Long cage, short cage, mid cage?
08-21-19, 07:46 AM
#26
Senior Member
you just have to decide which RD you're gonna use and what the gear range will be on your cassette/freewheel. then, you can figure the max chain length with some math
If....
short cage RD capacity = 28t
freewheel = 28-13t = 15
chainset = 46-30t = 16
16+15 = 31
so, that exceeds the RD capacity by 3 teeth
so, then figure what largest cog you can away with using while on the large ring to fall within the RD capacity
24-13t = 11
16+11= 27...within the RD capacity
so, set the chain length while on the 24t cog and largest ring. never shift to the 28t cog while on the largest ring you're safe
If....
short cage RD capacity = 28t
freewheel = 28-13t = 15
chainset = 46-30t = 16
16+15 = 31
so, that exceeds the RD capacity by 3 teeth
so, then figure what largest cog you can away with using while on the large ring to fall within the RD capacity
24-13t = 11
16+11= 27...within the RD capacity
so, set the chain length while on the 24t cog and largest ring. never shift to the 28t cog while on the largest ring you're safe
Shift to the large/large combination with a short chain and the derailleur is bent, twisted, sheared off. If you're lucky. Frame damage is likely as well. Crashing is not automatic but very likely. ALWAYS have enough chain for large/large. You cannot count on remembering. Recipe for failure.
08-21-19, 09:54 AM
#27
The dropped
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Advertised rear derailleur freewheel capacities for the most part were just that - the largest capacity freewheel that would work on the average bike without any (or much) trial and error adjustments.
Suntour V and V-Luxe short arm derailleurs were rated at a maximum 24T rear sprocket but back in the 70's they could handle 26T on any bike no problem - but that was the maximum.
Most of our casual rider customers wanted an RD to replace the Simplex Prestige or Huret Allvit that came on their bikes. They needed to handle "Alpine Gearing" - 10 speeds with a 14-28T FW and 52-42T or 52-40T chainrings.
The mid length Suntour VT would have been perfect but they weren't readily available so we had to use the the long arm VGT derailleurs with an overkill 34T FW capacity. They worked great, never a complaint.
BTW, Suntour V and V-Luxe RDs sold for $6.00 while the VGT RDs were $7.00-$8.00. Campy NRs sold for about $29.00 at the time.
Suntour Cyclones, there were at least 3 different versions of the original Suntour Cyclone RDs. The first one that came out in early 1975 could handle a maximum of 26T but was rated at 24T. The other two were rated at 24T and that was the maximum they could handle.
Suntour listed 3 different Horizontal Dropout Hanger Lengths: 24mm, 26mm, 28mm plus 30mm for their Vertical Dropouts. See chart below.
Variations in the Hanger Length gave different RD capacities plus many other makes and models of rear dropouts had unpublished lengths.
Throw all those things together and you'll get variations that don't match any published specs.
In June 1975 I got 2 sets from the first shipment of Suntour Cyclones to hit the US. They first appeared as vaporware in the trade rags in the fall of 1974.
I put one set on my then all Campy bike running a 13-26T 5 speed FW. It worked perfectly out of the box. The only issue was the hookie 1st generation Cyclone shift levers. Once I did modifications they worked fine too.
I still have the other set NIB!
I ran the first ones on 3 different bikes over the years. Late one afternoon as I was climbing up a short grade to finish my ride, some guy on a zoomie plastic bike passed me.
I threw it into my lowest gear - 26T x 45T to chase him down and the bike came to a sickening sliding stop. I'd sucked my all time favorite derailleur! The cage, the parallelogram and the mounting bolt broke. The derailleur hanger was bent in at 45°.
First time I'd sucked a RD since maybe 1973, a Simplex Prestige on a Gitane Gran Sport!
verktyg
Suntour V and V-Luxe short arm derailleurs were rated at a maximum 24T rear sprocket but back in the 70's they could handle 26T on any bike no problem - but that was the maximum.
Most of our casual rider customers wanted an RD to replace the Simplex Prestige or Huret Allvit that came on their bikes. They needed to handle "Alpine Gearing" - 10 speeds with a 14-28T FW and 52-42T or 52-40T chainrings.
The mid length Suntour VT would have been perfect but they weren't readily available so we had to use the the long arm VGT derailleurs with an overkill 34T FW capacity. They worked great, never a complaint.
BTW, Suntour V and V-Luxe RDs sold for $6.00 while the VGT RDs were $7.00-$8.00. Campy NRs sold for about $29.00 at the time.
Suntour Cyclones, there were at least 3 different versions of the original Suntour Cyclone RDs. The first one that came out in early 1975 could handle a maximum of 26T but was rated at 24T. The other two were rated at 24T and that was the maximum they could handle.
Suntour listed 3 different Horizontal Dropout Hanger Lengths: 24mm, 26mm, 28mm plus 30mm for their Vertical Dropouts. See chart below.
Variations in the Hanger Length gave different RD capacities plus many other makes and models of rear dropouts had unpublished lengths.
Throw all those things together and you'll get variations that don't match any published specs.
In June 1975 I got 2 sets from the first shipment of Suntour Cyclones to hit the US. They first appeared as vaporware in the trade rags in the fall of 1974.
I put one set on my then all Campy bike running a 13-26T 5 speed FW. It worked perfectly out of the box. The only issue was the hookie 1st generation Cyclone shift levers. Once I did modifications they worked fine too.
I still have the other set NIB!
I ran the first ones on 3 different bikes over the years. Late one afternoon as I was climbing up a short grade to finish my ride, some guy on a zoomie plastic bike passed me.
I threw it into my lowest gear - 26T x 45T to chase him down and the bike came to a sickening sliding stop. I'd sucked my all time favorite derailleur! The cage, the parallelogram and the mounting bolt broke. The derailleur hanger was bent in at 45°.
First time I'd sucked a RD since maybe 1973, a Simplex Prestige on a Gitane Gran Sport!
verktyg
Time for a story from gramps! Yay!Seriously, @verktyg, you're a gold mine of knowledge. Thanks for sharing.
08-21-19, 11:49 AM
#28
(rhymes with spook)
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NO. We have seen this movie before. We have seen this movie before way too many times. The following is not a theoretical concern. This happens.
Shift to the large/large combination with a short chain and the derailleur is bent, twisted, sheared off. If you're lucky. Frame damage is likely as well. Crashing is not automatic but very likely. ALWAYS have enough chain for large/large. You cannot count on remembering. Recipe for failure.
Shift to the large/large combination with a short chain and the derailleur is bent, twisted, sheared off. If you're lucky. Frame damage is likely as well. Crashing is not automatic but very likely. ALWAYS have enough chain for large/large. You cannot count on remembering. Recipe for failure.
dude asked. i sent him a link and explained where he was confused. likely he's an adult and can figure for himself if he wants to risk it. and, if he's read the link or anything else on this matter, he knows the risks
08-21-19, 11:59 AM
#29
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if you are referring to moi, i get it. i'm not technical shifter, and will probably use the big chainring with the outer freewheel cogs, and inner ring with the low gears. never the bigs shall meet, resulting in the end of all life on earth.
afterthought.. i take the advice about going big/big being dangerous and damaging very seriously.
afterthought.. i take the advice about going big/big being dangerous and damaging very seriously.
Last edited by cocoabeachcrab; 08-21-19 at 12:53 PM.
08-21-19, 12:58 PM
#30
(rhymes with spook)
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lol....end of all life on earth. exactly
really, though, on a double ring set up one would ideally be able to use big on big, anyway. i mean, why not be able to use all range of gearing? and, i'd have to agree there's not much "practical" benefit in using a short cage over a long cage unless maybe you're racing where shifting speed is kinda critical. but, if you're a tinkerer, have that "special" short cage you wanna use, or actually too broke to get a long cage in the moment, i get it. i support the choice.
in the end, it's always a risk riding a bike. i've wrecked so many times regardless of my drivetrain. am still alive with working limbs. and, i think the world is still here
really, though, on a double ring set up one would ideally be able to use big on big, anyway. i mean, why not be able to use all range of gearing? and, i'd have to agree there's not much "practical" benefit in using a short cage over a long cage unless maybe you're racing where shifting speed is kinda critical. but, if you're a tinkerer, have that "special" short cage you wanna use, or actually too broke to get a long cage in the moment, i get it. i support the choice.
in the end, it's always a risk riding a bike. i've wrecked so many times regardless of my drivetrain. am still alive with working limbs. and, i think the world is still here
08-21-19, 01:23 PM
#31
(rhymes with spook)
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if you are referring to moi, i get it. i'm not technical shifter, and will probably use the big chainring with the outer freewheel cogs, and inner ring with the low gears. never the bigs shall meet, resulting in the end of all life on earth.
afterthought.. i take the advice about going big/big being dangerous and damaging very seriously.
afterthought.. i take the advice about going big/big being dangerous and damaging very seriously.
08-21-19, 01:27 PM
#32
Myrtle Beach Crab
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i hear you. i think about chain lines (unconsciously), and i'm lazy, so don't really care if i'm making the best use of all 10 gearing choices.
08-21-19, 02:37 PM
#33
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I think Billy Joel would say "it's all rock and roll to me"
__________________
Life is too short not to ride the best bike you have, as much as you can
(looking for Torpado Super light frame/fork or for Raleigh International frame fork 58cm)
Life is too short not to ride the best bike you have, as much as you can
(looking for Torpado Super light frame/fork or for Raleigh International frame fork 58cm)
08-21-19, 02:49 PM
#34
Senior Member
If you want to jump off a cliff and expect that you are going to have a different result than the last person who jumped off the cliff feel free to do so.
Setting up any machine with a very predictable failure mode is a bad idea. Only in your imagination is the non-working gear combination never touched. Someone risks imminent harm I am going to speak. Also, as originally posted, this very bad mechanical practice was being commended to one and all. Damage and injury to multiple unsuspecting parties was and is possible. If speaking up in such a circumstance is a horrible breach of internet etiquette you may all go directly to Hell. Mechanical advice given was sufficiently egregious and ridiculous an alert mod should have stopped it, deleted it instantly. Not everything that occurs in social media can or should be instantly controlled. Passing out instructions for how to go hurt yourself simply should not appear. This does seem to be a place where instructions for causing harm get distributed all the time and people get upset if it is ever called out. Screw you all.
Likes For gomango:
08-21-19, 04:38 PM
#36
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i think he just means me...lol!
08-21-19, 06:04 PM
#37
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NO. We have seen this movie before. We have seen this movie before way too many times. The following is not a theoretical concern. This happens.
Shift to the large/large combination with a short chain and the derailleur is bent, twisted, sheared off. If you're lucky. Frame damage is likely as well. Crashing is not automatic but very likely. ALWAYS have enough chain for large/large. You cannot count on remembering. Recipe for failure.
Shift to the large/large combination with a short chain and the derailleur is bent, twisted, sheared off. If you're lucky. Frame damage is likely as well. Crashing is not automatic but very likely. ALWAYS have enough chain for large/large. You cannot count on remembering. Recipe for failure.
fwiw I am a big fan of small/small sizing I have used this method with great success with both modern 105 5800 and vintage (dura ace 12/28 and 39/52 front)
__________________
Life is too short not to ride the best bike you have, as much as you can
(looking for Torpado Super light frame/fork or for Raleigh International frame fork 58cm)
Life is too short not to ride the best bike you have, as much as you can
(looking for Torpado Super light frame/fork or for Raleigh International frame fork 58cm)
08-21-19, 09:09 PM
#38
Senior Member
Civility and comity before safety because if you don't have the first two the good information never gets passed around. Except at this place, where that last step with the good information never happens while all are so so polite.
I learned not to shortchain at age 15. Figured it out myself. Didn't even have to damage anything, just installed a chain and paid attention. And I am not and never was a good mechanic. Only weeks after that I saw examples of what happens with a short chain. There weren't even that many derailleur bikes around back then. It's something anyone and everyone knows. Plenty here know it. Plenty on the thread and posting know it. But don't rock the boat. Someone wants to post information on how to hurt yourself, hey, he's a voice on the intertoobs and has as much right to speak his piece as anyone.
Then some perfect creep comes along with his Gestapo routine. And that's cool too. No one tells him to get lost. No one tells him to STFU. No one defends the party presenting basic info that most know is correct.
But Campagnolo hubs will kill you. Learned that here just the other day. Good to collect bikes from days of toe clips but please, only look at them on the wall. Ride them and you will die. Downtube levers will kill you. Exposed brake cables will kill you. It's true. I read it all right here. On C & V.
Please ban me.
08-21-19, 11:32 PM
#39
(rhymes with spook)
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geez. at one point i was gonna say more. then, i decided maybe not say anything at all. but, that about sums up this exhausting thing that is internet venting. yeah....geez
rather than waiting for the ban that's likely not gonna happen, why not just stop posting? but, maybe you won't get as much thrill out of that
rather than waiting for the ban that's likely not gonna happen, why not just stop posting? but, maybe you won't get as much thrill out of that
Last edited by thook; 08-22-19 at 12:13 AM.
08-22-19, 01:22 PM
#41
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fwiw I am a big fan of small/small sizing I have used this method with great success with both modern 105 5800 and vintage (dura ace 12/28 and 39/52 front)
https://www.youtube.com/watch?v=QuhHn7HaZcQ
https://www.youtube.com/watch?v=QuhHn7HaZcQ
