Stems are not a performance item, hence not many people compare the differences/advantages. Let me clarify the best features.

1. Threadless- Most high end bikes use threadless stems. Folding bikes are the same. Low end models use heavier threaded setups. Stick with a threadless setup to lighten the bike and no performance loss.

2. Adjustable height- Folding bikes are one size fits all, hence an adjustable height stem is essential to provide a comfy fit for everyone.

3. QR on the handlebar- A QR on the handlebar allows riders to adjust the handlebar angle on the fly. It also allows one to move the brake levers up and out of the way, so as not to scratch the bike.

4. Inner diameter needs to be a standard for bike stems. Our old stems used 29.4mm ID it limited  modifications to the controls. The new ones use 28.6mm ID, so the top part can be removed. A 28.6mm tube of aluminum can be inserted, and a standard 1 1/8" bike stem can be attached. This will allow short or tall riders to customize the virtual top tube length. Makeing the bike super comfirtable.