Not true: deep section disc brake

Everything about building wheels, glueing tubs, etc.
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urbanspaceman
Posts: 20
Joined: Thu May 25, 2017 7:05 pm

by urbanspaceman

Hi all.

I race cyclocross and am currently using a set of Planet X 38/38 deep sections (tubular for disc brakes). My problem is that I have noticed that they are not running very true at all.

Obviously the disc brakes mean that I'm not having to worry about brake block rub but is there any other reason why I should get them trued ASAP?

I'm hoping that I'll be told that they can survive a few months till the end of the CX season as I have fixed the tub using the "Belgian Method" and do not relish the prospect of ruining a nearly new tyre by having to remove it (not to mention the time and slog of having to remove and reglue!!).

Cheers,
Matt

by Weenie


joejack951
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by joejack951

Do the wheels have internal nipples or something? If not (and my deepest condolences if they do), there is no need to remove the tire to true the wheel. For me, the issue isn't the out of trueness so much as what caused it in the first place. If the root cause is poor tension balance, I'd want to fix that before it did any more fatigue damage to the spokes, or before you break a spoke at a really bad time.

Note that taking the wheel somewhere and simply asking for it to be trued isn't going to get you a properly tension-balanced wheel. The LBS mechanics I've witnessed attempt to true a wheel knew little more than myself at the time. Now that I've built my own wheels for a number of years I'd never let anyone but another wheelbuider touch my wheels. Certainly not the guy who gave up trying to true my rear wheel years ago and convinced me it needed to be replaced. A properly tensioned wheel is a reliable one. A true wheel may or may not be properly tensioned.

bm0p700f
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by bm0p700f

This is the problem when you get someone asking how much a wheel true is my answer it depends on how much time it takes for the above reason.
Last edited by bm0p700f on Sun Oct 08, 2017 9:34 pm, edited 1 time in total.

FIJIGabe
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by FIJIGabe

I just checked on your wheels, and I'm afraid that that tub is a goner. Internal nipples on a tubular CX wheel should be outlawed!

https://www.planetx.co.uk/i/q/WPPXCX38D ... e-wheelset

You can ride the wheel all you like, but at some point, it's going to give up the ghost and fail on you (most likely on the last turn of a big race, when you're up front and you can see the top step of the podium and taste the beer). If I were in your shoes, I'd bite the bullet, take the wheel to a reputable shop, and have them true the wheel and make sure all the spokes are properly tensioned. Don't be afraid of asking them what tools they use for this, and what experience they have. If they get angry or don't have an answer, then walk out.

Best of luck!
Madone 9 https://goo.gl/7UwZpV
Crockett https://goo.gl/f5PdCN
Madone 5 https://goo.gl/cMdyFo

Madone 4, Cobia. I own a lot of Treks.

whosatthewheel
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by whosatthewheel

Planet X typically use internal nipples, as above and they are a pain. To add to the grief of having to remove the tub, you need to find out which standard of nipple you have. There (at least) two sizes of hexagonal and one size of square internal nipple. Park tool make a triple key that should work.

If a wheel is not true, typically there is a reason, which might well be poor and uneven tension, which in turn will lead to spoke fatigue and breakages. If you have noticed it in a disc wheel, it means it is pretty severe and should ideally be addressed.

joejack951
Posts: 384
Joined: Fri Feb 18, 2005 6:50 pm
Location: Wilmington, DE

by joejack951

bm0p700f wrote:This is the problem when you get someone asking how much a wheel true is my answer it depends on how much time it takes for the above reason.


To your point, I recently borrowed a set of wheels from a coworker for a weekend and in turn I offered (naively) to address a 'small out of true issue' on the rear wheel. 9pm the night before I planned to leave for a small weekend excursion I put the wheel in my truing stand (mistake #2). NDS tension was all over the place and DS was precariously low, too. An hour later, I finally had the wheel sorted. But I could have built a wheel from scratch in that time (note that a real wheel building pro likely would have finished in half the time).

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Miller
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Joined: Thu Sep 21, 2006 8:54 pm
Location: Reading, UK

by Miller

urbanspaceman wrote:I race cyclocross and am currently using a set of Planet X 38/38 deep sections (tubular for disc brakes). My problem is that I have noticed that they are not running very true at all.


How much out of true? Are any spokes slack?

A positive, or, viewed in another light, a negative of disk wheels is that you can indeed tolerate some out of trueness with no apparent effect on ride quality. Question is, is the out of trueness:
(a) a feature, that's just how they roll
(b) a sign of imminent collapse.

Up to you to assess that!

urbanspaceman
Posts: 20
Joined: Thu May 25, 2017 7:05 pm

by urbanspaceman

Thanks a million everyone. With just a few weeks of racing left (I only use the wheels on race day), based on the above I think I'm going to chance it till the end of the season and then bite the bullet on tub removal and a visit to a decent wheel builder (there are a few around me). There are no spokes loose so I'm hoping it's not catastrophic.

Again, a massive thanks to all :)

by Weenie


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WinterRider
Posts: 396
Joined: Tue Feb 05, 2013 2:46 pm

by WinterRider

joejack951 wrote:
Mon Oct 09, 2017 12:41 pm
bm0p700f wrote: An hour later, I finally had the wheel sorted. But I could have built a wheel from scratch in that time (note that a real wheel building pro likely would have finished in half the time).

Whew... :thumbup: Well done.

Suggesting.. speed/time to build is of questionable value. I used to think that.. since learned.

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