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Why did rear derailleur cable move from top to bottom of chainstay?



 
 
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  #1  
Old August 6th 19, 03:34 PM posted to rec.bicycles.tech
Sir Ridesalot
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Default Why did rear derailleur cable move from top to bottom of chainstay?

I was looking at a couple of my old bicycle frames with the rear derailleur cable routed along the top of the chainstay. I'm curious now. Why did the rear derailleur cable routing get moved to under the chainstay?

Cheers
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  #2  
Old August 7th 19, 05:36 AM posted to rec.bicycles.tech
[email protected]
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Default Why did rear derailleur cable move from top to bottom of chainstay?

On Tuesday, August 6, 2019 at 9:34:51 AM UTC-5, Sir Ridesalot wrote:
Why did the rear derailleur cable routing get moved to under the chainstay?



In the OLDEN days, shifters were mounted on the downtube up by the headtube.. Or on stem shifters either side of the quill stem. AND there was a clamp on guide at the bottom of the downtube that directed the shift cables (cable only for the rear derailleur, not the housing) to their respective derailleur, front and rear. See the eBay picture below.

https://www.ebay.com/p/Suntour-Gear-...45941129&rt=nc

https://www.ebay.com/itm/Suntour-gea...0AAOSwY7ZdF-pv

https://www.ebay.com/itm/Shimano-28-...AOxy IMhRGUOt

The long groove piece was for the rear cable. The bare cable from the shifter went into the groove/trough and was directed along the TOP of the chainstay to the cable stop at the rear of the chainstay, where a cable housing then formed the loop to the rear derailleur. And the other side of this clamp on piece directed a piece of cable housing from this clamp on up to the front derailleur. This was how cables were routed on bikes before someone invented the under bottom bracket guides bolted to the bottom of the bottom bracket. Under bottom bracket guides made of slippery plastic probably work better than the old clamp on guide contraption.
  #3  
Old August 7th 19, 04:17 PM posted to rec.bicycles.tech
Sir Ridesalot
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Default Why did rear derailleur cable move from top to bottom of chainstay?

On Wednesday, August 7, 2019 at 12:36:34 AM UTC-4, wrote:
On Tuesday, August 6, 2019 at 9:34:51 AM UTC-5, Sir Ridesalot wrote:
Why did the rear derailleur cable routing get moved to under the chainstay?



In the OLDEN days, shifters were mounted on the downtube up by the headtube. Or on stem shifters either side of the quill stem. AND there was a clamp on guide at the bottom of the downtube that directed the shift cables (cable only for the rear derailleur, not the housing) to their respective derailleur, front and rear. See the eBay picture below.

https://www.ebay.com/p/Suntour-Gear-...45941129&rt=nc

https://www.ebay.com/itm/Suntour-gea...0AAOSwY7ZdF-pv

https://www.ebay.com/itm/Shimano-28-...AOxy IMhRGUOt

The long groove piece was for the rear cable. The bare cable from the shifter went into the groove/trough and was directed along the TOP of the chainstay to the cable stop at the rear of the chainstay, where a cable housing then formed the loop to the rear derailleur. And the other side of this clamp on piece directed a piece of cable housing from this clamp on up to the front derailleur. This was how cables were routed on bikes before someone invented the under bottom bracket guides bolted to the bottom of the bottom bracket. Under bottom bracket guides made of slippery plastic probably work better than the old clamp on guide contraption.


I have bicycles that have brazed on cable guides that are located on top of the bottom bracket shell. The radius of the rear gear cable is greater and the loop is smoother on the bicycles with the cable stop on top of the chain stay.

It looks like the move to under the chainstay was just to save time and money in t he manufacturing process. Having the cable guides under or through the bottom bracket sure does expose them to a lot more crud though.

Cheers
  #4  
Old August 7th 19, 04:22 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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Default Why did rear derailleur cable move from top to bottom ofchainstay?

On 8/7/2019 12:36 AM, wrote:
On Tuesday, August 6, 2019 at 9:34:51 AM UTC-5, Sir Ridesalot wrote:
Why did the rear derailleur cable routing get moved to under the chainstay?



In the OLDEN days, shifters were mounted on the downtube up by the headtube. Or on stem shifters either side of the quill stem. AND there was a clamp on guide at the bottom of the downtube that directed the shift cables (cable only for the rear derailleur, not the housing) to their respective derailleur, front and rear. See the eBay picture below.

https://www.ebay.com/p/Suntour-Gear-...45941129&rt=nc

https://www.ebay.com/itm/Suntour-gea...0AAOSwY7ZdF-pv

https://www.ebay.com/itm/Shimano-28-...AOxy IMhRGUOt

The long groove piece was for the rear cable. The bare cable from the shifter went into the groove/trough and was directed along the TOP of the chainstay to the cable stop at the rear of the chainstay, where a cable housing then formed the loop to the rear derailleur. And the other side of this clamp on piece directed a piece of cable housing from this clamp on up to the front derailleur. This was how cables were routed on bikes before someone invented the under bottom bracket guides bolted to the bottom of the bottom bracket. Under bottom bracket guides made of slippery plastic probably work better than the old clamp on guide contraption.


The other common alternative was to have cable guides like the clamp-on
models, but brazed on permanently. I have several bikes with that setup.

I find I get less trouble with this braze-on setup than with the
under-BB guides on our Cannondales. As mentioned, the Cannondales
shifting occasionally gets sticky. It usually means dirt and dust has
messed up the lubrication of the cable passing through the plastic
grooves. The cable guides above the bottom bracket pick up much less dust.


--
- Frank Krygowski
  #5  
Old August 7th 19, 07:04 PM posted to rec.bicycles.tech
Jeff Liebermann
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Posts: 3,062
Default Why did rear derailleur cable move from top to bottom of chainstay?

On Tue, 6 Aug 2019 07:34:48 -0700 (PDT), Sir Ridesalot
wrote:

I was looking at a couple of my old bicycle frames with the rear derailleur
cable routed along the top of the chainstay. I'm curious now. Why did the
rear derailleur cable routing get moved to under the chainstay?
Cheers


My guess(tm) is that someone tried to use their bicycle as a ladder.
They stepped on the right rear chainstay, tripped over the derailleur
cable, crash landed, and sued everyone involved. In honor of this
event, the bicycle manufacturer probably moved the derailleur cable to
a less hazardous location to avoid further litigation.

Topic drift follows...

Some manufacturers may have decided that locating moving parts in the
"mud zone" is somehow a great idea. Here is a Specialized Stump
Jumper with both the drailleur cable and the rear brake positioned for
maximum exposure to mud, rain, dust, rocks, gravel, tar, etc.
http://www.learnbydestroying.com/jeffl/pics/bicycles/slides/Specialized-StumpJumper02.html
http://www.learnbydestroying.com/jeffl/pics/bicycles/slides/Specialized-StumpJumper.html
Extra credit for using rather small rear brake pads.

I would normally guess(tm) that such a brake location would not matter
because disk brakes are at approximately the same height above the
ground and presumably will be exposed to an equal amount of road
rubbish. My guess(tm) is the difference in brake pads, where the
softer pads in rim brakes tend to collect more abrasive road debris
than the harder and self cleaning pads used on disk brakes.

If you look at the rims, you might notice that there is more gouging
and wear on the rear rim, than on the front. This is backwards from
normal wear, where the front rim tends to show more wear because of
higher grip pressure. Most of the wear on the rear rim seems to be
from rocks and debris imbedded into the rear brake pads.

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #6  
Old August 7th 19, 10:58 PM posted to rec.bicycles.tech
Sir Ridesalot
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Posts: 4,398
Default Why did rear derailleur cable move from top to bottom of chainstay?

On Wednesday, August 7, 2019 at 2:04:48 PM UTC-4, Jeff Liebermann wrote:
On Tue, 6 Aug 2019 07:34:48 -0700 (PDT), Sir Ridesalot
wrote:

I was looking at a couple of my old bicycle frames with the rear derailleur
cable routed along the top of the chainstay. I'm curious now. Why did the
rear derailleur cable routing get moved to under the chainstay?
Cheers


My guess(tm) is that someone tried to use their bicycle as a ladder.
They stepped on the right rear chainstay, tripped over the derailleur
cable, crash landed, and sued everyone involved. In honor of this
event, the bicycle manufacturer probably moved the derailleur cable to
a less hazardous location to avoid further litigation.

Topic drift follows...

Some manufacturers may have decided that locating moving parts in the
"mud zone" is somehow a great idea. Here is a Specialized Stump
Jumper with both the drailleur cable and the rear brake positioned for
maximum exposure to mud, rain, dust, rocks, gravel, tar, etc.
http://www.learnbydestroying.com/jeffl/pics/bicycles/slides/Specialized-StumpJumper02.html
http://www.learnbydestroying.com/jeffl/pics/bicycles/slides/Specialized-StumpJumper.html
Extra credit for using rather small rear brake pads.

I would normally guess(tm) that such a brake location would not matter
because disk brakes are at approximately the same height above the
ground and presumably will be exposed to an equal amount of road
rubbish. My guess(tm) is the difference in brake pads, where the
softer pads in rim brakes tend to collect more abrasive road debris
than the harder and self cleaning pads used on disk brakes.

If you look at the rims, you might notice that there is more gouging
and wear on the rear rim, than on the front. This is backwards from
normal wear, where the front rim tends to show more wear because of
higher grip pressure. Most of the wear on the rear rim seems to be
from rocks and debris imbedded into the rear brake pads.

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558


Might be that the rider of that bike uses the rear brake a lot to make sliding turns?

I have a bicycle with the rear brake in the same position. I turned that bike into a single-speed with a 12" long handlebar.

https://flic.kr/p/Gwf98X
https://flic.kr/p/Gwfatx
https://flic.kr/p/GtMt7A

It's fun to ride.

Cheers
  #7  
Old August 8th 19, 08:54 PM posted to rec.bicycles.tech
Tom Kunich[_5_]
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Posts: 601
Default Why did rear derailleur cable move from top to bottom of chainstay?

On Tuesday, August 6, 2019 at 7:34:51 AM UTC-7, Sir Ridesalot wrote:
I was looking at a couple of my old bicycle frames with the rear derailleur cable routed along the top of the chainstay. I'm curious now. Why did the rear derailleur cable routing get moved to under the chainstay?

Cheers


Andrew told us about when it happened but not why. The rear derailleur cable was moved when the downtube friction shifters were moved to Shimano Brifters in the 70's.

Running the cables under the downtube gave the cables a cleaner run from the head tube to the under bottom bracket plastic runner.
  #8  
Old August 8th 19, 09:12 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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Posts: 7,471
Default Why did rear derailleur cable move from top to bottom ofchainstay?

On 8/8/2019 3:54 PM, Tom Kunich wrote:
On Tuesday, August 6, 2019 at 7:34:51 AM UTC-7, Sir Ridesalot wrote:
I was looking at a couple of my old bicycle frames with the rear derailleur cable routed along the top of the chainstay. I'm curious now. Why did the rear derailleur cable routing get moved to under the chainstay?

Cheers


I'll ignore the mistakes in your other post (yet again). I'll note just
the bike tech mistakes below.


Andrew told us about when it happened but not why. The rear derailleur cable was moved when the downtube friction shifters were moved to Shimano Brifters in the 70's.


Sorry, that's wrong.

Running the cables under the downtube gave the cables a cleaner run from the head tube to the under bottom bracket plastic runner.


But since the under bottom bracket guides appeared earlier, that's not
the reason.




--
- Frank Krygowski
  #9  
Old August 8th 19, 09:39 PM posted to rec.bicycles.tech
AMuzi
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Posts: 10,606
Default Why did rear derailleur cable move from top to bottom of chainstay?

On 8/8/2019 2:54 PM, Tom Kunich wrote:
On Tuesday, August 6, 2019 at 7:34:51 AM UTC-7, Sir Ridesalot wrote:
I was looking at a couple of my old bicycle frames with the rear derailleur cable routed along the top of the chainstay. I'm curious now. Why did the rear derailleur cable routing get moved to under the chainstay?

Cheers


Andrew told us about when it happened but not why. The rear derailleur cable was moved when the downtube friction shifters were moved to Shimano Brifters in the 70's.

Running the cables under the downtube gave the cables a cleaner run from the head tube to the under bottom bracket plastic runner.


First modern under-BB guides were steel, mid 1970s.
First nylon gear plate was Vitus in 1979.
First integrated shifter was Shimano 1990, followed by
Campagnolo Ergo a year or so later.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


  #10  
Old August 9th 19, 01:55 AM posted to rec.bicycles.tech
JBeattie
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Posts: 4,096
Default Why did rear derailleur cable move from top to bottom of chainstay?

On Thursday, August 8, 2019 at 1:39:57 PM UTC-7, AMuzi wrote:
On 8/8/2019 2:54 PM, Tom Kunich wrote:
On Tuesday, August 6, 2019 at 7:34:51 AM UTC-7, Sir Ridesalot wrote:
I was looking at a couple of my old bicycle frames with the rear derailleur cable routed along the top of the chainstay. I'm curious now. Why did the rear derailleur cable routing get moved to under the chainstay?

Cheers


Andrew told us about when it happened but not why. The rear derailleur cable was moved when the downtube friction shifters were moved to Shimano Brifters in the 70's.

Running the cables under the downtube gave the cables a cleaner run from the head tube to the under bottom bracket plastic runner.


First modern under-BB guides were steel, mid 1970s.
First nylon gear plate was Vitus in 1979.
First integrated shifter was Shimano 1990, followed by
Campagnolo Ergo a year or so later.


With the Vitus, the cables were structural. https://tinyurl.com/y4kh5o3g It was the first cable-stay frame design and ensured that the tubes would not separate in the event of epoxy failure.

-- Jay Beattie.
 




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