Some guys get really into their rig for mountain climb races. Since I have no delusions of winning Mt. Washington this year it didn’t make sense for me to spend a day moving my entire Shimano XP mountain bike drivetrain over to my road bike, nor to spend a boatload of money buying a new crankset/cogset/etc.
Much like a skydiver doesn’t go jumping without his parachute, I could not send myself off to attack the mountain with a 53-39 crankset.
So I started hunting for the cheapest way to add some low hill-climbing gearing to my bike, and to my surprise, found everything I needed in our apartment.
My wife has a bike with a similar (and perfectly maintained, of course) drivetrain: 10 speed Shimano 105 (vs my 10 speed Shimano Dura Ace). The key difference being hers has an FSA triple crankset which I discovered is compatible with my Chris King Bottom Bracket. Done deal.
Next challenge was to work out a cadence sensor. While I *could* port the one over from my crankset, it would be a pain to move due to the double-sided tape and zip-tie mess. Additionally, the gossamer cranks sit a little further away from my frame so I’d have to find something else.
After experimenting with three different magnets I settled on a stack of three plain refrigerator magnets, affixed using a roll of gaffer tape. Gaffer tape, by the way, is one of the greatest things ever. Technically designed for movie sets and the like to temporarily hold cables to the floor/walls/whatever, it’s good for so much more. It’s a cloth based tape that has some stretch so that it can bend around objects that are not perfectly flat. It has a fairly strong stick like a duct tape, and is torn along the x or y axis with just a pinch and pull. You should get a roll for yourself. Now.
So with all of the parts in place all I had to do was make a few turns to the front derailleur to adjust it to the new bailout gear and we’re set to go.
Will post an update some time after the race to put the stamp of “worked” on this method in the case that you find yourself in a similar situation where you need to climb one of the tallest mountains in your region and don’t have the budget or time to switch drivetrains.