How much can you re-true a wheel?

[nirakaro]

After my argument with a car this morning, my front wheel is obviously a write-off. The back wheel, to my surprise, is also well out of true - perhaps an inch overall. Is that the kind of distortion I can pull back into shape, or should I write it off and replace?

[531colin]

As long as the curves are gentle, it should true up OK. Don't crank 3 turns on the spoke in the middle of the buckle, give the 2 middle ones half a turn*, then quarter turn working outwards, and keep going on like that, working first on the worst buckle at any particular time. Ideally when you finish the wheel should be true, round and centred, without a huge difference in spoke tension (on the same side of the wheel.....it varies between the 2 sides.)
If its kinked, its probably toast.

*tighter and looser opposite sides

[Brucey]

what he said.

Additionally it isn't a bad idea just to check that you haven't somehow busted a spoke before you start truing. If you have it may soon become blindingly obvious, mind...

cheers

[[XAP]Bob]

what he said.

Additionally it isn't a bad idea just to check that you haven't somehow busted a spoke before you start truing. If you have it may soon become blindingly obvious, mind...

cheers

Not always as blindingly obvious as I thought though. The one that snapped in the nipple, but had rough enough edges that I could feel resistance as I turned the nipple, but obviously no change in tension took at least three or four visits to realise that it was the same darned spoke each time...

[Ayesha]

Get most of the buckle out using a sandbag.

Don't try to pull all the buckle out with spoke tension. The rim might fail at a later date.

[Mick F]

Would it not be better to remove the rim, straighten it a bit, then re-build?

[meic]

If I had that happen to one of mine, I would have to slacken all the spokes off and retrue it from scratch.

In the absence of a tension meter, I can see me correcting a buckle by adding additional tension to tight spokes rather than "slack" spokes. As both the tight and "slack" spokes seem very tight to me.

Reducing the tension on all the spokes helps you to stop adding tension errors on to spokes which already have a tension error.

The first two posts were about the same idea but much more localised. I can generally spot and correct a tension error in a small area of the rim but not if it is a whole half or quarter of it.

[nirakaro]

Doh! Ayesha, what do I do with the sandbag?

[531colin]

As above, if a wheel has an inch overall buckle, so maybe half an inch left, and half an inch right, then bending the rim would NOT be my first approach.
With a really bad buckle, bending the rim may salvage the wheel, and with a kinked or acutely bent rim, bending it may get you home.
Jumping on the wheel may let it go round without hitting the stays, but doesn't often result in a durable repair.
The best (or least worst) way to straighten a bent rim is by leverage, this is much more controllable than jumping on it.
Slacken off all the spokes in the bent area**, insert the wheel in a park bench or park railings, and using the straight bit of the wheel as a lever, bend it.
Trailside, you can do the same with eg. 3 sticks on the ground......one at the start of the buckle, one in the middle, one at the end. stand on sticks one and three. pull the opposite side of the wheel up towards you.

**If you bend it without slackening the spokes, you will be bending and altering the tension at the same time

[Brucey]

Would it not be better to remove the rim, straighten it a bit, then re-build?

if the rim is fairly badly bent, yes. However, it may not be necessary.

A reasonably quick and easy method for a bent rim (rather than a wheel that can be trued back straight by adjusting spokes)is to slacken all the spokes in the wheel by exactly two (or three) turns (one turn at a time), and check the rim is straight. If it isn't, it can be straightened by bending etc. Within 5mm is more than good enough at this stage. Then just retension the spokes by exactly as many turns as they were slackened by, one turn at a time until you get to the last turn which is better done half a turn at a time.

Often the wheel will come back straight within a couple of mm like this, even before any truing is done.

cheers

[ambodach]

Surprising what you can do with a wheel sometimes. A couple of years ago on North Uist I wheeled the bike up to the Air Ambulance memorial. On the way down I slipped and landed on the back wheel which was completely tacoed. This is in the middle of nowhere and miles away from my van! With the wheel off I stood on the rim on the worst bits and managed to my surprise to get it more or less round and then tweaked it a bit by adjusting some spokes.I was able to cycle the rest of the way back which was about 30 odd miles with no problem.Mounted the bike on the cycle rack on the back of the van and managed to get the wheel good enough for the rest of my trip.

[Mick F]

This reminds me of an incident when me and my mate Paul rode up Rivington Pike (Lancashire to the NE of Wigan) - must have been 1967 or so. We were 15.

I was on my 26" wheel Hercules with 3sp SA fitted with a double sprocket, and Paul was on his 27" wheel Carlton with a 5sp derailleur. Near the top, Paul hit a rock and his front wheel bent rather badly. Paul had a rotten temper, and rather kicked and stamped on his wheel. I stood back and let him rant.

His wheel popped back into shape, so maybe that was it - fixed!