bmx crank on a road bike ?
 

Hi there,

I am looking for a 180mm single speed crankset. I have found one second hand but it is a BMX crankset ,Truativ BMX ISIS crankset 180mm with Giga Pipe ISIS bottom bracket.

Will this run on a normal road bike with 68cm BB . Will there be chainline issues , I am hoping to get close to 50mm to match the rear cogs chainline (single speed setup).

Any other things to factor in ?

Thanks

J

Is that crank designed to work with a 1/8" single speed chain? If so, a derailleur chain will not fit the chainring

I believe BMX refers to 68mm threaded bottom brackets as 'Euro' style. If that is the BB then it will likely fit. But as mentioned above, the BB fitting is not the only thing you need to consider.

Well on this particular crank I can switch out the chainring so that should not be an issue

3/32" chainrings are readily abundant, so you should be able to use a chain intended for use with a derailleur. However, BMX chainlines are among the narrowest of all bicycle drivetrains, often between 40-42 mm. They have to be narrow to accommodate the narrow spacing of the dropouts (110 mm) in the rear of the frame. I do not know the chainline of the crank you referenced, but if it is a true BMX crank, the chainline is going to be too narrow. You aren't going to find a true BMX crank with a 50mm chainline. Depending on the size of the chainring, there also is a chance the chainring will not clear the chainstay.

You are better off looking for a mountain bike singlespeed crankset which will have a chainline much closer to 50 mm.

Really depends on if it is thru axle or square taper. My daughter's road and track bikes both have 130mm bmx cranks on them. With the road bike it is a little less then ideal, the thru axle crank limits the amount of adjustability though a couple of thin spacers allowed the cranks to be moved slightly enough to solve the chainline while still making sure both fixing bolts were over the axle for security. The track bike has the same rear spacing as a BMX track bike and isn't remotely an issue. If it uses a euro BB then you can find a spindle that will work with no trouble in a 1x setup

Some BMX cranks I've seen have spiders to fit a chainring on either side, and many good ones you can add spacers to move the drive side out a bit. Most of the spline BB spindles are available in several lengths.

You can probably get it to fit with a decent chainline if you start with the right crank and work at it.

I didn't read properly. You should test fit, then measure the chainline. Different lengths of ISIS bottom brackets are available. Sounds like a nice solution.