Schwinn Heay-Duti Build Questions

[SziTech]

I am putting together a very sweet Heavy-Duit build. Everything is coming together nicely – except for one thing; the drive train / chain line is WAY off. The front sprocket is too far out!
What size BB should I be using?
I bought a standard American SunLite BB (130 mm). Should I have gotten the 122 mm? With the BB aligned as far as possible in, the crank is already hitting the frame. Won’t the 122 mm be worse?
I am using a standard coaster brake rear wheel. The cog is definitely installed correctly. The cog is dished and is installed with the dished part facing the centerline of the hub – making the making the teeth sit as far out as possible. If that make sense.
Any help will be much appreciated.

 

[Bike Bum]

Any pix? That might help. Also, are you using a one piece or three piece crank?

 

[SziTech]

Sunlite BB Conversion Kit (130 mm)

No pix of the install just yet. I'll take some later.

 

[SziTech]

C’mon guys…
I know I have not been able to post pix yet but, beyond my description of the front sprocket not being in alignment with the rear cog, I know a lot of you have built Schwinn Heavy-Duti Klunkers.
What drive train components did you use that were successful?
I have downloaded every Heavy-Duti build I could find here on the site but the drive train components are hard to identify.
Please someone chime in. I am SO close on this build and would really love to be ridin’.

 

[SziTech]

I don't think this will help but here goes:

From this:

To this! Rock on!

The offending chain line:

Please help!

 

[ind-chuckz]

It's hard to tell from your picture. The crank looks like they're for a track bike has no space where the chain would be farther in. If you brought that crank in looks like it would hit the frame say if you put a 113 spindle on it.

 

[SziTech]

The cranks are Dia-Compe BMX Comps from Porkchop BMX.

 

[SziTech]

Thanks for the reply ind-chuckz! Recognize the frame? How do you think it cam out?

 

[ind-chuckz]

The cranks are Dia-Compe BMX Comps from Porkchop BMX.

Nice!!!!

 

[ind-chuckz]

Thanks for the reply ind-chuckz! Recognize the frame? How do you think it cam out?

Looks good....

 

[MIGZ]

Your bottom bracket is too wide, get some adaptors and buy a euro square taper BB 110mm that should fit it.

 

[ind-chuckz]

Migz he said he has a 130mm on there 110mm might put it to close that straight crank might hit the frame.

 

[jamesdart]

thats weird. I have the diacompe crank on my worksman. I guess the heavy duti frame is just that much wider.
just curious, did all of your chainring bolts tighten up?

 

[Bicycle808]

Yeah, you're gonna want to either use a different crank or use a deep-dished cog out back. If you ran a spindle short enough to fix that chainline, you'd be hitting the chainstay with your crank every time. You'll need to bring the cog outboard to compensate; a deep-dish cog might be a good start.

**EDIT- added the "deep" to "deep-dished" for clarity's sake.

 

[MIGZ]

To be safe go with a 118mm and you can use a normal rear cog. I highly doubt you will hit the chain stay because that back is pretty long.

 

[ind-chuckz]

/\?

 

[Bicycle808]

I'd be stunned if that crank didn't bump the stays on a SHD with a 118mm spindle. I've seen old-school Schwinn OPCs from light- and middle-weight that bump the stays when mounted on a late-model SHD. That rear triangle is reallllly wide.

We might be able to help a little bit better if Szitech offered us some exact measurements. As in, what is the chainline in the rear with the current cog? (Should be in the neighborhood of 42mm.) What is the chainline up front if the spindle is dead-centered? What is the chainline up front if you have the spindle skewed as far inboard as possible without hitting? With these figures, we wouldn't be simply guessing; we could figure out what the most narrow workable chainline is, what length of fixed spindle would offer that chainline with those cranks, and we could find ways to increase the chainline out back to precisely match the front. Right now, we're just making some well-educated guesses.

Of course, the menschy thing to do here would be to hang those Dia-Compes on a more appropriate project, and roll an OPC on the SHD. Save some $$$, headaches, and conjecture.

 

[SziTech]

Thanks for everyone's input.

The BB was cheap enough that I bought a more narrow one at 120 mm. I also dropped for another crankset that seems to have a deeper spider, if that makes sense and with what looks like a 'bowed' crank arm. We'll see.

Bicycle808; I'll try to get more specific measurements this weekend.

In my ignorance, I didn't even know there was such a thing as a 'deep dish' cog! Hmmm, deep dish pizza...

Oh, and yes, the chainring bolts were all tightened down evenly.

 

[jamesdart]

The chainring bolt thing was unrelated to your problem, Just something I was curious about.

 

[SziTech]

Done! Going with a 120 mm crank shaft and the new Red-Line crank arms did it!