RD hanger threads, anyone?
 

A few years ago someone posted in C&V that Campy's RD hanger threads were slightly different from those of Shimuntour. They could be forced to work but one shouldn't switch back and forth. (I know, Simplex hangers are completely different and incompatible with even the Simplex RD's they were designed to work with.)

Is there really a difference in the threads? The world is awash with wonderful old Suntour RD's and Campy dropouts. Do any of you folks mount Cyclones or similar on your High-talian bikes? Or non-High-talian bikes built with Campy DO's?

I'm just curious about build options.

Not true. All hangers (except simplex) are created equal.

Until fairly recently Campagnolo RDs used a 10mm x 26tpi thread as did their rear axles.

BTW -- While I believe that they changed to 10x1, I can't state that as an absolute fact. But, if they did, it would probably have been about 2001 when they introduced 10s and changed the RD geometry entirely.

And what did the rest of world use? That is the question.

What?

Did I leave off a smiley face again? Oh dang.

It's so close to true that it went unnoticed. :)

26tpi is very close to m10x1. With the total thickness of even an aluminum dropout, about 7 mm, there is rarely an issue. Bigger issue most of the time is a build up of paint in the threads.

Ok, here's what you can do. Get a candle and twist it into the aforementioned derailleur hanger enough to leave thread marks. Then you can count/compare 'til the cows come home, and tell us.:p

The poor man's (woman's) thread pitch gauge?

The rest of the world used 10mm x 1mm which would be 25.4tpi. Very close, but not quite the same. Over the short depth of the derailleur hanger, it works ok.

Thanks, everyone. A quick comparison of the threads on the end of a Suntour axle and a Cyclone hanger bolt shows them the same, but of course that's an imprecise comparison. I'm familiar enough with 26tpi vs.1mm to know that a Campy bearing cone will not even come close to fitting on a Suntour axle, nor the other way around. But then, cones and axles are made to pretty tight tolerances.

So it raises the possibility of using a nice Suntour on a Campy DO, which I think I suspect I'm sure, or at least pretty sure, people do all the time. Options are always good.

Just bolt the derailleur on and see if it works. If gets hung up a little bit, apply lots more force. Maybe use the biggest hammer you can lay your hands on? That's what I do.

Campagnolo forged dropouts are mild steel, so threading a 10 x 1 hanger bolt would slightly reform the threads.

It doesn't work so well with cones and axles because those parts are hardened steel and resist reforming.

one hanger variable i have not seen much discussed on the forum is the distance from the centre of the axle slot in the dropout to the center of the hanger hole/tab.

on campag and on the copyolo dropouts this dimension is about 26mm. on most asian hanger plates and some asian dropouts this dimension is about 32mm. some home builders get a surprise when they attempt to get their maeda touring mechs rated at 34t to handle that size cog when fitted to a campag dimension dropout as happened to member LucasT-603 on his allegro build -

http://www.bikeforums.net/classic-vi...storation.html

Shimano has a tech sheet on this and describes for road dropouts 26mm is approved, and then also shows 32mm as being ok, and standard on mtbs.
what seems to be just as significant (for indexing) dimension is the face to face dimension between the inside of the axle land and the derailleur mount face, 7 mm as I recall is the suggested max.
There is also a radial dimension tolerance for the stop.

The technical term is called THREAD PITCH ERROR.

In the case of Campagnolo 26 tpi (Threads Per Inch) versus ISO Standard 1.0mm Pitch, it's considered THREAD MISMATCH.

The 2 Pitches are so close that the differences over the 5mm to 7mm thread length of a dropout or claw hanger is insignificant.

ISO Standard Pitch 1mm = 0.0394”

Campagnolo Thread Pitch 26 tpi = 0.0385” = 0.98mm

Campy vs. ISO Pitches:

http://bikeforums.net/attachment.php...hmentid=494916


Basis Thread Terminology:

http://bikeforums.net/attachment.php...hmentid=494917


Hub axles are a different matter because cones are usually much longer and after about 6-7 turns. thread interference becomes significant.

0.02mm x 15mm (average cone length) = 0.3mm = 0.012"

(dropouts are 5mm to 7mm thick so only 5 to 7 turns)


Yes you can force fit metric cones onto Campy axles and vice versa but it should only be done as a last resort because it damages the axle threads.

Folks who do it all of the time need to put down their wrenches and use this Campagnolo tool #1 .... :eek:

http://bikeforums.net/attachment.php...hmentid=494918

The origin of the term "hammer mechanic" :roflmao2:


verktyg :50:

Chas.

I used to have the dropout hanger dimension (non) standards. There were at least 3 different length from the theorethical center of the axle to the center of the hanger bolt hole.

This allowed for the use of larger freewheel sprockets.

Suntour made 3 different undocumented versions of the original Cyclone rear derailleurs. They had a maximum capacity 24 or 26 teeth sprockets. One version was designed for 24 or 26T depending on the length on the hanger drop....

Discovered this through trial and error plus an old Suntour instruction sheet in Japanese!!!

verktyg :50:

Chas.

rep, verk, JDT, thanks for the technical explanation. FWIW, I have a rubber-coated BFH, technically known as a dead-weight mallet. It is a necessary tool for disassembling (and re-assembling) a GT6 transmission. I have used it for removing FW's, once for removing cranks, and once for loosening a BB lockring. But I have been reluctant to use it on bearing cones. :eek:

I think I will postpone that particular experience until it becomes absolutely necessary.

I generally keep my threads on hangers:

http://www.sidelinesinc.com/prod_img...ntsRack_SN.jpg

I love a good pun! Good one!