How foolish would this be?
#1
Senior Member
Thread Starter
Join Date: Jan 2008
Location: Beaverton, OR
Posts: 14,744
Bikes: Yes
Mentioned: 525 Post(s)
Tagged: 0 Thread(s)
Quoted: 3230 Post(s)
Liked 3,868 Times
in
1,439 Posts
How foolish would this be?
Unrelated (mostly) to my other effort to replace the spring in a LePree derailleur, and inspired by previous efforts by The Golden Boy (here) and coolkat (here), I've been trying to transplant a 3 pulley cage onto a SunTour Superbe Pro rear derailleur. The Superbe Pro uses the same pulley cage spring mechanism as their 3 pulley derailleurs, so I thought it might work. It bolts on easily enough, but there's a problem. The pivot stop on the body of the Superbe Pro derailleur is about 90 degrees rotated from the stop on the 3 pulley derailleurs, so it stops here (see pivot stop pin in the red circle):
The result is that it doesn't give me the extra chain wrap I need to use a triple crankset.
So, I was thinking about how I could solve this problem. My first idea was to tap another hole in the cage and move the stop pin right next to where it says "3 pulley system". I think that would work, but it would require me to figure out the threading of the stop pin, buy a tap, drill a hole, etc.
Then a second idea came to me. What if I just removed the stop pin. The chain will stop the pulley from folding back too far as long as the chain is engaged. Bad things could happen if I dropped the chain, but possibly(?) not too bad. So I tried it out.
It looks (!) like it's going to work. What could possibly go wrong?
What do you think?
The result is that it doesn't give me the extra chain wrap I need to use a triple crankset.
So, I was thinking about how I could solve this problem. My first idea was to tap another hole in the cage and move the stop pin right next to where it says "3 pulley system". I think that would work, but it would require me to figure out the threading of the stop pin, buy a tap, drill a hole, etc.
Then a second idea came to me. What if I just removed the stop pin. The chain will stop the pulley from folding back too far as long as the chain is engaged. Bad things could happen if I dropped the chain, but possibly(?) not too bad. So I tried it out.
It looks (!) like it's going to work. What could possibly go wrong?
What do you think?
__________________
My Bikes
My Bikes
Likes For Andy_K:
#2
Senior Member
Join Date: Oct 2015
Location: PDX
Posts: 13,041
Bikes: Merz x 5 + Specialized Merz Allez x 2, Strawberry/Newlands/DiNucci/Ti x3, Gordon, Fuso/Moulton x2, Bornstein, Paisley,1958-74 Paramounts x3, 3rensho, 74 Moto TC, 73-78 Raleigh Pro's x5, Marinoni x2, 1960 Cinelli SC, 1980 Bianchi SC, PX-10 X 2
Mentioned: 267 Post(s)
Tagged: 0 Thread(s)
Quoted: 4511 Post(s)
Liked 6,378 Times
in
3,667 Posts
I think you need to dial it in and go for a test ride, cautiously.
Likes For merziac:
#3
Senior Member
Join Date: Nov 2013
Location: Near Pottstown, PA: 30 miles NW of Philadelphia
Posts: 2,186
Bikes: 2 Trek Mtn, Cannondale R600 road, 6 vintage road bikes
Mentioned: 83 Post(s)
Tagged: 0 Thread(s)
Quoted: 472 Post(s)
Liked 1,028 Times
in
404 Posts
IIRC the stop pins/screws are a convenience vs a necessity. Convenient for the original assembler and for the owner while maintaining the bike. During operation it does nothing so, as you know about RD rotation and can accommodate that while removing and installing the wheel and while changing the chain, then you should be fine. "Weight reduction". However check to be sure nothing is damaged if the cage ever pops back (broken chain, fumble fingers while out on the bench, etc). Does the cage hit some other part of the RD hard and damage it or does it catch a finger and damage that? If so, think on that one a bit.
On the RDs I've worked on or overhauled, some cages relax gently after that pin is removed. Others have much stronger torsion springs and can snap back quite smartly. Could even pinch a finger badly in a scissor action. I don't recall one that would "wap" the RD body and damage it. It also depends on how the high limit screw is set.
On the RDs I've worked on or overhauled, some cages relax gently after that pin is removed. Others have much stronger torsion springs and can snap back quite smartly. Could even pinch a finger badly in a scissor action. I don't recall one that would "wap" the RD body and damage it. It also depends on how the high limit screw is set.
Likes For Prowler:
#4
Senior Member
Join Date: Dec 2005
Posts: 17,158
Mentioned: 481 Post(s)
Tagged: 0 Thread(s)
Quoted: 3810 Post(s)
Liked 6,694 Times
in
2,611 Posts
I had a Shimano Deerhead RD in use some time back in which the stop pin had gone missing. As you note, it was all fine as long as I didn’t have to remove the rear wheel, say like when on a long ride and I got a flatted rear tire and putting it all back together was an origami experiment that failed. So, yeah.
Likes For nlerner:
#5
seńor miembro
Join Date: Dec 2018
Location: Pac NW
Posts: 6,624
Bikes: '70s - '80s Campagnolo
Mentioned: 92 Post(s)
Tagged: 0 Thread(s)
Quoted: 3887 Post(s)
Liked 6,482 Times
in
3,206 Posts
Yeah, rear flats are enough of a problem without compounding it.
#6
Senior Member
Thread Starter
Join Date: Jan 2008
Location: Beaverton, OR
Posts: 14,744
Bikes: Yes
Mentioned: 525 Post(s)
Tagged: 0 Thread(s)
Quoted: 3230 Post(s)
Liked 3,868 Times
in
1,439 Posts
It turns out that if I use the chain hanger braze-on, the cage stays put pretty well even with the wheel off.
__________________
My Bikes
My Bikes
Likes For Andy_K:
#8
Friendship is Magic
Join Date: Nov 2010
Location: Sacramento, CA
Posts: 22,984
Bikes: old ones
Mentioned: 304 Post(s)
Tagged: 0 Thread(s)
Quoted: 26418 Post(s)
Liked 10,380 Times
in
7,208 Posts
.
...they laughed at Galileo, too. Well, actually they stopped laughing after a time and sent him before the Inquisition. YMMV
...they laughed at Galileo, too. Well, actually they stopped laughing after a time and sent him before the Inquisition. YMMV
Likes For 3alarmer:
#9
Senior Member
Join Date: Oct 2005
Location: SW Ohio
Posts: 3,682
Bikes: Puch Marco Polo, Saint Tropez, Masi Gran Criterium
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 1163 Post(s)
Liked 442 Times
in
315 Posts
Is it possible to wind the spring another (almost) full turn and use the existing stop screw in order to get the chain wrap you need for your triple? Or is the spring too stiff?
#10
Senior Member
Thread Starter
Join Date: Jan 2008
Location: Beaverton, OR
Posts: 14,744
Bikes: Yes
Mentioned: 525 Post(s)
Tagged: 0 Thread(s)
Quoted: 3230 Post(s)
Liked 3,868 Times
in
1,439 Posts
No, the problem isn't spring tension. The problem is that the pin stops the derailleur where it's shown in my first picture regardless of spring tension. You can't even manually move it past that point.
__________________
My Bikes
My Bikes
#11
Senior Member
Thread Starter
Join Date: Jan 2008
Location: Beaverton, OR
Posts: 14,744
Bikes: Yes
Mentioned: 525 Post(s)
Tagged: 0 Thread(s)
Quoted: 3230 Post(s)
Liked 3,868 Times
in
1,439 Posts
Spaghetti Legs sent me this picture when I told him what I was doing.
Totally accurate, right down to me beating on this when it wouldn't work and then later hearing grumbling coming from the garage. (OK, that last part isn't entirely true.)
__________________
My Bikes
My Bikes
Likes For Andy_K:
#13
Senior Member
Join Date: Mar 2013
Location: Maryland
Posts: 3,800
Bikes: Lots of English 3-speeds, a couple of old road bikes, 3 mountain bikes, 1 hybrid, and a couple of mash-ups
Mentioned: 53 Post(s)
Tagged: 0 Thread(s)
Quoted: 887 Post(s)
Liked 335 Times
in
225 Posts
It doesn't need to be true, it only needs to be repeated over and over and over, and then it'll be enough true.
Likes For dweenk:
#14
Senior Member
Thread Starter
Join Date: Jan 2008
Location: Beaverton, OR
Posts: 14,744
Bikes: Yes
Mentioned: 525 Post(s)
Tagged: 0 Thread(s)
Quoted: 3230 Post(s)
Liked 3,868 Times
in
1,439 Posts
It provides extra chain wrap. When the derailleur cage is forward, the third pulley isn't engaged and it acts like a short cage 2 pulley derailleur. When the cage swings back, the third pulley engages to force the chain to cover more distance. A longer cage accomplishes basically the same thing, but this is weirder.
__________________
My Bikes
My Bikes
Likes For Andy_K:
#15
Senior Member
Join Date: Dec 2005
Posts: 17,158
Mentioned: 481 Post(s)
Tagged: 0 Thread(s)
Quoted: 3810 Post(s)
Liked 6,694 Times
in
2,611 Posts
Three pulleys is 1/3 cooler than two.
Likes For nlerner:
#16
Bike Butcher of Portland
Join Date: Jul 2014
Location: Portland, OR
Posts: 11,639
Bikes: It's complicated.
Mentioned: 1299 Post(s)
Tagged: 0 Thread(s)
Quoted: 4682 Post(s)
Liked 5,799 Times
in
2,284 Posts
Grant Petersen would say it's 0.333 cooler, because metric.
__________________
If someone tells you that you have enough bicycles and you don't need any more, stop talking to them. You don't need that kind of negativity in your life.
If someone tells you that you have enough bicycles and you don't need any more, stop talking to them. You don't need that kind of negativity in your life.
#17
Senior Member
Join Date: Dec 2005
Posts: 17,158
Mentioned: 481 Post(s)
Tagged: 0 Thread(s)
Quoted: 3810 Post(s)
Liked 6,694 Times
in
2,611 Posts
#18
Bike Butcher of Portland
Join Date: Jul 2014
Location: Portland, OR
Posts: 11,639
Bikes: It's complicated.
Mentioned: 1299 Post(s)
Tagged: 0 Thread(s)
Quoted: 4682 Post(s)
Liked 5,799 Times
in
2,284 Posts
#19
Senior Member
Join Date: Dec 2014
Location: Central Virginia
Posts: 4,781
Bikes: Numerous
Mentioned: 150 Post(s)
Tagged: 0 Thread(s)
Quoted: 1678 Post(s)
Liked 3,097 Times
in
913 Posts
Its actually 150% cooler. That’s OK though, I know you’re an English major.
__________________
N = '96 Colnago C40, '04 Wilier Alpe D'Huez, '10 Colnago EPS, '85 Merckx Pro, '89 Merckx Century, '86 Tommasini Professional, '04 Teschner Aero FX Pro, '05 Alan Carbon Cross, '86 De Rosa Professional, '82 Colnago Super, '95 Gios Compact Pro, '95 Carrera Zeus, '84 Basso Gap, ‘89 Cinelli Supercorsa, ‘83 Bianchi Specialissima, ‘VO Randonneur, Ritchey Breakaway Steel, '84 Paletti Super Prestige, Heron Randonneur
N = '96 Colnago C40, '04 Wilier Alpe D'Huez, '10 Colnago EPS, '85 Merckx Pro, '89 Merckx Century, '86 Tommasini Professional, '04 Teschner Aero FX Pro, '05 Alan Carbon Cross, '86 De Rosa Professional, '82 Colnago Super, '95 Gios Compact Pro, '95 Carrera Zeus, '84 Basso Gap, ‘89 Cinelli Supercorsa, ‘83 Bianchi Specialissima, ‘VO Randonneur, Ritchey Breakaway Steel, '84 Paletti Super Prestige, Heron Randonneur
Likes For Spaghetti Legs:
#20
multimodal commuter
Join Date: Nov 2006
Location: NJ, NYC, LI
Posts: 19,808
Bikes: 1940s Fothergill, 1959 Allegro Special, 1963? Claud Butler Olympic Sprint, Lambert 'Clubman', 1974 Fuji "the Ace", 1976 Holdsworth 650b conversion rando bike, 1983 Trek 720 tourer, 1984 Counterpoint Opus II, 1993 Basso Gap, 2010 Downtube 8h, and...
Mentioned: 584 Post(s)
Tagged: 0 Thread(s)
Quoted: 1908 Post(s)
Liked 574 Times
in
339 Posts
But that's assuming that a derailleur's coolness is directly proportional to the number of pulleys. I submit that though those three-pulley derailleur's are pretty cool, the S-1 (with only two pulleys) is cooler still.
Well, at least it's weirder.
Last edited by rhm; 05-28-20 at 11:28 PM.
Likes For rhm:
#21
Senior Member
Join Date: May 2013
Location: Pacific Northwest
Posts: 1,991
Bikes: ‘87 Marinoni SLX Sports Tourer, ‘79 Miyata 912 by Gugificazione
Mentioned: 166 Post(s)
Tagged: 0 Thread(s)
Quoted: 502 Post(s)
Liked 466 Times
in
256 Posts
I think it’s extremely cool and a worthy quarantine project.
Last edited by Dfrost; 05-28-20 at 11:58 PM.
#22
Senior Member
Thread Starter
Join Date: Jan 2008
Location: Beaverton, OR
Posts: 14,744
Bikes: Yes
Mentioned: 525 Post(s)
Tagged: 0 Thread(s)
Quoted: 3230 Post(s)
Liked 3,868 Times
in
1,439 Posts
#23
Senior Member
Thread Starter
Join Date: Jan 2008
Location: Beaverton, OR
Posts: 14,744
Bikes: Yes
Mentioned: 525 Post(s)
Tagged: 0 Thread(s)
Quoted: 3230 Post(s)
Liked 3,868 Times
in
1,439 Posts
#24
Senior Member
Thread Starter
Join Date: Jan 2008
Location: Beaverton, OR
Posts: 14,744
Bikes: Yes
Mentioned: 525 Post(s)
Tagged: 0 Thread(s)
Quoted: 3230 Post(s)
Liked 3,868 Times
in
1,439 Posts
Yeah, that's some next level stuff right there.
__________________
My Bikes
My Bikes
Likes For Andy_K: