Hi Aradell and Serge_K,
thanks for your answers!
About the 1x13 setup, the only cassette currently available has 10-11-12-13-15-17-19-21-24-28-32-38-46 teeth
I was thinking of a 50t chainring with the 10-46 cassette. I of course want to run the cassette in den middle, so let's say 13-21 teeth.
At a cadence of 90/min, I would run 30.6 km/h on 50/21 and 44.8 km/h on 50/13. At the extremes, 50/46 would result in 12.6 km/h and 50/10 in 58.2 km/h.
Therefore I thought this might be a good choice. However, I have done all my triathlons on a regular 2 x 11speed road bike so far, so I have zero experience with triathlon bikes and indeed the jumps, especially form 13 to 15 might be too high. So any advice is highly appreciated!
By the way: Does anyone have a contact to ICAN? I tried to get a quote via their homepage, but no answer so far.