Stem too short?
 

I'm thinking of building up frame that's a wee bit too big for me. Standover-wise I'm OK, but reach is a little longer than I'd like.

I'll have to use an 80mm stem, and maybe even a 70mm to achieve proper reach. I'll also be using a shorter reach bar that's 2cm narrower, which will also help to reduce reach.

I've used 90-130mm stems, but never a 70 or 80. Would this stem be so short that it would negatively impact steering and handling, and if so, is it a little that I'd become accustomed to with riding? I'll be using this bike for exercise/commuting/touring.

Thanks for your opinion.

If you're just commuting/touring, I'd say it should be fine. I'm using an extremely short (40-50mm would be my guess) mountain bike stem on my commuter (with road bars) at the moment.

Don't waste your time building a frame that won't fit you. Dump it and find another frame.

Get an adjustable stem (for at least angle). They are cheap, and will allow you to tune the reach to your liking. Once you have it set, you can get a really nice one.

Having said that, if the frame is too big for you, dump it on feebay and get a new one.