I've only ridden the short section between Bakersville and the Loveland Pass exit on the Triple Bypass route, The shoulders are very wide so the cars/trucks aren't close but there are a lot of them and they go pretty fast, ie it's noisy and a bit nerve wracking. Also the shoulders of interstates often have lots of misc debris on them. Personally, I'd avoid riding on I-70 unless you have to do it to get where you want to go.