The TOUR seatpost test is based on three types of load that a seatpost experiences or can experience during use. The preload caused by assembly and repeated adjustment, the fatigue caused by recurring loads during use from the rider and the road surface, and the possible overload caused by a violent impact, e.g. when riding through a very deep pothole.
1. application of defined preloads:
a.) On the shaft of the seat post:
- Tighten the bolt of the saddle clamp ten times to a torque of 5 Nm
- Tighten the bolt of the saddle clamp once with a torque of 7 Nm
b.) Screw(s) of the seat post head:
- Tighten the screw connection ten times to the specified maximum torque
- Tighten the screw connection once with 1.5 times the specified maximum torque (according to EN standard)
2. dynamic testing:
The seat post is mounted as described in the operating instructions. The seat height is left the same for all seat posts. The force is applied 70 mm in front of or behind the centre of the seat post clamp on a saddle dummy.
A dynamic test is carried out according to the following table:
Block
Load change
Frequency [Hz]
Force [N]
Application of force
1.
1300
5
1200
back
2.
100
4
1200
front
3.
300
3
1350
back
4.
100
4
1200
front
5.
100
2
1500
Back
6.
100
4
1200
front
The tests continued until the test specimen failed or a total of 150,000 load cycles were reached.
During the tests, the force-displacement curve was documented for every ten load cycles.
A dynamic test lasted just under twelve hours.
Note: The DIN EN standards stipulate 100,000 load cycles with a load of 1,200 N in front of and behind the saddle. A test at a 90 degree angle from the front is also required. TOUR was unable to understand the purpose of the latter test on the basis of its own real data measurements. This test was therefore omitted. 100,000 load cycles in the front saddle area also do not correspond to the results of the real data recordings. The selected test forces and load cycles therefore also cover the loads that occasionally occur in the front area. In the last TOUR test in 2005, 100,00 load cycles with 1,200 N were tested with the force applied at the rear.
3. determination of the overload behaviour or the residual load-bearing capacity after the test:
Finally, the seat post is loaded with a maximum of 3,000 N to check whether the post does not fail at all, suddenly or "plastically", i.e. good-naturedly.
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