Chain Ring Wobble

Kscheel

Finally riding a big boys bike

• May 27, 2014

• #1

I am in the process of assembling my 1948 Roadmaster Luxury Liner and I'm finding that there is some troubling wobble in the chain ring. About 1/4 left to right movement.

I did remove the bearing cups when working on the frame, but they did not appear to be bent. Currently booth appear to be fully seated into the bottom bracket. How can you really tell though?

The bearings are original. When the wobble is occurring the bottom bracket is tight, no slop or looseness anywhere.

What's the deal here? Is the chain ring bent? If it's not the chain ring what could be the culprit?

Thanks

 

Freqman1

Riding a '37 Dayton Super Streamline

• May 27, 2014

• #2

1/4" is pretty significant and you should be able to see this when you spin the crank or take it off and lay it on a flat surface. If bearing cups are seated then I would inspect the chainring. V/r Shawn

 

Obi-Wan Schwinnobi

Riding a '38 Autocycle Deluxe

• May 27, 2014

• #3

Chain ring.... All mine have a slight wobble... throw it in a vice and give it a good tug...

Sent from my SCH-I545 using Tapatalk

 

bikecrazy

I live for the CABE

• May 27, 2014

• #4

May be time to get out the rubber mallett.

 

Kscheel

Finally riding a big boys bike

• May 27, 2014

• #5

Okay, now the question is which way do I bend it? Do I bend it towards the frame or away from the frame? Would seeing pictures of how close and how far it is from the frame help in determining that?

 

bikecrazy

I live for the CABE

• May 27, 2014

• #6

Take off the chain and spin the crank. Check the distance between the ring and the frame tube and you should come up with a feel as to where it needs to go. Use light taps because the ring will bend easily. There are other ways to do this, but this is my favorite. Keep in mind that the origional bend may have forced the other half of the ring to be bent in the other direction. Again, light taps at first.

 

jpromo

Cruisin' on my Bluebird

• May 27, 2014

• #7

bikecrazy said:

Take off the chain and spin the crank. Check the distance between the ring and the frame tube and you should come up with a feel as to where it needs to go. Use light taps because the ring will bend easily. There are other ways to do this, but this is my favorite. Keep in mind that the origional bend may have forced the other half of the ring to be bent in the other direction. Again, light taps at first.

Click to expand...

This. Rubber mallet should work. I'd keep it all mounted on the frame and you'll tell exactly what needs to happen. For those who aren't dainty, use a large crescent wrench closed to the width of the ring. Find the high point and wrench the other way.

 

rollfaster

Riding a '38 Autocycle Deluxe

• May 27, 2014

• #8

Rubber mallet

This worked well for me, my roadmaster sprocket had to be tweaked a bit as well. Light taps as you watch the sprocket while turning the crank.

 

Kscheel

Finally riding a big boys bike

• May 27, 2014

• #9

Okay, so the chain ring is not bent. Took it off the crank and laid it flat, no high points. When assembled on the bike I noticed a gap is observed between the bearing race and back of the chain ring. As you rotate the crank the gap comes and goes in sequence with the observed wobble. I am using new bearings as well.

I'm not sure what is going on here.

 

THE STIG

Cruisin' on my Bluebird

• May 27, 2014

• #10

the crank has a bow between the races, usually when they get bent ( arm offline ) and bent back, most dont know to check for that .