Incorrect information from Sheldon Brown on 700D?

[Ryan Watson]

Warning: the content of this post is probably uninteresting to 99.9999% of cyclists!

I used to take everything at sheldonbrown.com as gospel, but then found this regarding 700D:

“Oddball size formerly used on some GT models. Not available. 584 mm tires may work. Note: 700D is often incorrectly identified as 587mm bead seat” 

They say it is actually 583mm.

https://www.sheldonbrown.com/harris/tires/587.html

I probably have as much 700D experience as anyone and it is most definitely bigger than 584 and smaller than 590. 650B tires can fit but are very tight, while 650A is almost too loose, but a better fit than 650B. No way it’s 583, at least for the Araya RM-17 and RM-20 rims, which are the only 700D rims I know about. 

Does anyone know where this 583 number came from?

Ryan 

 

[daxo potato]

it looks like this might be a post- Sheldon edit? 

but it might also be true. 

i have an araya 700d rim (and tyre) and a 584 hetre is a pretty loose fit on that rim. that would indicate the rim is smaller than 584, no? 

Dave 0.0001% in NY

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[rswatson]

That's interesting, I've mounted Hetres and other 650B tires on Araya 700D rims and they were VERY tight. 650A tires fit well, but can also be too loose. That tells me it's somewhere between 584 and 590. 587 sounds about right ;-)

Ryan

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[rcnute]

I've always gotten a big lump when trying to mount 650B tires onto 700D rims that I couldn't get rid of.  I've had a 650A tire blow off a 700D rim on a ride because it was too loose, but that was on one of the narrower Araya rims.  No problems yet with 650A tire on the wider Araya rim (RM-20?).

So, I think you're right!

Ryan (part of the .0001%)

[etorg...@yahoo.com]

It is possible two, and maybe three of us here have used some of the same rims and tires in our stable of bikes.  I too have the same experience as the Ryans.  I happily use the Araya (wider version) 700ds with 650b tires. I think I once cut the wire bead to remove a tire. And I also read Sheldon's post with puzzlement. 

Eli

In Corrales

[rswatson]

I've been in contact with John who maintains Sheldon's site now and he sent me this:

"At this point, I don't know what to think. It would help for me to get ahold of an actual 700D rim to measure. Or you could measure one of yours and let me know. That would be a useful service. Measuring techniques are here: https://www.sheldonbrown.com/rim-sizing.html

And by the way, neither the 587mm nor the 583mm number originated with Sheldon"

So if you want to help the cause, please measure your rims and I'll pass it along! 

My only 700D rims are in currently in Japan.

Ryan 

To view this discussion on the web visit https://groups.google.com/d/msgid/650b/765f90e9-e327-414c-915b-2216d0724e64n%40googlegroups.com.

[Brad]

One of the challenges of measuring rims by tire fit is that some tires can stretch on off size rims.   The infamous Sun CR-18 rim in the 650B flavor being an example.*  It was suspected as being made on left over tooling for 700D rims for GT.    In my humble opinion 700D is probably 587. 

*After a year plus on the Sun rim one tire I had was too loose to fit on another brands known 650B rim.  A new tire of the same kind fit the known 650B rim.  The tires had wire beads.  They were Panaracer Col de la Vie.

[Brad]

.... and then there is this.  https://budgetbicyclectr.com/700d-crossover-tires-by-gt-for-sale-online.html

On Monday, November 7, 2022 at 6:25:33 PM UTC-5 Ryan wrote:

[daxo potato]

On Thu, Nov 10, 2022, 20:18 Brad <riendeau...@gmail.com> wrote:

One of the challenges of measuring rims by tire fit is that some tires can stretch on off size rims.   The infamous Sun CR-18 rim in the 650B flavor being an example.*  It was suspected as being made on left over tooling for 700D rims for GT.   

not sure how this ^ would be true.

from what i understand, rims are extruded diameter agnostic, and then rolled and cut to the desired BSD. are they rolled via some fixed device? i assumed it would be an adjustable mechanism but perhaps not. and are araya and sun part of the same company? it seems unlikely that they would share tooling decades later if not. 

i do know that i would love to see cr-18 rims in true to size 650B/584. i recognise they are not as high quality as velocity/pacenti (which i believe are or were manufactured for them by sun ringlè?) etc but they hit a great price v quality ratio for the type of riding i do

dave .0000001% in NY