I heard that steel framed bicycles were nicer to ride than aluminium: that myth and it turned out to be true. I also heard that tubular tyres are nicer to ride than clinchers, so I decided to test that myth as well. I didn’t want black/carbon wheels on my traditional-looking steel bike; I needed to find some wheels with silver-coloured tubular rims and silver spokes. It’s difficult to find these elements in factory-built wheels, so I built my own instead. You can see the building process for the front wheel here.
The rear wheel is the same rim (Mavic Reflex) on the corresponding rear hub (Shimano Dura-Ace FH-9000), which is somewhat problematic: the 900N upper limit on tension on the drive-side spokes, combined with the offset required on a cassette hub, means that the non-drive-side spokes have to be at less than 450N. This is very much lower tension than any spoke on any other set of wheels I have, which makes me slightly nervous.
Dynamically, as a loaded bicycle wheel rolls over the ground, the wheel deforms into an ellipse: longer front-to back and shorter top-to-bottom than when it is unloaded. The tension in the fore and aft spokes is thereby increased, the tension in the top spokes is almost unchanged and the tension in the lower spokes is reduced. My concern is that the lower overall tension will allow more elliptical elongation, reducing the tension in the lower spokes more than usual and making it more likely that the nipples will become partially undone.
There are many approaches I’ve seen suggested for dealing with this:
- Ignore the 900N upper tension limit.
- Don’t lube the spoke threads or eyelets on the non-drive-side.
- Leave out half of the spokes on the non-drive side.
- Use a thread-lock glue on the spoke threads on the non-drive-side.
- Use thinner spokes on the non-drive-side.
- Use heavy grease on the spoke threads and eyelets on the non-drive-side.
Some have ignored the 900N limit with success, others have found cracks in the rims around the spoke holes. I decided not to take a chance.
Not lubing the threads would let the nipples seize onto the spokes after their first encounter with moisture. If it works, great, but if it doesn’t you’ve thrown away any chance of fixing the wheel without replacing that spoke/nipple. It also makes it harder to turn the nipples while building the wheel. I didn’t like this trade-off.
Leaving half of the spokes out would double the tension in the remaining ones and is a sensible strategy used by Campagnolo on the Zonda wheels etc. I didn’t adopt it because it wouldn’t look right on a traditional-looking bike, and I am unsure it is wise on a rim not specifically designed for it. In the longer term I would like to see rear hubs and rims designed for this on sale as a standard pattern.
Using thread-lock glue on the spoke threads would be better than not lubing them; they would turn smoothly during building and it would allow the tension to be adjusted later, but that adjustment would break the bond and remove the benefit of the glue. I preferred to look for a more permanent solution.
Using thinner spokes means that they will elongate more under the same tension force. The conjecture is that the elliptical deformation needs to reduce the effective length by more than the initial elongation before the spoke will start to have problems. Anecdotal reports from people who have tried this method as well as using the same spokes as the drive-side suggest that the longevity of the wheels built this way is superior. While I am not convinced that the proposed mechanism is correct, I am reasonably convinced that the system works. I therefore used DT Swiss Competition spokes with a 1.8mm centre on the drive-side and DT Swiss Revolution spokes with a 1.5mm centre (31% less cross-sectional area) on the non-drive-side. This means the tension-per-unit area is 72% on the non-drive-side rather than the 49% it would be if I used the same size of spokes.
Using heavy grease on the spoke threads prevents them seizing without making them so easy to turn that they can undo themselves. I used waterproof grease which I hope will mean the nipples remain adjustable over the long term.