Calling all people who love to design frames or have knowledge of kinematics/engineering. I have a particular new interest that has been curious about ever since I bought my first steel hardtail a month ago. Purchased a used Chromag Stylus from a gentleman and really like it. However I am wondering, could I turn the steel hardtail frame into a full suspension bike of my liking?
I would like to use a Chromage stylus frame. Removing the rear triangle and mounting a horizontal trunnion shock to the bike via a simple single pivot designed frame. The bike would ideally be 140mm of travel with a mulleted 29er 160mm fork in the front. Somehow landing it near 64° HTA.
My only question is, how should I approach this to design it. Software recommendations for the pivot and remeasuring the tubes to work. In theory this should be able to work. But Ive never done something like this and I want to try.
As well, for a pivot, I was thinking of mounting a bottom bracket for a main pivot like the creator of the BTCHN Bikes Jerk frame.
Would love all recommendations or warnings. Thank you!
Can you tig or braze thin wall tubing? That's your first hurdle to figure out before software. Next hurdle is fixturing. You need to hold the existing frame and new bits in place to weld.
Bottom bracket isn't the right option as it would then require you to turn up a unique axle. Use a 44mm headtube then you can use the steer tube from an old fork for your pivot axle.
To do it all you'll need an accurate 3d cad model of the frame. Fusion360 is frr for home use, model up the frame, figure out if you can fit your main pivot, and shock mounts in....and giv'er.
Having had a few primers, rootdowns and a samurai and now a Darco the main traingle is quite different to have the pivots.
Maybe if you wait a few months a chromag fs frame will be around with the travel you want.
I do not have experience personally, but a good friend of mine is a professionaly welder and hes confident he could do welds that a frame would require.
The rest sounds pretty straight forward. I appreciate the tips.
Ask your friend if he has experience on 0.35" 4130?
In a decade of frame building as a hobby and many years reading frame building forum stuff online before that I have seen 20-30 people make a post like you s and say a friend is a welder that can do it...and never seen a posted frame.
Place an order to Aircraft Spruce for some length of 4130 in 0.35" for your buddy to practice on before they blow holes in your frame. Bike tubing is paper thin compared to what most welders are dialed in on and it takes some time to adjust.
+1 for Aircraft Spruce! They offer great seamless chromoly. I built a frame around a second gen Santa Cruz Bullit swing arm and the BB pivot is a super easy and bullit proof option for the main pivot. Mine's a DH bike with 91/2" rear travel and a 1 3/4" 0.49 down tube. I say dive in head first and make it happen!
Awesome! How did you spec the main pivot bolt/axel? Or did you make your own?
Any tips on aligning jigging the frame?
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