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Slowtwitch Forums: Triathlon Forum:
HED3 Runout numbers: Roundness vs. trueness

 

   


stal

Apr 26, 09 20:15

Post #1 of 12 (3866 views)
HED3 Runout numbers: Roundness vs. trueness Quote | Reply

looking at a few wheels on ebay (clincher fronts) it seems that some have only the runout/'trueness' numbers sharp-ied in and some have both the roundness and trueness numbers written in there.

Did they change their protocol for writing this on the wheels or something...and what are acceptable numbers for both if you don't want to feel a hop?


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Titanflexr

Apr 26, 09 20:51

Post #2 of 12 (3837 views)
Re: HED3 Runout numbers: Roundness vs. trueness [stal] [In reply to] Quote | Reply

I think HED rates anything with runout <0.03" as an top grade wheel. Anything beyond that, and you will feel a hop (mine is 0.032, and I can notice it, but only at very high speeds, or when my bike is in the workstands and I rev up the wheel)). Trueness won't cause a hop.

There are some HED employees on ST, hopefully they can chime in.


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In theory, there is no difference between theory and practice.


justfast

Apr 26, 09 21:28

Post #3 of 12 (3819 views)
Re: HED3 Runout numbers: Roundness vs. trueness [Titanflexr] [In reply to] Quote | Reply

In Reply To:
I think HED rates anything with runout <0.03" as an top grade wheel. Anything beyond that, and you will feel a hop (mine is 0.032, and I can notice it, but only at very high speeds, or when my bike is in the workstands and I rev up the wheel)). Trueness won't cause a hop.

There are some HED employees on ST, hopefully they can chime in.

I'm very interested in this thread b/c I'm considering purchasing a new set of H3 clinchers.

I don't wanna hop and I'm willing to purchase new from authorized dealer to avoid issues.

It's difficult to believe that anyone would even considering buying/selling a wheel that is known to have performance flaws (short of blowout pricing).


Titanflexr

Apr 26, 09 21:43

Post #4 of 12 (3806 views)
Re: HED3 Runout numbers: Roundness vs. trueness [justfast] [In reply to] Quote | Reply

This has been an issue since DuPont first made these wheels. The fiber/resin comes out of the mold , and you get what you get. There is a natural variation in the manufacturing process, and no way to change it after the fact (with deep-V rim wheels, you can adjust the variations out with spoke tension). As a result, HED grades the wheels (I think the top grade is <0.02"). To be fair, all wheels have some variation; the wire spoked wheels we all own are built to some manufacturing tolerance (varies by builder). There is no such thing as a perfectly round/true wheel.


__________________________________________________
In theory, there is no difference between theory and practice.


justfast

Apr 26, 09 21:59

Post #5 of 12 (3800 views)
Re: HED3 Runout numbers: Roundness vs. trueness [Titanflexr] [In reply to] Quote | Reply

In Reply To:
This has been an issue since DuPont first made these wheels. The fiber/resin comes out of the mold , and you get what you get. There is a natural variation in the manufacturing process, and no way to change it after the fact (with deep-V rim wheels, you can adjust the variations out with spoke tension). As a result, HED grades the wheels (I think the top grade is <0.02"). To be fair, all wheels have some variation; the wire spoked wheels we all own are built to some manufacturing tolerance (varies by builder). There is no such thing as a perfectly round/true wheel.

Thanks for your response.. puts things into perspective.

However, I've never noticed a hop with a spoked wheel?


tridork

Apr 26, 09 22:21

Post #6 of 12 (3786 views)
Re: HED3 Runout numbers: Roundness vs. trueness [justfast] [In reply to] Quote | Reply

In Reply To:
In Reply To:
I think HED rates anything with runout <0.03" as an top grade wheel. Anything beyond that, and you will feel a hop (mine is 0.032, and I can notice it, but only at very high speeds, or when my bike is in the workstands and I rev up the wheel)). Trueness won't cause a hop.

There are some HED employees on ST, hopefully they can chime in.

I'm very interested in this thread b/c I'm considering purchasing a new set of H3 clinchers.

I don't wanna hop and I'm willing to purchase new from authorized dealer to avoid issues.

It's difficult to believe that anyone would even considering buying/selling a wheel that is known to have performance flaws (short of blowout pricing).


Buying new from a dealer makes no difference. The wheel is the wheel. You get what you get.

I bought HED3, 650C pair, from a dealer about 2 years ago and the front is arguably perfect for trueness and roundness (I can't detect any fault with either on the front wheel)

The rear wheel has a slight wobble (out of true by a tiny tiny bit), but the roundness is not particularly impressive IMHO. It's within somebody's tolerance, but not mine. I downhill like a man with no brain and it becomes apparent at speed. At normal speeds (up to say 60kph or so) I don't consider it a problem, but over 60 it can be felt for sure.

I have found that if I mark the high spot of the wheel, and mount the tire carefully. I can scooch (technical term) the tire just a bit, on the rim, to fix almost all the difference, to minimize it. Not ideal of course, but works well enough.

Regardless, still great wheels and I love them to bits. I just wish I could love them that little bit more.

TriDork

"Happiness is a myth. All you can hope for is to get laid once in a while, drunk once in a while and to eat chocolate every day"


Titanflexr

Apr 26, 09 22:51

Post #7 of 12 (3775 views)
Re: HED3 Runout numbers: Roundness vs. trueness [justfast] [In reply to] Quote | Reply

In Reply To:
In Reply To:
This has been an issue since DuPont first made these wheels. The fiber/resin comes out of the mold , and you get what you get. There is a natural variation in the manufacturing process, and no way to change it after the fact (with deep-V rim wheels, you can adjust the variations out with spoke tension). As a result, HED grades the wheels (I think the top grade is <0.02"). To be fair, all wheels have some variation; the wire spoked wheels we all own are built to some manufacturing tolerance (varies by builder). There is no such thing as a perfectly round/true wheel.

Thanks for your response.. puts things into perspective.

However, I've never noticed a hop with a spoked wheel?

For contrast, Easton trues their wheels to 0.004" round/true in production (for reference, a sheet of standard copy paper is about 0.003"). However, as we all know, spoked wheels can go out of true with use; while the H3 will remain as true/untrue as the day you got it (crashes excepted). My guess is most racers would true up a spoked wheel once the hop was noticeable.


__________________________________________________
In theory, there is no difference between theory and practice.


G-man

Apr 26, 09 23:13

Post #8 of 12 (3768 views)
Re: HED3 Runout numbers: Roundness vs. trueness [Titanflexr] [In reply to] Quote | Reply

If you buy from a volume dealer, ask them to put them in a wheel jig and give them a spin. If they have 5 or 10 they should have one better than the others. My Hed 3 seems to have warped over the years and has a bigger whop than it used to. My Hed3 rear disk remains one of the truest discs I have ever seen. Stored in the same double wheel bag for years together.


stal

Apr 27, 09 4:31

Post #9 of 12 (3700 views)
Re: HED3 Runout numbers: Roundness vs. trueness [Titanflexr] [In reply to] Quote | Reply

Thanks for all the responses...but a question remains.

There are two numbers, roundness and trueness. <0.03 = an 'A' grade wheel. Is that for roundness or trueness? or both? and the 'hop' is felt by a roundness number, usually greater than 0.03 I imagine?

Also, if there is only one number sharp-ed onto the rim, is that the roundness or the trueness number?


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p.VDB

Apr 27, 09 4:59

Post #10 of 12 (3677 views)
Re: HED3 Runout numbers: Roundness vs. trueness [stal] [In reply to] Quote | Reply

Does HED list those numbers on the wheel?

Where can I find those numbers? My girlfriend has a H3 (bought new in oct 2008) and I am curious...
___________________________________
Paul | Medisch Info | Medisch Zoeken


stal

Apr 27, 09 5:02

Post #11 of 12 (3675 views)
Re: HED3 Runout numbers: Roundness vs. trueness [p.VDB] [In reply to] Quote | Reply

take your tire (and any rim tape...yes it happens) off the wheel. It should be written in black marker on the inside of the rim somewhere near the valve hole.


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shish

Mar 16, 11 21:57

Post #12 of 12 (3059 views)
Re: HED3 Runout numbers: Roundness vs. trueness [stal] [In reply to] Quote | Reply

Roundness is important but the hop discussed in this thread is likely due to an imbalanced wheel.

   
 
 
 



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