# Shimano SF-MX30 freewheels



## Trevor Ash (May 19, 2005)

Okay, I'm creating a SS freewheel roadie project. Currently shopping for cheap frame on Ebay with about 125mm rear spacing (track frame or at least with horizontal dropouts). I want this to be as cheap as possible while still having good components (which probably means I'll be having old components).

When trying to figure out the rear wheel I'm confused as all get out. I can find Shimano SF-MX30 freewheels for dirt cheap on Ebay (or newer Shimano models for about $12 new). 

Can you explain how I can determine what hubs are compatible with a BMX freewheel like the one mentioned?

For what it's worth, I plan on building my own front and rear wheels as a learning process. I expect to make plenty of mistakes but am trying to waste as little money as possible.

One reason I'm looking at BMX components for the rear wheel is because there is a good amount of cheap BMX options for the BB, cranks, and front chainring. I assume that I should have the rear hub, freewheel cog/cassette (not sure the proper term), and chain BMX as well so that the whole drivetrain is BMX "compatible". I further assume that it doesn't matter what the rim and spokes are (bmx, road, whatever) so long as the spoke count is correct between hub and rim. I realize that I need to pay close attention to spoke length.

Ultimately, I plan on building a 700c wheel and that's more important to me than choosing BMX components for the drivetrain. BMX just seemed a cheap route with lots of options.

How dumb do I sound?  

Thank you!


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## Lab Worker (May 31, 2004)

Trevor Ash said:


> How dumb do I sound?



ok, here we go 

A BMX freewheel will fit onto any FREEWHEEL hub, that means any old hub that is NOT a 'cassette' hub. Ask your LBS and they will give you a cheepie Joytech hub that they'll have in their parts bin. These hubs come with either quick-release or bolt-on axles. If you're buying a horizontal dropout frame then you want a bolt-on axle. They are easy to re-space to whatever chainline and whatever chainstay width you want.

Another option is to use a standard cassette style wheel whose width matches your frame. You can use one cog on the cassette and spacers to take up the excess. This works well if you've already got a wheel lying around. Its very easy to get the chainline correct with this method.

Since you're going SS and not fixed you can use a standard road frame with vertical dropouts, and use an old derailleur or a single-speed tensioner to take up chain slack.

Cranks: Well there are a lot of options out there. If you are planning on riding this bike a lot, then you probably want to keep a low Q factor, and therefore you want to use BMX race cranks or (ideally) a road crank. BMX cranks are heavy and freestyle cranks have a high Q and usually require a bolt-on spider or a special BMX sprocket. If you are buying second hand there is no advantage to buying BMX cranks, find a decent set of old road bike cranks.

Once you've got cranks and a BB you can mount a chainring (usually mounted on the 'outside' ring position) and calculate your chainline. Once you've done this you can space your freewheel hub so that the freewheel sits in the right place, then calculate spoke length, build the wheel and off you go. If you choose to use a cassette wheel then you simply put the cog where you want it, fill the gaps with spacers (plead with your LBS for some of these, or ask for old cassettes that you can disassemble) and, again, off you go.

To be honest the cheepest way to do this is find an old road bike that will be your donor. Look for one with either a cassette or freewheel hub, and with downtube shifters. You can remove the shifters, leave the brake levers, and use the frame, cranks and wheels. If its an old downtube-shiftered bike chances are it has horizontal dropouts which make your job even easier.

Hope that helps you


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## Trevor Ash (May 19, 2005)

Thanks LW, it definetely helps. I've been absorbing more than my share of information this last week while researching this project 

I think I should spend some time at an LBS that is friendly enough to spend some time with me and let me look through their parts bin. I have a tough time visualizing how everything fits together by using the internet. That should boost my confidence and allow me to pick the right parts from the get go.


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## Trevor Ash (May 19, 2005)

Got it all figured out


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## Lab Worker (May 31, 2004)

Bling Bling


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## Jamieshankland (Jan 8, 2005)

Dam now you got me thinking how cool it would be to build a set of SS wheels for my pista using Shimano DX BMX hubs. Now that would be pimp. An almost entirly all black bike with bling'n red hubs!


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