5/27/15 8:41 PM

Has anyone ever come across a device that bolts to the tab on the frame and to which you can attach the derailleur in order to have it mounted lower than the tab on the frame will allow? I want to fit a crankset with a 44t large chainring to a BH Quartz frame that I bought my wife, and the derailleur needs to be about an inch lower than the lowest adjustment that fitting to the tab allows. In the past I've got around this problem by fitting a band-on clamp below the tab on the frame, but the seat tube on this frame isn't round below the tab, so I can't do that.

I guess if I have to, I can fashion my own adapter from a piece of stainless steel strap, but if such a device already exists I'd rather just buy it.

5/27/15 9:24 PM

Just build one, she loves it when you do stuff like that.

5/28/15 8:07 PM

To lower it a few mm, the old rat-tail file works but to lower it an inch (25 mm) you are going to need to find or make an adapter. I've never seen a commercial one.

5/28/15 8:29 PM

??

http://www.bike24.com/p2125696.html

Or use a Dahon or other folding bike DR mount that clamps on and comes up from below for a normal braze on. Or use an E Type Shimano MTN DR ??

http://www.thorusa.com/accessories/special.htm



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http://www.ebay.com/itm/Aluminium-Alloy-Braze-On-Front-Derailleur-Clamp-Adapter-For-Folding-Bike-/221305680916


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e type

<img src="http://www.universalcycles.com/images//products/large/25197.jpg" width=320>

5/30/15 4:16 PM

Thanks. After a bit of searching I ordered a couple of replacement front derailleur frame plates, and I'll chop the side of them off and fashion something to do the job. I also ordered a slightly older model SRAM front derailleur, as I found that the latest braze-on models only have a single mounting hole in the middle of the mounting tab, whereas the older models have two alternative holes top and bottom, giving a greater range of mounting height.

6/13/15 11:03 PM

Well, I got impatient waiting for the FD I'd ordered to arrive from Taiwan, so I found a used Ultegra braze-on FD in one of my parts bins, disassembled it (easily done as the top two pivot points are held in place by allen-headed bolts), and drilled and tapped an additional hole at the top of the mount. That's brought the outer derialleur cage down to about 3mm above the large chainring, and that seems close enough for the front changing to work properly: