That helps a lot. The advice about thiner tires is good. A good drop bar road bike will make a small difference. But the main thing is just time in the saddle. The spin class is good, but you need to do some big hills too. That will help your top speed a lot. Start asking the riders that you can't hang with about training and how long they have been riding. Unless you are really hammering 12 to 15 miles is a short ride. Ride really hard then take a rest day. When you train hard enough to really get stronger it takes two days for your muscles to repair themselves 100%. Ask the faster guys about training smarter not just riding more. You will probably discover most of them have been riding for years. Two months is a very short time. Have FUN!
