Another day, another wheel (and so on).
I built a wheel using a DT 350 hub, DT Competition spokes, and a DT RR440 rim.
Both front and rear are 28H.
The front wheel is built in radial lacing (non-drive side).
DT's narrowest XC MTB rim is 21.8mm wide,
but the RR440 rim is 21mm wide, so 20C tires don't seem ideal for it.
On the flip side, 28C fits comfortably, and depending on frame and fork clearance,
it could probably even handle 35C tires.
The rear wheel is done too.
The nominal weight written on the rim is 450g, so I find myself thinking "then why not call it RR450?"
But there's already an R450 rim, so it gets confusing.
It's a 48-spoke lacing with no cross-bracing, but for an all-Competition (same diameter both sides) build,
the spoke tension tracking on the non-drive side is pretty good.
The rear uses an offset rim, which is probably related to this.
Come to think of it, a while back I received a comment abouta narrow-flange rear hub with only good rotational performance—
suggesting I use this offset rim and build it with higher spoke tension instead.
But an offset rim changes the spoke boss offset, not the hub flange width,
so it doesn't fundamentally solve the lateral stiffness issue.
Also, this rim's specified tension limit is 1200N,
which isn't particularly high among aluminum rims in general (though it's not low either).
This rim clearly has a tubeless rim cross-section shape.
The essential conditions for a tubeless rim are "an airtight seal at the valve area and rim edge"
and "a depression for seating the bead."
Also, not strictly necessary but highly desirable is the "hump."
↑This is what a tubeless rim looks like.
The bead depression is structurally necessary—
without it, you can't initially seal a tubeless tire into an airtight state.
A hump is a protrusion that firmly holds the stiff, thick bead of a tubeless tire onto the rim lip.
When you inflate a tire on a rim with a hump,
the tire bead snaps on with a satisfying "pop"—
and the hump also keeps the bead from easily slipping off the rim even when you deflate it.
There are rims without humps that use high-sealing rim tape to work as tubeless,
but without the hump, the next moment after a puncture during riding,
the tire can slip right off (extremely dangerous)—I've actually heard about three cases like this.
Even if a rim has a hump,
if it's the type with rim tape on a rim with holes around the outer edge,
the hump becomes pointless.
I'd recommend using tubeless tires only on "rims with no holes except the valve hole and equipped with a hump."
So with this RR440,
it's not aimed at tubeless conversion using sealing rim tape.
The outer edge holes on this offset rear rim are cut in a hump shape.
I wondered if they were repurposing a tubeless wheel rim from the same company as a regular rim,
but it's different in width and shape from Tricross wheel rims.
Hmm... I wonder why?
The shape is clearly that of a tubeless rim though.
I built a wheel using a DT 350 hub, DT Competition spokes, and a DT RR440 rim.
Both front and rear are 28H.
The front wheel is built in radial lacing (non-drive side).
DT's narrowest XC MTB rim is 21.8mm wide,
but the RR440 rim is 21mm wide, so 20C tires don't seem ideal for it.
On the flip side, 28C fits comfortably, and depending on frame and fork clearance,
it could probably even handle 35C tires.
The rear wheel is done too.
The nominal weight written on the rim is 450g, so I find myself thinking "then why not call it RR450?"
But there's already an R450 rim, so it gets confusing.
It's a 48-spoke lacing with no cross-bracing, but for an all-Competition (same diameter both sides) build,
the spoke tension tracking on the non-drive side is pretty good.
The rear uses an offset rim, which is probably related to this.
Come to think of it, a while back I received a comment abouta narrow-flange rear hub with only good rotational performance—
suggesting I use this offset rim and build it with higher spoke tension instead.
But an offset rim changes the spoke boss offset, not the hub flange width,
so it doesn't fundamentally solve the lateral stiffness issue.
Also, this rim's specified tension limit is 1200N,
which isn't particularly high among aluminum rims in general (though it's not low either).
This rim clearly has a tubeless rim cross-section shape.
The essential conditions for a tubeless rim are "an airtight seal at the valve area and rim edge"
and "a depression for seating the bead."
Also, not strictly necessary but highly desirable is the "hump."
↑This is what a tubeless rim looks like.
The bead depression is structurally necessary—
without it, you can't initially seal a tubeless tire into an airtight state.
A hump is a protrusion that firmly holds the stiff, thick bead of a tubeless tire onto the rim lip.
When you inflate a tire on a rim with a hump,
the tire bead snaps on with a satisfying "pop"—
and the hump also keeps the bead from easily slipping off the rim even when you deflate it.
There are rims without humps that use high-sealing rim tape to work as tubeless,
but without the hump, the next moment after a puncture during riding,
the tire can slip right off (extremely dangerous)—I've actually heard about three cases like this.
Even if a rim has a hump,
if it's the type with rim tape on a rim with holes around the outer edge,
the hump becomes pointless.
I'd recommend using tubeless tires only on "rims with no holes except the valve hole and equipped with a hump."
So with this RR440,
it's not aimed at tubeless conversion using sealing rim tape.
The outer edge holes on this offset rear rim are cut in a hump shape.
I wondered if they were repurposing a tubeless wheel rim from the same company as a regular rim,
but it's different in width and shape from Tricross wheel rims.
Hmm... I wonder why?
The shape is clearly that of a tubeless rim though.