I have an adjustable seatpost with very little setback. I think that's the problem. It's ok with the Ruby, but I have to adjust it as far back as it will go.

Someone here mentioned that if you experience problems (like knee pain) you should look at the last thing you changed on your bike - in my case, the saddle. I never even thought about it before that, but if you look closer, the Ariel has about the same length as the Ruby, but it's rails are shorter.

Muirenn, judging only by looks, I like the old version too, but the new one looks very different. Are the edges on the old model rounded? It looks very much like the Ruby to me.