Bicycle Mechanics - Replacing A Non-Replaceable Derailleur Hanger
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I have a Kestrel 500SCi with a one-piece, non-replaceable derailleur hanger which snapped off suddenly as I was changing gears (not under a big load). I checked with Kestrel and was told they couldn't repair it. It would be a real shame to turn this frame into a single-speed and I can't spend the money to get an internal hub either.
Could I rivet on replaceable hanger with a similar profile onto the dropout? I'd probably need to rivet the hanger instead of using a bolt because there is little clearance between the inside face of the dropout and the cassette lockring. I would even consider using an adaptor claw except that the dropouts are horizontal. Thanks!!!
09-09-10, 12:55 PM
Have a Machine shop or a frame builder fabricate a overlaying hanger.
A Milling machine , like Bridgeport could, like a router in wood,
thin down the dropout to fit an existing replaceable hanger ,
Machine shop time is not cheap, unless your father or a family member has one..
Dremel hand tools is not going to give you a flat, machined to be that way, surface
that needs to be made for strength and shifting accuracy.
If you aren't budgeting even a hundred for even a IG hub I don't know ..
cheap kludge then eBay it , transfer the problem ..
Though if you convert it to a single speed with an Eno hub, you may be able to sell it , without too huge a loss..
Fixies are a hot market , maybe a Trustafarian with money to burn out there,
you never know..
There's just barely enough meat below the area where you'd need to clear the skewer to screw or rivet a new hanger fabricated to fit. The problem is that if you use a flat extension it'll offset the RD outboard 5-6mm more and the derailleur may jot have enough travel to reach the innermost sprocket.
If you're making a hanger from scratch make it with a "Z" bend offset so the lower section is back in the plane of the dropout. Or if modifying an existing hanger use two sections, the hanger section which replaces the broken part (you might even salvage it) and an adapter plate (possibly also a thinner one in the back) to go from the dropout to the lower extension. Whatever you do try to have a longer extension coming up to the dropout behind QR nut so to get some overlap distance and rigidity.
Be sure to file the existing section perfectly flat and in plane, because you don't want to be bending it too much as you square the hanger, and consider gluing and screwing the assembly for maximum strength.
Looking at what's left of the dropout you have enough to work with and with some care can end up with something every bit as good as new.
09-09-10, 03:17 PM
This is an aluminum frame? Is there some reason you can't tig weld a new hanger on? Some funky alloy?
It's a carbon fiber frame, although the dropouts appear to be aluminum. I was wondering if anyone has ever attempted to graft on a replaceable hanger onto the remnants of a non-replaceable hanger/dropout. I could go with an aluminum hanger, but, as fietsbob and FBinNY note, I will run into spacing issues since the hanger will be moved farther outboard. I have no problems giving up my lowest gear to make this work.
A steel hanger is thinner, but I can't weld steel to aluminum and hence my plan to use rivets. Also, since the hanger has already broken once, I am inclined not to weld a new hanger to the dropout in case it breaks again. In that event, I would simply grind off the rivet heads.
Thanks again for your responses and input.
09-09-10, 04:01 PM
Trouble with TIG welding aluminum in a composite frame is the heat transfer is fast..
. you cook the bonding between the CF and the aluminum to failure.
You can fabricate a steel hanger, and if you keep it to 2mm or so you shouldn't lose the innermost gear. Before going further, bolt the RD to something and see how much inboard travel is still available. In your shoes, I wouldn't shave anything off the existing dropout, because that's what your looking to protect at all costs. If you lose or fracture that, the next repair is vastly more complicated.
I suggest you work in two pieces, screwed together.
1- a hanger to replace the broken off part that lies in the same plane, as the original
2- a long, sender steel plate which if you use a decent spring grade can be as thin as .080 or 2mm, to run from the bottom of the new hanger, up behind the QR nut to near the top of the dropout. That'll give it good support and rigidity. Drill and tap the frame in two places, and the lower unit in one with the RD providing the second fastener.
It's a job that you can do yourself, with a power hand drill, a hand tap, a hacksaw (and/or jewelers saw or scroll saw), a purchased replacement hanger, or your broken hanger, and a piece of spring steel. If you want to go this route, I'll give you a piece of the material I used to make cone wrenches out of, and tell you how to heat treat it after you've prepared it.
BTW- however you repair it, make sure your repair is weaker than the dropout, otherwise the next incident will cost you the frame rather than the hanger.
If you decide it's beyond you, PM me and I'll refer you to a few shops or builders that can do the job for a reasonable price.
09-09-10, 05:32 PM
Check with Calfee. They repair carbon frames.
09-09-10, 05:59 PM
look at some of the older Cdale hangers from when the cantilever frame first came out. IIRC they metal 'Leafs' or ears that slipped over each side of the dropout then bolted into place perhaps you can modify one of those and your frame.
your not the original owner I take it? or did Kestral not offer a lifetime warranty
I can't belive that Kestrel can't fix it by replacing the entire plate. I've known of Trek to do this, for about $300.
.....your not the original owner I take it? or did Kestral not offer a lifetime warranty
Unless the bike is brand new, where one could blame the shop which set it up, this wouldn't normally be a warranty issue. RDs have been getting caught in spokes and breaking hangers or entire dropouts for decades, but it isn't a frame defect, just bad luck.
09-09-10, 06:05 PM
This might be the solution to your problem: http://www.derailleurhanger.com/
I have not searched their db, but they appear to have many varieties. A friend of mine used them several years back, and he's still riding that bike.
I would check out the derailer hangers web site http://derailleurhanger.com/allderailleurhangers.htm
and have a machine shop cut out the broken dropout into the shape of one of the hangers available off the site.
Alternatively, use #199, which is for emergency on the road repairs for broken hangers, or #301, which is usually found on cheap bikes.
09-09-10, 08:09 PM
One non-DIY fix is to contact Craig Calfee at Calfee Designs (www.calfeedesigns.com). His company has a well established repair service for carbon frames.
Edit: Whoops, I missed davidad's recommendation but, obviously, I concur.
Thanks, everyone, for your insight. FB, thanks so much for your kind offer for a piece of spring steel. At this time, I think I'll go for a standard replacement hanger. Bianchigirll, thanks for pointing out the Cannondale hangers; I found one which should fit over the width of my dropout. I think having a plate on both sides of the dropout should provide more strength and rigidity. My spin on this hanger failure is that I can now modify the dropout to accept a replaceable hanger in case the hanger fails again. Just wanted to see if anyone has tried this type of fix before and whether it ended up in utter failure.
I am not the original owner, but did contact Kestrel for help. They advised me that they couldn't fix it, but offered a "great deal" on a new frame. I also contacted Calfee and am awaiting a reply, but I'm sure it will be cost-prohibitive (for me) if they can fix it at all.
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