ehcoplex 

Possibly this belongs in the Tandem sub-forum, but the bike and the parts are vintage (and 'vintage' brains have more wisdom), so...

I'm building up some wheels for my '81 Peugeot TH-8 (the original steel wheels were kinda trashed and heavy....). I've got some vintage Phil Wood 40h tandem hubs, a pair of NOS Mavic Module E rims. Now trying to figure out spokes and spoke pattern. I've built several wheel sets for 'single' bikes, and always used 2.0/1.8/2.0 db spokes, 3x pattern. I've thought about mixing different gauges on the DS/NDS sides of rear wheels, but have ended up just using the same on both sides. Anyway, I know a tandem is a different story, and I've seen some recommendations for 4x on tandem wheels. Team combined weight is around 280lbs, I'd guess the bike is around 40lbs. No plans for heavy/loaded touring- just some panniers on the front rack for day-tripping/picnic, getting veg at the farm stand. Guage and pattern recommendations? Thx!

bulgie 

Your normal 2.0/1.8 butted spokes will probably be fine for 40 hole tandem, no need to change. You could consider the 2.3 mm butted spokes, haven't bought them in decades so I don't know who sells them anymore. They took a regular 2.0 mm nipple, were only thicker near the J-bend. They often (usually) require drilling the hub holes larger, but your drum brake hub might fit them already. Or are you ditching the drum for a plain old Phil? The Phil "would" need to be drilled. I used some number drill, I forget, maybe a #40 = 2.49 mm? The hole needs to be a little larger than the spoke but maybe you could go as small as #42 = 2.37 mm. I'd only use the heavier butts in the rear wheel. On my racing tandem with the deep-V "aero" rims, on the rear I used ACE3 from Wheelsmith, which were not only 2.3 mm at the bend but also a flat-oval "aero" shape in the middle. (Regular ACE aero spokes in front, 2.0 at the bends). Those spokes were rather annoying to use because you had to file/grind/drill each spoke hole in the hub to let the flat aero section through. Wheelsmith's founder has a blog article about them here including details on how to modify the hub holes. For historical interest only, I don't think those spokes are an option anymore.

3x or 4x makes no practical difference to the durability or "performance", so pick whichever one results in a spoke length you have available. This may be a controversial claim, some people ascribe magical properties to one spoke pattern or another, but I have seen zero evidence of a real difference between 3x and 4x.

Those rims are on the light side, are you OK with some risk of lower reliability for the benefit of lighter weight? There's benefit to using the rims you have on hand, so don't worry too much, rims can always be replaced later.

Lighter rims usually have a lower max tension they can handle before they're at risk of callapsing into a potato chip. Most people will stop tightenming the spokes before reaching that limit, i.e. most wheels are under-tensioned, but it's good to be aware it is possible to over-tension. In general, a tighter wheel is a stronger wheel, up until the point where the rim warps and the wheel is ruined! Also tighter spokes are more likely to cause cracks at the spoke holes in the rim.

Isn't a Module E a single-eyelet? Supposedly the E2, with the thimble-like double eyelts, can handle more tension without cracking. That won't affect the tension where potato-chip instability starts to be a factor, E and E2 should be the same there.

Have fun, and keep us posted.
Mark B

ehcoplex 

Ah, typo in my OP- the rims are Mavic Module 4, not Module E! They ain't light- in fact probably even overkill for this tandem/team. But the price was right. The rear Phil hub is threaded for a disk, but we'll run without for now. Thanks bulgie for the tips re gauge & x-pattern. I think I'll calculate for 3x and for 4x and see if the length makes any difference as far as what's available/$. I'm slightly curious about some of what I've read about different DS/NDS gauges, but that curiosity will likely be overpowered by desire to keep it simple.....

bulgie 

Different spoke gauge/pattern right versus left is only worth thinking about for highly dished wheels. You should do everything within reach to reduce the dish for a tandem, zero dish being the goal, at which point even the spoke length is the same R&L.

Module 4 is perfect for your application. I promise you won't notice the extra weight. And you won't notice them breaking either, because they won't.

A little search shows me Sapim sells a single-butted 2.3/2.0 spoke that takes a 2.0 nipple, seen here. I used to be able to get "triple butted" 2.3/1.8/2.0 spokes, forget who made them, Wheelsmith or DT probably, but I don't know if they still exist. I stopped searching after finding that Sapim. The benefit of the narrower 1.8 mm middles would be very slight, not worth obsessing over. Sapim spokes seem to me to be very good quality, only used them a couple times but I was impressed.

Not saying 2.3 is necessary, but I would use them on a rear tandem wheel, for me. On the theory of "why not?"

ehcoplex 

I'll have to take a closer look and see if 2.3 would fit the drilling of the hubs- if so, I may go with those. On the subject of the hubs, I was kind of surprised- well, actually initially thought this seems crazy...- when I discovered that the axle for this hub is in two pieces. An 'extension' piece fits snugly over the hub axle. The person I bought the hubs from said they originally had a single piece axle, but at some point he sent them to PW for extension to accommodate an 8 speed freewheel and this is how they came back (and that he and his stoker rode it for over a decade without problem). It still seems kinda crazy, but PW has a pretty darn good reputation, so.... I highly doubt I'll be running an 8 speed freewheel, so maybe I'll have a machinist friend shave a bit off the extension so the wheel ends up needing less dish... or maybe I'll leave it alone....

bulgie 

Yes that's how Phils are made. I think they call those extensions "caps" and you can get caps in quite a few lengths. The left side has a cap too. The caps are supposed to be a press fit, does your right side cap just fall off? I suppose that won't be an issue in use, the skewer will hold it all in compression.

Yes on reducing the dish as much as possible. The dish looks kinda extreme on that hub as-is. I'd rather go to 5-speed spacing than accept tha much dish, though I'll understand if you'd rather do 6/7 speed space. Maybe you can put a longer cap on the left and shorten the right? If your machinist friend is cheap, like beer/pizza, maybe he'll make you a left-side cap too, it's not difficult. Or Phil will sell them to you, I think. Newer Phils have the "field-serviceable axle" but I'm 98% sure this is the older, Pre-FSA style, just tell them that when ordering.

Making the hub fit the OLD space on the frame would have the nice advantage of not having to respace the frame, which is non-trivial on a tandem.

ehcoplex 

No, it takes a some wiggling to get it off. I only discovered that it's 2-piece because it got knocked off-kilter in shipping and I thought the axle was bent.


The hub fits the frame well as-is. I'd totally forgot that if I shorten the DS, I have to lengthen the NDS..... So I think I'll build up as-is and see how it goes. If there end up being issues I can respace and re-dish...

bikingshearer 

A contrarian thought from a possibly not perfectly apples-to-apples comparison(48-spoke wheels); slightly thinner gauge spokes on a tandem. Like maybe 15 gauge instead of 14 gauge. (I think that translates to 1.8mm instead of 2.0mm, but someone will have to confirm that.)

Wait, hear me out: it worked on my tandem with captain/stocker combos a lot heavier than 280. Heck, I'm 260 myself, and I put not-small people on the back, so we're talking captain/stoker/bike combined weights approaching 500lbs. (Quick aside - that thing accelerated from zero to "I'm gonna die" scary-scary fast and I would never put me on a tandem on a downslope greater than about 2% without a working drag brake.)

My friend built the wheels after reading and studying Jobst Brandt's book in minute detail (my friend speaks engineering - I don't) and even tracking down and talking on the phone with Jobst himself. Mr. Brandt agreed that the thinner spoke theory made sense - something about the little bit more deformation under stress spreading that stress over one or two additional spokes, with the one or two extra thinner spokes being collectively stronger than the one or two fewer thicker spokes. It all sounded like voodoo to me, but the wheels worked well and held up nicely under the idiotic loads I put on them. I haven't ridden that tandem in an embarrassing number of years, but I never had a lick of trouble from those wheels. Did they flex a little more? Not enough for me to notice.

Anyway, food for thought. Make of it what you will.

Schreck83 

These are 48 spoke wheels from my Paramount tandem. Look to be straight gauge, 3x but not laced under crossing spokes at all!


Drive side rear

Front dished for brake

ehcoplex 

Hmm, interesting. Seems the theory about more deformation under stress spreading the stress wider would still hold, though spread to fewer on a 40h vs 48h wheel.... We did some riding last season on the tandem with wheels I pulled from a Cannondale T900 (which I don't really like that much)- 36h, Acera hubs, CR18 rims- I just rebuilt the hub with a longer axle and some spacers. It was mostly just to get the bike rolling, but no problems with what riding we did do on those wheels. Point is, I'm probably over thinking it- and at least at this point I've built enough wheels that, aside from the expense of possibly having to buy more spokes, the idea of rebuilding the wheels with different spokes, and/or having Phil Wood re-space the hub if we experience issues isn't daunting. I think I'll just go for 2.0/1.8/2.0, as they seem pretty easy to find.

Now to have at the calculators.....

jimmuller 

Now I have to go check the rear wheel on our Peugeot tandem!

When I first obtained what was purported to be a wheel with the original 36-spoke Atom hub it had been strung with a replacement Matrix rim by a shop on Martha's Vineyard (but strung improperly). Eventually it popped a spoke and then another, so I replaced them. Then I noticed that the rim was showing longitudinal cracks, so that got replaced immediately! I don't recall the spoke size, will have to check. However I did nothing special with the stringing, 3-cross IIRC, and just trued everything up carefully the way I would do with any wheel. The wheel has been just fine since then. Our team weight is about the same as yours. The point being, it wasn't anything special or more complicated than any other wheel.

FWIW, we did two camping trips with it, with the loaded bike weighing about 100 to 105 lbs. It worked just fine.