Rim straightening tips ?

Amit Gosh said:

I have a rim which I'm sure I bent (don't ask how), but it's pretty
minor. How should I go about straightening it ?

Quoted message said:

I have slackened all the spokes, but do I have to unlace the wheel or
is there an acceptable way to go about it the way it is ?

Quoted message said:

It's a 32 hole shallow rim if that has any relevance.

You didn't say what sort of bend your rim has. A radial low spot is
hard to fix but, if smooth, can be pulled out. I have a special tool
for that:

http://www.yellowjersey.org/photosfromthepast/RIMTRUE.JPG

but have done it by loosening only those spokes in the zone of the
flat spot, hung the wheel on a 2x4 between rafters and pulled down
with my weight as I lunged on it.

Lateral wow's are easier to do.

Xplain!

Jobst Brandt

Quoted message said:

Lateral wow's are easier to do.

Xplain!

Okay. It's lateral. So slightly potato chip shaped, but not severe.

I imagined I could lay the wheel horizontally on with some wooden
blocks at either end ie : "12 o'clock" and "6 o'clock" and push down at
"3 o'clock" and "9 o'clock" where I would have positioned the "high"
points.

-Amit

Quoted message said:

Quoted message said:

Lateral wow's are easier to do.

Xplain!

Okay. It's lateral. So slightly potato chip shaped, but not severe.

I imagined I could lay the wheel horizontally on with some wooden
blocks at either end ie : "12 o'clock" and "6 o'clock" and push down
at "3 o'clock" and "9 o'clock" where I would have positioned the
"high" points.

I have found that lightweights such as I (135lb) require either dangerous
leaping in the air to attain the required force for plastic deformation
(often with slipping and falling), or simple slamming of the deflated wheel
on a non-marring surface to bring the wheel back into true. There is
overshoot, but careful, meticulous correction with additional slamming
teaches the rim who's boss. 😉
--
Phil, Squid-in-Training

Amit Gosh said:

Quoted message said:

Lateral wow's are easier to do.

Quoted message said:

Quoted message said:

Xplain!

Quoted message said:

Okay. It's lateral. So slightly potato chip shaped, but not severe.

The wheel must be moderately tensioned to do this. Just the rim will
not respond to this treatment and the spoke compliment makes sure that
the rim remains round. If the wheel was properly tight when it got
out of shape all spokes, regardless of current tension should be
uniformly backed off a half turn if a spoke nipple. Then lay the
wheel on the floor and kneel on it with knees to either side of the
wow with hands adjacent to knees.

Carefully bouncing on it and checking for results after each loading,
you will find how much force it needs. You may need to correct
elsewhere after the main wow is back in line. When the wheel looks
ridably straight with minor wobbles, true it as you re-tighten the
spokes after putting a drop of oil in each spoke nipple/eyelet
junction from the spoke side.

Jobst Brandt

Quoted message said:

I have a rim which I'm sure I bent (don't ask how), but it's pretty
minor. How should I go about straightening it ?

Lay it flat on a surface. If it's out-of-flat by 2-3 mm OR LESS at
the worst point, I wouldn't bother straightening it; just true it
straight. If it's an old 1980's "heat treated rim", then the best way
to deal with it is to send it straight to the landfill.

- Don Gillies
San Diego, CA

Donald Gillies said:

Quoted message said:

I have a rim which I'm sure I bent (don't ask how), but it's pretty
minor. How should I go about straightening it ?

Lay it flat on a surface. If it's out-of-flat by 2-3 mm OR LESS at
the worst point, I wouldn't bother straightening it; just true it
straight. If it's an old 1980's "heat treated rim", then the best way
to deal with it is to send it straight to the landfill.

I didn't want to unlace it if I could help it, and in fact I think
having a laced rim is easier to straighten.

This is what I did and the result was pretty good:

The wasn't tacoed, but rather the lateral bend was localized at one
spot.

I had initially totally slackened the spokes, this was a rear so I used
the drive side spokes to radially true it as best I could, with fairly
decent tension. I made sure the left side spokes were totally slack.

On the truing stand I eyeballed as best I could where the "wow" was

Then I used Jobst's suggestion and laid it on the ground, kneeling or
stepping on one edge and using my weight to bend back the wow.

I was surprised how much the wheel could deform and still spring back.
It took more force then I expected, but I could feel it yield when it
did.

I radially trued and bent the rim iteratively until it looked like I
could simply use the left side spokes to laterally tue and dish the
wheel.

I have thrown out a few bent rims over the years, but I wish I had
tried this first, I probably could have saved some of them.

-Amit