward and to coast. To maintain a ride-able gear ratio (which I will get into in a bit) with a 16t freewheel, you need a 43-45t sprocket or chainring.
• If you have a flipflop hub, each side of the hub will have a threaded protrusion for a thread-on freewheel, but one side is larger than the other. The large side of a bmx flipflop hub accepts 16t and larger freewheels, while the smaller size accepts 13-15t freewheels. Odyssey and KHE sell 13t freewheels that are fairly reliable. It should be noted that DK made a 12t freewheel, but quickly dropped the product after it failed many riders. Avoid.
• If you want that cool micro-gear ratio setup that all the cool kids have, you need a bmx cassette hub. A BMX "cassette" hub (not the same as a "cassette" on a multi-geared bike) has a built-in ratcheting drive mechanism similar to that of a freewheel. Because the ratcheting mechanism is inside the hub, it allows for smaller sprockets. A bmx cassette hub has a driver, which engages the drive mechanism inside the hub and is home to a cog of some sort. Some drivers have separate cogs that can be changed out (this is what is referred to as a "two-piece driver"), while other drivers have cog teeth built onto the driver, known as a "one-piece driver." Two-piece drivers typically don't go smaller than 12t, while a one-piece driver can be as small as 8t. Eight teeth is crazy-small!

Gear ratio

Now that you have an idea what components are available, you need to take into consideration the size of your sprocket relative to the size of your driver. A typical gear ratio for a 20" bmx bike is 2.75:1. This means that the front sprocket is 2.75 times larger than the rear sprocket, or that the rear wheel will make 2.75 rotation for every full rotation of the cranks. The standard for bmx bikes for many years was 44/16. Mathematically, 16 times 2.75 is 44 and 44 divided by 2.75 is 16. So if you want a smaller sprocket you need a combination that is mathematically similar to the 44/16 combo.

If you ride a combo that is much higher than that, the bike will be difficult to accelerate but will be easy to maintain a high top speed. With a ratio much lower than 2.75, the bike will accelerate quickly but soon "top out" and you will be spinning like a hamster and going nowhere. Some people prefer a non-standard ratio and that is fine, just don't end up riding a difficult gear ratio by arming yourself with knowledge before buying parts. For simplicity, keep your gear ratio between 2.5 and 3.0 and you should be fine.

If all that math sounds complex, let's simplify. Stick with the common combos that most riders trust. Common gear combos that are close to the standard ratio are:
43-45/16
39/14
36/13
33/12
30/11
28/10
25/9
22-23/8

As these numbers get smaller, a change in a single tooth becomes more profound. In other words, if you go from a 43/16 to a 44/16, you won't feel as much of a difference as if you changed from 28/10 to 29/10. Also, a change in the number of teeth on the rear wheel makes a bigger difference than a change in the number of teeth on the sprocket. This is clearly illustrated if you do the arithmetic but I will spare you the calculations for now.

You will be limited to a 44/16 ratio if you have a regular freewheel hub. The smallest freewheel for this kind of hub is a 16t, so putting a smaller sprocket on your bike will lower your ratio. If you want to flail wildly like and fool and go nowhere in "hamster gear," be my guest. Please, for your own sanity, don't get a sprocket smaller than 36t if you have a 16t freewheel.

If you have a flipflop hub, your options are a little less limited. You can run a 13t freewheel (Odyssey and KHE make these) and a 36t sprocket and have the same ratio as the old 44/16 setup.

A bmx cassette hub gives you a widest array of gear ratio options. Many cassette hubs have the option of a two-piece driver with 12t and larger drivers, or a one-piece driver with 11 teeth and as low as 9t on most hubs. A few hubs go as small as 8t. A tiny one-piece driver used to be an after-market upgrade to your hub, but most modern cassette hubs and freecoaster hubs (more on those another day) come standard with a tiny one-piece driver.

Durability: Is the smallest combo always the best?

I will answer that with a resounding NO! There are advantages to a tiny gear combo: it's lighter due to a smaller sprocket and shorter chain, it creates more clearance under your bike for dropping in on ramps and grinding, and the sprockets are generally stronger due to their small size. However, smaller drivers and sprockets will wear out faster. When a chain is wrapped around a sprocket, it basically engages half of the teeth on the sprocket. So on a 44/16 ratio, the front sprocket engages the chain on 22 teeth and the rear engages 8 teeth. you can mash down on that all you want and it's going to take a long time to wear out the teeth on those cogs, assuming they are quality components. On a multi-geared bike, the smallest chainrings and smallest cassette cogs are always the first to wear out.

Now picture a 22/8 combo. The chain is engaging only 11 teeth on the front and 4 teeth on the rear. Mash down on that and you are putting the same amount of force as with a larger combo, but each tooth is taking more force per tooth. The result is prematurely worn teeth and a more quickly-stretching chain. If you don't mind frequently replacing your driver, sprocket, and chain, this is not an issue. If you want the peace of mind of a drivetrain that will last a while longer, compromise between a small combo and one that has more teeth. I run a 28/10 combo on my own bike and that is the lowest I feel safe.

A note about tiny drivers and bearings: most hubs with 9t drivers use tiny sealed cartridge bearings that are known to blow out more quickly than larger drivers. It seems that 9 teeth and 10t is the cut-off point where a smaller bearing must be used due to size restrictions. Anything 10t and larger probably uses a larger bearing that is not so prone to exploding when you sneeze at it. However, many companies are dealing with this issue by putting needle bearings that handle the pressure of a tiny drivetrain better than standard cartridge bearings. When buying a tiny driver, be aware of the bearings in the driver you you will be stuck with a frequently broken driver, constantly shelling out money and labor replacing them. Manufacturers have recently found ways to make hubs with more durable bearings (even needle bearings) but be aware that, if your driver bearing blows up, that's probably why.

That is it for my compendium on bmx hubs and gear ratios. Please let me know if you have any suggestions, corrections, etc.

first things first

I love bicycles. The only thing I enjoy more than riding bicycles is taking an old, unloved bike and giving it new life. In the days that follow, I will document my adventures in finding, resuscitating and rehabilitating old bikes. I will probably write about a lot of other adventures and misadventures along the way.