Track crank/bottom bracket questions...
 

Ok, I have an old Miyata track bike that I am working on. It has a regular Suntour Sprint rear track hub, 120mm spacing, etc. The problem is that it for some reason has a Shimano 600 road crank, and the chainline is not straight. I am pretty novice working on bikes, and I'm really not clear on the differences between "track" or road cranks. (Would just getting track cranks put the chainwheel in the right place?) At the same time, could it also be a question of the size of the bottom bracket? The bottom bracket seems to be a Sugino 75, so I think that is all right. As the crank arms are mismatched I have been wanting to get something a little nicer anyways, so I guess I need a suggestion for a track crank that will work properly, or if I need a matched crank/bottom bracket, or if just any track crank should work..?? Basicly whatever explanation and recommendations the more knowledgable people can give will be much appreciated. :)

-Jason

sugino makes a track crankset to go along with the bottom bracket you have. oddly enough, it's also called the Sugino 75.

the biggest difference between a track crank and a road crank is A) the bolt circle diameter, and B) fitting more than one chainring to a track crank is not possible.

Is the chainring currently in the inner or outer position on the spider? I find that putting the chainring on the inner position gives a pretty straight chainline on my singlespeed and on my fixed gear.

I know sheldon brown also sells a set of spacers to move the chainring in a few mm when you position it on the inner position.

Here is a link to American Cyclery track cranksets they carry including the Sugino 75
http://fixedgear.americancyclery.com/Store/Cranksets

HarrisCyclery also carries some Track cranks
http://www.sheldonbrown.com/harris/fixed.html#cranks

Jason.........in addition to the differences mentioned above, track crank chainrings, cog, and chain are all 1/8" thick.......as opposed to 3/32" for road. But other than that, with most road cranks, mounting the chainring on the INSIDE of the spider will generally result in better chain alignment........that's if your chainring is small enough to clear the chainstay. I'm assuming your chainline right now is way out (outward).
Since you already have a Sugino BB, a Sugino track crankset should do the job also. Generally speaking, it's best to have matching BB/crancksets.
I'm using a Campy track crankset with a Shimano bottom bracket, but had to experiment with a couple or three BB spindle lengths to find one just right to achieve perfect chainline. I just happened to have several Shimano BB of varying lengths in my junk drawer at the time. But on the other hand, I don't think a Shimano crankset would work with a Campy BB. The crank would just bottom out at the spindle taper, therefore not compatible. Thank you!