Race Face ARC40 ERD.

serviceguy

Well-Known Member
#1
So I was looking at the specs for the RaceFace ARC40 that I just received and they provide the ERD as 558++, where you’re supposed to add to the 558 twice the height of the nipple head. I’m using squorx nipple and will have to use washers because these rims don’t have ringlets, what should I enter as ERD in the spike calculator? I guess twice the thickness of the washer but I’m not sure about the squorx as their head has the torx head on top...any word of advice would be greatly appreciated. This is going to be my winter wheel set using 27.5x3.0 tires.
 

Mr.Moto

Well-Known Member
#2
sorry, got nothing. Just looked at ARC instructions and it's confusing with the adding of the nipple head to erd. Never used squorx so combo of both is new to me.
 

serviceguy

Well-Known Member
#4
Uhm, all the washers I see being sold for wheel building are stainless steel, which could cause a corrosion issue reacting with the aluminum of both the rim and the nipples. Brass is no better. I'm guessing I am not the first one building a wheel with washers (it's my first set without eyelets), nevertheless...what gives?
 

Mr.Moto

Well-Known Member
#7
My whisky carbon rims came with washers for the build. Only rims I’ve built that needed washers. Don’t remember if I used aluminum or brass but didn’t really worry about it.
 
#8
I built a front wheel using a Race Face AR40 offset rim last week. Using the Race Face published ERD (600 for a AR40 29+ rim) and Shutter Precision's published hub specs in Spocalc, the calculated spoke lengths put the ends of the spokes right around the bottom of the screwdriver slot. I definitely have a bit of margin left before the spoke is flush with the head of the nipple. Spocalc gave me 292.2 and 293.7 so I went with 292 and 294 Sapim Race double butted spokes and brass nipples. I have the rear laced up (same rim, Hope hub) but I just discovered that my rusty old TS-2 truing stand will not accommodate a 190/197 rear hub. Either I run a straightedge across my frame or I have to pick up a pair of the $55 extensions. Note that the thru-axle from your bike functions well as a truing stand adapter for your thru-axle hub.

Sapim HM washers add 1.4mm to ERD. I'm running them on both sides of the rear wheel to bring the calculated lengths from 293.3/293.5 to 294.0/294.2 so I can run 294s on both sides without worry. In a pinch, I could probably replace a 292 on the front wheel with a 294 and one HM washer.

Yes, stainless washers are stupid when they touch aluminum rims and/or aluminum nipples. Anodizing may help a bit by adding electrical insulation. This is my first build using them. I'll know more in a year or two.
 

serviceguy

Well-Known Member
#9
I ended up using the same criteria, except my build is a 27.5+. We’ll see when the spokes finally make it here, hopefully by this weekend.
 

serviceguy

Well-Known Member
#10
I finally got around to lace these wheels. There's really no way that you can make lacing mistakes with the straight pull hubs other than incorrectly cross a spoke, and yet I ended up with the right spokes going to the left hand holes and the left spokes going to the right handed holes. I can't see any way to lace these wheels any different without getting the valve hole in the wrong place. Is there any issue with this specific configuration? Maybe typical of 28, straight pull hubs?
 

serviceguy

Well-Known Member
#12
Actually, scrap that. It appears that the holes at the inner diameter (where the nipples stick out) of the rim are centered while the hole on the outermost diameter (where the tape goes) are angled to match the ideal extension of the spokes. Duh.

ARC40 Profile.jpg