Experiment #1: 20h disc front wheel

[Gummee]

Just 'finished' a rebuild of a front wheel. I think I need 2mm longer nipples for looks. The threads are at the bottom of the nipples inside the rim

Its an experiment. 'They say' that you can't run a 20h disc hub up front. We'll see. I'll either keep this as is, re-do the nipples, or sell it to someone smaller than me.

As it is: 650g Sapim butted spokes (14/15), black brass nipples, Bitex CX hub. The rear is up next. I'm debating ordering some longer nipples 'just because.'

M

I can't seem to get the 2nd pic to upload. Someone wanna try it for me?

[weisan]

When they first move to 32h, the 36h people was like
And then when they move to 28h, the 32h people was like
And then when they move to 24h, the 28h people was like
And then when they move to 20h, the 24h people was like
And then when they move to 16h, all hell breaks loose.

I have an expression for this phenomenon, it's called Generational Gap.

[cachagua]

[zap]

Regarding "they say you can't" Rolf has been making them for years..........20h front disc wheel for singles and tandems.

[oldpotatoe]

Originally Posted by weisan

When they first move to 32h, the 36h people was like
And then when they move to 28h, the 32h people was like
And then when they move to 24h, the 28h people was like
And then when they move to 20h, the 24h people was like
And then when they move to 16h, all hell breaks loose.

I have an expression for this phenomenon, it's called Generational Gap.

Build a couple of low spoke count DISC brake wheels...and then see how they do. I guess the generational gap is the gap between experience and comments on the interweb. That's my 'expression'...

IMHO, of course, 'pal'..

[93KgBike]

Originally Posted by weisan

When they first move to 32h, the 36h people was like
And then when they move to 28h, the 32h people was like
And then when they move to 24h, the 28h people was like
And then when they move to 20h, the 24h people was like
And then when they move to 16h, all hell breaks loose.

I have an expression for this phenomenon, it's called Generational Gap.

That's awesome!

[GonaSovereign]

Data point: Boyd had to replace some hubs under warranty in a set of deep carbon wheels I owned. I asked them to replace the hubs with disc versions, but they wouldn't do it b/c the wheel had too few (20) spokes. It was annoying to me, but I respected that they know a lot more about wheels than I do.

[Pastashop]

I’m sure you could get away with it for some number of miles and uses... What I don’t fully understand is what compelling gain there would be / reason for running a 20h wheel... (But then again, neither do I understand the reason for running a radially spoked wheel instead of 3-cross, NDS tension mitigation excluded.)

[hollowgram5]

Originally Posted by weisan

When they first move to 32h, the 36h people was like
And then when they move to 28h, the 32h people was like
And then when they move to 24h, the 28h people was like
And then when they move to 20h, the 24h people was like
And then when they move to 16h, all hell breaks loose.

I have an expression for this phenomenon, it's called Generational Gap.

And then Shimano and Campy did 12h front wheels and the world started burning...

[Gummee]

Originally Posted by Pastashop

I’m sure you could get away with it for some number of miles and uses... What I don’t fully understand is what compelling gain there would be / reason for running a 20h wheel... (But then again, neither do I understand the reason for running a radially spoked wheel instead of 3-cross, NDS tension mitigation excluded.)

I had an 'extra' wheelset that didn't brake well, so I figured an experiment was in order

Next CX season, I'll be rockin and rollin the disc tubulars

M

[ergott]

Originally Posted by Gummee

The threads are at the bottom of the nipples inside the rim

Where are you with respect to this chart?

[CiclistiCliff]

I don't like where this is going.....

Low spoke count, spoke/nipple interface not ideal and disc brake.

[Mark McM]

So, take a look spoke loading from the disc brake:

Torque loads (as from pedaling or hub brakes) are distributed nearly equally among all the spokes. So with a large number of spokes, the stresses from torque loads will be much smaller than the stresses from radial (weight bearing) loads, which are distributed over a smaller number of spokes. But with a smaller number of spokes, stresses on individual spokes increase. But there are several mitigating factors at work on this particular wheel:

1) Stresses from torques are inversely proportional to flange size. Since rotor-side flange on this wheel is oversized, that will help reduce spoke stress.

2) Spoke stresses from torque also decrease with spoke angle. The rotor-side spokes on this wheel are laced in a 2x pattern which results in a 72 degree spoke angle, which isn't far from tangential (and also greater than the 67.5 degree spoke angle in the popular 32 spokes 3x pattern).

Personally, I wouldn't have a problem with this 20 spoke disc brake wheel. Spoke stresses from disc brakes are small and infrequent enough to begin with, and this particular wheel doesn't increase them by much.

[Gummee]

Originally Posted by Mark McM

So, take a look spoke loading from the disc brake:

Torque loads (as from pedaling or hub brakes) are distributed nearly equally among all the spokes. So with a large number of spokes, the stresses from torque loads will be much smaller than the stresses from radial (weight bearing) loads, which are distributed over a smaller number of spokes. But with a smaller number of spokes, stresses on individual spokes increase. But there are several mitigating factors at work on this particular wheel:

1) Stresses from torques are inversely proportional to flange size. Since rotor-side flange on this wheel is oversized, that will help reduce spoke stress.

2) Spoke stresses from torque also decrease with spoke angle. The rotor-side spokes on this wheel are laced in a 2x pattern which results in a 72 degree spoke angle, which isn't far from tangential (and also greater than the 67.5 degree spoke angle in the popular 32 spokes 3x pattern).

Personally, I wouldn't have a problem with this 20 spoke disc brake wheel. Spoke stresses from disc brakes are small and infrequent enough to begin with, and this particular wheel doesn't increase them by much.

I knew 2x was minimum and I got that. This is a race wheel. Or at minimum a training wheel that will strictly be for CX. The wheelset is likely to have this year's race tires glued on as I buy another pair of new new race tires for next season

I don't plan on this wheel seeing a whole lot of mileage.

If it starts to be a problem child, I'll sell it to someone small.

The rear is 24h. Should be Ok.

AFA the nipples, from the outside, they look like they're OK (the good pic)

M

[Gummee]

Let's try this