I’ve got a future project that needs the seatstays bent. Would something like this be possible?
Like usual, not speaking from experience here, but if you poke around Instagram there’s a few builders using pretty economical setups to bend seat stays. A 4" CLR is probably a bit tight, but if you can make a CLR somewhere in the ballpark of 10" work for your design you can get by with pretty basic tools.
Feather Cycles uses an old 700c rim:
Signal Cycles used a wood v-groove die:
Joel of Clockwork has a fancy looking bender, but the way it acts on the tube is very similar to a fork blade bender (v-groove die, lever arm that is eccentric to the CLR):
Joel’s dies are labelled as 10" CLR, so that’s where I got that value from. No idea what the minimum CLR is for a set up like this, but a fancy bender isn’t really required for SS’s unless you’re trying to get tight bends.
Thanks for posting that inspiration @photon ! crazy what you can do with a little creativity.
@Spencermon this has been the coolest bender mod I have seen:
@Seriousbicycles added a follow bar and a better “clamp” system
We have the same bender to do curved bridges. With thinner wall tubing (.035) you sometimes get some ripple artifacts on the inside of the bend. I think a follow-bar will mitigate that problem.
Pretty much everyone is using straight gauge rear ends! Its the “pro” thing to do!
This bender is for 1/2" EMT (electrical metallic tubing, or at the hardware store it’s every man’s tubing). The nominal ID is 1/2", actually .62" and the OD is .71". That means your 1/2" tubing that’s actually 1/2" OD will fit loosely in the groove. If you already have the bender, and some spare tube to play with, give it a try. Otherwise, some of the other suggestions here will probably give you better results.
I was actually wondering if that was the case. I’m glad you spoke up. I didn’t have my calipers with me to measure so I didn’t buy it. I could go back and get it. It’s only $12. I wonder if a thick piece of leather would be ok to take up the space? I’ve had some ideas about making a v groove in a piece of wood that sits on the ground and acts like a follow bar. I might buy it because that’d be the cheapest experiment and if it works, great. If not, oh well. It’s only $12.
Hard to go wrong for 12 bucks. If it doesn’t work, it’s the start of a new career as an electrician.
I bought it. Then I tested it. I only had a scrap piece of 1/2” x 1/16” tube to test, so this might not work for thinner walls, but it worked just fine for this tube. I used a broom handle and then placed the tube on the floor of a wooden deck so it sat in a little groove. Then I stood on the little foot position on the tool and pulled on the broom handle. I’m still going to make a leather piece to take up some gap and maybe increase accuracy.
Those ridgid bender works fine.
Some examples from a rack , and seatstays
Really into those seat stays. With the radius matched bridge it almost looks as though they were bent from a single tube, wishbone style.
Thanks
Have to say that it was my intend, but it happened with luck.
The bridge just fell on the spot
4130 is pretty forgiving if you’re bending on a larger radius. I bend seat stays using a simple plywood mandrel based on instructions that came with my Henry James fixture for a plywood fork blade bender. It’s one of the most useful DIY tools in my shop. 10" clr, if I remember correctly. Just fix one end and off you go. I put some marks on it to help match two tubes to the same bend. No need for a follow bar or anything fancy. I have one of the Ridgid benders for tighter radius bends, but rarely use it.
