Truing the rim first

Hello All,

I am reaching the critical mass of my moped (magnum xk '78 i think) knowledge, that is to say without advice i am likely to start hurting things more than repairing them...

Truing the front wheel...had some serious wows in it, the problem i am facing now is that some spokes are so tight that they will not tighten more while others are pretty lose and the wheel is not true yet. This is the case on both sides, that is the rim is not pulled all the way to the left and needs to go to the right, some sections are one way and others the other way...

Thanks

-nathan

Re: Truing the rim first

bump

Re: Truing the rim first

Ok, you really need to re-tension your wheel.

WARNING: Plan to spend from 4 to 6 hours on the following process.

Take the wheel off your 'ped, take the tire off, and put the wheel

on a truing stand (could just be a piece of pipe through your wheel,

with the pipe in a bench vise).

Loosen all the spokes until they go thump instead of

_ting_.

Now, get something to measure your deflection. You really

want to get yourself a dial caliper set ("$25 at Harbor Freight tools":http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93051 )

If you're a cheap-ass, a magic marker clamped so that the tip just barely

touches the highest spot (and you lower it as you true, and wipe off the

marker as you go) will do in a pinch.

And speaking of magic markers, make your like easier by putting a piece

of making tape all around your rim so that you can number your spokes.

It'll save a lot of time if you need to undo a step, or if you have a

troublesome area.

Anyhow, here are my stages to truing a wheel:

(I'm assuming you are truing it horizontal)

Gross up/down

In this phase, you will be tightening all of your spokes so that the

will is _basically_ flat, and your rim is centered on your hub.

DO NOT OVER TIGHTEN HERE! You will need to spare tension later.

You just need to bring the rim in line with the hub's center.

Gross in/out

Using just a 1/4 turn at a time, adjust the spokes so that when

you spin the wheel, it's _mostly_ round. A 1/8" deflection is

fine.

Fine up/down

Now, we get rid of the 'bumps' in the wheel. In this phase, your

dial caliper (or marker) should be hitting high points either between

or right on a spoke. If right on, tighten for spokes that go down,

and loosen for spokes that go up. If between, adjust both spokes.

Remember - GO SLOW! Only tighten by a 1/4 turn, then move on to

another part of the wheel. If you work only on one side at a time,

that side will be over tightened, and, like a spring, will rapidly deflect

when you adjust the other side.

You're looking for a final deflection of about 1/16", and your spokes

should go _tang_. Not _ting_ yet, but we're getting there!

Fine in/out

Same as fine up/down, but when you adjust for in/out deflection,

you must tighten or loosen two or more spokes at a time -

one going 'up', and one going 'down'. They must be adjusted

at the same time, and, please check your up/down deflection after

every in/out adjustment!

I cannot stress this more - if you over tighten during the in/out phase,

you can rapidly warp your wheel out of true. If you check up/down

every time, it's easy to undo what you last did.

Torqing

Now come the what you've been waiting for - _ting_ _ting_ _ting_

This is the trickiest part - you need to _gradually_ adjust all the

spokes to be in tension without messing up all of your hard work.

What I usually do is rig up the dial caliper to right where I'll be

doing the adjustments (set for measuring up/down deflection),

and tighten only the loosest spokes until the tiniest deflection is

measured, then back off a little. I go round and round, slowly

torquing it all in, a little at a time, until all the spokes make a nice

_ting_ sound. For my wheels, a higher pitched _tink_ sound is

too much, and I back off.

You're Done!

Re-tire and mount your wheel, and have fun!

Re: Truing the rim first

Hmm. I should probably put this on the wiki..

http://www.mopedarmy.com/wiki/Wheel_Truing

Re: Truing the rim first

Leon Swarmer /

excellent write up Jason.

Re: Truing the rim first

Thanks. It was all fresh in my mind, as I had to true my rear wheel

last week.

I was in a hurry, and got it all wrong. I had deflections of over 1/4"

of an inch, and all my spokes went thump.

So, I talked to a guy at my office who makes his own bicycle wheel ... _for fun_ ...

and I got a lot of great hints from him.

So I went back, took the tire off (puncturing my tube in the process

- DOH! - ) and followed his advice.

After 4 hours of following the above procedure, I had it perfectly

tensioned, with a final deflection of +/- 0.02 inches (that's half a millimeter,

for the rest of the world) on both in/out and up/down.

I was beaming for _days_, I was so proud of myself

Re: Truing the rim first

Thank you so much for the in-depth adivce, although i do not look forward to undoing all that i did, a striaght wheel is better than an almost striaght wheel any day!

thank you again.

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