By © Ralf Roletschek – Fahrradtechnik und Fotografie (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons
Johannes b. kerner
By © Ralf Roletschek – Fahrradtechnik und Fotografie (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons