Originally Posted by
jskash
My ride this morning verified that as I rode almost a full mile per hour less than I had been doing. I will give it a week, and if I can't get used to it I will change back to the regular tubes.
I'm not surprised. The thick thorn-resistant tubes add a considerable amount of rolling resistance in addition to the increased weight. As the tire rolls you flex both the tire sidewall and the tube inside. The thicker tube takes significantly more energy to flex than a regular tube and slows you down.