Another day of wheel building (and so on...).
A customer entrusted me with a Paul's rear hub for single-speed.
The model is called
DISC WORD, and the through-axle width is either 142mm or 148mm.
The right side cog seat comes in fixed gear or single freewheel versions,
and the left side has a 6-bolt rotor mount.
WORD is technically written W.O.R.D., an acronym for
Wacky One-Speed Rear
Device.
Wacky means "unconventional."
This hub is 142mm wide with fixed gear spec, so
it can be used for building a single-speed disc road bike or
non-BOOST standard MTB frame.
For the left and right flange widths, my measurement showed
the left side was about 0.2mm wider,
but since the left end is a nut threaded onto the hub axle,
the manufacturer probably intended them to be equal, and the slight variation
is due to variance in the threading.
The rim is a 40mm tall carbon rim with no holes except the valve hole
on the outer perimeter.
Built it.
Paul Disc Word hub, 24H, all CX Sprint,
66-spoke JIS lacing, no cross-lacing.
With this wheel, apart from the mechanical aspects of wheel building,
there were some complicated considerations.
↑Photo of the rim's valve hole phase from the inside before building.
As you can see, this rim is an offset rim.
↑These are the dimensions of a Dura-Ace track hub with large flanges
in the single-sided threaded version.
If it were double-sided threaded, the flange width would be 65.0mm
with left and right flanges equal, making it easy to calculate
32.5mm for both sides.
For the single-sided threaded version, Shimano's documentation states
flange width 75.5mm and offset amount 5.25mm,
but doesn't directly list the actual individual left and right flange widths.
The calculation method for left and right flange widths is
"flange width / 2 plus or minus offset amount."
Actually calculating: 75.5 ÷ 2 = 37.75, so
37.75 plus or minus 5.25 gives
43mm and 32.5mm as results.
Naturally, adding these two gives 75.5mm.
When building a velodrome rear wheel with a 36H version of this hub,
regulations require 8-spoke lacing on both sides,
but even when building rear wheels not subject to that,
I do equal-spoke equal-diameter lacing on both sides.
If it's 32H or 36H and not for velodrome use,
using equal-diameter spokes with 68-spoke or 46-spoke lacing
might be the reasonable compromise point
in terms of evaluating the magnitude of factors—bringing the left-right difference
in spoke deformation caused by dish closer to uniform
compared to equal-spoke equal-diameter lacing.
With Shimano's RS770 disc front hub,
the flange width is 59.6mm and
the offset amount is 6mm, so
↑The left and right flange widths work out like this.
With this hub, as you probably know, I do
unequal-spoke unequal-diameter lacing with half-CX Sprint 46-spoke pattern.
The left-right spoke weight difference is about 13%.
Shimano's so-called offset amount for hub flanges
is 5.75mm for the single-sided Dura-Ace track and
6mm for the RS770 front hub, so
looking at just the numbers, they seem similar,
but the RS770 has narrower overall flange width,
so the proportion of left-right difference
relative to a given offset amount becomes larger.
For a hub with dish, setting the narrower flange width to 100%,
the wider flange width is about 130% for the
single-sided Dura-Ace track, and
about 150% for the RS770 front hub.
However, I don't base my decisions on these numbers, thinking
"if it's 130%, equal-spoke equal-diameter lacing is fine" or
"if it's 150%, I'll use unequal-spoke unequal-diameter lacing
with about 13% spoke weight difference,"
and so on.
For fixed gear rear wheels, I often do full cross-lacing both sides,
so with equal-spoke equal-diameter lacing, the result is that
I don't feel the left-right difference in spoke deformation,
and I haven't given much thought to
incorporating small-effect unequal-diameter or unequal-spoke lacing
in dished fixed gear hubs.
Earlier I wrote that the single-sided Dura-Ace track hub
might be best with 32H 68-spoke equal-diameter lacing,
but now I'm thinking that equal-spoke lacing with
Comp/CX Sprint pattern having 7-8% spoke weight difference
might be better.
By the way, the RS770 rear hub has
flange width 55.7mm and offset 7.5mm, giving
right flange 20.35mm and left flange 35.35mm,
making the left flange about 170% (173.71%) of the right.
For this, my usual approach is half-Comp 46-spoke lacing,
with a large left-right spoke weight difference of about 21%.
The RS770 front hub's flange width is
59.6mm, which when I set my caliper to 59.6mm beforehand
and measure the actual hub flanges,
I can confirm that Shimano's specification refers to
outside-to-outside width.
So when using this as the basis for spoke length calculation,
strictly speaking it's the "non-dished spoke length," and
the dished spoke should be calculated to the flange inner edge for
greater accuracy, but that length difference is
far outweighed by the spoke thread runout, and when
assembling a wheel with spokes prepared in 1mm increments,
there's no need to say "the dished spokes need to be 1mm shorter."
Besides, when weaving the final cross with tangent lacing,
the spoke path is no longer a straight line.
With radial lacing, most cases use dished radial,
so it might be better to calculate the "dished spoke length,"
but as I mentioned, the difference from non-dished length is
actually swallowed comfortably by the spoke thread runout, so
there's no need to go that far.
Shimano's documentation treats flange width as outside-to-outside,
which is the same interpretation I use when measuring unknown hubs.
For Shimano hubs, I trust the documented values and use them directly.
For Tni hubs, their manufacturer documentation often shows
hub flange width as center-to-center of the flange thickness,
but I ignore that completely and use
measured values just like I do for unknown hubs.
So, here's this hub.
The flange widths are my measured values.
At this magnitude, even if I calculate spoke length using
35.9mm for both left and right without dish,
there's absolutely no problem.
A 0.2mm flange width difference means
the hub body slid 0.1mm to the left from the no-dish state, making
the right flange width minus 0.1mm and
the left flange width plus 0.1mm, thus
the 0.2mm left-right difference. So Shimano's so-called offset amount refers to
how much the hub body slides sideways
from the no-dish state.
If the rim were a non-offset rim,
I wouldn't question building it with
equal-spoke equal-diameter lacing at all. But
this time, unfortunately,
the rim was an offset rim.
Measuring, the rim holes are offset 2.5mm from center.
Here's what's crucial: if you build a rear wheel with an offset rim
following the rule that "the rim hole offset should be opposite the sprocket side,"
you end up with an awkward wheel where
the gear side has lower tension
(strictly, larger spoke deformation).
The only real example of that is Roval's disc brake rear wheels.
So this time, I oriented the offset rim holes toward the gear side.
When the rim is at wheel center, the
"spoke structural flange width" including not just the hub
but also the rim's offset is as shown in the diagram.
The ratio of the wider flange width to the narrower is
right between a no-dish hub and a single-sided track hub.
This is what I wanted to know.
So if I incorporated unequal-spoke unequal-diameter lacing,
I'd risk building a wheel where the left-side spokes
actually have less deformation, so
I went with all CX Sprint 66-spoke lacing instead.
A customer entrusted me with a Paul's rear hub for single-speed.
The model is called
DISC WORD, and the through-axle width is either 142mm or 148mm.
The right side cog seat comes in fixed gear or single freewheel versions,
and the left side has a 6-bolt rotor mount.
WORD is technically written W.O.R.D., an acronym for
Wacky One-Speed Rear
Device.
Wacky means "unconventional."
This hub is 142mm wide with fixed gear spec, so
it can be used for building a single-speed disc road bike or
non-BOOST standard MTB frame.
For the left and right flange widths, my measurement showed
the left side was about 0.2mm wider,
but since the left end is a nut threaded onto the hub axle,
the manufacturer probably intended them to be equal, and the slight variation
is due to variance in the threading.
The rim is a 40mm tall carbon rim with no holes except the valve hole
on the outer perimeter.
Built it.
Paul Disc Word hub, 24H, all CX Sprint,
66-spoke JIS lacing, no cross-lacing.
With this wheel, apart from the mechanical aspects of wheel building,
there were some complicated considerations.
↑Photo of the rim's valve hole phase from the inside before building.
As you can see, this rim is an offset rim.
↑These are the dimensions of a Dura-Ace track hub with large flanges
in the single-sided threaded version.
If it were double-sided threaded, the flange width would be 65.0mm
with left and right flanges equal, making it easy to calculate
32.5mm for both sides.
For the single-sided threaded version, Shimano's documentation states
flange width 75.5mm and offset amount 5.25mm,
but doesn't directly list the actual individual left and right flange widths.
The calculation method for left and right flange widths is
"flange width / 2 plus or minus offset amount."
Actually calculating: 75.5 ÷ 2 = 37.75, so
37.75 plus or minus 5.25 gives
43mm and 32.5mm as results.
Naturally, adding these two gives 75.5mm.
When building a velodrome rear wheel with a 36H version of this hub,
regulations require 8-spoke lacing on both sides,
but even when building rear wheels not subject to that,
I do equal-spoke equal-diameter lacing on both sides.
If it's 32H or 36H and not for velodrome use,
using equal-diameter spokes with 68-spoke or 46-spoke lacing
might be the reasonable compromise point
in terms of evaluating the magnitude of factors—bringing the left-right difference
in spoke deformation caused by dish closer to uniform
compared to equal-spoke equal-diameter lacing.
With Shimano's RS770 disc front hub,
the flange width is 59.6mm and
the offset amount is 6mm, so
↑The left and right flange widths work out like this.
With this hub, as you probably know, I do
unequal-spoke unequal-diameter lacing with half-CX Sprint 46-spoke pattern.
The left-right spoke weight difference is about 13%.
Shimano's so-called offset amount for hub flanges
is 5.75mm for the single-sided Dura-Ace track and
6mm for the RS770 front hub, so
looking at just the numbers, they seem similar,
but the RS770 has narrower overall flange width,
so the proportion of left-right difference
relative to a given offset amount becomes larger.
For a hub with dish, setting the narrower flange width to 100%,
the wider flange width is about 130% for the
single-sided Dura-Ace track, and
about 150% for the RS770 front hub.
However, I don't base my decisions on these numbers, thinking
"if it's 130%, equal-spoke equal-diameter lacing is fine" or
"if it's 150%, I'll use unequal-spoke unequal-diameter lacing
with about 13% spoke weight difference,"
and so on.
For fixed gear rear wheels, I often do full cross-lacing both sides,
so with equal-spoke equal-diameter lacing, the result is that
I don't feel the left-right difference in spoke deformation,
and I haven't given much thought to
incorporating small-effect unequal-diameter or unequal-spoke lacing
in dished fixed gear hubs.
Earlier I wrote that the single-sided Dura-Ace track hub
might be best with 32H 68-spoke equal-diameter lacing,
but now I'm thinking that equal-spoke lacing with
Comp/CX Sprint pattern having 7-8% spoke weight difference
might be better.
By the way, the RS770 rear hub has
flange width 55.7mm and offset 7.5mm, giving
right flange 20.35mm and left flange 35.35mm,
making the left flange about 170% (173.71%) of the right.
For this, my usual approach is half-Comp 46-spoke lacing,
with a large left-right spoke weight difference of about 21%.
The RS770 front hub's flange width is
59.6mm, which when I set my caliper to 59.6mm beforehand
and measure the actual hub flanges,
I can confirm that Shimano's specification refers to
outside-to-outside width.
So when using this as the basis for spoke length calculation,
strictly speaking it's the "non-dished spoke length," and
the dished spoke should be calculated to the flange inner edge for
greater accuracy, but that length difference is
far outweighed by the spoke thread runout, and when
assembling a wheel with spokes prepared in 1mm increments,
there's no need to say "the dished spokes need to be 1mm shorter."
Besides, when weaving the final cross with tangent lacing,
the spoke path is no longer a straight line.
With radial lacing, most cases use dished radial,
so it might be better to calculate the "dished spoke length,"
but as I mentioned, the difference from non-dished length is
actually swallowed comfortably by the spoke thread runout, so
there's no need to go that far.
Shimano's documentation treats flange width as outside-to-outside,
which is the same interpretation I use when measuring unknown hubs.
For Shimano hubs, I trust the documented values and use them directly.
For Tni hubs, their manufacturer documentation often shows
hub flange width as center-to-center of the flange thickness,
but I ignore that completely and use
measured values just like I do for unknown hubs.
So, here's this hub.
The flange widths are my measured values.
At this magnitude, even if I calculate spoke length using
35.9mm for both left and right without dish,
there's absolutely no problem.
A 0.2mm flange width difference means
the hub body slid 0.1mm to the left from the no-dish state, making
the right flange width minus 0.1mm and
the left flange width plus 0.1mm, thus
the 0.2mm left-right difference. So Shimano's so-called offset amount refers to
how much the hub body slides sideways
from the no-dish state.
If the rim were a non-offset rim,
I wouldn't question building it with
equal-spoke equal-diameter lacing at all. But
this time, unfortunately,
the rim was an offset rim.
Measuring, the rim holes are offset 2.5mm from center.
Here's what's crucial: if you build a rear wheel with an offset rim
following the rule that "the rim hole offset should be opposite the sprocket side,"
you end up with an awkward wheel where
the gear side has lower tension
(strictly, larger spoke deformation).
The only real example of that is Roval's disc brake rear wheels.
So this time, I oriented the offset rim holes toward the gear side.
When the rim is at wheel center, the
"spoke structural flange width" including not just the hub
but also the rim's offset is as shown in the diagram.
The ratio of the wider flange width to the narrower is
right between a no-dish hub and a single-sided track hub.
This is what I wanted to know.
So if I incorporated unequal-spoke unequal-diameter lacing,
I'd risk building a wheel where the left-side spokes
actually have less deformation, so
I went with all CX Sprint 66-spoke lacing instead.