i have a 2012 flatbar focus arriba. it really goes. problem is, if i have to pull up quickly, it tends to throw me off the seat over the handlebars. i weight about 90kg (198lb) and the bike is light. alloy frame - carbon forks. i don't know if the weight ratio of the bike to me is too great, if it's the design of the bike, whatever. some have suggested i get a mountain bike and put road tyres on it or purchase a 'heavier' road bike. any ideas on why that particula bike seems to want to kill me and suggestions on a remedy?

Technique, maybe.

https://sheldonbrown.com/brakturn.html

If you want to stop quickly, practice pushing backwards on the handlebars. This will move your center of gravity rearward, making your brakes much more effective. Also practice moving your butt behind the saddle- this has the same effect.

I'm 6-foot-4, 230 pounds. Using these maneuvers I can stop very quickly.

Learn how to brake properly. Jeff Wills hit the nail on the head when it comes to braking. It has very little to do with the weight of the bike. Your bike accounts for 11% of the weight of the vehicle (you and the bike). When you apply the brakes you aren't stopping just the bike, you are stopping yourself. The center of gravity (CG) of the system is relatively high compared to most vehicles. The CG is just a little north of your belly button when you are seated in the saddle in an upright position. When you apply the brakes in this position, your CG continues in a straight line. If you try to decelerate too fast, the bike lifts up and spins around the hub and throws you off over the handlebars.

Deceleration can be expressed in terms of "g" which is the deceleration due to gravity. It doesn't matter what the value is but only the proportion of "g" you can experience. In an upright position, the most deceleration you can experience on a bicycle before going over the handlebars is a little over 0.5g. If you push back and move down on the bike only moderately...we're talking moving the CG 3" to 4" back and 2" to 4" down...you deceleration shoots up to around 0.9g before you'll be thrown over the bars. You can almost double your braking ability by a simple body shift.

Put simply, when you are braking, push back with your arms and crouch down with your legs at the same time. You'll stop more effectively and won't be thrown over the bars.