Velocivixen

I purchased a 1st generation Suntour Cyclone rear derailleur from a co-op in Portland for $10. Other than a little grease it was in great condition. It was, of course, missing the cable pinch bolt. The bike shop cobbled together a m5 allen bolt and some washers & a nut on the back that would certainly "pinch" the cable in place, but didn't look great. It was also missing the b limit screw, which I took off a "parts" Suntour derailleur.

I scoured the internet along with this forum and found that Suntour only used this particular pinch bolt design on two of it's derailleurs, thus they're hard to find. They apparently get stripped and that's what necessitates replacement. I didn't see any specific instruction on how to make a replacement so I decided to post what I did.

Here is the front view of the tab. The pinch bolt inserts from the rear, to the front where it's held by an "acorn" nut.
!st Gen. Cyclone Rear Derailleur by velocivixen, on Flickr

Here is the rear of that tab. Notice the trough which ends on a "lip" then the metal dips to the circular tab. The shift cable exits the derailleur via that trough, passes through a hole in the pinch bolt, which is then secured via the acorn nut on the front.
Cable trough rear by velocivixen, on Flickr

Here is the straddle cable hanger nut/bolt from an old Dia Compe cantilever brake setup. The original acorn nut on the Suntour Cyclone was 8mm, and the straddle cable nut is 9mm, so it's a little bigger but looks ok. We will use this acorn nut and the accompanying pinch bolt from the back side to modify.


Eye bolt by velocivixen, on Flickr

Here is the rear of the straddle cable hanger. Notice where the cable passes through the bolt. You can't see the hole because it's under the head of the bolt. We will file a "flat" on one side of the head of this bolt, so that it will seat properly on the rear of the tab on the derailleur.


Bolt Holding Cable by velocivixen, on Flickr

I don't have any big grinding wheels or tools, but I do own a Dremel with various attachments. I used this attachment and it worked well.

Dremel Grinding Attachment by velocivixen, on Flickr

The pinch bolt must be situated through the rear of the derailleur tab coming forward (acorn nut will be on the front of the derailleur). The hole, which traverses the bolt must align with that cable trough. The cable will come through the trough, through the hole in the nut and will be "pinched" down when you tighten the acorn nut on the front. See here how I've ground down a flat spot on the head of the bolt. It now fits down against that "lip" I illustrated earlier. Original bolt on the table and modified bolt in the tab of the derailleur (back side).



Finished bolt head in derailleur by velocivixen, on Flickr

A couple more angles from the back side of the tab on the derailleur. Notice how that newly formed "flat" allows the head of the bolt to sit snugly against the lip by the cable trough.

NOTE: I had to cut about 3-4 mm off the end of the bolt. I used a metal cutting wheel attachment on the Dremel. It took a bit to get the acorn nut to want to thread onto the bolt, but I worked at it and it finally worked out.


Side of bolt head ground down by velocivixen, on Flickr
View Suntour Cyclone 1st Gen by velocivixen, on Flickr


Underneath the head of the original pinch bolt there are "flats" on the sides where the holes are. It's the other sides of the bolt, perpendicular to the holes, which are a little wider and I focused my grinding on those two sides. I polished the acorn nut and here's what it looks like on the front of the derailleur.


Acorn nut front of derailleur. by velocivixen, on Flickr

Here's what the finished product looks like from the side. I may go to the hardware store tomorrow and see about finding an acorn nut that's 8mm that will fit the threads.


IMG_5084 by velocivixen, on Flickr

I inserted a cable in there and tightened it up just to see if the pinch bolt would really hold a cable and it did great. I hope this tutorial with photos was helpful. When you think about it, it really is quite simple and makes sense. Just use some creativity and don't be afraid to try something "outside the box".

Cheers.

hairnet

Yeah, that's what I did for a couple of mine.



That's one clean derailleur. How did you get it so spotless?

verktyg 

vv, that's what I was going to recommend too. Looks like you have a handle on it. Great job.

verktyg

Velocivixen

I use a 2.5 liter ultrasonic cleaner with water, Dawn dish detergent and a splash of citrus degreaser. I have a supply of tiny brushes and Q-tips.
@verktyg - I figured that a bunch of folks did this on their own. I know I've come up with some creative solutions, but never took the time to post. I just wanted future cyclists to find this if they did a search. Maybe give a person, who doesn't have as much experience or live near a co-op, the idea of how to find a solution.

OldsCOOL

Nice job. That should hold it just fine. You've inspired me to spiff up my 1st gen cyclone. It's on my '80 Centurion Elite with barcons and deserves a shining up.

top506

I'm surprised one doesn't see more of these, as Sun Tour pinch bolts of all flavors were rather soft. I've snapped many over the years.

Top

poprad

Great tutorial VelociV! You ever thought of starting a blog?

Sir_Name 

Neat thread, Vv. Creative problem solving.

Velocivixen

Thanks everyone for the feedback.
@poprad - no blogs for me. I've no idea what I'd write about. I see blogs that I get interested in, then find they just stop. Drives me nuts.

unworthy1

I'm a bit late to this but that's a great How-to...I'm amazed at how well these are made by several of our members who have done them over the years. It's no easy thing to make good ones with clear written instructions and clear, close-up pix, so kudos to Velocivixen!

On a tangent/hijack: I have 10 NOS SunTour cable anchor bolts in a bag, these are from earlier days than the Cyclone, probably will fit many of the V series derailleurs, see the pix.
(I think they take an 8mm wrench and the 5M shaft is approx 8mm long)...
I will give ONE BOLT FREE one to a customer for the cost of postage, let's say $1 via PayPal or you could mail me a SSAE and I'll mail you one back in your envelope.
Once all 10 have been spoken for the deal shuts off.
PM me your address if you want one.

long john

I use a 2.5 liter ultrasonic cleaner. Interesting what's your day job?
great work my cyclone is missing that bolt. Thank you for the photo diy.