The new "CR1" suspension seatpost from Ergon is as simple as it is effective: two parallel spring rods, formed from unidirectionally laid carbon fibres, work in a similar way to a leaf spring and spring backwards and slightly downwards when an impulse is applied. In laboratory tests, the German-made seatpost achieved a spring stiffness of 115 Newtons per millimetre under test load. In comparison to the most comfortable frame-post combinations of conventional design that we have tested to date, this is theoretically half as hard - or twice as soft.
The effect is clearly noticeable on the road, with the seatpost moving one to two centimetres to the rear. Smaller bumps are barely noticeable, the ride feel remains direct, although the two hinges that connect the spring bars to the saddle clamp had some lateral play on our test specimen. Our test riders did not miss any damping.
Nevertheless, the bold design has a few disadvantages: due to the limited aluminium clamping range and the extension length of 17 to 23 centimetres, the seatpost is only suitable for sloping frames with a sloping top tube. For frames with a straight top tube, the cant between the saddle and handlebars is too extreme. Ergon does not yet supply any adapters for frames with a seat tube diameter greater than 27.2 millimetres.
The 31.6 millimetre diameter version on offer, with 3.5 centimetres of travel, is designed more for mountain bikes. Heavy riders hoping for a comfort gain from the suspension post will unfortunately fail due to the weight limit of 90 kilograms specified by the manufacturer. In the EFBe test laboratory, the shock absorber passed an endurance test with 100,000 load changes and a test force of 110 newtons.
PLUS: Significantly increased ride comfort; familiar, sleek look
MINUS: Adapters for different seat tube diameters not available; spring stiffness not adjustable; tall and heavy riders fail due to weight limit; not suitable for all frame geometries
Reference/Info: RTI Sports; phone 02630/9552-0; www.rtisports.de
Price: 239.95 euros, diameter 27.2 mm, weight: 335 grams
Variants: CM1, 31.6 mm diameter, 3.5 cm travel
Photo: Daniel Simon
