Help needed

hallie-lk

I was wondering does anyone know how to install a rear derailleur on a front fork of a bike?, somehow drill some holes around the dropout or something.

or would even welding work?

I would like to do what this guy did... just for a bit of fun

http://www.motherearthnews.com/top_...cumbent_Bicycle

if not, i will just settle for a single speed.

blazingpedals

You'd have to spread the fork to fit a freehub - 126mm for 7 speed, 130 for 8/9 speed. You can get a piece that goes in the axle slot and will attach a derailleur, but I don't know if it'll fit in a front dropout. You may have to cut out the existing dropouts and weld some rear drops to the fork tips.

Bentriderlon

Yeah, spreading the fork is easy. Stand on one blade and pull up on the other. Easy, don't pull too much. Then flip it over and do the same on the other side (you don't want it unbalanced). Alternatively, if you are built like a gorilla, you can grasp both fork ends and spread them apart. Otherwise, repeat 'till the width is adequate. This is called "coldsetting" and should be ok with the sort of steel most cheap forks are made of.

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"If something is worth doing, it's worth doing poorly."

"My other car's a Bianchi!"

hallie-lk

Is there any way of knowing whether a frame is made of steel or aluminum, or do you just have to know really?
Would it be easier to spread the rear triangle and weld that on the outside?
And sorry i don't quite understand with the axle slot part?

1. cold-set the forks or rear triangle, which ever is easier.
2. Axle slot or weld.
3. attach derailluer. + cabling etc
4. cut chain and attach around crank and dearailluer.
5. insert wheel, then adjust cables

Does that sounds about right.

Thanks for the help Bentriderlon and blazingpedals.

Bentriderlon

Without knowing what sort of bike it is it is hard to say. If it is an older cheap frame, it will likely be steel. Steel is much heavier and so, if the frame is a heavy sucker it is probably steel. Also, steel is a ferris metal and a magnet should stick to it. If it's aluminum, the magnet will fall off as soon as you let go of it.

I think it would be easier to spread the fork.

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"If something is worth doing, it's worth doing poorly."

"My other car's a Bianchi!"

aa9t8

aluminium welds are much larger than steel welds.
if you compare steel welds side by side to aluminium welds you will be able to see the difference.

hallie-lk

so would i bend the front fork then attach the rear derailluer to the OUTside of the the fork and then put the rear wheel, rear triangle and cassette on the inside of the fork?

i reckon doing above would work better than what the guys done in the article more secure. especially if i weld it, and then i could just weld the seat tube to the top of the fork above the wheel, since im am fairly short this should work, if it doesn't fit i can always bend that too and add tube. :P

so it all basically looks like the rear triangle on a normal bike.

Cause the guy in the article looks like he put the rear triangle on the outside of the fork but has the single speed cassette and wheel on the inside.

Sorry about the never ending posts,
thanks for the help,
Nick.

chuckchunder

Have a look at www.cruzbike.com , this may give you ideas about an alternative way to do it using brackets welded to the rear triangle and bolted to the front drop outs.....

cheers
chuck

Bentriderlon

I had a look at the Cruzbike video and I think it would be a bit uncomfortable to ride. The riders all looked cramped on these modified mtn bikes. The bars seemed to be set too high for comfort. Any lower and their knees would be striking the bar. The homebrew in the Mother Earth News article shared that appearance of "cramp-ness." I wonder if that is characteristic of minimal home builds and other modifications made to df bikes. I think I'd take a pass and shop for a proper swb bent. I did like the seat, however. The Evox lacks a seat tube and so, there is no place to put a seat pillar. There is a sort of seat post stub which the saddle mounts on. Also, the Evox 'main tube' is considerably larger in diameter than the top tube on a df bike. Now, if I could find a way around these problem areas and find a way of mounting it on my Evox, I might be interested...

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"If something is worth doing, it's worth doing poorly."

"My other car's a Bianchi!"

hallie-lk

thanks for the site, it gives me an idea, having the fork a bit seperate from the derailleur.

ill try and get some plans done, i probably will try to get it done b4 the end of the year, ill have some draft plans up soon, umm thanks for the help.

hallie-lk

i think i will do what cruz bike has done, by welding some kind of metal with a hole through it to hold the front fork with a nut/bolt. And have the cassette, wheel and rear derailluer further forward. It would mean I dont have to disassemble anything (ie. chain, dearailluer) and i will probably have the forks spread so they are on the outside. of the nut/bolt bracket.

Instead of having the 'seat tube' going into the stem/handles, probably welding to the fork might be better.

And cruz bikes seat doesn't seem too bad... bit pricey though, might try to make something. would anyone have any ideas on that? materials etc.

I've never welded in my life, should i get someone to do it for me, or is it something you can learn pretty easy?