My current side project is a pair of steel hardtail mountain bikes. 

Both bikes are meant to be relative do-all mountain trail bikes so they have very similar geometry but are different sizes. Each frame is meant to be able to switch between 27.5+ and 29 wheel sizes, but one is optimized for 27.5+ with Syntace dropouts, and the other for 29 with sliding dropouts.

Both frames will also feature:

• Internal dropper seat post routing
• Boost spacing
• 3 Bottle cage mounts
• 44mm Internal headtube diameter
• 1x12 Drivetrains with clearance up to a 34t chainring