View Full Version : Front derailleur on bottom bracket spindle?
I seem to remember reading about a front derailleur mechanism that fixes on to the bottom bracket spindle somehow. I may have seen it on these forums, bit I'm not sure. Could anyone point me in the right direction?
Thanks.
I posted a link previously, I think it was of a pic at the Shimano site, of a Deore LX front derailer, e-type. Problem is these are designed for smallish mountain chainrings so are of limited use on a folder, if useful at all.
SesameCrunch
02-26-07, 07:07 AM
+1 What Jur said. Here's a picture ...
http://i39.photobucket.com/albums/e157/sesamecrunch/etype.gif
I wonder... if you're handy with tools, it may be possible to replace a road cage on the assembly. Verical spacing will be critical.
SesameCrunch
02-26-07, 05:20 PM
I wonder... if you're handy with tools, it may be possible to replace a road cage on the assembly. Verical spacing will be critical.
I don't think it would be worth the time. The bracket does not result in a very solid installation. I have one on a mtb right now. POS, in my opinion. I think they're designed for situations where the seat tube is not round.
I don't think it would be worth the time. The bracket does not result in a very solid installation. I have one on a mtb right now. POS, in my opinion. I think they're designed for situations where the seat tube is not round.
Rat farts. Jur, can you please help me out. I really want to put a front derailleur on the Swift. The best solution I can come up with is the following: hose clamp ($1.00US) at the hardware store. Then somehow weld it to a 34.9mm braze-on clamp. I have a Shimano 105 Braze-on FD now and have dremmeled a Nashbar 34.9mm clamp (http://www.nashbar.com/profile.cfm?category=&subcategory=&brand=&sku=2189&storetype=&estoreid=&pagename=Show%20All%20Products) to a stub that ideally I would like welded to the hose clamp.
The last issue is the chain angle. The join between the hose clamp and braze-on adapter would not be perpendicular, rather at a roughly 110 degree angle to take into account the funny slope.
Let me know if you have any success. The reason for my original post was that I want to fit a FD to my Giant Halfway RS. I've given up on the BB derailleur as it only seems to accommodate 44-tooth chainrings. I have a 54 and would like to add a 36. Unfortunately, the Halfway doesn't have anything resembling a tube to which I can fix a FD.
I am also looking at this issue, my wife wants one on her Dahon Yeah, it has an even bigger seat tube than the Swift, plus it is at an odd angle, plus it does not enter the BB shell so there is a fore-aft position issue. So lots of issues.
The idea I am toying with is to get a 34.9mm clamp adapter for a braze-on FD, such as the nashbar one you linked to, and dremel the thick portion (where the screw goes through) to widen the radius a bit. The thinner portion, just force it, perhaps around something else of the same diameter as the Swift seat tube, so it adopts the proper diameter. I know they say don't bend aluminium, but this is not a seat tube or such critical part, so if it breaks off after 1,000 shifts who cares. The unthreaded screw hole also will need to be ovalised a bit since the angle will be different.
An alternative idea, probably the one I will probably do to SWMBO's bike, is to just use a 2-3mm ali or s/s strip, bend it around the tube in a P-shape, put a screw through to clamp it. The leg of the P would then be modded to accept the braze-on derailer.
Hmmm, looking at the Nashbar part reveals another possibility:
An ordinary hose clamp can pass through the oval hole where the derailer mounting screw goes through. To accept the strap of the hose clamp, dremel a shallow wide groove so it doesn't interfere with the FD. Also dremel the back of the clamp bit where it rests against the seat tube so the radius matches up.
Hmmm, looking at the Nashbar part reveals another possibility:
An ordinary hose clamp can pass through the oval hole where the derailer mounting screw goes through. To accept the strap of the hose clamp, dremel a shallow wide groove so it doesn't interfere with the FD. Also dremel the back of the clamp bit where it rests against the seat tube so the radius matches up.
Yes, thank you. That looks like a definite possibility. Just eyeballed it and it just might work. I now need to get the next hose clamp size larger since this will be going around it.
The next question is how best to cable route for a bottom pull front derailleur.
I've heard a rumor that the Nobel Committee is seriously considering a prize for anybody who can come up with an easy and practical front derailleur solution for the Swift.
Speedo
Andreasaway
05-14-07, 09:58 PM
If you got to Nova Cycle Suppies website, they have a section with small parts, I suggest you buy a front deraileur mount, maybe the one for riveting in place, but instead shape it to fit your seat tube. Then rough up your paint a little, rough up the mount and epoxy in place. If you felt brave enough to go down to the bare aluminum, you could get a very permanent solution. Keep in mind, the first aluminum frames were glued together, and some lasted quite well. The reason I would recommend the one with rivet holes, is I think they might grip a bit better.
Just a question (one I've had myself, due to my KHS Flite 700 seat tube), "What about taking a piece of 3/8" to 1/2" flat aluminum stock and cutting out your own odd shaped braze-on adapter clamp?" You would have to drill and tap it, but spacing and so on would be at your discretion. Since a cross section of my seat tube is roughly "arrowhead" shaped, this is one of my only options for a braze-on adapter.
maunakea
06-18-07, 11:54 AM
That's called "machinist's work" and is simple, fast, and maybe reasonably priced if you know a machinist. The S&S BTCs arose because the owner of S&S rides tandems and wanted to put one in a suitcase for travel. S&S does have a few machinists at hand, including the owner.
Just a question (one I've had myself, due to my KHS Flite 700 seat tube), "What about taking a piece of 3/8" to 1/2" flat aluminum stock and cutting out your own odd shaped braze-on adapter clamp?" You would have to drill and tap it, but spacing and so on would be at your discretion. Since a cross section of my seat tube is roughly "arrowhead" shaped, this is one of my only options for a braze-on adapter.
This is what I will probably do. I don't foresee complicated work beyond handling a file; even taps are not necessary, although that would be more elegant. Maybe this month. I have to get hold of a derailer first.
I bought an aluminum derailler bracket from Nova and drilled 4 holes in it, JB Welded it and added 4 3/16" pop rivets. I picked up the 2004 KHS frame for 30 bucks since the front derailleur tab was broken. I just bought a '07 Raleigh Super Course, so I stripped everything off my old steel Nishiki International (1990-ish) and am building up a low buck road bike for my wife to try. She rides mountain bikes with me on the road and some local rail trails and I've been trying to get her on a road bike so she can cover more ground. Tomorrow the JB Weld will be set and maybe I can get her to give it a try.
...Or you can just do it the easy way...
http://sheldonbrown.com/harris/schlumpf.html
JB Weld and rivets held up like a champ and the wife is on her way to feeling the road bike bug. Next is a set of Sora brifters so we can ditch the Suntour downtube shifters and she should be set for now.
maunakea
06-25-07, 01:06 AM
SuperC, congrats. JB Weld +1.
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