Sea Sucker 20mm Fork Mount If you’re riding a bike with a through axle on the front, you have two options for mounting to a Sea Sucker rack: use a Fork Up adapter, or use the new dedicated 15mm or 20mm fork mounts. These fork mounts are bolt on, meant for people who are always using their rack with their thru axle bike According to Sea Suckers MTB pro Macky Franklin: “ So much steadier than using the adaptor ” To attach, unbolt the existing fork mount (you’ll need an adjustable or 7/16″ wrench & a 5/32 hex wrench). Place the new fork mount in position & bolt on using the same hardware you just removed from the original fork mount Buy Sea Sucker Accessories from Chain Reaction Cycles, the World's Largest Online Bike Store.