I recently purchased a tri bike for use in my first triathlon (a sprint). Before this I was using a really old road bike that was too small for me but nevertheless allowed me to train on. While the new bike looks the part and is much larger, I am starting to regret purchasing it because I just don't *enjoy* riding it.

I'm not sure if it's the bullhorn handlebars or the much thinner tyres but I feel very unstable on the bike. The handling is very twitchy and I find that I have to brake when going down a hill because I can't lean it into a turn at high speed like I could my old road bike - no fun. I feel so unstable on it that reaching down with one hand to pull out my drink bottle while steering with one hand is virtually impossible, and riding with "no hands" IS impossible. Why should this be? I have never had trouble with balance or co-ordination!? Going in a straight line is OK - but this new bike makes every corner a potential crash. I'm sorry to fans of bullhorn handlebars but I just don't feel like I have the control that I did with drops. So annnyway what I'm asking is should I switch out the bullhorn handlebars and bar-end shifters for drops and STIs and would this cost me a great deal? Wider tyres?

Even with this upgrade, what is the cause of being unable to ride with no hands? Never had a problem with it before

Tri bikes are often twitchier than road bikes, due to the position of your center of mass relative to the wheelbase and your contact points on the bike.

However, to give a better answer than that, you may want to post a picture of your bike and/or your position on said bike (or at the very least, post what bike you purchased, its size and your height/weight). It's quite possible that your balance woes are attributable to a poor fit on your tri bike, or purchasing the wrong size bike.

To answer your question, though, no--do not put drops and STI on a tri bike. A tri bike is designed to be ridden in the aerobars, and putting drops and STI on will only give you a new set of handling issues.