Step one: Find an online seller with a wide selection. Someone that stocks from QBP will do.
Step two: Notice that these are available from multiple manufacturers.
Step three: Consider America's litigious environment.
They may not be the best idea on the planet, for a few reasons, but yeah, they are reasonably safe when used according to directions.
This is an old thread and I noticed no one here has actually installed or used a steerer extension. Good news! I have one on an aluminium frame Malvern Star oppy A4. The stock frame is very racey (small headtube). Bike is a lot more comfortable and the geometry is now more like an endurance bike when on the hoods and of course you still have the drops when you need some speed. This was my first race bike and I bought the large size (56cm top tube) on the recommendation of the bike shop owner. I'm 185cm tall and 55 when I bought it. I have also installed a shorter stem so no problem with cables. In retrospect a more comfortable geometry would have been the way to go but because of my inexperience I didn't know any better. I assumed race bikes were meant to be uncomfortable!
Extender works fine and is solid. I've completed 100km plus rides on this bike without any problems.
A stem extender is OK unless you have a carbon steerer, then it's dangerous. If you are looking to get some handlebar height, why are your bars tilted so low. You can get "free height" by tilting them up. Better yet, get bars with a shorter reach and a stem with a greater rise.
This being said, as Finx said, the bike looks too small for you anyway. These "fixes" are all a Band-Aid on a broken leg.
And as duriel implied, your saddle angle looks like you would struggle to not slide forward. I can't imagine that's very comfortable.
A forum community dedicated to Road Bike owners and enthusiasts. Come join the discussion about bike parts, components, deals, performance, modifications, classifieds, troubleshooting, maintenance, and more!