hatrabbit

I just won a rear rack on Ebay, an old school bare aluminum one. The front struts are going to need a dramatic bend to fit my bike. I think I can get a tubing bender in there to do the offsets but I'm wondering, can this alloy just bend cold without any issues?

Andrew R Stewart 

Well the educated would ask "what's the alloy and heat treatment (if any)?". Then ask about bend radius WRT rod diameter. But the time tested way to deal with this is to bend it and see what happens.

But the first aspect I look at is whether the rack will sit "right" on the bike if the seat stay struts are kept the OEM length. This is a biggie if the struts are not length adjustable. "Right" is usually thought to be having the deck parallel to the ground, where the rod's turn up at the front sits WRT the seat and your butt also comes into play real quick. These fixed length seat stay strut racks these days are pretty much only found on new bikes currently, as how can the rack manufacturer know what your bike's fit needs are.

A smooth and gentle curve to the strut is best. If your bending has a corner or crease it's compromised to some degree. Also if the bend involves a weld or stamping. With no other data I would not expect this rack to fit your bike in a way that I would think best. Andy.

100bikes

Why not buy a front specific rack?

berner

That rack looks almost like my rear rack. In any case, I had to use a separate bracket to clear the rear brake cable. You might stop in your LBS to see what they might have in stock.

fietsbob

How much does it have to bend ? ' a dramatic bend ' is imprecise .. measure state measured distance..

FiftySix

I'm thinking I'd try and support that weld near the bottom with some wood and a strong c-clamp while attempting the bend. Maybe even use a vise, but that would probably interfere with a tubing bender being used.

jimc101

I think the OP has just given a confusing title (maybe he can clarify), thinking what he meant by 'rack front stays' is the integrated rack stays, and where the attach to the frame, not as for fitting the fack to the front of the bike.

For the OP, would see no issues in cold setting, I have done this with a few Tubus racks and have had no issues with them since, have put over 40,000 km on 3 different bike with Tubus tacks and cod set stays (although Tubus have separate stays, so if you mess up, you can just buy replacements) and when I bent mine, I just used a hammer & and a block of wood (really should look into a tube bender for any future bike + rack builds)

dsbrantjr

Don't feel compelled to use the provided hardware as-is, you might consider making your own using things like P-clamps, aluminum bar or angle plumber's hanger tape, or other stuff.
Here's an example, it was made from a handlebar-mounted bottle cage adapter and some aluminum angle. I made it with hand tools and a Dremel sanding wheel, no machine tools needed. There is not much stress on those front struts except when accelerating or braking, most of the weight is taken by the vertical members

dedhed

Define "dramatic".

If I was doing this I would clamp the weld as suggested and slip a piece of pipe just large enough to go over and use that to do the bend. I don't know that you'll bend a solid (which that is) with a hand tubing bender.
You'll likely have to go L/R as well as U/D. If it goes without breaking you're good. If it cracks you're likely OK as well as the weight is borne by the other stays and the fronts just stabilize it. f you have to shorten them cut off, flatten withh a hammer and "anvil" and redrill.
Back in the day these were designed for a specific frame size.

rumrunn6

I guess you didn't realize it wouldn't fit your bike when you bought it? maybe, instead of bending this rack you can just fabricate an adapter. hardware store sell lots of bar stock from various materials that can be bent, cut & drilled. or just buy a rack that fits & sell this one? but the industry sells all kinds of pre-made adapters for all sorts of applications. maybe some of these will give you some ideas?

https://www.ebay.com/p/Monostay-Bike...ter/1403952286

https://www.hermosacyclery.com/sunli...rear-rack.html

https://www.ebay.com/itm/Sunlite-Rea...-/361999995548

https://www.ebay.com/p/Hot-Bike-Rear...r-HF/723908986

Jasongrace313

Any pictures of the finished product? I found a front low rider rack and rear. No idea what they came off of, but they were less than half of just the front rack I was considering so why not give it a shot?



Well, I thought about going inside because it would’ve been less of a bend, but as free asking people told me to go outside. I just bent it by hand and popped a bolt in. I’m going to swap out the hardware but it’s useable I believe.

oldbobcat

Generally, the alloy used for racks is considerably milder than what's used for frames and other applications that require high strength to weight (like ski poles). Work slowly and aim for large-radius bends.

ClydeClydeson

I would go for it, with caveat above - try for large radius bends. Also be careful you don't overshoot the correct amount of bend because bending back will weaken it more than the first bend.

The other thing to remember is that the front stays are not load bearing - they are only to provide stability. Bikes don't accelerate or decelerate fast enough that there would be significant momentum pushing towards or away from the seat stays. My justification for this hypothesis is that I have witnessed many basic P-clamps successfully used to mount upper rack stays to the seatstays, but also seen many P-clamps used to mount the lower legs near the dropouts that broke over time.