08 augustus 2011

First experiences with my new Alterra seat

In a previous blog posting I described the adaptations to my newly acquired RANS Alterra seat and the main differences between this and the classic CF-bike seat.

Yesterday my wife and I went for a 41-km (about 25.5 miles) ride so that I could gather some riding experience on my Dynamik Pro.

Most of the time the seat has a forward downward slope of 17º-17.2º , as measured afterwards. At this slope there is no tendency to slip downwards, so that it is not necessary to wriggle myself upwards from time to time. Yet the seat does not feel too horizontal, and it is also easy to put the feet on the ground while remaining seated.

The strong curve upward at the back of the seat -the effects of which I had minimized somewhat by applying and then modelling the 13 mm (0.5 inch) ibilite foam- nudges me gently into a more tucked position than the classic CF-seat. To my surprise, this has the effect that I am in a nearly perfect sitting position with regard to power transfer to the bike's drive train, and also minimizes somewhat the air resistance. The pressure on my hands is increased very slightly but gives no discomfort.

The absence of contact between the Alterra seat and the back of my upper legs -in stark contrast with the classic CF-seat- makes definitely for more comfort and a better pedal stroke.

A very important but somewhat subtle matter is the Alterra seat's influence on the muscles of the buttocks. I hope I can get my description of this matter right…

On the classic CF-bike seat, I have to be careful not to exercise the buttocks muscles too much. They will then feel downright uncomfortable because there is too much pressure on them when I am seated rather upright while pedaling.
(The situation on my rowingbike is very different: there I exercise the buttock muscles without constraint, because I easily and automatically minimize the pressure on them while rowing.)

Therefore, I am accustomed to exercise my leg muscles only on my CF-bikes, so that the buttocks do not hurt.

On the Alterra seat the problem of pressure on the buttocks muscles, and the discomfort that this causes, turns out to be much reduced! I can be less careful in exercising my leg muscles only, without being immediately punished with buttocks muscle discomfort.

For now, I can only offer this explanation: the reduced size of the Alterra seat, compared to the classic CF-bike seat, offers less area where the buttocks muscles can be pressurized.

However, I need more riding experience and some additional experimenting to make up my mind...

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