I’m sure that everyone who can build wheels fantasizes about what would be their ideal wheels be if they had the means and opportunity. Every now and then you get the opportunity to go close even if it does require a leap of faith.
BTW this is a long post about wheels, read it at your peril.
The subject of this fantasy were no holds barred, go fast, race wheels for the Heavy Tandem (220kg for riders and bike). The fantasy wheels were an item o discussion before John even started looking seriously for a bike. The ideal wheels would be useable for both disc and rim brakes, not too heavy, good aerodynamically, and reliable enough to use on a regular weekend basis.
Material. Aluminium. This was never much of a question for us. John already had designs on riding at the Nationals and the expectation was that rim brakes would be mandatory for a while yet. For the hills we have around here even single bikes can overheat their rims/tyres so carbon rims with rim brakes are not an option for us.
Decided on tubular rims rather than clinchers for a number of reasons. The pros include being lighter for the same strength, the ability of tubular rims to withstand greater tyre pressures, the ride qualities of tubulars and the virtual elimination of pinch flats. The pressure factor is significant because at our weight we find that we regularly exceed the maximum recommended pressure for the tyres (and probably the rims) just to get a reasonable ride. Typically we run 28mm tyres at 120-140psi. Big tyres and high pressures have a habit of pulling rims apart. With tubulars the pressure also helps to hold the tyre onto the rim. The intention was to use either Vittoria Pave or Challenge Parigi-Roubaix which are both notionally 27mm.
Having already determined material, the next question is shape/depth. Here there is a significant trade off between aero-ness, strength and weight. I have a pair of 32 hole rims that are 45mm deep but the rims alone weigh 880g each! At the other end of the spectrum sub-400g rims are around but are neither aero nor strong.
I decided that the ideal would be somewhere around 30mm deep which would be typically 520g or so.
At our weight, even with the more symmetrical wheels allowed by a 145mm rear wheel spacing , we would need at least 40 spokes.
CX-Rays are frequently used on weight weenie bikes because they are lighter than most. However they also have the best fatigue resistance numbers. At between 2 and 2.5 Euro each they are not cheap.
Tandem hubs are a specialty item so they tend to be rare and expensive. $500 is about the start point.
I would almost always go for brass, however aluminium is appropriate for special wheels.
This was all well and good but it was just a dream.
had a sale on tandem hubs. A pair of disc compatible 40 spoke White Industries hubs for $120 delivered was too good to pass up. So I convinced John to buy a set and I got a pair for me even though I don’t have a bike to fit the 145mm rear hub spacing yet. I figure that the wheel isn’t going to go off, and I might slip a bike past the Chancellor one day...
Now the build began:
Velocity (used to?) make a tubular version of their Deep V rims, the Pro Elite which is 30mm deep (520g) and suitably strong enough for this purpose. They also make some shallower and lighter rims, which would probably also have been suitable. Unfortunately for them they don’t advertise them in a 40 hole version and did not respond to any email requests as to whether they would make any.
Then I found a mob in Taiwan (Newsonsportec) who make 23mm wide tubular rims and they come in pretty colours too! I asked whether they would do a custom 40 hole drilling and they said yes (they will also do other rims in 40H drillings but you need to order 5 rims). The colours can be either anodised or powder coated. Naturally go-fast wheels need to be red and I chose anodised. At 25mm deep they are a little shallower than the Pro Elite but they are also 40g lighter. It is possible that the more rounded U section rather than the V section might be more aero to make up for it though.
The fantasy wheels would have Sapim CX-ray or DT Aerolite spokes. However Newsonsportec also make spokes, and have some semi-aero 2.3mm wide spokes (same width as CX rays) which also came in pretty colours. Naturally I got anodised red ones to match the rims. It turns out that whilst CX-rays are butted spokes that have been squashed, these are plain spokes that have been squashed. So CX-Rays end up being .8mm thick, where these are 1.5mm thick.
Unfortunately I wasn’t really happy with the spokes, so in the end I have had to buy 164 CX-Ray spokes (ouch!) and I will be re-building all 4 wheels.
Newson Sportec also do nipples in Brass Aluminium and Titanium. I’m normally a brass sort of person, but I’d use Al for special wheels though. However the Ti ones piqued my interest so I did some research.
Ti are lighter than brass but not as light as Al.
There is also an issue with galling so they can bind to the spoke when being turned.
They are much stronger than the others and therefore there is a very greatly reduced chance of rounding them off.
What I found really appealing about these was the shape of the head. Instead of finishing the top of the nipple in a standard screwdriver slot, these nipples finish in a star shaped spline which mates to a tool that goes on to a socket handle. The shoulders of the head are also curved so that there is a bit of movement to allow the nipple to angle towards the spoke rather than inducing a bend. These are expensive little beggers at about $1.20 each but I figured that they had sufficient bling factor that I thought I’d give them a go. These are the most extravagant part of the wheels, but they do make the wheels a bit special which is part of the exercise.
I did buy some copper anti-seize paste (a whole tub from a car-parts shop, (let me know if you want me to put some into a tiny packet and sell it to you for $10 like Ti-prep do), which certainly did reduce the galling issue but did not eliminate it. All in all I don’t think that from a building perspective that the Ti nipples were a great success. The head shape and tool combination was really good and they fitted so well together that the tool held the nipple well enough to place the nipple into the rim. Without the galling characteristic of Ti these would easily be my favourite nipple to build with. If they made the same shape nipples out of Al or Brass I’d be all over them.
My maths puts them at just a bit less than 2kg with the CX-Rays which is pretty respectable for disc hub tandem wheels.