billyk
Guru
I've avoided getting a regular rack because I wouldn't use it all that much, it requires some kind of rack-bag or paniers, and meanwhile I'd be carrying around an ugly structure around on the back of my bike. So I built a minimal rack that weighs less than 1lb total and nearly disappears when not in use.
I started with a light foldable backpack (orange of course). This folds into one of its pockets (6x6x2 inches), lives under the seat and is unnoticeable until you need it. It's supposed to hold 20L, and I guess it would if you filled it with, say, rice. For me, it holds a smallish shopping trip.
Four parts needed construction (photos below):
* rack bed. That's the piece of white PVC, bent to snap on to the seat support bar. PVC bends easily by dipping in boiling water. A piece of velcro holds the bed onto the seat-back when not in use.
* bag cradle. This is a tan PVC pipe (for hot water pipes, quite strong), bent with a heat gun. The cradle slides onto the bed via a slot cut with a Dremel tool.
* clips to hold the cradle, drilled and cut from white polycarbonate. The cradle snaps firmly into these, but any bending stress is really held by the tight fit of the bed in the slot. The clips also hold the cradle out of the way when not in use.
* aluminum hook to hold the backpack from sliding off the seat.
Thus I have a backpack handy to carry stuff around, and can easily clip it onto the bike. A few shopping trips with about 15lb of random groceries, making tight low-speed turns as well as regular street riding, show that it is stable. I like that the weight is closer to the cog of the bike+me than it would be on a rack sticking out back.
I have a separate cold-bag, holding 4L, that straps onto the seat bracket and fits snugly between the seatpost and the seat. Both the pack and the cold-bag can go on the bike together.
I started with a light foldable backpack (orange of course). This folds into one of its pockets (6x6x2 inches), lives under the seat and is unnoticeable until you need it. It's supposed to hold 20L, and I guess it would if you filled it with, say, rice. For me, it holds a smallish shopping trip.
Four parts needed construction (photos below):
* rack bed. That's the piece of white PVC, bent to snap on to the seat support bar. PVC bends easily by dipping in boiling water. A piece of velcro holds the bed onto the seat-back when not in use.
* bag cradle. This is a tan PVC pipe (for hot water pipes, quite strong), bent with a heat gun. The cradle slides onto the bed via a slot cut with a Dremel tool.
* clips to hold the cradle, drilled and cut from white polycarbonate. The cradle snaps firmly into these, but any bending stress is really held by the tight fit of the bed in the slot. The clips also hold the cradle out of the way when not in use.
* aluminum hook to hold the backpack from sliding off the seat.
Thus I have a backpack handy to carry stuff around, and can easily clip it onto the bike. A few shopping trips with about 15lb of random groceries, making tight low-speed turns as well as regular street riding, show that it is stable. I like that the weight is closer to the cog of the bike+me than it would be on a rack sticking out back.
I have a separate cold-bag, holding 4L, that straps onto the seat bracket and fits snugly between the seatpost and the seat. Both the pack and the cold-bag can go on the bike together.
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