Spokes for an Open Pro build

Phil

Maximum Pace
#1
This might be a bit overly specific of a question, but I know there are some wheel experts around, so...

Down in Boso on Saturday I managed to knock my rear wheel way out of true; took it into the LBS yesterday and it turns out the rim is cracked and done for.

Going to re-use the Dura-ace hub and have it laced to a 32-hole Open Pro (rim was Ambrosio), aluminum nipples. My LBS builds a decent wheel, but isn't into fancy schmancy and will probably just use the straight gauge spokes he has on hand.

I'm thinking I could probably do better, though. Something double butted, maybe aero, preferably lightish, and available from the LBS distributor's catalog. Would it be worth going with different spokes on DS/NDS for a 32-spoke build?

Cost isn't a factor, but durability, strength and weight of the build is, in roughly that order. Any suggestions?
 

GSAstuto

Maximum Pace
Oct 11, 2009
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tokyo
www.roadfixie.com
#2
Hi Phil - I've got a fairly decent selection of both Sapim and Pillar spokes. For Audax type work I think the PIllar's are quite nice. Sapim CX are definitely lighter - but not as forgiving in the build and tension. Open Pro will be either 602mm or 605mm ERD - so you need to check that. But based on the 605 (most popular):

NDS 288.1
DS 286.3

Pillar 1423's come in odd sizes - so you round up or down as your pref. Sapim come in even sizes. Generally I use a 14mm nipple which gives a little more shank to work with. You can use the larger hex-head, nipples in the OpenPro. I have them in both Silver or Black color.

Tension balance with DA hubs is about 2:1. (Spoked 2x,2x) You could also spoke them 2x, 0x - but with 32h it's not really buying anything. The whole idea of going radial on the NDS is to allow for slightly increased bracing angle at a sacrifice in wind-up. I think for a rough roads wheel, better to go 2x, 2x.

Most important will be the LBS builds an even tensioned wheel and has a proper tensionmeter to check against. We use a digital tensionometer AND a mechanical one to cross check. That plus the P&K method generally gives a wheel that is +/- .1mm and less than 5% spoke tension difference.

Mavic recommends between 70-90 kgf spoke tension. I ususally build the fronts at 70-75 and the rear DS right at 90 or 95. I like to squeak the DS as high as possible cause then there is lower chance of the NDS de-tensioning if you take a hard hit. Wheels and spokes fail because spokes are too loose - not too tight!
 

GSAstuto

Maximum Pace
Oct 11, 2009
945
242
103
tokyo
www.roadfixie.com
#4
3X would be fine - but not sure why you want to do that?? 3x has less bracing angle on the NDS side. Don't pay attention to urban myths about 3x being somehow stronger or more supple. Choice should be dependent more on what tension is required to maintain a wheel fully in pre-stressed condition. 3x will reduce bracing angle and lead to slightly more lateral flex. In fact, this is exactly what you DON'T want when using CX-Ray! See what I mean? Urban myths driving the decision rather than engineering. If you want to use 3X , then use a slightly more 'stretchy' spoke like the Pillar 1423 (Xtra) or even Hoishi Bladed.

You can look at the performance curves of each spoke then determine which will suit your wheel build better.

The slightly higher compliant spokes are more suitable to situations where the chance of more lateral or torque induced flex would occur. Since they unload more gradual and have a little more working room . Low compliance (high tension) spokes like CX Ray unload very fast as you move quickly out of the operational curve with any rim distortion. Therefore you need to build accordingly.

You can also use DT Revs - they are aero type and good spokes. Plus most LBS can get them in Japan. Sapim are horrendously expensive in Japan by comparison. Takizawa is a DT Agent - you can get great prices from DT directly from them. Probably 15-25% better than your LBS.
 

m o b

Speeding Up
Jun 22, 2008
341
23
38
Bremen
cyclitis.wordpress.com
#5
So far I used Swiss DT Competition 1.8/2.0 and the lighter DT Revolution 1.5/2.0 mm on my self built wheels. Both should be OK for 3 x and 32 spokes on the rear wheel. I think it is rather useless and expensive to use bladed spokes on the rear wheel; on the front wheel yes.
Be careful with the combination of alu nipples and alu rims, but with the eyelets on the Open Pro rim there shouldn't be any problem.
If your LBS does all the work - fine, otherwise I prefer hexagonal brass nipples for maximum tension.
But again, with the above combination you can't do wrong.
Safe ride!
 

Phil

Maximum Pace
#6
Thanks Michael, had forgotten about DTs. Always hum and haw about alum vs brass nipples, but for a build like this I agree with you and my LBS that aluminum are okay. Never had issues so far, anyway. Thanks also Tim for the additional spoke options...

Will give the shop the options and see what he does.
 

GSAstuto

Maximum Pace
Oct 11, 2009
945
242
103
tokyo
www.roadfixie.com
#7
FWIW - DT Comp's are my 'go to' for just about every other round spoke wheel. Easy to build, cheap and they cut and roll nicely. Other than that, Sapim Race are nice. If I do DT Comp wheel, it's always with brass nipples. Aerodynamics of the wheel are only applicable if you are riding at extended speeds above 40kph (expected). And 32spoke automatically puts the wheel into the 'egg beater' category, so even less advantage (or reason) to bother with bladed. Case in point: my Gokiso / 50mm /32spoke 'super rando' wheel doesn't roll as fast as my EDB/ 38mm / 20spoke 'Greenline' wheel. It just bottoms out at about 45-50kph on my test incline. The 20 spoke will roll at more than 55-60kph. Same spokes, btw. And If I repeat this with my old 36 spoke Nisi Sludi with handmade rolled blades (best at the time) , not as good as the 32 spoke. (But they look beautiful) 45kph is pushing it even with my nose buried into the top tube.