http://www.sphyke.com/products/wheel-anti-theft-locks/a-front-wheel-locks/front-wheel-skewer/
non li ho mai provati, sembrano (troppo?) complessi ma sensati
http://www.amazon.co.uk/Anti-Theft-Quick-Release-Skewers-3-Piece/dp/B004JMZLXQ
http://road.cc/content/review/1978-pinhead-security-four-pack
questo mi sembra il più intelligente