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I thought ridin' off-road was all rocks and rolls....especially here in the desert! That skull work is awesome. Nice touch! The bike has really clean lines and a great stance.
Truth! and thanks. I thought the landing gear would set it up nice, and while I'm not yet a bike geometry wizard, I believe I can contribute to the visual side of things. I passed at a chance to go to graphic arts school in the 70's... I sometimes wonder where I'd be at now...


Carl.
 
Truth! and thanks. I thought the landing gear would set it up nice, and while I'm not yet a bike geometry wizard, I believe I can contribute to the visual side of things. I passed at a chance to go to graphic arts school in the 70's... I sometimes wonder where I'd be at now...


Carl.
I backed out of the academy of art, ended up doing graphic design for a short time, haven't done it for years. I turned out ok, I think?
 
DedMetL 015.jpg
DedMetL 017.jpg

Flash shows the detail but wrong colors on the roses
DedMetL 020.jpg

Not a Dead Head but the imagery is cool for the build...

Carl.
 
I've been reading the web tonight trying to figure out what BB I need. I could go with Sunlight's conversion that slips into the American cups. But I think I want to spend more and go with a Truvativ conversion which leaves me guessing on the length of spindle I need...

Got my seat clamp today old chrome AS, and my rear hub's in the mail and I can't wait!

Carl.
 
I have a truvativ I didn't need for SkiTrap, won't help with spindle size but might be able to save you some money.
 
I love Wald and all the Wald BS.... just an fyi: you can run a 4080 with a 21.1mm stem, no problem.

Also, Wald doesn't currently offer 38t front sprockets (maybe they used to?), but you can easily get them in 36t (#536) or 40t (#540) flavors.

Bike looks cool so far!
 
Carl, one thing I found out on my Desert Sky klunker build this summer is that I went with a 40t chainring, so I could climb better off-road. What I found out is that for general cruising around town and the occasional dirt run, the gearing is too small. Hard to maintain a comfortable cadence, lots of "spinning". I think on Mesa Büggie I'm going to go with a 42 or 44, whatever is in the box that is on the way here from the frozen tundra....just my .02...

As far as BB spindle length goes, this Sheldon Brown link might have some useful info. By taking some of the measurements you will be able to come up with a BB size that should be close to what you need. I would also look at other bikes in your stable and measure one or two that resemble the configuration of your build. Might be able to get pretty close on that as well.

Sheldon's take:
http://www.sheldonbrown.com/bbsize.html
 
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Re: front sprocket size: Gearing depends on many factors, including front/rear sprockets, the size of the wheel, and even the length of the crankarm. You can easily hit your target gear ratio with a 36, 38, or 40t front sprocket, unless you're shooting for a really high gear. And, as far as offroad gearing goes, most folks shoot for a range between 45 and 55 gear inches, with 52" often considered the "classic" ratio for offroad single-speeding. If you're intending to hit the trails, that's probably a good target ration....and achieving it with a smaller front sprocket will help with clearance issues while hopping logs, if that's gonna be a factor.

Re: spindle length: @GuitarlCarl , hit me up if you need help with that. If you give me info on the make/model of your front crank and rear hub, and details about your rear cog (dished vs flat, etc), and any mods you made (eg, adding spacers to one or both sides), i can probably suggest a spindle that'll get you within a mm of perfect chainline. Of course, there are other potential pitfalls with these 3-piece conversions, such as a low tread figure leading to the crankarms colliding with the stays.....
 
Re: front sprocket size: Gearing depends on many factors, including front/rear sprockets, the size of the wheel, and even the length of the crankarm. You can easily hit your target gear ratio with a 36, 38, or 40t front sprocket, unless you're shooting for a really high gear. And, as far as offroad gearing goes, most folks shoot for a range between 45 and 55 gear inches, with 52" often considered the "classic" ratio for offroad single-speeding. If you're intending to hit the trails, that's probably a good target ration....and achieving it with a smaller front sprocket will help with clearance issues while hopping logs, if that's gonna be a factor.

Re: spindle length: @GuitarlCarl , hit me up if you need help with that. If you give me info on the make/model of your front crank and rear hub, and details about your rear cog (dished vs flat, etc), and any mods you made (eg, adding spacers to one or both sides), i can probably suggest a spindle that'll get you within a mm of perfect chainline. Of course, there are other potential pitfalls with these 3-piece conversions, such as a low tread figure leading to the crankarms colliding with the stays.....

Thanks. I have an old Schwinn forged crank, weighs a ton. I have sprockets that fit and clear the frame, 36t up to 48t. It's not the size of the sprocket or the gearing that I'm concerned with, it's the chainline, it's only spindle length I'm concerned with. What length spindle matches a Schwinn crank? My BB shell is 2 5/8" wide before the Truvativ...I have no idea what they add to the width, I'd hazard a guess at 1/8 inch each side , or 1/4" total call it 2 7/8" wide. I have no 3 piece parts at all in hand...

Carl, one thing I found out on my Desert Sky klunker build this summer is that I went with a 40t chainring, so I could climb better off-road. What I found out is that for general cruising around town and the occasional dirt run, the gearing is too small. Hard to maintain a comfortable cadence, lots of "spinning". I think on Mesa Büggie I'm going to go with a 42 or 44, whatever is in the box that is on the way here from the frozen tundra....just my .02...

As far as BB spindle length goes, this Sheldon Brown link might have some useful info. By taking some of the measurements you will be able to come up with a BB size that should be close to what you need. I would also look at other bikes in your stable and measure one or two that resemble the configuration of your build. Might be able to get pretty close on that as well.

Sheldon's take:
http://www.sheldonbrown.com/bbsize.html

Yeah, see above, I'm not worried about gearing now. Just chainline. Only 3 piece in my stable is an OCC... no help. It's not a thing I've ever messed with before. I know I could slap a Sunlight conversion in there but... I did read Sheldon's article before and was debating on putting my frame in my homemade jig and measuring centerlines etc. lot of hassle... But thanks for sure.
So...
It sure seems to me if you have a known crank lets just say SCHWINN, and you say you want to go single gear, then they oughta be able to say 103 or 110 or whatever. As far as my hub... it's here!
DSC00789.JPG

fixin' to build me a wheel...

Carl.
 
I have a few three piece cranks in the garage, when you figure out spindle length let me know and I'll see what I have.
 
Carl, a number of years ago (around 10 or so) I converted a triple chain ring crankset to just a single chain ring for a single speed mtb set up. I used just a freewheel hub (thread-on) rear wheel with a bmx freewheel in the rear. So I had to fit my chain line with that cog. I first started by finding the chain ring size I wanted, then used the "middle ring" position on the right crank arm to bolt on. Chain ring bolts come in different lengths, so once you find your position you can get the proper length bolts. I used hard nylon washers as spacers from that middle ring position, so I could cut them to the exact spacing I needed. Then factored in enough room for a small washer on either end of the nylon spacer for rigidity and bolted it on. This way, I could use the existing BB spindle and adjust the chain line from there. So, if you get close (within 5 mm or so) of the correct spindle length you should be able to make it work.
 
Yeah, haha, sometimes I'm not as smart as I think I am...:blackeye:
I have 4 Schwinn road bikes, a Next and a Cannondale that have 3 piece cranksets.
So my plan is to build my wheel, put it on with my 1 piece crank (Schwinn with an 1/8th inch washer behind the race) and check the chainline. This should aid me in measurements, and like OddJob and Bicycle808 noted above, from there figuring what I need should be fairly easy...

Carl.
 
Great plan, but you're including one totally unnecessary step (installing the OPC), and you're also planning on a time- and labor-intensive step (building the wheel) that you could save for later. Sure, you're going to have to lace the wheel at some point, but think about your order of operations; it'd probably make more sense to lace the wheel once you've ordered the proper size BB. (Sometimes, shipping takes forever. :D)

You can measure the hub's chainline by measuring the distance between the outer edge of both jam nuts (often referred to as OLD, or the O.ver L.ocknut D.imension)... I don't have one in front of me, but i think it's something like 112 or 114mm. Now, measure from the rear sprocket's teeth to the driveside jam nut; take that figure, and subtract it from half of whatever your OLD measurement is, and that's your chainline. I'm willing to bet that it's going to be 41 or 42mm.

This method will work, assuming that your frame is aligned, and there is no deliberate offset, which there shouldn't be on a Schwinn canti frame....

As for finding some clues on your crank and what spindle it needs, i'm hoping that your bb shell has no cups or adaptor in it. You said you have an OCC BB set, which is good b/c it has a JIS square taper spindle, and it's loose ball, so you can separate the spindle. If you have a crank-puller tool, you could install the driveside crankarm (with your intended chainring mounted to the spider) on the spindle, line it up by hand so you get your desired chainline, and via careful measurements, you could figure out how long the driveside half of the spindle would need to be to get that chainline. There's a lot of ways to do this; i can think of a few but I'm getting the sense that you wanna do this your way-- just remember that guesswork won't cut it.

While you're mocking this up to find chainline, please do make sure that the crankarm isn't going to hit the chainstay when the crank is on the proper chainline. It may not, but it very well might, if you're using a crank from a lightweight/road bike on a cruiser.

Once you figure out what the driveside half of your spindle needs to be in order to achieve chainline that matches the rear, double that figure (in mm, trust me) and then buy a symmetrical BB set in English-thread 68mm x ___mm (whatever your final measurement yields.) If they don't have the exact size, get one within a mm or 2, or see if there's an asymmetrical set available that'd suit your needs, and keep in mind that you can get a few more mm inboard or outboard by switching which side of the spider you use to mount the ring, or even using a few washers to space out the chainring bolts, like @OddJob mentioned. :rockout:

(Note-- many coaster hubs and IGHs take 3-tab sprockets; you can adjust rear chainline by using dished sprockets, and in many cases you can run the dish either inward or outward, or run a flat, so there's a few mm to play with there, too. The Bendix kickers, however, have one-piece drivers, and don't allow swapping of the rear sprocket, as it is actually part of the driver.)

Incidentally, buying the Sunlite conversion kit may or may not have avoided these problems; those kits come with a 127mm spindle. The spindle itself is threaded, so you can adjust the front chainline within a few mm based on how you set up the spindle, but that adaptor won't work with most modern cranks. You didn't say which cranks you're running---there were many Schwinn-branded cranks over the years, and it'd be helpful to know what model bike it came from-- but it sounds old school..... If that's the case, my best guess would be that you're gonna need a 125 to 127mm spindle in the end. So, in this case, that may've been the more expedient part to run.
 
Jamnut to nut = 120.65 half that 60.325 - 19.05 = 41.275 chainline, so ok it's what it oughta be... I'm not taking any of my roadbikes or the OCC apart. But slowdown @Bicycle808 read what I wrote, the Schwinn crank I have is a 1 piece. I don't have any 3 piece BB parts in hand for this bike. I have however run a chain from the one piece w/ sprocket to the hub, mounted on the bike and its all good. So I figure I can measure the distance to the sprocket on the 1 piece and compare it to the 3 pieces on my roadbikes to arrive at the ideal... I get the centerline of the hub for a symmetrical spindle too. So thanks for the info too. Still seems crazy that there's not a direct conversion for something as common as a Schwinn 1 piece with 7" arms circa 1974... Sheldon's list while nice isn't much help either. I'm building a RatRod and I'm not putting a 400 dollar crankset on it....

Carl.
 
...But slowdown @Bicycle808 read what I wrote, the Schwinn crank I have is a 1 piece. I don't have any 3 piece BB parts in hand for this bike. I have however run a chain from the one piece w/ sprocket to the hub, mounted on the bike and its all good. So I figure I can measure the distance to the sprocket on the 1 piece and compare it to the 3 pieces on my roadbikes to arrive at the ideal... I get the centerline of the hub for a symmetrical spindle too. So thanks for the info too. Still seems crazy that there's not a direct conversion for something as common as a Schwinn 1 piece with 7" arms circa 1974... Sheldon's list while nice isn't much help either. I'm building a RatRod and I'm not putting a 400 dollar crankset on it....

I think I see where the confusion is coming from...

The same reason that you can't find info on how to do a "direct conversion for something as common as a Schwinn 1 piece with 7" arms circa 1974" is the same reason that I'd wrongly assumed that the Schwinn crank you'd mentioned was a 3-piece. Once you've decided to convert the bike to 3-piece, the detail of the 1 piece becomes totally irrelevant. It doesn't matter how long the crankarms are, the brand, the vintage, none of it. The only relevant info you're need for that crankset is the knowledge that you're not gonna be using it. (Chainline would be an important spec, if you were running the original rear hub, but in this case, you're not. But you can also save yourself the hassle of mocking up the OPC to measure it's chainline, b/c we already know that, if it has the oem chainwheel and one standard washer between the sprocket and the driveside cone, the chainline is going to be really close to 41mm anyway.) There are, literally, no measurements that you need to get from that old crank.

Similarly, unless you intend to use the same exact crank on this project, there is no need to measure the chainline on your road bike's crank; none of that relates to this build at all.

You already have all the info you need, except for 2 items. You know you have a very "normal" Schwinn, with an American shell that measures 67mm wide; super normal. You know you're gonna run an English-threaded conversion, so you know that you'll need English-thread BB with a 68mm inner measurement. You know that your rear chainline is at 41.3mm, which thankfully is really standard for old-timey one speeds and modern track bikes. All you need to do is figure out what crank you're going to run, and then you need to figure out what length spindle you'll need to get 41mm front chainline. (And, trust me please, you'll want to determine that the crank you choose will clear the stays, b/c I've walked ppl thru this 1000 times, and that's usually the unexpected problem, where they have perfect chainline, but they can't ride it due to interference....)

I get it that no one wants to spend $400 on the crank for this build-off; I'm kinda "shooting the moon", and I'm eyeing up a $125 crank.... There's a really good chance that you'll find a 3 piece for free or cheap that you'll want to use, and that could clear your chainstays....and, at that point, you're most likely going to wanna drop the $25 for the right size BB. I'm willing to help you with that, but I'm getting the sense you want to do this your way. I totally respect that, but i just noticed that "your way" has involved some unnecessary measurements, so far. I'm just trying to help you make the process more efficient.
 
I get it @Bicycle808 and I appreciate it. But I do think a direct replacement for the forged crank as being a viable thing. The chainline is an exact number using one, without or with the spacer (it adds an 1/8th to it...) how often do rebuilders, using a Stock Schwinn decide to switch to a 3 piece? (Hehe the hub isn't the Orig, but it could have been as a 10 dollar option) I also understand that different drives may sit at different places on the same spindle, changing their chainline in the process. So a database would be probably difficult to execute, hence Sheldon's way of going with the new 3 pc and working backwards to discover what will fit.
I've done some more digging on my own and I may just go with a YST conversion, it costs about $35, but has JIS taper and is somewhat adjustable on the chainline... Alan Bonds uses it on some of his tributes so I trust it will work. As far as clearing the stays... I have a ball peen hammer (if I have to) and this is a ratrod... Worst case scenario, I shelf the 3 pc and use my original forged boat anchor (I mean crank o_O)

Carl.
 
Truth be told, they DID make a direct replacement for the OPC crank in 70s Schwinns and, really, pretty much all bikes with American BB shells. Virtually any tubular-style BMX crank is exactly that... quite easy to adjust the chainline, and soooo much stronger than the square-taper jobs. It's always boggled my mind that so many folks in Internet land want to convert from one- to three-piece, but they choose the square taper, which is seldom cheaper, always weaker, and most often a far bigger hassle as far as kludging it together. But, that's how it goes...

Either way, most folks who are into doing these sorts of custom mods, they're not necessarily going to want a "standard" direct replacement anyway. I suspect most of the square-taper conversion folks would end up having to reverse-engineer this sort of project anyway.... especially, once you start modding, you're likely to end up changing the rear-end anyway, which can often lead to different rear chainline.

I'm using the YST sealed american-to-square taper conversion; it's a really nice component, and i really like it, but I have one caveat: that spindle is long, at 127mm. There's a fair amount of adjustment to the chainline, and it's easy to adjust, but the little collars w/ set screws that allow you to change the chainline, the driveside one is wide enough that there's still a lot of exposed spindle on the right side of the BB shell, even when you have it maxed-out to the NDS. I ended up having to space out my rear sprocket on my fixed gear Worksman in order to get the chainline right, with the Dia-Compe crankset i got from Porkchop. It will work well with a truly old-school 3 piece, but it will be tough to acheve a 41.3mm chainline with any modern cranks, with the YST set.
 

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