Wheelbuilding / Wheel Building / Wheel build help

2 questions for the hive mind,

1 - Flat head v dome head spokes, aesthetic difference or a functional one? Flat head better on low spoke count non radial lacing as spokes may cross the heads of others?

2 - 28h 3 cross, mutually exclusive or just a bit harder due to aforementioned spokes crossing others spoke’s heads?

28h 3X will work on small flange hubs in shallow 700C rims. If your spokes start touching adjacent spoke heads you're over crossed and should change the pattern.

Dented disc brake rims... Is this fine? The dent is about 1.5cm long. The wheel is true and tensions fine, and the tyre holds air tubeless.

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If you'll pardon the expression, how large is your flange?
Got a rear Novatec track hub (62mm hole circle dia.) laced 3 cross to 88mm China carbon, and it's fine. Close, but the spokes don't cross each other's heads (CX-Rays).
Going to roll the dice on a 3-cross rear 28h DA HB7600/60mm carbon build in future.

Don't have the parts to hand as it's a wheelbuild I'm doing for a mate but I don't think as big as a Novatec or DA 7600.

Going to go 2x just to be safe.

Cheers.

Cheers, will just go 2x for ease.

When I'm calculating spoke lengths for a straight pull hub like this one here:

Do I take the measurement from the centre of the flanges with the spoke holes in them, or do I have to measure the spoke holes for the trailing and leading spokes separately and calculate them separately? A bit of basic trig and some dummy numbers suggests that the offset between the holes and the centre of the flange is going to result in differences in the spoke lengths which will get lost in rounding down to the nearest available spoke length, but it would be good to have some confirmation that this is correct. Or to have someone tell me the right way to do it before I order a whole load of spokes which are the wrong length.

do I have to measure the spoke holes for the trailing and leading spokes separately and calculate them separately?

Yes. As you have found, once you have the right numbers, the difference will very likely be lost in the rounding (for the same reason, we don't calculate inbound and outbound differently on J-bend spokes, even though strictly speaking they are different)

Thanks for the answer, but if the difference will very likely be lost in the rounding, isn't the answer 'no'?

if the difference will very likely be lost in the rounding, isn't the answer 'no'?

No, because "very likely" is not the same as "definitely". At some point, there is going to be an edge case where the correct solution is spokes of different lengths even when the length increment of available spokes is so large compared with the difference in calculated ideal length.

FWIW I just rebuilt a DT swiss straight pull wheel (see upthread) and all the spokes were equal length.

I’m getting ahead of my holidays, still got Halloween to go and I’ve built myself a nice christmassy wheel.

Hope Pro 2 singlespeed on an Onza trials rim that was until yesterday built onto a Tensile front hub.

The Tensile hub had smaller flanges than the Hope so to reuse the old spokes I snowflaked it which used up the extra spoke length perfectly.

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Do kinlin xr 31 come in a symmetric disk version or is it just rim and offset disk?

They exist but are a bit more rare now that superstar components don't sell them anymore.

bhs (in the us) have them http://www.bikehubstore.com/Kinlin-XR31TS-Disk-Rim-Black-p/xr31ts.htm

I think halo´s version is symmetrical

https://www.tritoncycles.co.uk/components-c9/rims-c123/devaura-700c-disc-rim-p13616

https://www.tredz.co.uk/.Halo-Devaura-Disc-700c-Aero-Road-Rim_102101.htm

Thanks, is that the exact same rim as the Kinlin? I was also looking at Velocity Rims Aileron as an option. Does anyone have any experience of them?

What is the snowflake lacing calculation?

I am interested in the pattern and would like some info if you have it

Danstuff as you have realised you can't get a spoke length calculator to work out the spoke length.

It is possible to do mathematically for the four rows of spokes.

I normally guess the lengths then work out the fractional crossing in spocalc for that hub.

For a hope pro 2 32h and a kinlin tl29 the lengths were 296/298mm. I guessed right first time. 297/298mm would have been better but I lacked 297mm.

Symmetric xr31ts do exist some one has just got to order them.

The aileron is quite good. Built with several. Tyres are an easy fit. Not always as round as they could be. I have over 20000km on a 24 spoke set. The rim is robust.

Do your calculation as normal for 2 cross, 3cross etc and then add 2mm to the spoke length for each twist.

Two twists needed to keep the spokes going into the holes they would go to normally. A single twist would have the twisted spokes going into each other’s holes if you see what I mean?

You built it just just like you would normally but instead of lacing over, over, under, you go over, over, twist.

For that 26” wheel and for a 27.5” one I did recently I put in all my inbound spokes on both flanges then just twist the outbound ones around them. For the 20” one I built for my folder I had to take the nipple off each each inbound spoke as I got to the relevant outbound one and twist them around each other.

Not sure how well this one will last, it’s going to have a disc brake on it so the spokes will be dealing with a lot of forces. The 20” one for my folder is a rear, with a coaster brake and it creaks a bit.

it’s going to have a disc brake on it so the spokes will be dealing with a lot of forces.

Why does everyone think dick breaks give the spokes a hard time? 🤔

dick breaks

And thus they shall ever more be referred to as.

They must get a harder time in a dick breaked wheel than a rim braked one no? Not saying too hard a time, well within what they can cope with, but you are braking the hub and the forward momentum of bike and rider and the friction between the tyre and the ground are trying to make the rim rotate (or rather, continue rotating) and you are relying on the spokes to stop that. Seems like that is asking more of spokes than on a rim braked wheel where the brake acts upon the rotation (rotating mass?) directly.

If the spokes on a dick breaked wheel deal with no more forces than a rim braked wheel, why aren't radially spoked dick break front wheels a thing?

Thanks for the info. Given the choice would you go with kinlin 31 or Aileron for an SP dynamo build for a hilly long distance ride/race (TAW). Or does the availability answer the question.

If the spokes on a dick breaked wheel deal with no more forces than a rim braked wheel, why aren't radially spoked dick break front wheels a thing?

For the same reason that radial on the drive side rear should not be a thing. The load path is slightly different between disc brakes and rim brakes, but the actual external loads are the same and they get from the tyre contact patch to rider via the spokes either way.

Think about a rim brake for a while; the ground pushes the bottom of the rim upwards and backwards, the caliper pushes the top of the rim backwards (and downwards a bit, as it isn't usually right at the top), and the fork ends push the hub forwards and downwards. All the vectors have to sum to zero at equilibrium. To a first order approximation, the hub is pushed forward by twice the horizontal force at the tyre contact patch and downward by the vertical reaction force at the tyre contact patch. Somehow, all these forces get from the rim to the hub. That somehow is called spokes.