rhm

I'm going to build a new wheel for my tandem. This is a Counterpoint Opus II tandem, the original semi-recumbent design, so the captain sits in the rear. The rear wheel takes more or less the captain's full weight in addition to the bike and touring gear. It has to be a tough wheel.

So, three questions: (1) how many times should the 48 spokes cross; (2) what gauge should I use (and, straight gauge, or butted)? and (3) am I crazy to use a NOS Weinmann A129 rim (the famous concave rim of the early 80's) or should I get a Sun Rhino Lite instead?

The original wheel, which has held up fine, seems to be 5X and straight gauge spokes.

For those who want all the details, the original 1984 wheel is fine, but it's 27" and six speed freewheel, and I want to go to 700c and cassette.

The replacement hub is a Shimano tandem hub, I believe this is an HF08. It takes the same drag brake. The original rim is a Weinmann A129, and I already have one just like it but 700c, so why not. I could get a Sun Rhyno Lite for not a ton of money, but it's black and modern looking, while the A129 looks just like the original rim.

fietsbob

I have built 2, 48 spoke rear wheels.. on medium flange hubs 1st was 5 cross Phil hub (tangent pull like 4 cross with 36 spokes)

2nd was 4 cross ,, Bullseye hub ... both freewheel type... I used 2mm straight ga spokes , partially because I bought so many of them..

Used a Sun Rhyno, 'Not Light... havent seen any since.. a 22 year old wheel, now,...
these were on my touring bikes.. 48_40 pairs of wheels , so 88 spokes







...

Bill Kapaun

Your max crosses is 5. I'd probably do 4? That should be similar to a 3 cross 36 spoke wheel.

I'd be inclined to use a butted spoke with a 13 ga. elbow. It fills the hole in the spoke flange better.

davidad

I have not built a wheel that takes that load. The most was a 36 double butted spoke wheel set for a 260 pounder for a touring bike. He has not had any problems. So my best advise is to go with double butted spokes and a strong rim.

nfmisso

I am really big guy, and for our tandem I built 48 spoke 622 wheels, 4 cross, with Wheelsmith DB14 spokes, Wheelmaster MT1110 hubs (cartridge bearing, steel cassette body) and Velocity NoBS rims. They work very well with absolutely no issues on a bike with a GVW in excess of 600lbs. The spokes have relatively high tension, and are properly stress relieved.

The wheels that I have built with Sun rims always take longer to build, because they are not as flat and round as the Velocity rims I have built with. This also results in less even tension for a given state of true. All of the Velocity rims I have built up have ±0.004" or better runout both radially (hop) and axially (side to side) with even tension all the way around. I cannot get a Sun rim to that level of runout with even tension.

As @Bill Kapaun mentions, the spokes with 13 guage elbows are potentially stronger; if you go that route look for a premium spoke with 13ga (2.3mm) elbow, 15ga (1.7 or 1.8mm) middle and 14ga (2.0mm) threaded end. DT Swiss DT Alpine III is one, Sapim Force is another, there are others.

The 1.7 or 1.8mm center section gives the spokes more compliance so that they share the load better than thicker center section spokes. This results in a stronger wheel under real life conditions. Whether you need the strength or not is another matter.

Andrew R Stewart 

Sun Rhyno rim (it has hooked edges and thus can handle air pressure better).
2.3 ended butted spokes
4 or 5 cross, which ever you can get the spokes for.

Do know that with 48 spokes the total wheel tension can be pretty high. So a tad lower spoke tension might be prudent. Andy

Retro Grouch 

Also, the extra spoke holes mean less material in the hub flanges and spoke bed.

Andrew R Stewart 

Yes, especially the hub flange. But one would hope that a manufacturer that offers a 48* hub has done their homework in designing the hub to deal with the added stress that the number of spokes exert. (And this isn't always a correct assumption as I have learned with a "high quality and fine designed American made hub). Andy

rhm

Right. I have emailed my spoke guy, we'll see what he says. Thanks, everyone!

speedevil 

+1 for this spoke in this application.

bakerjw

I had not thought of that. Very keen insight.
Thanks