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Bike Mechanic Tips

Bike Mechanic Tips

How to Build a New or Old School BMX Bike

Installing Profile Racing Cranks

You will need a cup pressing tool with a threaded rod with nuts and washers to press the Profile Cups into your frame. Use some grease to allow the cups to press in smoothly. Make sure the center bearing spacer is in place between the bearings and use the one that best fits your frame. The Profile crank tool will pull the arms onto your axle most of the way. The rest is done by tightening your crank axle bolts. Be sure to use the spacers to get a nice chain alignments and so that your left crank clears the frame sufficiently. Grease the 48 spline axle with the included anti seize grease and make sure the right arm goes on right side of bike as you look down when riding. Some cranks have a sprocket bolt on both arms so it can cause you to make a mistake.

Inner Tube Installation:

There are two valve types, Presta or Schrader. The Schrader valve is standard like on a car and the most common. The presta is a metal skinny valve that requires a smaller hole on your rim. Presta is sometimes called a French Valve. Presta Valves can be inflated using a Presta Valve pump or an adaptor that converts the tube valve to Schrader. Check your inner tire for sharp objects before installing your tube. Inflate tube slightly before installing so it keeps its round form. When the tire is ready for air push the valve up and down to seed the tire to the rim. Slowly inflate the tire while checking that the tire is equally seeded on the rim. If it is not seeded and you inflate it,  you could have a blow out and ruin your tire and tube. Don't bother patching tubes, just buy a new one unless you have had good luck with patching.

Do not drive around with a high pressure tire next to you especially in hot weather. If your tire blows out you could damage your ears or the girls ears next to you. Try a little baby powder between tire and tube to prevent sticking. A 20 x1.75 tube will inflate up to a 20 x 2.125 tire or even larger. The inner tubes will fit a range of sizes since they stretch. If you have a 20 x 2.3 or 2.5 you may want to use a wider tube to the tube does not have to stretch out so much and become thin making it easier to get a flat. However, using thinner tubes is lighter weight which is a advantage rolling resistance wise.

Chains Install:

Chains are sold in a standard length that will need to be cut to fit your bike. Chains are 3/32" narrow for race bikes and 1/8" for Freestyle Bikes. If you front sprocket is a 3/32" you can use either a 1/8" chain or 3/32" chain. If you sprocket is 1/8" you can not use a 3/32" chain. Chains are cut to length with the proper chain tool. Choose a tool for the width of your chain. For 1/8" chain the Shadow Interlock chain breaker tool is nice. If you have a multi speed bike then you buy the chain that says it works for your number of speeds. For example, if you have a 3 x 8 drive train then you get a 8 speed compatible chain. When using your chain tool, make sure the pin you pushed in is exactly the same as the other pins and the links are not damaged in the process. Most chains break because they are not installed properly. If you are replacing your old chain simply cut your new chain to the same length and install.

Custom Wheel Building

When some wheels are hand built there is a break in period where the spokes may loosen up.
Often you can tighten up the spokes by tightening each spoke by a half turn or full turn, until tight. This loosening of spokes occurs because all hubs, rims, spokes and nipples have different machining. For example, one hub may not be as compatible with the rim and spoke you choose. Buying prebuild factory wheels can often prevent this wheel break in period. A spoke wrench and a truing stand would be helpful in maintaining your wheels. Click wheel building rates for more info. Check this bmx bike wheel building video

If you can find your hub and or Rim on the BMX spoke calculators you will need to get the specifications from the manufacturer website and plug them into a spoke calculator like this one we link to.


Bearings, cups and other parts needed hold your fork to the frame. Old school frames take 1" threaded headsets. If you fork has threads on it it is threaded and not threadless. Then the industry when from 1" threaded to 1 1/8" threadless we had a change in the standard. 1" headsets would tend to loosen up so the new design took over. This collaborative industry change marks the new standard size. It just may just go down in history as the time when old school became new school. The forks became 1 1/8" threadless and the steerer tub became longer so the threadless new style stem would slide on to it. The old style stem (gooseneck) was called 1" shafted and always had that long expander bolt to hold it in place.

Traditional Threadless Headsets:

Traditional threadless headsets are headsets that use a cup and bearing system. These headsets use cups that must be pressed into the frame and by force of compression via a star nut can be tightened down. These headsets were most popular on all frames from 1994-2001. Set your 1 1/8" Aheadset spacers below your stem so that your ahead cap never touches the top of the fork. Usually a 1/8" gap is nice. If it touches your headset will not pull together to snug the bearings up. Use a Phil Wood or Park grease or any white Lithium. Even automotive axle grease is better than no grease on unsealed cartridge bearing headsets. 

Internal Headsets:

Internal Headsets are the newest headset design for modern Aluminum Race Frames. These headsets are commonly mistaken for Integrated Headsets (which are headsets that are made with no cups so that the bearing is sitting inside the frame). The Internal headset is a headset that still has a steel cup that sits in the frame, but rather than a traditional 1-1/8" Threadless Headset the cups are hidden inside the frame. Since Aluminum frames are pitted easily, bearings cannot be run on the metal with a steel divider so the cup must be used. Generally, you can tell an internal frame from a traditional frame by the width of the headtube and the hourglass design that they use to make the headtube wide enough to hold an entire headset inside. This style headset has only been used on frames for around five years.

Integrated Headsets:

Integrated Headsets are the most widely used headsets on newer style chromoly frames. Integrated Headsets utilized semi sealed or sealed bearings that rest inside the frame on a cup that has been bored out of the headtube. This makes easy assembly and disassembly. These headsets come in two sizes for different types of frames. One size is a 45 x 45 Campagnolo Style Headset. This would include the FSA Impact, FBM, Eastern and Campagnolo Hiddenset Integrated Headsets. This is the general size for integrated headsets and there are few exceptions to the rule. This would include all chromoly frames with the exception of Sputnic, Volume, Stolen and a few others denoted throughout the website. These frames use a slightly larger Cane Creek IS-2 integrated style headset. These headsets are the same design as the Impact Headset with a different sized bearing that will only fit those rare frames. You can tell an integrated frame by a coke can size or hourglass headtube that looks to have cups built in.


Cranks in the old school days were either 1pc or 3pc. The most common BMX crank lengths are 175mm and 180mm. If you are over 5'10" you can choose 180mm. Generally, 175mm has more room for frame clearance from the chain stays. Three piece cranks are usually smoother pedaling than one piece so riders like to upgrade from one piece. You need the 9/16" pedals for 3 peice cranks and 1/2" pedals for 1 piece cranks. I think the smallest cranks are in BMX is 130mm. Usually mini style, superlight weight, racing bikes have these short 3 piece cranks since the rider only about 6 years only and not very tall yet. The next size up, Junior size bikes usually take 150mm. Expert take 170mm and Pro 175mm. Most all the 20" bikes out there for riders who are about 13 years old and up can ride 175mm cranks.


Chains & Freewheel sizes are 3/32", 1/8" or 3/16". A sprocket is a one piece and a chainring uses chainring bolts to attach to the spider then to the crank. All chainrings are 3/32" so you would use a 3/32" chain or 1/8" would also work. The same applies to the rear freewheel. Freewheels are all right side drive unless Left Side Drive is required. LSD is not very common. An LSD bike set up would be you having your sprocket on the left side of your bike when you look down to pedal. Riders who use LSD are usually into grinding and less damage occurs to the bike. Its kind of a left handed/right handed thing. Freewheels require no install tools since they just spin on the hub threads. Do not cross threads when threading. The object when building your frame is to have a straight chain line with the front sprocket. You can space the right side 3 piece crank arm to line up with crank are spacers that come with all 3 piece cranks except the aluminum racing style that press on to a square or ISIS spindle. The common length for a 44T:16T gear ratio is 120 links and you will have extra after you cut it with a chain breaker tool. The new small gear set up like 25T:9T can use the micro drive 96 link length such as a Shadow Interlock chain.


Gearing standard uses 44T:16 for a 20" wheel bike. 24" cruisers take 39T:18T. You may have noticed the trend to go with small front sprockets. Riders are doing this, because the smaller front gears tend to get less destroyed when grinding. The common gearing here is 25T:9T. This gearing equals the 44T:16T. DK makes a 12T that fits on the small threaded side of flip flop hubs. 12T is the smallest freewheel that is threaded style. Anything smaller is a driver style. Profile, Odyssey and several other companies make hubs that accept drivers. Drivers come in 8T up to 12T. Drivers are usually available in chromoly or titanium. We carry special the 9T driver that fits Odyssey hubs as well as all other brand drivers that are quality.


Grips should be installed with soapy water or hair spray to help them slide over the bar. Let the hair spray dry before riding on the new grips so you don’t wipe out. You will find lots of grips here, even old school Ame Tri's. Ame Tri grips are standard length at 120mm. I had a pair of Oakley 3's some time ago, they had wings to rest your palms on and finger indentations. Lots of cool colors are available now like purple and gold grips. Check out the Animal or new ODI O grips. Get some bar ends to prevent handlebar end punctures to body.


Pedals are made in 1/2" or 9/16" thread. All three piece cranks take 9/16". All one piece cranks take 1/2". Three piece cranks always have a separate left and right arm. One piece cranks are one long piece that fits through the frame bottom bracket to form left and right. The left pedal always tightens in a counterclockwise direction. The right always tightens in a clockwise direction. You sometimes need a thin wall 15mm open end wrench to get your pedals tight. We do sell a special Pedal Tool you could add to your tool collection.

Seat Clamps

Come in three sizes for BMX. Measure the outside diameter of your frames seat tube to get your size. Old school metal pro and xl frames take 1" which equals 25.4mm. New metal frames most all take 25.4mm seat post so the clamp accommodates the metal thickness and takes a 1 1/8" clamp. Most Aluminum frames take 1 1/4" and wider clamps. If its wider than 1 1/4" you may find you need to order a mountain bike brand clamp. 

Seat posts

Were mostly all 7/8" (22.2mm) in diameter for old school bmx frames. Some minis take 13/16" which is even more narrow. The Uni Mini seat was 13/16" and the Uni Pro is 7/8". We still have these original seat post and seat combos in stock. We even have 7/8" chrome straight, laid back and snake posts still in stock. The newer school chromoly frames went to taking the 1" (25.4") seat post. All other frames take whatever the factory decided to use. There is a tool that measures to the 10th of a millimeter otherwise it is trial and error unless you know the required specifications.

Spokes BMX

We carry lots of spokes and we do lots of custom wheel building. We have Chrome, Black, assorted colors and Titanium. If you are building 20" in standard four cross lacing 36H Pro Race wheels, you need 194mm. If you are building 24" Pro Cruiser wheels you need 244mm. Most 48H freestyle wheels take 184mm. Generally, if you go from four cross lacing to three cross you can get your spokes at about 10mm shorter. We also carry aluminum nipples. If you don' feel like doing lots of measuring and you have the hubs and rims check out these links just below:

Note: Odyssey Hazard Lite on Odyssey V3 hub 48H takes 186mm spokes on 3 cross lacing.

If you can find your hub and or Rim on the BMX spoke calculators you will need to get the specifications from the manufacturer website and plug them into a spoke calculator like this one we link to.

Helpful Links for bicycle wheel building


Checkout How to Change Bike Tube Video on youtube


Need a Derailleur Hanger. Email this place who specializes in bike derailleur hanger replacements: & Since 1981