Wheel Trueness (is that even a word??)

GBDamo

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Ok, I admit it I've done a silly thing or should I say did a silly thing when I loosened all the spoke screws to repaint the the hub of my rear wheel. :rob yes I know....


Now this was over a year ago and all has been ok until I went in for an MOT and tester man pointed out about 3-5mm of lateral movement when viewed from behind. :eek: He didn't fail it but put it down as an advisory. This is definitely rim and not tyre.


So I've re-centered it and got that down to under 1mm and it's all torqued up and good,but when viewed from the side the rim is about 1-2mm off center.


Now I don't know how good/bad this is, it's not quite clown car territory, so before I pull it off and start again does anyone know the tolerances or could tell me from your, unviolated, wheel how true they are normally.


Cheers :beerjug:
 
Taken from http://www.motuk.co.uk/mcmanual_420.htm


The maximum allowable rim distortion limits are as follows
Lateral (ie run out or buckling)
(a) For steel rims 4mm
(b) For aluminium alloy rims 2mm (cast or fabricated)

Eccentricity:
(a) For all types of rim 3mm
 
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There is an art to wheel building not just tight spokes but evenly so,you should either ping them see if any have differing pitch or use a tension meter,Iv done my own cycle wheels but no motorcycles though,& a good jig is also needed for getting them right I'd doubt it'd cost much to get a wheel builder to do it ��
 
Bendy toy said:
Take it to a professional.
Click to expand...

Thanks for the vote of confidence however it's something I've got my teeth into and am determined to see through.....or bin.

All the spokes are torqued up correctly and all 'ping' a similar note. There is very little lateral movement but I am concerned about the eccentricity.

I've got a pin on stand aimed at the rim and when the wheel is spun there 1-2mm of movement.

So, I'm either looking for an official tolerance or someone to say mine is better/similar/worse.

TBH I was also expecting a bit more piss taking, you boys are getting soft in your dotage. :rob
 
Cross spoke wheels are built in a jig. Even the best builders of normal wire wheels say the cross spoke are a nightmare to build freehand.

Personally, I would say that a radial wobble is likely to affect the wheel balance at speed so I'd be more concerned it rotates as true as possible with lateral movement as a secondary issue.

Making that happen is a whole different issue.
 
It's the back wheel, and less sensitive to out of balance than the front. With the figures you quote if it feels ok to ride I'd leave well alone unless I had a spare wheel to keep me on the road whilst I seek perfection on the spoked rear.
 
GBDamo said:
Ok, I admit it I've done a silly thing or should I say did a silly thing when I loosened all the spoke screws to repaint the the hub of my rear wheel. :rob yes I know....


Now this was over a year ago and all has been ok until I went in for an MOT and tester man pointed out about 3-5mm of lateral movement when viewed from behind. :eek: He didn't fail it but put it down as an advisory. This is definitely rim and not tyre.


So I've re-centered it and got that down to under 1mm and it's all torqued up and good,but when viewed from the side the rim is about 1-2mm off center.


Now I don't know how good/bad this is, it's not quite clown car territory, so before I pull it off and start again does anyone know the tolerances or could tell me from your, unviolated, wheel how true they are normally.


Cheers :beerjug:
Click to expand...

you stupid fucker:D
 
Having been a professional cycle mechanic specialising in competition wheels I feel I may have an opinion on this-you stupid fecker:thumb2
Not only do you need to ensure that the spokes have an even tension, it needs to be true laterally and radially and also the rim is central to the hub or the correct amount of dish or offset; Its not a science its an art.
 
Devon Rim Company did the front wheel on my 2011 gsa and the difference was very noticeable, having built and trued a couple of conventional wheels in the past there is no way I would even think about trying to sort a cross spoked bmw myself
 
Rusty Bolts said:
Having been a professional cycle mechanic specialising in competition wheels I feel I may have an opinion on this-you stupid fecker:thumb2
Not only do you need to ensure that the spokes have an even tension, it needs to be true laterally and radially and also the rim is central to the hub or the correct amount of dish or offset; Its not a science its an art.
Click to expand...
Wheel building is not a science or an art, it's wheel building. Good on GBDamo for giving it a go and getting it fairly accurate. A wheel builder would not normally try to build a wheel with old spokes or a rim that has set out of true. They would start with a true rim and a new set of spokes.


Bendy toy said:
Cross spoke wheels are built in a jig. Even the best builders of normal wire wheels say the cross spoke are a nightmare to build freehand.

Personally, I would say that a radial wobble is likely to affect the wheel balance at speed so I'd be more concerned it rotates as true as possible with lateral movement as a secondary issue.

Making that happen is a whole different issue.
Click to expand...
Normal wire wheels are cross spoke. They are not difficult to build if you know what you are doing. BMW wire wheels are easy to build with the hole in the hub pointing to the relevant hole in the rim. Why would a wheel builder need a jig?
 
I'd say you have it bang on. I'm just doing my third set of GSA wheels and it is fun. Mindbendingly difficult fun but also complexly do able.
I've found radial (up n down) error on the rear makes the bike vibrate, side to side on the front makes the bars shimmy. Both are horrid and get it true the bike smooths right up and is a pleasure to ride.
Jig. No.
Wheel builder needs new spokes n rim. No.
Give it a go. Yes
 
Kev Blurton, the wheel builder in Derby, well known for "normal" rims with inline spoke holes, said the cross spokes (OK its not a totally correct terminology) is a booger to build because every spoke adjustment can move the rim in three directions. It take ages to get it right. A jig allows the rim and hub to be lined up and then progressively tighten spokes to the same tension.

He does not use a jig but charges 2x the price for a BMW rebuild that he does for "normal" wheels and he says that is losing him money. He's not one of those annoying blokes who always goes on about how much a job is costing him.
 
Bendy toy said:
Kev Blurton, the wheel builder in Derby, well known for "normal" rims with inline spoke holes, said the cross spokes (OK its not a totally correct terminology) is a booger to build because every spoke adjustment can move the rim in three directions. It take ages to get it right. A jig allows the rim and hub to be lined up and then progressively tighten spokes to the same tension.

He does not use a jig but charges 2x the price for a BMW rebuild that he does for "normal" wheels and he says that is losing him money. He's not one of those annoying blokes who always goes on about how much a job is costing him.
Click to expand...

I don't disagree with a word you said, trust me I know it's a pain. but it is doable if you've got the time, patience and money to buy a new wheel when you've taken a sledge hammer to it.

I can also imagine someone not wanting to do this for a living as it's incredibly time consuming, and a jig would make it a lot easier.

But it is fun and one of them jobs gives you a sense of achievement, especially when other are too scared/sane..:confused:
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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