I've never heard of pros or anyone else using weights or weighted vests for training on a bike. I'm a Cat 2 road racer, I've never heard of it. Doesn't make sense.
Bike power is measured in watts. The product of those watts is speed. If you're going up a climb, the magic ratio is
watts (power) vs. weight (gravity). If you're going along the flats, the magic ratio is
watts (power) vs. drag (aerodynamics).
So, added weight will not have an effect on the production of watts, it will only serve to retard your speed
on climbs.
Let's say you go up a hill while producing 300 watts for 30 minutes. Let's say your average speed was 15mph. Strap on 20 pounds of weight and the only thing that will change is the speed. If all you can produce is 300 watts for 30 minutes.....that's all you got.
The beauty of a bike is the resistance is built into the system. Why add weight? Drop a cog, hammer a tad harder and go from producing 300 watts to 325 watts.
No weights. You'll also run the risk of developing muscle injury or maybe just developing muscles unnecessary for cycling performance. Ankle weights wouldn't even work in a captive pedal stroke as the weight going down would in part be offset by the weight going up.
Cycling fitness is all about aerobic efficiency, efficiency at or above lactate threshold levels and a host of other boring things that suck the love out of riding a bike.
If you want to improve your bike fitness give me a buzz. Up to this year, I spent the last 24 seasons racing on the national and international elite levels in road, mountain and cyclocross racing. Now I just ride for fun......FAST!!!!
No weights.