What type of soreness are you talking about? Maybe you need some extra padding on the seat? Because my bike used to give me soreness for about a week and then my body got use to it. How long are you going on your rides and do you normally go the same distance each day? If you are overexerting yourself then if might not be the seat, but your body telling you you might be going overboard. I normally just put on some Anti monkey Butt to take care of the butt chaffing, deal with the hard plastic seat, and just chalk it up for my body getting used to the old bike again. And if your soreness is going on for a while, like 6 months or so, then get some padding for your seat. Hope you have a smoother ride.