I just got my new Cannondale 29er 1 and I am looking at replacing the stock flat bar. I am wonderring if i should go flat or riser, and if it matters. What kind of differences will a riser make in my bikes handling vs. a flat bar. thanks.
It doesn't really matter what type of plumbing you use to dial in your bar reach/height. The combination of bar (riser, flat, sweep) with spacers and stem (angle, length) will end up getting your hands in the most comfortable position for your best bike handling. The width of the bar and the sweep of the bar will have an effect on your handling. Narrow bars tend to quicken up steering and make things twitchy where wider bars are a tad more stable and - I hesitate to use the word - slow
the steering a bit compared to narrow bars.
If you are looking at replacing your stock flat bar with a riser bar, just realize that if you use the same amount of spacers and stem that your bike came with will end up with your bars being higher than they are right now. That's not a bad thing because maybe your bars are a little low for you in the stock set up. If that's the case, you could get a stem with more rise or a riser bar (or both) to jack up the front end. Or, if you really want a riser bar instead of your flat bar and want the same height, then you can remove enough of the spacers to account for the added height the riser bar gives you (or you could get a different stem angle if there are minimal spacers to remove from the stock set up if you are set on a riser and keeping the same bar height.
It's all plumbing and the options are there to dial in your best bar height.