Has anyone laced a 24H rim to a 32H hub (rear)?

Triathlon Forum
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It would be best to use 16 on the drive side, 8 on the other side. Thats how its usually done, but ask yourself if no reputable make makes a 24 hole disk hub why is that?
+1 for occam’s razor

The reason almost no one uses a 24 spoke disk rear hub is because with disk brakes you now have very large forces on both drive and non-drive side. Driving torque on the drive side, and braking torque on the non-drive side. While 16 drive/8 non drive makes an excellent wheel for rim brakes, you’re going to break a lot of non-drive spokes with only 8 resisting the braking force. Even 12 on the non-drive side is doubtful, and don’t forget you need 2 cross on the non-drive side to resist braking force, another reason why low spoke counts on that side are a problem.

Brian

bingo

wheelbuilders have the three strike rule: too few spokes, spokes too thin, and rim too light. With road racing wheels, you can skirt by a few or even all the strikes, but this just won’t fly for a disc-brake CX wheel.

now, that said, you can lace a 32H into a 24H, but wheelbuilders really don’t recommend it. It’s called a crow’s foot, and damn, a google search even turned up a conversation on slowtwitch

if i were you i’d get a 28H stallion build rim and a 28H hub and be done with it

Thanks to all for this little dose of sanity. I’ll try to get these silly project ideas out of my head. Two followup questions:

  1. You mentioned above going 28H rim and hub. I assume that this would solve most if not all of the mentioned problems, and that so many reputable hub makers (DT Swiss, etc) wouldn’t make 28H disc hubs if that were not the case.

  2. Would you advice be different regarding the 24H rim if I had a 24H hub as well? What about for a front rather than rear? That is, is the problem in the lack of spokes, or is the problem in having different numbers of spokes?

Thanks very much.
Hold on, all is not lost yet…

If you have a sturdy rear hub (like MTB styrdy…) you can lace the drive side 16 spokes 3x and use 8 spokes radial on the ND/disc side. That way you only transfer the driving AND braking torque through the 16 cross-laced spokes. The hub itself will be subjected to the brake torque but that is a non-issue.

The sorry 8 on the other side just take vertical and transverse load just like any other radial lacing setup. No problem. Rock on.

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So the 16/8 on a 32h Powertap hub used on the road is safe and reliable? Sorry for the hijack but I have been looking for a 32h carbon hoop in which to install my PT. They are hard to find. If the 16/8 is kosher that will make the search much easier. Thanks
I used a 16 hole Campy Shamal (old style, 41mm) rim for years, laced to a 32 hole PT hub. No problems, rock solid, always straight.

A 16/8 pattern should then work also. Just opposite of the discussion in this thread: 8 spokes 2x on the NDS, 16 spokes radial on the DS. There you go.

23

that used to be popular for making TT front wheels when hubs with less than 32 spokes were not as common. The issue with the technology of that day was breaking of the hubs at the flange. Not sure if it’s still an issue, people don’t do that kind of thing much any more.

For cross you just need some 32 spoke tubular wheels and good quality tires. I don’t buy all this stuff about the aero wheels are faster in the mud.

24

out of curiosity, how did that quasi-crow’s foot powertap wheel you mentioned in the WW thread turn out?

I guess it is still going well. The owner won the state TT this year…

The reason I don’t recommend it is because you end up with crossed spokes that are different lengths on each side, and it is easy to get confused about which go where. I “solved” it by adding a few threads to those spokes, but most people won’t have that option. I don’t think it makes the wheel weaker… at least not in any significant way.

Was there someone on weightweenies who came up with a different pattern that would work with 32-24? I remember someone who posted a good pattern I’d never thought of… might have been a different thread and a different combination though.

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  1. Would you advice be different regarding the 24H rim if I had a 24H hub as well? What about for a front rather than rear? That is, is the problem in the lack of spokes, or is the problem in having different numbers of spokes?

The difference between disc wheels and rim brake wheels is that the disc ones must resist the considerable torque generated when braking… especially on the front wheel… the back wheel will usually skid at lower torque. Rim brake wheels have none of that.

Whether a 24h wheel would be suitable depends on how heavy you are and how you ride (do you tend to destroy things or no?), the hub, rim, and spokes. If the hub has large flanges there will be less torque stress.

You mentioned carbon rims earlier. I’m guessing these are made for rim brakes? What are they exactly? Because I wasn’t aware anyone made low spoke count rims for disc brakes.

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36 hub, 24 rim can be done with a good pattern: http://weightweenies.starbike.com/forum/viewtopic.php?f=3&t=91823&hilit=lacing+pattern&start=30#p791388
.

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  1. Would you advice be different regarding the 24H rim if I had a 24H hub as well? What about for a front rather than rear? That is, is the problem in the lack of spokes, or is the problem in having different numbers of spokes?

The difference between disc wheels and rim brake wheels is that the disc ones must resist the considerable torque generated when braking… especially on the front wheel… the back wheel will usually skid at lower torque. Rim brake wheels have none of that.

Whether a 24h wheel would be suitable depends on how heavy you are and how you ride (do you tend to destroy things or no?), the hub, rim, and spokes. If the hub has large flanges there will be less torque stress.

You mentioned carbon rims earlier. I’m guessing these are made for rim brakes? What are they exactly? Because I wasn’t aware anyone made low spoke count rims for disc brakes.

I’m 155-165 pounds, and I do not destroy things. The rims I’ve been looking at are the zipp 303 CX, the Revolution WheelWorks 50-X, and the Reynolds Assault. All are designed/intended for CX, but you are right, all are designed for rim brakes. The zipps are the most appealing to me because of the 27.5mm brake track, however, they have only 24 holes front and rear. The Rev-50X has 24/28, and the Reynolds’ have 24/24. Reynolds will be selling a disc version of the Assault, the Assault-CX this year. I believe they will be using a Reynolds 24H disc hub that won’t exist anywhere else. I can’t afford to buy any of these nice things new, so I’ve been looking for used rims to mate to disc hubs. I have a line on an older set of zipp 404CX wheels, which are both 28H. That would solve the hub problem, but I still do not know if using any of these rims will disc brakes is a good idea. I have to admit I’m a complete novice when it comes to the intricacies of wheel building. I greatly appreciate all your information and would love to hear thoughts on these rims and carbon rims in general.

Thanks,
-Colin

28

So tubulars… yes/no?

Carbon clinchers have a lot of extra material to deal with rim braking, but tubulars not so much. You are “paying” for strength where you don’t need it when you use a clincher rim-brake rim. But like I said, not so much with tubulars.

So… you can’t afford new carbon rims. Are you sure you want carbon at all? You’ll be running low pressure tires and hitting rocks and ruts (right?), and really the chance that you will crack the rims is pretty good. They will generally be stronger than an aluminum rim, but the cost is hugely different. Aero isn’t going to help… and the rims won’t be all that light.

EDIT: I’ll admit that the pickins are pretty slim when it comes to aluminum tubulars, but carbon rims are pretty iffy for someone who is low on cash.