I have not worked with bamboo yet for bows so you can do whatever with this bit of information:
When making bamboo flyrods it is very common for the maker to temper / harden the bamboo. It is often done one of two ways. The first method is to flame temper. This is done with a torch and it takes a lot of practice to get it even and done well without scorching. (Native Americans used to harden their arrows by inserting the tips into the sand right below the fire.) Heat treating or hardening the wood can also be done with a heat gun. Some bowyers actually prefer to use a heat gun and then add oil to the wood as they temper it. This method is discussed in the bowyers bible series #4. In addition to flame tempering, some bamboo flyrod makers prefer to use an oven and literally bake the bamboo rod sections until tempered. (Some makers would do this by storing the split bamboo culms in their hot summer attics in sand boxes for years at a time.) Now days most folks that do this use electric ovens and I know some bowyers that use the same oven that they use to cure the glue and/or to dry out staves. No matter what heat source and method you choose, it is critical that you know what the moisture content is of the stave that you are attempting to temper before you add heat to it. Why? Because the higher the moisture content is, the slower you need to dry it in order to prevent splits, checks and other damage to the wood as you temper it. This is exactly the reason that there is the old saying that says "use moist heat for moist wood" when using heat to alter the shape of the wood piece. But remember that heat bending and heat tempering are two totally different things. If you try to flame temper some "green" wood, it will just explode on you. The wood first has to be dry to about 10-15% moisture content before you can even attempt to temper it. The bottom line here is that you need to do two very important things: 1). Do your research before you try to temper any wood 2). Practice first on some similar wood scraps before trying it on a bow. You will be amazed and how much more you will learn when you do some practice trials first!