The wheelbuilding thread

Everything about building wheels, glueing tubs, etc.
whosatthewheel
Posts: 122
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by whosatthewheel

pdlpsher1 wrote:
Mon Nov 16, 2020 6:36 pm
Thank you whosatthewheel. It seems the DT Swiss calculator also makes a length recommendation on spoke length to account for spoke stretch. If the chosen spoke is thick it rounds up, and vice versa.

I have a new question which the calculator doesn't account for. My new rear hub has 36 holes and a smaller hub flange diameter than I realized. It's only 52mm in diameter. I think that's quite small for a disk-brake hub with 36 holes. I was planning on using 4x spoke cross pattern but now I'm concerned about spoke heads being covered by adjacent spokes making spoke replacement difficult. Am I safe to use 4X with a flange as small as 52mm in diameter? This wheelset is for a tandem and it'll have strong spokes with huge spoke heads (4.3mm diameter). Thanks.
I've only built 4 cross once on an old pair of Campagnolo Record hubs, which have a relatively small flange... probably smaller than 52, certainly the front is smaller than 52... more like 38 I seem to recall... no problem at all, no covering of spoke heads as you describe.

jever98
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by jever98

If you use the Roger Musson calculator, it gives you the spoke head clearance: https://www.wheelpro.co.uk/spokecalc/
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by Weenie


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pdlpsher1
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by pdlpsher1

Thank you whosatthewheel and jever98! I'll give the new calculator a try.

I found this image online. This is what I want to avoid. The spokes are bending around the spoke heads. This was a 36H 4x on an Ultegra 6600 front hub with smaller flange diameter (38mm).

Image

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pdlpsher1
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by pdlpsher1

Update: the Roger Musson calculator says I'll have a 0.7mm negative clearance on the spoke head. So it looks like 4x is a no-go unless I can find some images online proving that it works. Bummer.

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pdlpsher1
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by pdlpsher1

I found some pics comparing 3x vs. 4x on a 36H hub. On the 4x you can see some spokes are bent slightly going around the adjacent heads. I really like the strength of the 4x but the bent spokes is not ideal. On 3x the wheel strength is compromised significantly. My hub is for a tandem rear wheel with disk brake. Bummer.

One advantage that 3x has over 4x is that the spokes will enter the rim at a shallowed angle, perhaps providing longevity to the nipple/spoke/rim.

UPDATE I did more online research and it seems some builders say the spoke crossover is not an issue as far as longevity goes. So perhaps I'll go with 4x.

4x
Image

3x
Image

jever98
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by jever98

I don't know how much difference in strength / longevity 4x makes over 3x, but the overlap at least sounds like a pain if you ever need to change a spoke.
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alcatraz
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Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

A 72 spoke wheelset puts a bit more pressure to get it right than 37 spoke wheelsets (16h/21h) because of the larger investment in spokes.

Sometimes you're lucky in the sense that your spoke lengths can come out to be pretty close to oneanother. So if they're too long you can put the DS spokes on the NDS side. Or swap front wheel spokes with the rear wheel etc. Whatever is left can be used for future wheel builds.

If you have a spare front wheel you don't always use you could practice to take it apart and see if you can recreate the spoke lengths with the calculator. That would probably guarantee you won't have to reorder spokes for the other wheelset you're building as you can apply the necessary corrections to your calculated spoke lengths.

bm0p700f
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by bm0p700f

pdlpsher1 wrote:
Mon Nov 16, 2020 7:27 pm
Update: the Roger Musson calculator says I'll have a 0.7mm negative clearance on the spoke head. So it looks like 4x is a no-go unless I can find some images online proving that it works. Bummer.
Done 4x many times on 36h small flange hubs. It is no problem.

4x 36h is also what i do for 120 to 150kg riders. If it works for them...

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pdlpsher1
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by pdlpsher1

Thanks bm0p700f. I ordered the spokes yesterday for a 4x lacing. I'm also using Sapim's polyax nipples and that should help with the sharper angle of the spokes to the rim.

petermadach
Posts: 5
Joined: Fri Sep 13, 2019 4:32 pm

by petermadach

Hey guys :welcome:

I'm working on my first ever build, so I thought its a good idea to double check my calculations, hope you can confirm my results, or let me know if I screwed up something.
I have the hubs and the rims already. The hubs are Novatec D791SB-CL and D792SB-CL, 100x12 and 142x12 axle, and my choice of rims are DT swiss G 540, 700C, 28 hole. I'm not yet decided on the type of spokes or nipples.

I guess my first question would be, what type of lacing would you recommend for a wheelset for a disc gravel bike? I don't plan to do heavy mountain stuff, more like commuting and touring on paved and dirt roads. I can't decide if I should go 2cross or 3 cross, given that 28 seems like a hole count were both can be used. I might add I'm not a featherweight rider (about 90kg), and might also do some light bikepacking in the future, so I figured I should go 3 cross everywhere.

I based my calculations about these sketches:
Front http://www.nguide.eu/sites/default/file ... -CL-12.pdf
Rear http://www.nguide.eu/sites/default/file ... CL-X12.pdf

And used the calculator DT swiss site, as none of the other calculators seem to have the G 540 rims listed, and I couldn't find info about it's wall thickness. The DT calculator needs the flange distances from the centerline, so I did some math on paper based on the drawings to come up with these numbers.
It gave me this result: https://i.imgur.com/EvFt6EV.png
I'm a bit confused about its spoke recommendations based on the calculated numbers, I'd figure I should go for the closest mm number, rounding up, but it recommends size more than a mm shorter than the calculated number

I would very much appreciate any feedback.

Ben689908
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by Ben689908

petermadach wrote:
Thu Dec 10, 2020 8:33 pm
I might add I'm not a featherweight rider (about 90kg), and might also do some light bikepacking
I'd go 32 spoke, to be honest.
Ben

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petermadach
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Joined: Fri Sep 13, 2019 4:32 pm

by petermadach

Ben689908 wrote:
Thu Dec 10, 2020 10:29 pm
petermadach wrote:
Thu Dec 10, 2020 8:33 pm
I might add I'm not a featherweight rider (about 90kg), and might also do some light bikepacking
I'd go 32 spoke, to be honest.
guess I'll need to go on a diet then because I already have the hubs and the rims

alcatraz
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Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Rear right flange offset is 19.575mm and left 34.775mm.

Spoke holes are closer to 3mm than 2mm. Usually 2.6-2.7mm on hubs I've measured.

If the ERD is measured at the inner wall (without nipples) then you need to specify nipples in the calculator.

If you do use erd with nipples, ensure the calculator doesn't assume nipples and adjusts the lengths.

Specify a spoke with a similar gauge to the ones you intend to use. Different spokes stretch differently. Especially rear DS and front left will probably shorten if you go under a certain gauge. Running an alloy rim instead of carbon could also cause the value to decrease because of compression.

Depending on your measurements and the calculator you can get a feel of its deviation. For the first time using one it's hard to say which way it will deviate. Sometimes the hub geometries are not accurate. Sometimes the ERD isn't accurate or the rim compresses a lot under tension or the spokes stretch. In my rather short experience (amateur) the lengths usually come out a bit too long. But I can't say that's going to happen here. I measure hub/rim myself and I use thin spokes. That could be the reason I need to buy -3mm high tension spokes (rear DS) and -2mm medium tension (front rim brake + rear NDS). I can't recommend that you do this as I haven't measured the stuff myself, nor have I recently used the dtswiss calculator.

Yemble
Posts: 37
Joined: Tue Apr 10, 2012 1:15 pm

by Yemble

petermadach wrote:
Thu Dec 10, 2020 8:33 pm
I'm working on my first ever build, so I thought its a good idea to double check my calculations, hope you can confirm my results, or let me know if I screwed up something.
I have the hubs and the rims already. The hubs are Novatec D791SB-CL and D792SB-CL, 100x12 and 142x12 axle, and my choice of rims are DT swiss G 540, 700C, 28 hole. I'm not yet decided on the type of spokes or nipples.

I guess my first question would be, what type of lacing would you recommend for a wheelset for a disc gravel bike? I don't plan to do heavy mountain stuff, more like commuting and touring on paved and dirt roads. I can't decide if I should go 2cross or 3 cross, given that 28 seems like a hole count were both can be used. I might add I'm not a featherweight rider (about 90kg), and might also do some light bikepacking in the future, so I figured I should go 3 cross everywhere.
28h 3x is good and fine. My first build was a 32h/28h light weight alloy build (Novatec, DT XR331, laser spokes, 1395g). I'm a bit lighter but also beat them up regularly.
Attachments
Front Novatec 28h 3x
Front Novatec 28h 3x

petermadach
Posts: 5
Joined: Fri Sep 13, 2019 4:32 pm

by petermadach

alcatraz wrote:
Fri Dec 11, 2020 12:36 pm
Rear right flange offset is 19.575mm and left 34.775mm.

Spoke holes are closer to 3mm than 2mm. Usually 2.6-2.7mm on hubs I've measured.

If the ERD is measured at the inner wall (without nipples) then you need to specify nipples in the calculator.

If you do use erd with nipples, ensure the calculator doesn't assume nipples and adjusts the lengths.

Specify a spoke with a similar gauge to the ones you intend to use. Different spokes stretch differently. Especially rear DS and front left will probably shorten if you go under a certain gauge. Running an alloy rim instead of carbon could also cause the value to decrease because of compression.

Depending on your measurements and the calculator you can get a feel of its deviation. For the first time using one it's hard to say which way it will deviate. Sometimes the hub geometries are not accurate. Sometimes the ERD isn't accurate or the rim compresses a lot under tension or the spokes stretch. In my rather short experience (amateur) the lengths usually come out a bit too long. But I can't say that's going to happen here. I measure hub/rim myself and I use thin spokes. That could be the reason I need to buy -3mm high tension spokes (rear DS) and -2mm medium tension (front rim brake + rear NDS). I can't recommend that you do this as I haven't measured the stuff myself, nor have I recently used the dtswiss calculator.
well the drawings I linked above show the wall of the flange, not it's centerline, so what I did is halved it's wall thickness and added that to the distance of the flange from the centerline of the hub.

Also, just in general, how big of an issue is if the spoke is longer? I'd figure it's a smaller problem than if it's shorter, as you have to overtighten it. Is it possible to make the threading deeper if I accidentally buy larger than necessary spokes? scrap this, got my answer.

And how much tolerance are usually in these calculations? Now I updated the values, and chose some DT spokes and nipples for the calculation, and it now gave 291 and 293mm as a recommendation, however on the webshop I'm trying to buy from there are only even digit lengths. In this case would it be okay for me to go for 290/292?

by Weenie


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