how do you space out a big chainring?

[jackdaw]

I have a cruiser frame with a one piece crank. I'm putting a large chainring on it. In order for it to clear the frame I had to spacer it out on the crank (a one piece). So it works fine except there is not enough thread on the off side to put a locknut on.

1- Do one piece cranks come in different widths?
2- Will I have to get it split and welded?
3- How far will it go without a locknut before it all goes bad?

Thanks loads! The bike is here:

viewtopic.php?f=21&t=47113

 

[KJV]

you could use a crank off a mountain bike. :idea:

 

[jackdaw]

Are one piece cranks off mountain bikes wider than one piece cranks from cruisers?

 

[KJV]

yes, the ones with 2-3 sprockets are wider.

 

[ozzmonaut]

Once you space out the chainring, how will you move the rear sprocket to keep the chainline straight? Especially with single speeds, it is easy to throw a chain if the chainline is off at all.Generally, the side of the crank hanger lines up to somewhere near 1/4" from the dropout on the chain side. Moving the chainring out will make it pull the chain to the outside of the rear sprocket. Not being critical, just wondering what steps you are taking to keep the chain on, or if it is even neccessary with the distance you had to move things.

 

[ozzmonaut]

I'm guessing with those plates on the rear, the wheel sprocket is moved closer to the dropout and the chain alignment will be passable?

 

[jackdaw]

I moved the chainring out about 3/8". The chainline seems ok, the chainring is from a double ring so I think it will allow the chain to keep sliding on. If you think about how the chainline is on a 10 speed when you're cross chaining it, it can be off by an inch. It doesn't like it, but it'll take it.

How do folks put those HUGE excercycle chainrings on? The ones that are the size of dinner plates? This one isn't anywhere near as big, it's a 48 I think but they must run into the same problems?

I do have a Roadmaster Mountain Climber out in the pile, I will try the crank off it.

Thanks for your help guys, anyone else?

ozz, I like yr Timothy Leary qoute. 8)

 

[c.p.odom]

Have you looked at adding a dimple to the chain stay? I have done this hundreds of times.

 

[jackdaw]

c.p.odom, I wondered about that, I guess it's not too hard? Do you use a vice or what?

Thanks a lot for your help. What bikes on here do you like?

 

[c.p.odom]

I once posted a picture of the tool I made. It is very simple and makes professional looking dimples. The tools was used on hundreds of frames at the Quintana Roo Triathlon bicycle Factory as well as on a large number of projects.

Try here:

viewtopic.php?f=3&t=1140&start=0&st=0&sk=t&sd=a

 

[jackdaw]

Thank you so much! I think I'll be able to make that work.

 

[ratina]

All I have ever had to do to put an exercise sprocket on a bike was put a spacing washer on the crank before the sprocket, and put the sprocket on backwards to give it more clearance.

 

[gcrank1]

Breath really deeply, then hold...........