Has anyone had any experience with weight training (particularly legs) while training on the bike. Are there any correlations with improved or decreased performance on the bike?

I've never heard anyone say they receive decreased performance. Over-training can definitetely hurt though if rest is not factored in. I find squats and full leg extension weight training always helps in my pedal stroke.

One possible cause of decreased climbing performance would be an increase in weight due to muscle growth which would make climbing more difficult.

Don't think I'm in any danger of over training as I haven't began riding as regularly as I would like but I usually hitting legs twice a week and riding at least twice a week (normally on weekends due to my work schedule).

I'm definitely stronger and more stable in the drops since I started climbing. I'm also more flexible. Upper body strength has its benefits in road cycling.

Maximal strength training improves cycling economy in competitive cyclists.
Maximal strength training improves cycling economy in competitive c... - PubMed - NCBI
https://www.hokksund-rehab.no/filarki...ES_CYCLING.pdf

In-season strength maintenance training increases well-trained cyclists' performance.
In-season strength maintenance training increases well-trained cycl... - PubMed - NCBI

I used to go to the gym and did heavy weight leg pushes, but I now don't have access to a gym. I now use a KK 2.0 road machine trainer. I use it for about an hour each session of continuous pedaling

Thanks [MENTION=78894]Carbonfiberboy[/MENTION] very informative.