I've gotten a couple of emails since i posted this project from people that were concerned about damaging their bike rims. There are 2 potential concerns:
(1) Using a metal hook could scrape up your fancy aluminum rim. As shown in the project, I recommend covering your hooks in vinyl tubing or innertube wrap, this will create a thick and tough rubberized surface to protect the rim
(2) Too much leverage on the hook will deform the rim itself. This is not possible if you use metal hooks that extend at least 4" from the wall, like in all the project photos. The only way you could risk deformation is by using a much smaller metal hook, however a hook small enough to deform your rim would also make hooking the bike on and off the wall very difficult in the first place.
Here's the math on this just in case you are not convinced:
(2a) how strong is your rim? very strong! it is designed to handle at least a 200 lbs person riding over the edge of a curb or pothole. at very slow riding speed you could estimate that the contact area of a pothole corner is similar to the hook we are using. fortunately, when you bike is hanging from the rack it is only supporting itself (25 lbs), and not 200 lbs. and your rim can handle that pothole at speed too...
(2b) how much leverage do we have? as shown in the photo, the weight of the bike "X" is pulling down at the hub. this sets up a torque around point A. if i recall my high school physics properly this means:
- torque = force x distance
- since there is no motion, there must be equal and opposite torques applied around A
So, the force at the hook Y = (L1 / L2) * X
(2c) the hook point B is about 5" from the wall. this sets the distance L2 nearly as long as L1. that means the force at Y is only slightly more than the weight of the bike. no chance of deforming your rim!
(2d) lets say you used a really small hook that only extended 2" from the wall and hooked at point C. first off, it would be fairly tricky to even get your bike on and off this hook. but, you do get a leverage ratio of perhaps 5:1. even that is not likely to be able to deform the rim from the bike weight alone. perhaps then your buddy is drinking some beers while you are cleaning up from a long ride, and he stumbles, flails about and catches his entire drunken weight on the hanging bike! now you've got 200 lbs at a 5:1 leverage. based on some unrelated experience trying to hang a large sculpture from my ceiling, if you used the same 1/4" steel hooks that i did you still won't bend your rims, instead the hook is going to un-bend until the bike unhooks itself and falls off. if you did happen to use some industrial grade hooks here, and they don't rip out of the wall - then perhaps your rim is toast.