Dark eyes (of this forum, though more of a lurker than contributor) has just replaced the Marathons on the front of his Greenspeed tandem with Trykers. I was out on Saturday piloting him around a 25 mile loop of West London. First impressions were that they run/roll very well. they are certainly a lot quieter, I couldn't hear them above the tractor like hum of the Marathon on the back, which is probably 12 feet away from me ! One concern is that the side walls aren't as thick, will be interesting to see how they hold up to the strain of cornering on the tandem, but as I say first impressions pretty good. Of course only having them on front means that we still have the chunky and maybe grippier Marathon on the back to deliver the power.