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Fixed Gear on the Cheap

Les's bike

by Tom Deakins
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Thinking of building a fixed gear bike?
This article is a step-by-step "walk through" of fixed gear conversion issues.
It is an adjunct to Sheldon's excellent article on Fixed Gear Conversions.

Also, see Sheldon's article on why people like fixed gear bikes.

Fixed Gear For The Road

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Many bikes and frames are suitable for fixed gear use, but older road bikes are the ones most commonly available. A typical example is this 10-speed Univega (pictured above). Made in Japan, around 1977-78, the bike came with a steel lugged frame, friction shifting, 27 inch wheels with steel rims, a 5 speed freewheel, and double chainrings.

Choosing a bike

If you are looking for an inexpensive way to get into fixed gear riding, you may want to consider starting with an older road bike.

If you are not sure what to look for, see Sheldon's article Fixed Gear Conversions., the "Frames for Fixed Gear Conversion" section.

Also, if you are not sure how to determine if the bike fits you, please read Sheldon's article on bike fit. And some additional thoughts for conversion useage.

Warning: Fixed-gear riding is habit forming, and once you get hooked, you are likely to want to upgrade to a better fixer!

6 Steps to Fixed Gear
What to Do Why to do it.
Remove un-needed components. No need to carry the stuff around anymore.
Select your chainring and determine your chainline. Straight chainline works best.
Replace the freewheel with a track sprocket. One sprocket= fixed gear.
Respace the rear wheel's axle To put the sprocket in correct alignment with the chainring.
Redish the rear wheel To center the rim in the frame.
Put on a new chain. New sprocket will quickly wear out with an old chain.

Original Drivetrain

The original drivetrain.

If the bike has the older 27 " wheels, you don't have to replace the 27 " wheels because Tires , and rims , are still available for this size.

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Components to Remove
This is the stuff you won't need any longer.
ComponentsWhy
Shifters and CablesYou won't need them
Both DerailersYou won't use these either.
Chain If it's old and worn.
Chainring The one you aren't going to use.
Tools You Will Need
Because there so much variation in older bike components, this list is meant to cover most possibilities, but not all. So plan on at least one trip to get the correct size tool.
ToolSize or TypeWhy
ScrewdriversSlotted and PhillipsFor removing shifters and cable guides.
Allen Wrenches4, 5 and 6 mm For removing handlebars,stems,derailers,...
Open/box
end wrenches
At least 8, 10, 12, 13, 14, 15, 16, 17 mm Have a set handy, for removing derailers, cables, hub locknuts, etc...
Freewheel toolsFreewheel remover You will need the appropriate removal tool for your brand of freewheel...
Freewheel toolsSturdy vise or BIG adjustable wrench The freewheel is probably very tight, it will take a lot of leverage to break it free...
Cone Wrenches Most rear hubs use 15 mm; most fronts 13 mm Depending on the hub, you will need 2 of the correct size to move spacers around and to retighten the cones and locknuts.
Extras Chain Tool Needed if you want to replace the chain.
Extras Cable Cutting tool A bike cable housing cutter, diagonal cutter or shear cutter should be used.
Extras Small Ruler To measure chainlines front and rear.
Possibles Crank Puller On some cranksets, the chainrings can't be removed without removing the crank.
Possibles Allen Wrench or socket wrench For cotterless cranks.
Possibles Hammer If it's a cottered crank.

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Reworked Crankset

Old Bike Maintenance

If your old bike has not had any work done on it recently, then you should also check and replace as needed:

If you are not sure how to approach the above repair items, look here for Sheldon's repair index.

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The bike parts you will need are:
ItemWhy
Short Stack Bolts For use with only one chainring.The stock bolts will be too long.
Rear Sprocket Hopefully you know the answer to this one.
New Chain 3/32 "is the derailer standard. We recommend going with it unless you are using 1/8 "sprockets and/or a 1/8"chainring.
Brake Cables and housing You should replace them if they are old.
Brake Pads You REALLY should replace these if they are old.
Ball bearings and grease In case the hubs need them.
Thread Locker To put on the sprocket to ensure it doesn't unscrew.
Bottom Bracket Lockring To put on the hub to hold the sprocket on.
Rear Axle spacers Get a variety of sizes 1,2,3,4 mm, so that you can select the correct combination for spacing the rear axle.
New Fixed-Gear Rear Wheel Optional, but the easiest way to go. Can get a fixed/free flip/flop hub.

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Conversion Work:
WorkWhy
New vs. Old Wheel Decision First you have to decide if you want to use your old wheel or buy a new fixed-specific one.
Freehub Rear Wheels Not for fixed gear, only for singlespeed.
Setting chainline A procedure to ensure it is staight.
Respacing to get this chainline To get the sprocket in the correct position for a straight chainline.
Redishing To move the rim into correct alignment with the frame.
Sprocket/Chainring Selection Thoughts on deciding what gear ratio you want.
New Chain Length A procedure to select the best length of chain.
Setting Chainring Roundness To have the same tension on the chain for the entire revolution of the chainring.

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New wheel vs old wheel:

The lowest cost way to create a fixed gear bike is to keep and reuse it's rear wheel.

However, the simplist and fastest is to buy a fixed-gear specific rear wheel.

A new wheel has significant advantages over reusing an old freewheel-rear wheel. The main advantage ( other than it being new, straight and shiny ) is the ability to run a lockring to hold the rear sprocket on.

Hubs made for fixed-gear use have two threaded sections on one, or both, sides.

You can check out the fixed gear wheel options and decide if that's the way you want to go.

Removing the freewheel.

If you decide to use your old wheel, you will need to remove the freewheel and replace it with a track sprocket ( size of your choice ).

If you haven't removed a freewheel before, you'll need to get the specific removal tool for your freewheel.

The harder part is redishing the wheel and aligning the track sprocket with the chainring.

Your local shop can respace the axle and redish the wheel. However, be aware that if problems crop up in the rework of the old wheel, you can easily spend more in shop labor than in the cost of a new fixed gear wheel. Things like spokes breaking, bent axles, spokes rusted to nipples, rims not being straight, hubs worn out, etc., can create havoc in reusing an old wheel.

Freehub rear wheels

If you have a freehub wheel, the ratcheting freewheel mechanism is built into the hub body. So you can't ( practically ) have a fixed gear bike with one of these. However, you can build a singlespeed by replacing the cassette cogset with one sprocket and a set of spacers

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Chainline

The Chainline should run straight from the chainring to the sprocket. A couple millimeters either way will make a difference. Please read Sheldon's article on Chainline.

If you hear the drivetrain making noises, it's probable that the chain's side plates are hitting the sprocket or chainring teeth. You will have to get the chainline closer to perfect.

Check the picture of our project bikes' chainline before I respaced the axle and redished the wheel. The sprocket is inboard of the chainring by a few millimeters. While this isn't terrible, it's not good enough for a fixed gear.

Since both the rear sprocket and the front chainring can be positioned in or out ( from the centerline of the bike ) with spacers, you have two variables with which to work.

Since we're talking about older road bikes, the distance from the centerline of the bike to the center of the smaller/inner chainring is about 41-42 mm for most road-double chainrings.

Respacing the rear axle

Respacing the rear wheel requires taking off the cone lock nuts and moving spacers from the right side to the left side until you get the sprocket in direct fore/aft alignment with the chainring.

Like most 10-speeds, our project bike's rear wheel did not need a lot of rim movement. It only needed to be moved about 5 mm to the right.

Solid Axle

If you have a sold (nutted) axle, you should re-center the axle on the hub. It's nice to have both ends of the (solid) axle stick out of the dropouts the same length.

Loosen both cone locknuts and turn both cone-nuts to the right to move the axle to the left.

This is a good time to backoff the cone locknuts and regrease your hub's bearings.

Once you have the axle recentered and the correct length of spacers on the sprocket side, add enough spacers on the left side of the hub to exactly match the inside width of your dropouts.

Follow Sheldon's article on cone adjustment.

Hollow axle(quick release)

You will Definitely have to center the axle and move spacers.

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Redishing

Redishing the wheel involves moving the rim to the left so that it is, again, in the center of the frame.

You can do this on the bike. You don't need a wheel stand.

You WILL need a spoke wrench that fits your wheel's nipples.

Now, before starting to tighten the left side spokes, it's a good time to get extra spokes in the correct lengths. With old wheels, it's possible that some spokes will break when tightened. And/or nipples will round off or crack.

Take one from each side to your local bike shop and get at least 3-4 of each length. That way, you will have them if any of the old ones break during the dishing/truing process.

Also, with old wheels, it's good to lube the rim eyelets and spoke threads. Some may be corroded or even rusted. They won't tighten easily without some oil or grease on them.

Sprocket/Chainring selection

We are frequently asked, "What should I use for a sprocket if I'm running an X-tooth chainring?".

I wish I could just answer, "Well, you use an 18 tooth sprocket for a 42 tooth chainring.". But it depends on you and the terrain you're riding.

We advise most people to buy two sprocket sizes so they can experiement. You should expect to change either the sprocket or the chainring or both before you have a combination you're happy with.

I, being old and slow, ride a 17 tooth sprocket with a 42 tooth chainring in hilly New England. Therefore: the cliche...

"Your mileage may vary."

I also advise people to ride their currrent road bike (if they have one) in each gear combination and decide which one they would like to be 'stuck' in for a long ride.

Remember, you can't coast. So you will be spinning on every downhill.

You are looking for a midpoint where it is possible to crank up hills, in or out of the saddle, and spin down those hills without having to clamp the front brake hard enought to overheat the rim.

Read Sheldon's section on Gearing.

One more thing. Don't use cheap track sprockets. They are not threaded across their entire width. Because of that, their few steel threads can strip the hub's aluminum threads.

Good ones are wider and fully threaded.

When installing the sprocket, we recommend you use some sort of thread locker, along with a lockring.

These lockrings also fit bottom bracket cups. Same diameter and threads.

The hub you use may not have a lot of threads showing after you install the sprocket, so make sure the sprocket is fully seated and carefully thread on the lockring and tighten.

New Chain Length

You should set your chainring for optimum roundness. So that there is equal tension on the chain for the complete rotation of the chainring. It makes for smoother pedaling.

Finish

HandIf you haven't installed brake cables before, check the article on cutting brake cable housing.

Handlebar Taping:

Handlebar taping can take practice. If you are picky, you may want to take the bike to your local shop. There are lots of articles around on this topic.

Fixed gear conversions make nice weekend projects. If you have questions about this process, call or e-mail us here at Harris Cyclery.

Good luck and happy riding!

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