Another day of wheels (and so on).
A customer dropped off a rear wheel from a WH-M8020 for me.
The WH-M8000 has a rim height of 18.8mm and rim width of 23.9mm,
intended for XC-type riding,
while the WH-M8020 has a rim height of 18.8mm and rim width of 27.9mm,
designed more for all-mountain use.
Either way, the 18.8mm rim height is the key point this time.
The rim diameter comes in both 27.5 inches and 29 inches,
but this one is 27.5 inches.
The bead hook got dented, so the customer wants a rim replacement.
I took it apart.
The replacement rim the customer wants is also 27.5 inches, 28 hole,
a Raceface
ARC27 rim.
It's ARC, not ARCH, so we pronounce it "arc."
The ARC series comes in ARC24, 27, 30, 34, 40, and 45.
With road bike rims, the numbers typically indicate the rim height,
but with the ARC rim, the numbers refer to the rim width (more precisely, the internal rim width).
The rim height is consistently 20mm, the hole count is either 28H or 32H,
and the rim diameter is only available in 27.5 inches.
The original XT rim is 27.9mm in external width,
so the rim replacement will make it slightly wider.
The manufacturer's site doesn't specify external rim width.
The thinking seems to be that you can figure it out from internal width plus 3mm,
and internal width specifications are more useful anyway since they tell you what width tubeless tape you need.
The ARC rim's stated height is 20mm, but for some reason
it's actually slightly lower than the XT wheel's stated 18.8mm.
The customer wanted to reuse straight spokes,
but lower rim height means larger internal rim diameter, which means longer spokes,
so normally reusing the spokes wouldn't seem possible.
However, the proprietary aluminum nipples used on XT wheels have a longer thread length,
and when I calculated the effective internal rim diameter using XT rim plus proprietary nipple versus Raceface rim plus standard nipple,
it turned out that I'd actually need to shorten the spokes slightly.
That difference falls within the plain section beyond the nipple end of the spoke, so
I confirmed that the spokes can be reused.
Of course, they can't be used again with the original XT rim.
Also, the ARC rim is not an offset rim.
The XT rim is an offset rim.
There is an ARC Offset rim, but
it says "NEW" on the manufacturer's site, so it might not have existed when the customer was looking for rims.
By the way, the ARC Offset comes in both 27.5 inches and 29 inches,
with internal widths of 25, 30, 35, 40,
and also a 30 Heavy Duty.
The 30 Heavy Duty is the same size as the 30
but intentionally made about 100g heavier for added durability.
The rim widths tend to be narrower than the regular ARC,
and the manufacturer markets it for not just all-mountain and enduro
but also XC.
This one does have external rim width specifications: for internal widths of 25, 30, 35, 40mm,
the external widths are 28, 33.5, 38.5, 43.5mm,
giving an internal-to-external difference of 3mm for the 25 and 3.5mm for the others.
Got it built up.
The spokes are round butted on both sides with the same diameter,
but since it's no longer an offset rim, I made the drive side plain
to even out the spoke deflection difference between sides.
Since more than 2mm of spoke length gets cut for the rim replacement,
the original uncut drive side spokes
can serve as spare spokes for the non-drive side after rebuilding, and so on...
The final cross pattern is on neither side where it wasn't originally,
though I could weave just the non-drive side (you see this on Prime rear wheels too)
and add spoke ties, and so on—I had various ideas,
but this time I stuck to just the rim replacement without getting fancy.
I cleaned the hub before building the wheel.
A customer dropped off a rear wheel from a WH-M8020 for me.
The WH-M8000 has a rim height of 18.8mm and rim width of 23.9mm,
intended for XC-type riding,
while the WH-M8020 has a rim height of 18.8mm and rim width of 27.9mm,
designed more for all-mountain use.
Either way, the 18.8mm rim height is the key point this time.
The rim diameter comes in both 27.5 inches and 29 inches,
but this one is 27.5 inches.
The bead hook got dented, so the customer wants a rim replacement.
I took it apart.
The replacement rim the customer wants is also 27.5 inches, 28 hole,
a Raceface
ARC27 rim.
It's ARC, not ARCH, so we pronounce it "arc."
The ARC series comes in ARC24, 27, 30, 34, 40, and 45.
With road bike rims, the numbers typically indicate the rim height,
but with the ARC rim, the numbers refer to the rim width (more precisely, the internal rim width).
The rim height is consistently 20mm, the hole count is either 28H or 32H,
and the rim diameter is only available in 27.5 inches.
The original XT rim is 27.9mm in external width,
so the rim replacement will make it slightly wider.
The manufacturer's site doesn't specify external rim width.
The thinking seems to be that you can figure it out from internal width plus 3mm,
and internal width specifications are more useful anyway since they tell you what width tubeless tape you need.
The ARC rim's stated height is 20mm, but for some reason
it's actually slightly lower than the XT wheel's stated 18.8mm.
The customer wanted to reuse straight spokes,
but lower rim height means larger internal rim diameter, which means longer spokes,
so normally reusing the spokes wouldn't seem possible.
However, the proprietary aluminum nipples used on XT wheels have a longer thread length,
and when I calculated the effective internal rim diameter using XT rim plus proprietary nipple versus Raceface rim plus standard nipple,
it turned out that I'd actually need to shorten the spokes slightly.
That difference falls within the plain section beyond the nipple end of the spoke, so
I confirmed that the spokes can be reused.
Of course, they can't be used again with the original XT rim.
Also, the ARC rim is not an offset rim.
The XT rim is an offset rim.
There is an ARC Offset rim, but
it says "NEW" on the manufacturer's site, so it might not have existed when the customer was looking for rims.
By the way, the ARC Offset comes in both 27.5 inches and 29 inches,
with internal widths of 25, 30, 35, 40,
and also a 30 Heavy Duty.
The 30 Heavy Duty is the same size as the 30
but intentionally made about 100g heavier for added durability.
The rim widths tend to be narrower than the regular ARC,
and the manufacturer markets it for not just all-mountain and enduro
but also XC.
This one does have external rim width specifications: for internal widths of 25, 30, 35, 40mm,
the external widths are 28, 33.5, 38.5, 43.5mm,
giving an internal-to-external difference of 3mm for the 25 and 3.5mm for the others.
Got it built up.
The spokes are round butted on both sides with the same diameter,
but since it's no longer an offset rim, I made the drive side plain
to even out the spoke deflection difference between sides.
Since more than 2mm of spoke length gets cut for the rim replacement,
the original uncut drive side spokes
can serve as spare spokes for the non-drive side after rebuilding, and so on...
The final cross pattern is on neither side where it wasn't originally,
though I could weave just the non-drive side (you see this on Prime rear wheels too)
and add spoke ties, and so on—I had various ideas,
but this time I stuck to just the rim replacement without getting fancy.
I cleaned the hub before building the wheel.