spoke head clearance

[foo_fighter]

I ran some numbers for 28h 3x and got:

Left Right
Spoke length 270.6
mm 272.4
mm
Bracing angle 5.5° 7.6°
Tension distribution 100% 72%
Spoke head clearance 1.32 mm 0.73 mm

Then with 2x:

Left Right
Spoke length 259.1
mm 263.1
mm
Bracing angle 5.8° 7.8°
Tension distribution 100% 74%
Spoke head clearance 6.08 mm 4.57 mm

Does the low spoke head clearance mean I should run with 2X?

Much Thanks!

[Kontact]

Off the top of my head, you don't lace 28h or less 3x. Because of the paucity of spokes, 2x is going to put the heads nearly 90 degrees round the flange.

To illustrate the problem, imagine trying to go 2x on an 8 spoke wheel. Yet with an 80 spoke wheel you could easily go 8x.

[oldpotatoe]

I ran some numbers for 28h 3x and got:

Left Right
Spoke length 270.6
mm 272.4
mm
Bracing angle 5.5° 7.6°
Tension distribution 100% 72%
Spoke head clearance 1.32 mm 0.73 mm

Then with 2x:

Left Right
Spoke length 259.1
mm 263.1
mm
Bracing angle 5.8° 7.8°
Tension distribution 100% 74%
Spoke head clearance 6.08 mm 4.57 mm

Does the low spoke head clearance mean I should run with 2X?

Much Thanks!

I generally lace 3 cross 28h rear, and heads out or inside pulling since the headin spoke does overlap the flange more than on 2 cross..2 cross fronts for 28h.

[ergott]

I do 28 3X all the time. 2X isn’t tangential. Closest to tangiential is 20 2X.

[Mark McM]

The main purpose of spoke head clearance is to allow you to replace a spoke on a built wheel. As long as the spokes don't overlap the heads of adjacent spokes, there should be no issues. The 3 factors affecting spoke head clearance are spoke count, number of crossings, and flange size. On all but the smallest flanges, 3 crossings with 28 spokes works fine.


Oh, on an 8 spoke wheel, 1X would be tangential - 2X would be tangential for a 16 spoke wheel (I've built one). However the most common case of tangential spoking is 36 spokes with 4 crossings (I've built a few).

[foo_fighter]

This is a front 650b disc brake wheel if it matters. In the past I've built all my 28h wheels 3x front and rear, but those were 700c. I never even thought about the spoke head clearance....I guess I'll have to take a look to see what the clearance is.

Still not sure if I should go 2x or 3x.

[ColonelJLloyd]

Careful of spoke/caliper interference if using a dynamo or other large flange hub.

[oldpotatoe]

This is a front 650b disc brake wheel if it matters. In the past I've built all my 28h wheels 3x front and rear, but those were 700c. I never even thought about the spoke head clearance....I guess I'll have to take a look to see what the clearance is.

Still not sure if I should go 2x or 3x.

Disc? Do 3 cross, inside pulling.

[Mark McM]

Disc? Do 3 cross, inside pulling.

For a front disc wheel, which direction is "pulling"?

(This is why I prefer the terms "leading" and "trailing".)

[oldpotatoe]

For a front disc wheel, which direction is "pulling"?

(This is why I prefer the terms "leading" and "trailing".)

Pulling=the ones that radiate aft...
Pushing=the ones that radiate forward...old dog and all, how described by Mike Howard who taught me in 1985 at Colley Ave Bike’s in Norfolk.

[Mark McM]

Pulling=the ones that radiate aft...
Pushing=the ones that radiate forward...old dog and all, how described by Mike Howard who taught me in 1985 at Colley Ave Bike’s in Norfolk.

So, here's where I'm confused: Previously, you have recommended the spokes to be laced inside pulling on rear wheels - presumably due to the direction of drive torque in a rear wheel.

But on a front disc brake wheel, the only torque is from braking - which is in the opposite direction from the drive torque on a rear wheel. So shouldn't the spokes on a front disc brake wheel be laced inside "pushing"?

[oldpotatoe]

So, here's where I'm confused: Previously, you have recommended the spokes to be laced inside pulling on rear wheels - presumably due to the direction of drive torque in a rear wheel.

But on a front disc brake wheel, the only torque is from braking - which is in the opposite direction from the drive torque on a rear wheel. So shouldn't the spokes on a front disc brake wheel be laced inside "pushing"?

Only on 28 and 3 cross..for 32 and 3 cross, outside pulling.

Disc brakes, inside pulling because of torque and how the spokes 'may' deform under braking and how they 'may' hit the rotor.

How I do it.


“The front ISO Disc should be laced 3-or-more-cross with the rotor (left) side pulling spokes (relative to braking direction) heads out/elbows in (when laced 3-cross). The final cross of the pulling spoke must be on the outside so that as braking force is applied, increased pulling spoke tension will pull the crossed spokes towards the center of the hub and away from the caliper. .”


BUT I lace the rear on disc, outside pulling drive side, inside pulling rotor side and inside pulling both sides front..and 3 cross for 28 or 32h.

[ColonelJLloyd]

I've only built with traditional flange hubs and j-bend spokes and almost exclusively 32h hubs with a handful of 28h and 36h. I've laced every one how it is laid out in a 40 year old book (The Bicycle Wheel) and haven't had any issues with my disc wheels. I'm not saying it's not a good idea to alter your lacing for disc wheels, but it would seem in my experience it is wholly unnecessary.

[foo_fighter]

That statement below comes from king?

I try to follow the advice here(that quote is also referenced):
http://www.peterverdone.com/wiki/index.php?title=Disc_wheel_Lacing
and use the lacing pattern from Zinn's book on the rear so that both "pulling" spokes are on the outside.

In my case, it's a boost wheel so there is lots of space for the caliper vs the spokes...


“The front ISO Disc should be laced 3-or-more-cross with the rotor (left) side pulling spokes (relative to braking direction) heads out/elbows in (when laced 3-cross). The final cross of the pulling spoke must be on the outside so that as braking force is applied, increased pulling spoke tension will pull the crossed spokes towards the center of the hub and away from the caliper. .”