what I use when you shove the stem up against a bike rack there's almost zero clearance, it's perfect. Plus you can wrap the cable through the back tire if you so desire.
SIGTUNA Bike locks - 16mm Heavy Duty Bicycle U Lock Combo with Square Steel U-Lock Shackle and 1800mm Woven Steel Double-loop Cable Chain plus Key-hole Cover and 2 High-Security Keys https://www.amazon.com/dp/B01MREL334/ref=cm_sw_r_cp_api_glt_fabc_CWJ8SG965XD9V7WW62SD?_encoding=UTF8&psc=1
What I use the shorter length makes a very tight fit around the stem and pole, highly recommended.
What I use best of both worlds, lock and cable for the rear tire.
This is what I use, it's perfect for the neck area right next to a bar.
I usually lock my segway outside. I use this u lock around the main column: https://smile.amazon.com/gp/product/B01MREL334/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1.
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I carry the u lock in a small backpack that fits it perfectly.