Spoke Tensile Test
with Benjamin Allen, Jorge Revelo and Juan Amador
ENGR45, SRJC,
2012
Spoke Tensile Test
Objective: Observe the effects of different methods of
heat treatment to the properties of a bicycle spoke via a
tensile test
Typical Loading of Bicycle Wheel
*DT Swiss rated max
spoke tension:
1200N = 265lbs
*Ian’s Test:
220lbs w/ one 16”
wheel
(Overload?)
The spokes are coloured according
to the change in force within them
when 1000N (100kg, 220lbs) total
load is applied. Negative values
indicate a compression. This is
a change from the unloaded state, so
compression doesn't actually mean
compression, it means reduction in http://www.astounding.org.uk/ian/wheel/
tension.
Loading in the “Elastic
Region”
0.3
304 Spoke Untreated Strain/Stress
0.25
Stress PSI
0.2
Untreated
0.1
Quenched
0.15
Air-Cooled
Slow Cooled
0.05
0
0.100
1.000
10.000
Strain 1/1000 in
100.000
1000.000
Heating/Cooling Process:
 Heated spokes above their Eutectic Temperature
 800C for 20min
 Cooled Spokes three different ways
Air cooled for several minutes
Immediately Quenched
Cooled slowly in the oven for >1hr
Cooling time had a drastic effect on grain growth creating
different properties
Initial Spoke Dimension
*Double Butted spokes are thinner in the middle than at the ends . This
is achieved through DT Swiss’ unique cold-forging technology which
reduces the diameter of the spoke for better strength to weight
performance and improved elasticity.
L0= 11.75 in
Tensile Testing or Pulling Wire?
∆LControl=.23in.
∆LAir-Cooled=3.375 in.
Stretching
Necking
Credits

Credits
Spoke dimensions -http://www.dtswiss.com/Resources/Support/TECH-SPECS/Techn-specifications-Spokes-2013
Callister,William D., 1940Materials science and engineering : an introduction / William D. Callister, Jr.—7th ed.
http://www.astounding.org.uk/ian/wheel/