Tandem Cycling - Wheel build: double butted or straight gauge spokes?
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Hi folks. I'm building a front disc wheel for our Speedster (700c) with a Phil hub and a 36 hole Dyad rim. We are a 320 lb team who mostly ride 30-40 mile rides on the weekends here in Marin pretty much on pavement with a few dirt short cuts here and there - nothing radical. We typically run 32c Gatorskins at about 95psi. Any reason not to use a 2.0/1.7/2.0 spoke instead of a straight gauge?
09-21-11, 11:27 PM
We have opted for double butted spokes 4 times out of 5 . . .
Our first tandem back in 1975 (Follis) had straight spokes. The next 4 custom tandems after that always had double butted spokes.
Thanks. I thought it would be OK but I thought I'd put it out there and see if anyone vehemently disagreed...
09-22-11, 05:44 AM
I woudn't hesitate to use those spokes, they should be fine.
09-22-11, 10:03 AM
Double-butted spokes are thicker at the ends than in the middle. The most popular diameters are 2.0/1.8/2.0 mm (also known as 14/15 gauge) and 1.8/1.6/1.8 (15/16 gauge).
Double-butted spokes do more than save weight. The thick ends make them as strong in the highly-stressed areas as straight-gauge spokes of the same thickness, but the thinner middle sections make the spokes effectively more elastic, allowing them to stretch (temporarily) more than thicker spokes.
As a result, when the wheel is subjected to sharp localized stresses, the most heavily-stressed spokes can elongate enough to shift some of the stress to adjoining spokes. This is particularly desirable when the limiting factor is how much stress the rim can withstand without cracking around the spoke holes.
09-22-11, 11:22 AM
If you want to be more conservative; go with 13/14 single butted spokes like Wheelsmith DH13 - and I believe that some of the other spoke manufactures have something like a 13/15/14.
Disc brakes put a LOT of load on spokes; even more than the drive side on rear wheels. All of the warnings/suggestions about drive side spokes on rear wheels are applicable to the disc side on the front wheel you are building.
Thank, everyone - I'll be using the DB spokes.
09-24-11, 09:18 AM
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