Author Topic: Trueing wheels - especially roundness  (Read 1628 times)

Trueing wheels - especially roundness
« on: 11 July, 2010, 09:23:04 pm »
OK, had a new bike delivered. Unfortunately, when it arrived, one of the spokes on the rear wheel was so loose, it was almost out of the nipple :o

As I was tightening it up & trueing the wheel I noticed that instead of being round i.e. O it's more like D not that bad but just about noticable when you spin the wheel & look down on the rim at a tangent. Can this be trued out?

It's going back for a refund rather than replacement as the wife has said I can't keep it even though she agreed I could get another bike :-\

Charlotte

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Re: Trueing wheels - especially roundness
« Reply #1 on: 11 July, 2010, 09:28:24 pm »
Yes, you can correct for ovality.  It's something that you should check for during a wheel build.  You tension a matched pair of L/R spokes so as to "pull in" a high spot without affecting lateral truth.

A good, new rim should be pretty much round from the word go, though.  More importantly, a millimetre or so isn't such a big deal because most tyres will have that sort of imperfection in them anyway, so you won't notice it when you're riding.
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Re: Trueing wheels - especially roundness
« Reply #2 on: 11 July, 2010, 09:33:43 pm »
Trouble is, it's not oval, but has a flat section. I Suppose loosening the spokes on the flat part & tightening those immediately either side would have the desired results??

I had a quick read of Sheldon's page, but it doesn't have anything so, another resource would be grateful  :thumbsup:

Biggsy

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Re: Trueing wheels - especially roundness
« Reply #3 on: 11 July, 2010, 10:10:08 pm »
Depending on the tension at the moment, you can loosen the spokes at the flat part, and/or tighten all the rest (not just either side of the flat spot).  Note that more difference in tension is needed to affect roundness than lateral trueness.  You'll probably mess up lateral trueness in the process, but that can be corrected.

Or just leave it alone if you can't feel anything odd as you ride.

Sheldon does include roundness (radial trueness) in his wheel building instructions.
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Re: Trueing wheels - especially roundness
« Reply #4 on: 11 July, 2010, 10:23:08 pm »
Cheers for the replies, I've not had much to do with wheels & spokes as you can gather!

I saw the references to radial trueness but wasn't sure how to put it in to practice with a flat spot as opposed to an egg shape.

Biggsy

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Re: Trueing wheels - especially roundness
« Reply #5 on: 11 July, 2010, 10:30:14 pm »
It's not easy for a novice truer to get rid of a flat spot.  If you want to give it a go, you've got to be prepared to spend quite a lot of time if you mess up.

Messing up doesn't matter as long as you don't over-tighten any spoke, which could damage the rim.  Trouble is, you don't know how much is too much until you've actually done it once in your life (or use an expensive tension meter).
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Re: Trueing wheels - especially roundness
« Reply #6 on: 11 July, 2010, 10:37:08 pm »
OK, had a new bike delivered. Unfortunately, when it arrived, one of the spokes on the rear wheel was so loose, it was almost out of the nipple :o


Don't even try to improve the wheel just send it back and hope the rest of the bike is put together better.

Re: Trueing wheels - especially roundness
« Reply #7 on: 11 July, 2010, 10:38:30 pm »
Well, I tightened the loose spoke enough to stop it flopping around, span the wheel then noticed the flat spot. At that point I called the retailer & they are collecting the bike on Tuesday. So this is more out of curiosity.

Re: Trueing wheels - especially roundness
« Reply #8 on: 11 July, 2010, 10:41:46 pm »
The rest of the bike is fine, brakes needed adjusting, not sure on the gears as I haven't ridden it.

TBH, unless it's a simple trueing wheels are the only part on a bike I wouldn't do.