If they make it it's not too long. However, personally I don't feel comfortable using anything longer than 120mm. Longer stem = more leverage for a fork steerer or the stem itself to break. Maybe that's not really the case, but IMO if you need a 120mm stem you are already riding a frame that's one size too small anyways. Again, that might not be the case either but to me a 100mm stem is "standard" when you are riding a "properly sized" frame. I'm building a race bike right now that is one size smaller just so I can use a slightly longer 120mm stem. I could have gone with one size smaller than that and used a 130-140mm stem, but that would be pushing it for me.