A23 wrong ERD on Velocity web site

[Nick Payne]

Velocity show an incorrect ERD on their web site for the A23 and A23 OC
in 650B. They show an ERD of 560mm for both rims
(http://www.velocityusa.com/product/rims/a23-650b and
http://www.velocityusa.com/product/rims/a23-oc-650b). My measurements on
the A23 and A23 OC rims that I have give 568mm for the front rim and
566mm for the OC rear. I measured by threading a couple of nipples
backward onto spokes, poked them into a couple of the spoke holes on
opposite sides of the rim, measured the distance between the bottom of
the nipples, and added 24mm for the length of two nipples. I did this at
two diameters 90 degrees apart and took the average of the two readings
if they were different (they weren't).

FWIW, their weights for the rims are also over the odds, though rim
extrusions do get heavier over the life of a die as it wears. Those web
pages show 435g for the A23 and 445g for the A23 OC. Measuring on some
accurate digital scales, I get 403g for the A23 and 422g for the OC. I
wouldn't have been surprised if I measured the rims as heavier than
claimed, I am a bit surprised that they are lighter.

Nick

[Nick Payne]

p.s. One other thing I noticed while I had the front and rear rims
stacked on top of each other for these measurements is that the outer
diameter of the standard A23 rim was ~2.2mm greater than that of the OC
rim. As a good set of vernier calipers showed that the height of the rim
wall above the bead seat was the same on both rims to within 0.1mm, this
can only mean that one rim is oversize or the other rim undersize.

So it looks as though Velocity still have problems manufacturing 650b
rims to the correct diameter - I've noticed the same problem with 650b
Synergy rims in the past - Synergy 650b rims I've purchased at different
times have varied in diameter by about the same amount.

[Anthony King -- Longleaf Bicycles]

On Friday, February 6, 2015 at 1:40:14 AM UTC-5, NickP wrote:

Velocity show an incorrect ERD on their web site for the A23 and A23 OC
in 650B. They show an ERD of 560mm for both rims
(http://www.velocityusa.com/product/rims/a23-650b and
http://www.velocityusa.com/product/rims/a23-oc-650b). My measurements on
the A23 and A23 OC rims that I have give 568mm for the front rim and
566mm for the OC rear. 

I don't think any of those are correct. 

Here's the measurements I have used for 650B A23's.

Silver Anodized first run made for me: 564.5mm

Polished run distributed by EAI: 563mm

I believe the slight change was made because I told Velocity the initial run fit tires a bit too tight compared to the 700C extrusion. 

[Jason Marshall]

Can't speak to the measurements but I will say that my tires (loup loup pass) mount nicely.

[Jeremy Shlachter]

I got 562mm for both the A23 and A23OC, silver anodized.

[Mark Reimer]

Hmm interesting. I just built up a pair of A23 rims, rear is the offset version, using the specs on the website. My spokes were the perfect length using their numbers. I haven't mounted tires yet though. 

[Anthony King -- Longleaf Bicycles]

On Thursday, May 12, 2016 at 2:12:29 PM UTC-4, Mark Reimer wrote:

Hmm interesting. I just built up a pair of A23 rims, rear is the offset version, using the specs on the website. My spokes were the perfect length using their numbers. I haven't mounted tires yet though. 

I measure 563mm on current production A23 650B rims. Being off by 1 or 2mm probably won't matter, but if you are off by 1 or 2mm and you round up or down to an even length spoke you can run into some trouble.

BTW Velocity's site says 601 for the 700C A23 erd. If you do the math, one of those measurements (700C or 650B) has to be wrong.

Anthony

[satanas]

So what measurement should one use? Or perhaps every rim needs to be checked if they are making it up as they go along, or quality control is abysmal.

Since these seem to be about the only light non-disc 650b rim potentially available in Oz it's a bit of a worry.

Later,
Stephen (who will need to build a rear later in the year)

[Chris Cullum]

I'd go with Anthony's measurements, he has a lot of experience with these rim builds.

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[Stephen Poole]

Thanks Chris, I should have thought of that...