Singlespeed & Fixed Gear - 52T chainring?

so i'm building a fixie, but i think i just ran into a slight problem. the only chainring that i can use from this bike is a 52 tooth.

i know that most people here run 42 tooth, or sometimes something like 46 for taller gearing.

i want to start off with the equivalent of a 42x17 (don't know what that is in inches), which by my calculations, would be 52x21, so i need a 21-tooth cog.

what are you recommendations for this situation? should i shell out for another crankset or find a used crankset with a usable 42T ring, or is the 52x21 ok?

thanks.

Why not just get a 42 tooth chainring? Check harris cyclery he carries quite a few different size chainrings. Once you find the BCD of the crankset should be able to put another one on their.

The reason a 42 is popular is because on most roadie conversions,at least the ones Ive done is because anything bigger might not clear the chainstay with a BB spindle length that gives a straight chainline.If you can run the 52 go ahead and use it,sometimes its doable,if it clears use it.If not you can get chainrings pretty easy and cheap for like 10-20$.

The chain ring will be cheaper than a cog, but you will probably have to get a cog anyway.
If you use the fiftytwo and want to gear lower, you will probably have to change the ring anyway, finding big cogs is hard.

i've run into older cranks that have some crazy BCDs that i couldn't find new chainrings for, so i was stuck buying a larger cog. or new cranks. the cog was cheaper, and i'm all about doing things the cheap way.

The thing about this ring is that it's not screwed onto the spider like you normally see. the ring and the pedal are one piece; it's not replaceable, unless i get a new crankset, or new crank arms and ring.

I have an old Fuji with a more modern crankset that does have a 42T chainring. I might have to resort to taking that apart, but I'd rather get it working as it is.

Thanks for the tips.

Is this a one piece crank, the arms and spindle are all one piece? If so, with the crank out of the BByou should be able to remove the race next to the chainring with a large wrench or spanner.
I would use the Fuji crank, but thats just me.

I have a OPC on my fixie 39T. You can take the chainring off and replace it with a spider. Email Sheldon Brown at Harris Cyclery he knows all about this, or you could get a coversion BB to put on a modern three peice crank but that will cost some money. My advice is use the OPC.

I ride 52 and 53 on all my road fixies, I have an MTB set up with a 48, I don't like it half as much as hammering with that big ring. I also mash a 16,17,18 on the rear end, a 21 isn't out of the question if that is your thing, actually it is considered better than what I run as the more teeth the better pull on the chain and the less destruction of the chain, at least that's how it's been explained to me.

well the bike shop guy heavily recommended against my crankset. he said that these cranks without a spider are notorious for starting to "freewheel" on the chainring, especially on fixed gears.

so i took apart the fuji's crankset and now have an arm with a spider and a 42T and 52T to work with. i'll probably go with the 42/17, but i'll keep the 52T around if i ever want to go crazy on gearing.

thanks for all the help.

I just built up a fixie, an 80's Schwinn Traveler with a 52X19 set-up. I hauls pretty good on the flats and will get me up all but the steepest hills here in Seattle. I also have a 42X16 on another bike and while it's not geared as high they still seem pretty similar. I think 52X21 would work fine for what you are looking for.

I know this is an old post but ACS makes a Claw 22 for about $15. It is a 3/32. I have decided to go 52/20 on one of my old Falcons. If it ends up to tough on the hills may have to swap cog.

I know this is an old post but ACS makes a Claw 22 for about $15. It is a 3/32. I have decided to go 52/20 on one of my old Falcons. If it ends up to tough on the hills may have to swap cog.
The Claw is nice. 36 engagement points. I paid a bit more than $15 though. It also comes in 19T and 20T. The 19T isn't even mentioned on their site, but I got a local bike shop to order one for me for the winter.

I have a really nice Sugino Mighty Comp 52 chain ring if you are interested.

I just got a Soma 19T in 3/32", and despite some of the bad references to Soma cogs in the past around here, I can personally say that quality and fit of this cog is excellent. Oh yeah, and it also comes in a 21T for 18 bucks (http://www.universalcycles.com/shopping/product_details.php?id=17053).

I haven't attempted to put on the old sprocket as yet but have a question.

Did anyone using old 52's have to add any spacers or such to get chainlines in alignment?

I hope to in install this weekend but making sure I have all my facts straight. This will be my first attempt at putting together at single-speed from an old 12 speed. Rear spacing is 110, crank arms are 170 cotter-pinned. I bought some lighter Sun Cr18 27 x 1/4 rims. Those were the origial rim size and shoud be able to use old brakes. For tyres using Ultra Gatorskins because bike will be used a bit more on peet gravel trails than paved outlets. I am an old roadie guy so even though going to try the trail thing feel most comfortible on a roadie. Didn't want to buy a bike just for trails and will not use my nice vintage roadies.

If anything I need to watch out for or be aware of during the build input welcome. I will post pics when complete. Weather is going to be nice this weekend so hope to take it for a spin. Finally!! As bored with the Kurt Kinetic.

PS - Dennis that is sweet. Almost considering doing something like that to an old raleigh Twenty.
GO Giants!!! I am an old CA boy myself.

My first FG is a conversion of a steel frame with an Italian bottom bracket. Had a decent 52 on the front with cottered cranks. Cheapest way to build this up was to leave it be. Went with a 20 on the back and it works just fine.