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Sun CR18 rim ERD - different depending on eyelets or no?

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Sun CR18 rim ERD - different depending on eyelets or no?

Old 08-26-17, 12:36 PM
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TallRider
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Sun CR18 rim ERD - different depending on eyelets or no?

Sun rims has produced the CR18 for 15-20 years already, and has versions for a range of diameters and drillings, without a lot of publicly-available information about the range.

The 700c version has a listed ERD of 612mm. This is presumably for the version with (single) eyelets. There is, however, a less-common version without eyelets. I ended up with one of the eyelet-less rims, and I wonder what is the ERD.

Normally, rims without eyelets have thicker aluminum extrusion on the spoke bed.
Does anyone know if this is true for the eyeletless version of the Sun CR18? If yes, then the rim will be heavier and the ERD will probably be about the same. If not, then the rim will be weaker (more prone to cracking). and the ERD will be larger.
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Old 08-26-17, 01:55 PM
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Always good to measure it yourself, even if the manufacturer does publish specs.
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Old 08-26-17, 03:14 PM
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How thick is the eyelet material?
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Old 08-26-17, 03:36 PM
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When I measured a new CR-18 rim with eyelets, it agreed with the manufacturer's number. I still prefer doing my own measurement, because I can account for my own (possibly wrong) opinion about where I want the spoke ends to sit in the nipples when all is said and done. It means that I can't order the rim and the spokes at the same time, but I get them from different suppliers anyway.
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Old 08-26-17, 03:50 PM
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Eyelets ALWAYS increase the ERD by twice the thickness of the nipple side of the eyelet. Typically they add about 3mm per side, or 5-7mm to the ERD.

Obviously measuring is best, but if you have a history of calculating lengths, you can add 6mm to the ERD, and fudge the rest.
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Old 08-26-17, 04:45 PM
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Thanks all. I understand that I can measure, and that eyelets add some distance from hub to spoke nipple.

My question is a bit different though - I was unsure if Sun extrudes two versions of the CR18 rim.
If the eyeletless version of the CR18 is the same extrusion as eyeletted, then the eyeletless rim will be more prone to cracking at the eyelets, and should probably be built with nipple washers at least. (That said, I realize the CR18 is a fairly strong rim.)

Assuming no one knows whether Sun produces one or two different extrusions of the CR18 (my guess would be one), then my best course of action would be to measure and see if I get 605-607 mm (612 for the official/replicated measurement with eyelets, less 5-7mm as FBinNY says).

Last edited by TallRider; 08-26-17 at 06:21 PM. Reason: corrected math
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Old 08-26-17, 05:24 PM
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Originally Posted by TallRider View Post
, then my best course of action would be to measure and see if I get 617-619 (612 for the official/replicated measurement with eyelets, +5-7mm as FBinNY says).
I think you have this backwards. The eyelets add to the ERD. Without the eyelets you should see minus 5-7 assuming that the spoke hole area is not thicker.

The 2 pair of Sun CR-18 rims (with eyelets) that I built up had a measured ERD of 611. I know that this doesn't help you much other than reinforce the need to measure yourself.
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Old 08-26-17, 06:22 PM
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Originally Posted by Hoopdriver View Post
I think you have this backwards. The eyelets add to the ERD. Without the eyelets you should see minus 5-7 assuming that the spoke hole area is not thicker.
Thanks - I wrote that too quickly. Edited to correct that now.
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Old 08-26-17, 06:38 PM
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Originally Posted by TallRider View Post
...

My question is a bit different though - I was unsure if Sun extrudes two versions of the CR18 rim.
If the eyeletless version of the CR18 is the same extrusion as eyeletted, then the eyeletless rim will be more prone to cracking at the eyelets, and should probably be built with nipple washers at least. (That said, I realize the CR18 is a fairly strong rim.)
IME - nobody uses different extrusions for eyelet and non-eyelet versions of the same rim. I've always found that the model name defines the extrusion used.

So, if a rim is offered in both versions, the maker is saying that the non-eyelet version is OK, and the eyelet version is somewhat stronger (or more tolerant of stouter spokes or higher tension).

When selecting rims, I may set a lower max tension, or max gauge on the non-eyelet version. If I felt I needed washers, I'd probably simply buy the eyelet version in the first place.
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Old 08-26-17, 07:13 PM
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Is it a rim that could have had the eyelets removed before you got it, or a rim through normal retail channels.
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Old 08-26-17, 08:27 PM
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Since the CR18 is marketed as a heavy-duty rim, there is no doubt plenty of material in the spoke bed whether eyelets are installed or not. Just don't do anything stupid, and they should hold up fine. (The Sun-Ringle FAQ says not to use more than 110kgf, FWIW.)
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Old 08-26-17, 08:38 PM
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Originally Posted by FBinNY View Post
IME - nobody uses different extrusions for eyelet and non-eyelet versions of the same rim. I've always found that the model name defines the extrusion used.
So, if a rim is offered in both versions, the maker is saying that the non-eyelet version is OK, and the eyelet version is somewhat stronger (or more tolerant of stouter spokes or higher tension).
Thanks FB - that is the answer I was after.

Originally Posted by Bill Kapaun View Post
Is it a rim that could have had the eyelets removed before you got it, or a rim through normal retail channels.
I don't remember where I picked up the rim, but if it had been designed for eyelets, the drillings would have been slightly wider. This rim was intended to be sold eyeletless.
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