Inertial

So I bought a RD 6500 Ultegra for a steal on ebay to upgrade my old steel bike to modern components. However, I found out that the RD doesn't bolt onto my frame hanger.

I'm pretty sure modern components are metrically dimensioned, and the bolt diameter appears to be 3/8 or about 9.5mm, which I had bored to on the existing hole on the frame hanger. However, now I can't figure out the threading on the mounting bolt. Does anyone have any information? Or if there are alternative solutions... I wouldn't mind buying a frame hanger to accept modern RD's but there don't seem to be any on the web.

T-Mar

With the exception of Campagnolo, hanger threads are 10mm x 1.0mm.

davester

Here is the information you need. Do you have a french bike perhaps?

Derailleur Hangers Demystified - Red Clover Components

Homebrew01

Really ?? I thought all "modern" hangers and derailleurs were 10 x 1

T-Mar

The OP is trying to install a relatively modern derailleur on an "old steel bicycle". This raises the possibility of the frame having a hanger with 10mm x 26TPI threading as used by Campagnolo and other Italian dropout manufacturers. Installing the subject derailleur into one of these dropouts would be a Class B fit. It will work but the slightly different pitch and thread form will require higher installation torque to reform the more malleable hanger threads. Alternately, the existing hanger threads may be damaged. I'm assuming it's not a non-threaded Simplex hanger, in which case the problem should be readily evident. Knowing the more details about the frame, particularly the dropout brand, would be beneficial in determining the root cause of the problem.

dddd

The OP said that they had the hole bored already, which led me to believe that it had to be a Simplex hanger.

A threaded "thin" nut of the sort used to repair stripped hanger threads would seem to be needed at this point, as finding a tap for M10x1mm threaded holes would likely be a costly chore.
https://www.sjscycles.co.uk/accessor...r-mech-hanger/

Campagnolo derailers of current production are finally all being made to the M10x1mm standard. I don't know exactly when this change occurred, but I have seen this in writing in Campagnolo's literature. I never had any problem installing the old ones to a standard English or Japanese dropout hanger however, because the threaded hole was too short to cause any serious binding of the slightly mis-matched thread pitch.

T-Mar

10mm x 1mm taps are relatively inexpensive and readily available. However, the tap drill size is 8.8mm (11/32'), so if it's already been bored to 9.5mm there will be insufficient thread material and the dropout hanger saver insert is the best resort.

dedhed

I could get a tap in 2 days locally for about $8 or less

https://www.grainger.com/product/WES...ytics=altItems

https://www.fastenal.com/products/details/0323377

dddd

Good to know, dedhed.


So a Simplex hanger can easily be tapped directly for standard derailers, and with the ability to go back to using the original Simplex mech with it's retaining nut.
A tension step still needs to be carved into the bottom of a Simplex hanger, except where a derailer's (as with early Shimano) tensioning plate contacts the front edge of the hanger.

Inertial

The machine shop at my school doesnt have such a 10mmx1mm tap, and according to the other user, I bored past the tap diameter.

So my next solution is this:
Well seems like I am too new of a user so I cant post links. But it is a "SunRace" branded frame hanger that claims to be shimano compatible and has the catch at the 6 o'clock position.

Now hopefully this is modern 'shimano' compatible.

The only thing I see I would have problems with is:

1. I am not too familiar with bike components, but the B-Screw adjustment on the RD 6500, which is a separate piece that is held into the RD bolt with a U-lock ring, looks to be integrated with the rear derailleur. I say this because there is a catch on the rear derailleur that interacts with the B-screw adjustment. Maybe I am wrong and this is how they are supposed to function, but I wonder how the B-screw would interact with the catch on the ebay frame hanger, if at all, or if I would have to cut the catch on the frame hanger.

2. I did not receive a nut to secure the rear derailleur bolt. My google skills seem to be a bit off for finding things like these, so can anyone point me to a product page for these nuts? They are an odd-size and I can't find them in any hardware stores.