A Cycling & bikes forum. CycleBanter.com

Go Back   Home » CycleBanter.com forum » rec.bicycles » Techniques
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Gravel bikes



 
 
Thread Tools Display Modes
  #21  
Old July 30th 20, 11:36 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 884
Default Gravel bikes

On Thursday, July 30, 2020 at 2:52:38 PM UTC-7, Lou Holtman wrote:
On Thursday, July 30, 2020 at 11:14:59 PM UTC+2, wrote:
On Wednesday, July 29, 2020 at 5:53:08 PM UTC-5, John B. Slocomb wrote:
On Wed, 29 Jul 2020 15:39:48 -0700 (PDT), "
wrote:

On Tuesday, July 28, 2020 at 4:09:31 PM UTC-5, AK wrote:
What do you think of a gravel bike?

Does anyone have one?

https://www.youtube.com/watch?v=XC_xFpg_UmA

Andy

I've done a few rides recently on gravel roads. They were fun with the group. Not sure
riding them by myself would be any fun. I used a Nashbar cyclocross
bike. Heavy steel. 38mm tires. STI ten speed. Cantilever. Shimano
105 rear derailleur died at the end of one ride and had to be
replaced. So I'm not sure gravel riding is good or not. Not sure
what a gravel bike means. I've ridden many different bikes on gravel
roads just fine. Most gravel roads have two or three perfectly smooth
strips on them that you ride on. Much smoother than many potholed
roads. Less wear and tear on the bike. But you do have to run over
loose rocks when making turns. Those are the rough pothole portions
of gravel roads. Pros ride the cobblestone classics each year on road
racing bikes converted to gravel by putting huge 28mm tires on them.
They ride 150 miles at 30 mph.

Out of curiosity "Shimano 105 rear derailleur died" What actually
happened?

Cheers,
John B.


It stopped shifting with the STI levers. I replaced it with another new 105 long cage rear derailleur and the shifting works perfectly again. It happened a few months ago so I cannot remember exactly what happened. But shifting was bad, not precise, move the STI one click and the derailleur did not shift the chain. Move it two or three clicks and it would sort of move the chain. Everything imprecise. New derailleur, no change to cable, and everything shifts perfectly again. So I am pretty sure it was the derailleur, not the cable or shifters. Perfect shifting for several years before the one gravel ride. End of gravel ride bad shifting. New derailleur perfect shifting again with no other changes. So I assume the 20 miles of gravel riding killed the derailleur somehow.


A RD being a spring loaded lever, what can possibly went wrong. What could have happened is a cracked pulley cage plate (inner or outer). My brother had that once causing also weird shifting. Replacing the cracked outer cage plate was less than 10 euro:
https://www.bike-components.de/en/Sh...8-grey-GS-type

Lou


I've gotten used to the Di2 right lever but I keep having to use trial and error on the left. I took my Campy 10 speed bike out the other day on a climbing ride and it was sure nice not having to think about any shifting.
Ads
  #22  
Old July 31st 20, 01:37 AM posted to rec.bicycles.tech
news18
external usenet poster
 
Posts: 987
Default Gravel bikes

On Thu, 30 Jul 2020 11:49:52 -0400, Frank Krygowski wrote:

On 7/30/2020 11:35 AM, AMuzi wrote:


The most common failure being "merge with spokes".


I've seen such things in real life. On two different occasions, I fixed
similar problems for other riders so they could finish their rides, with
perhaps fewer gears than they had at the start.

But that sort of failure can happen anywhere if the derailleur is
adjusted badly enough. It doesn't have anything to do with gravel
riding.

I wondered if Russel's derailleur tried to swallow a rock.


Or a stick. Very common here on bush tracks. Gum trees shed leaves and
branches copiously when heat stressed and you have to be carefull you
don't flick a bit into the spokes, etc.

  #23  
Old July 31st 20, 05:19 AM posted to rec.bicycles.tech
John B. Slocomb
external usenet poster
 
Posts: 29
Default Gravel bikes

On Thu, 30 Jul 2020 14:14:56 -0700 (PDT), "
wrote:

On Wednesday, July 29, 2020 at 5:53:08 PM UTC-5, John B. Slocomb wrote:
On Wed, 29 Jul 2020 15:39:48 -0700 (PDT), "
wrote:

On Tuesday, July 28, 2020 at 4:09:31 PM UTC-5, AK wrote:
What do you think of a gravel bike?

Does anyone have one?

https://www.youtube.com/watch?v=XC_xFpg_UmA

Andy

I've done a few rides recently on gravel roads. They were fun with the group. Not sure

riding them by myself would be any fun. I used a Nashbar cyclocross
bike. Heavy steel. 38mm tires. STI ten speed. Cantilever. Shimano
105 rear derailleur died at the end of one ride and had to be
replaced. So I'm not sure gravel riding is good or not. Not sure
what a gravel bike means. I've ridden many different bikes on gravel
roads just fine. Most gravel roads have two or three perfectly smooth
strips on them that you ride on. Much smoother than many potholed
roads. Less wear and tear on the bike. But you do have to run over
loose rocks when making turns. Those are the rough pothole portions
of gravel roads. Pros ride the cobblestone classics each year on road
racing bikes converted to gravel by putting huge 28mm tires on them.
They ride 150 miles at 30 mph.

Out of curiosity "Shimano 105 rear derailleur died" What actually
happened?

Cheers,
John B.


It stopped shifting with the STI levers. I replaced it with another new 105 long cage rear derailleur and the shifting works perfectly again. It happened a few months ago so I cannot remember exactly what happened. But shifting was bad, not precise, move the STI one click and the derailleur did not shift the chain. Move it two or three clicks and it would sort of move the chain. Everything imprecise. New derailleur, no change to cable, and everything shifts perfectly again. So I am pretty sure it was the derailleur, not the cable or shifters. Perfect shifting for several years before the one gravel ride. End of gravel ride bad shifting. New derailleur perfect shifting again with no other changes. So I assume the 20 miles of gravel riding killed the derailleur somehow.


Thanks.

Cheers,
John B.
  #24  
Old July 31st 20, 07:34 AM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 1,652
Default Gravel bikes

On Thursday, July 30, 2020 at 4:52:38 PM UTC-5, Lou Holtman wrote:
On Thursday, July 30, 2020 at 11:14:59 PM UTC+2, wrote:
On Wednesday, July 29, 2020 at 5:53:08 PM UTC-5, John B. Slocomb wrote:
On Wed, 29 Jul 2020 15:39:48 -0700 (PDT), "
wrote:

On Tuesday, July 28, 2020 at 4:09:31 PM UTC-5, AK wrote:
What do you think of a gravel bike?

Does anyone have one?

https://www.youtube.com/watch?v=XC_xFpg_UmA

Andy

I've done a few rides recently on gravel roads. They were fun with the group. Not sure
riding them by myself would be any fun. I used a Nashbar cyclocross
bike. Heavy steel. 38mm tires. STI ten speed. Cantilever. Shimano
105 rear derailleur died at the end of one ride and had to be
replaced. So I'm not sure gravel riding is good or not. Not sure
what a gravel bike means. I've ridden many different bikes on gravel
roads just fine. Most gravel roads have two or three perfectly smooth
strips on them that you ride on. Much smoother than many potholed
roads. Less wear and tear on the bike. But you do have to run over
loose rocks when making turns. Those are the rough pothole portions
of gravel roads. Pros ride the cobblestone classics each year on road
racing bikes converted to gravel by putting huge 28mm tires on them.
They ride 150 miles at 30 mph.

Out of curiosity "Shimano 105 rear derailleur died" What actually
happened?

Cheers,
John B.


It stopped shifting with the STI levers. I replaced it with another new 105 long cage rear derailleur and the shifting works perfectly again. It happened a few months ago so I cannot remember exactly what happened. But shifting was bad, not precise, move the STI one click and the derailleur did not shift the chain. Move it two or three clicks and it would sort of move the chain. Everything imprecise. New derailleur, no change to cable, and everything shifts perfectly again. So I am pretty sure it was the derailleur, not the cable or shifters. Perfect shifting for several years before the one gravel ride. End of gravel ride bad shifting. New derailleur perfect shifting again with no other changes. So I assume the 20 miles of gravel riding killed the derailleur somehow.


A RD being a spring loaded lever, what can possibly went wrong. What could have happened is a cracked pulley cage plate (inner or outer). My brother had that once causing also weird shifting. Replacing the cracked outer cage plate was less than 10 euro:
https://www.bike-components.de/en/Sh...8-grey-GS-type

Lou


I went down to the basement and cleaned up, looked at the bad Shimano 105 rear derailleur. I took the plate and pulleys off. No broken cage/plate. Pulleys and their bushings looked OK. About the only thing that might be wrong is the spring to pull the cage backwards was not really consistent over the whole travel. Can't remember if all rear derailleurs have that varying spring tension for pulling the pulley cage backwards. The side to side spring in the derailleur was strong and consistent. No problem with it. Everything looks OK on the derailleur. It still looks new. And it sort of is new. But it died on me at the end of the gravel ride. Would not shift. And the new 105 long cage derailleur I installed now works perfectly. So....
  #25  
Old July 31st 20, 05:02 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
external usenet poster
 
Posts: 9,156
Default Gravel bikes

On 7/31/2020 12:19 AM, John B. Slocomb wrote:
On Thu, 30 Jul 2020 14:14:56 -0700 (PDT), "
wrote:

On Wednesday, July 29, 2020 at 5:53:08 PM UTC-5, John B. Slocomb wrote:
On Wed, 29 Jul 2020 15:39:48 -0700 (PDT), "
wrote:

On Tuesday, July 28, 2020 at 4:09:31 PM UTC-5, AK wrote:
What do you think of a gravel bike?

Does anyone have one?

https://www.youtube.com/watch?v=XC_xFpg_UmA

Andy

I've done a few rides recently on gravel roads. They were fun with the group. Not sure
riding them by myself would be any fun. I used a Nashbar cyclocross
bike. Heavy steel. 38mm tires. STI ten speed. Cantilever. Shimano
105 rear derailleur died at the end of one ride and had to be
replaced. So I'm not sure gravel riding is good or not. Not sure
what a gravel bike means. I've ridden many different bikes on gravel
roads just fine. Most gravel roads have two or three perfectly smooth
strips on them that you ride on. Much smoother than many potholed
roads. Less wear and tear on the bike. But you do have to run over
loose rocks when making turns. Those are the rough pothole portions
of gravel roads. Pros ride the cobblestone classics each year on road
racing bikes converted to gravel by putting huge 28mm tires on them.
They ride 150 miles at 30 mph.

Out of curiosity "Shimano 105 rear derailleur died" What actually
happened?

Cheers,
John B.


It stopped shifting with the STI levers. I replaced it with another new 105 long cage rear derailleur and the shifting works perfectly again. It happened a few months ago so I cannot remember exactly what happened. But shifting was bad, not precise, move the STI one click and the derailleur did not shift the chain. Move it two or three clicks and it would sort of move the chain. Everything imprecise. New derailleur, no change to cable, and everything shifts perfectly again. So I am pretty sure it was the derailleur, not the cable or shifters. Perfect shifting for several years before the one gravel ride. End of gravel ride bad shifting. New derailleur perfect shifting again with no other changes. So I assume the 20 miles of gravel riding killed the derailleur somehow.


I'm still curious. A rear derailleur is not a complicated machine. ISTM
a specific cause could be identified.


--
- Frank Krygowski
  #26  
Old July 31st 20, 05:10 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
external usenet poster
 
Posts: 9,156
Default Gravel bikes

On 7/31/2020 2:34 AM, wrote:
On Thursday, July 30, 2020 at 4:52:38 PM UTC-5, Lou Holtman wrote:
On Thursday, July 30, 2020 at 11:14:59 PM UTC+2, wrote:
On Wednesday, July 29, 2020 at 5:53:08 PM UTC-5, John B. Slocomb wrote:
On Wed, 29 Jul 2020 15:39:48 -0700 (PDT), "
wrote:

On Tuesday, July 28, 2020 at 4:09:31 PM UTC-5, AK wrote:
What do you think of a gravel bike?

Does anyone have one?

https://www.youtube.com/watch?v=XC_xFpg_UmA

Andy

I've done a few rides recently on gravel roads. They were fun with the group. Not sure
riding them by myself would be any fun. I used a Nashbar cyclocross
bike. Heavy steel. 38mm tires. STI ten speed. Cantilever. Shimano
105 rear derailleur died at the end of one ride and had to be
replaced. So I'm not sure gravel riding is good or not. Not sure
what a gravel bike means. I've ridden many different bikes on gravel
roads just fine. Most gravel roads have two or three perfectly smooth
strips on them that you ride on. Much smoother than many potholed
roads. Less wear and tear on the bike. But you do have to run over
loose rocks when making turns. Those are the rough pothole portions
of gravel roads. Pros ride the cobblestone classics each year on road
racing bikes converted to gravel by putting huge 28mm tires on them.
They ride 150 miles at 30 mph.

Out of curiosity "Shimano 105 rear derailleur died" What actually
happened?

Cheers,
John B.

It stopped shifting with the STI levers. I replaced it with another new 105 long cage rear derailleur and the shifting works perfectly again. It happened a few months ago so I cannot remember exactly what happened. But shifting was bad, not precise, move the STI one click and the derailleur did not shift the chain. Move it two or three clicks and it would sort of move the chain. Everything imprecise. New derailleur, no change to cable, and everything shifts perfectly again. So I am pretty sure it was the derailleur, not the cable or shifters. Perfect shifting for several years before the one gravel ride. End of gravel ride bad shifting. New derailleur perfect shifting again with no other changes. So I assume the 20 miles of gravel riding killed the derailleur somehow.


A RD being a spring loaded lever, what can possibly went wrong. What could have happened is a cracked pulley cage plate (inner or outer). My brother had that once causing also weird shifting. Replacing the cracked outer cage plate was less than 10 euro:
https://www.bike-components.de/en/Sh...8-grey-GS-type

Lou


I went down to the basement and cleaned up, looked at the bad Shimano 105 rear derailleur. I took the plate and pulleys off. No broken cage/plate. Pulleys and their bushings looked OK. About the only thing that might be wrong is the spring to pull the cage backwards was not really consistent over the whole travel. Can't remember if all rear derailleurs have that varying spring tension for pulling the pulley cage backwards. The side to side spring in the derailleur was strong and consistent. No problem with it. Everything looks OK on the derailleur. It still looks new. And it sort of is new. But it died on me at the end of the gravel ride. Would not shift. And the new 105 long cage derailleur I installed now works perfectly. So...


Odd.

I had a rear derailleur whose jockey pulley spring failed. But IIRC the
symptom was no takeup of chain slack. The shift cable still moved the
derailleur side to side, so that main part of shifting action worked.

When I disassembled, the jockey pulley's torsion spring had broken at
its end. It was a close wound helical spring made of square wire, ending
in a short axial tang that plugged into a hole or slot. The tang had
broken off at the 90 degree angle to the main coil. I just bent a few
millimeters of the coil out to make a new tang, and all was well.

That pivot motion should be smooth and consistent, AFAIK. I wonder if
gravel dust, etc. jammed that pivot? Would cleaning and lubricating fix it?

--
- Frank Krygowski
  #27  
Old July 31st 20, 11:01 PM posted to rec.bicycles.tech
Roger Merriman[_4_]
external usenet poster
 
Posts: 252
Default Gravel bikes

Lou Holtman wrote:
On Tuesday, July 28, 2020 at 11:09:31 PM UTC+2, AK wrote:
What do you think of a gravel bike?

Does anyone have one?

https://www.youtube.com/watch?v=XC_xFpg_UmA

Andy


I fully agree with their statements. From the moment I bought a cross
bike never touched my FS mountain bike. So much more fun. Same goes for
my gravel bike which is more capable on road than my cross bike. Sold
both of my ATB; FS and hardtail.

Lou

Lou


Probably worth noting that they where being deliberately provocative, don’t
get me wrong it’s certainly true that gravel bikes taken off road do remind
one of MTB of the 80/90’s but there is quite a lot of clear sea between the
two.

I’ve had two first was nominally a CX bike, but like a number of them it
clearly wasn’t intended for racing but riding in the woods etc.

My 2nd is my workhorse it’s happy on a club run or embarrassing MTB’s up a
Gravel climb. I use it to explore and knit together interesting trails/farm
tracks and what not.

My best bike is my MTB which is lovely beast but Is overkill for a lot of
this.

Roger Merriman

  #28  
Old August 1st 20, 01:26 AM posted to rec.bicycles.tech
John B.[_3_]
external usenet poster
 
Posts: 4,098
Default Gravel bikes

On Fri, 31 Jul 2020 12:10:15 -0400, Frank Krygowski
wrote:

On 7/31/2020 2:34 AM, wrote:
On Thursday, July 30, 2020 at 4:52:38 PM UTC-5, Lou Holtman wrote:
On Thursday, July 30, 2020 at 11:14:59 PM UTC+2, wrote:
On Wednesday, July 29, 2020 at 5:53:08 PM UTC-5, John B. Slocomb wrote:
On Wed, 29 Jul 2020 15:39:48 -0700 (PDT), "
wrote:

On Tuesday, July 28, 2020 at 4:09:31 PM UTC-5, AK wrote:
What do you think of a gravel bike?

Does anyone have one?

https://www.youtube.com/watch?v=XC_xFpg_UmA

Andy

I've done a few rides recently on gravel roads. They were fun with the group. Not sure
riding them by myself would be any fun. I used a Nashbar cyclocross
bike. Heavy steel. 38mm tires. STI ten speed. Cantilever. Shimano
105 rear derailleur died at the end of one ride and had to be
replaced. So I'm not sure gravel riding is good or not. Not sure
what a gravel bike means. I've ridden many different bikes on gravel
roads just fine. Most gravel roads have two or three perfectly smooth
strips on them that you ride on. Much smoother than many potholed
roads. Less wear and tear on the bike. But you do have to run over
loose rocks when making turns. Those are the rough pothole portions
of gravel roads. Pros ride the cobblestone classics each year on road
racing bikes converted to gravel by putting huge 28mm tires on them.
They ride 150 miles at 30 mph.

Out of curiosity "Shimano 105 rear derailleur died" What actually
happened?

Cheers,
John B.

It stopped shifting with the STI levers. I replaced it with another new 105 long cage rear derailleur and the shifting works perfectly again. It happened a few months ago so I cannot remember exactly what happened. But shifting was bad, not precise, move the STI one click and the derailleur did not shift the chain. Move it two or three clicks and it would sort of move the chain. Everything imprecise. New derailleur, no change to cable, and everything shifts perfectly again. So I am pretty sure it was the derailleur, not the cable or shifters. Perfect shifting for several years before the one gravel ride. End of gravel ride bad shifting. New derailleur perfect shifting again with no other changes. So I assume the 20 miles of gravel riding killed the derailleur somehow.

A RD being a spring loaded lever, what can possibly went wrong. What could have happened is a cracked pulley cage plate (inner or outer). My brother had that once causing also weird shifting. Replacing the cracked outer cage plate was less than 10 euro:
https://www.bike-components.de/en/Sh...8-grey-GS-type

Lou


I went down to the basement and cleaned up, looked at the bad Shimano 105 rear derailleur. I took the plate and pulleys off. No broken cage/plate. Pulleys and their bushings looked OK. About the only thing that might be wrong is the spring to pull the cage backwards was not really consistent over the whole travel. Can't remember if all rear derailleurs have that varying spring tension for pulling the pulley cage backwards. The side to side spring in the derailleur was strong and consistent. No problem with it. Everything looks OK on the derailleur. It still looks new. And it sort of is new. But it died on me at the end of the gravel ride. Would not shift. And the new 105 long cage derailleur I installed now works perfectly. So...


Odd.

I had a rear derailleur whose jockey pulley spring failed. But IIRC the
symptom was no takeup of chain slack. The shift cable still moved the
derailleur side to side, so that main part of shifting action worked.

When I disassembled, the jockey pulley's torsion spring had broken at
its end. It was a close wound helical spring made of square wire, ending
in a short axial tang that plugged into a hole or slot. The tang had
broken off at the 90 degree angle to the main coil. I just bent a few
millimeters of the coil out to make a new tang, and all was well.

That pivot motion should be smooth and consistent, AFAIK. I wonder if
gravel dust, etc. jammed that pivot? Would cleaning and lubricating fix it?



I have seen a rear derailer that the spring that moves the cage
sideways was weak and the bike shifted normally when the cable was
pulling the derailer and didn't shift as well when the shifter moved
under spring power. But, if I recollect that was a no name 7 speed
derailer on a $100 bike.
--
Cheers,

John B.

  #29  
Old August 1st 20, 04:05 AM posted to rec.bicycles.tech
Mark J.
external usenet poster
 
Posts: 686
Default Gravel bikes

On 7/31/2020 5:26 PM, John B. wrote:
On Fri, 31 Jul 2020 12:10:15 -0400, Frank Krygowski
wrote:

On 7/31/2020 2:34 AM, wrote:
On Thursday, July 30, 2020 at 4:52:38 PM UTC-5, Lou Holtman wrote:
On Thursday, July 30, 2020 at 11:14:59 PM UTC+2, wrote:
On Wednesday, July 29, 2020 at 5:53:08 PM UTC-5, John B. Slocomb wrote:
On Wed, 29 Jul 2020 15:39:48 -0700 (PDT), "
wrote:

On Tuesday, July 28, 2020 at 4:09:31 PM UTC-5, AK wrote:
What do you think of a gravel bike?

Does anyone have one?

https://www.youtube.com/watch?v=XC_xFpg_UmA

Andy

I've done a few rides recently on gravel roads. They were fun with the group. Not sure
riding them by myself would be any fun. I used a Nashbar cyclocross
bike. Heavy steel. 38mm tires. STI ten speed. Cantilever. Shimano
105 rear derailleur died at the end of one ride and had to be
replaced. So I'm not sure gravel riding is good or not. Not sure
what a gravel bike means. I've ridden many different bikes on gravel
roads just fine. Most gravel roads have two or three perfectly smooth
strips on them that you ride on. Much smoother than many potholed
roads. Less wear and tear on the bike. But you do have to run over
loose rocks when making turns. Those are the rough pothole portions
of gravel roads. Pros ride the cobblestone classics each year on road
racing bikes converted to gravel by putting huge 28mm tires on them.
They ride 150 miles at 30 mph.

Out of curiosity "Shimano 105 rear derailleur died" What actually
happened?

Cheers,
John B.

It stopped shifting with the STI levers. I replaced it with another new 105 long cage rear derailleur and the shifting works perfectly again. It happened a few months ago so I cannot remember exactly what happened. But shifting was bad, not precise, move the STI one click and the derailleur did not shift the chain. Move it two or three clicks and it would sort of move the chain. Everything imprecise. New derailleur, no change to cable, and everything shifts perfectly again. So I am pretty sure it was the derailleur, not the cable or shifters. Perfect shifting for several years before the one gravel ride. End of gravel ride bad shifting. New derailleur perfect shifting again with no other changes. So I assume the 20 miles of gravel riding killed the derailleur somehow.

A RD being a spring loaded lever, what can possibly went wrong. What could have happened is a cracked pulley cage plate (inner or outer). My brother had that once causing also weird shifting. Replacing the cracked outer cage plate was less than 10 euro:
https://www.bike-components.de/en/Sh...8-grey-GS-type

Lou

I went down to the basement and cleaned up, looked at the bad Shimano 105 rear derailleur. I took the plate and pulleys off. No broken cage/plate. Pulleys and their bushings looked OK. About the only thing that might be wrong is the spring to pull the cage backwards was not really consistent over the whole travel. Can't remember if all rear derailleurs have that varying spring tension for pulling the pulley cage backwards. The side to side spring in the derailleur was strong and consistent. No problem with it. Everything looks OK on the derailleur. It still looks new. And it sort of is new. But it died on me at the end of the gravel ride. Would not shift. And the new 105 long cage derailleur I installed now works perfectly. So...


Odd.

I had a rear derailleur whose jockey pulley spring failed. But IIRC the
symptom was no takeup of chain slack. The shift cable still moved the
derailleur side to side, so that main part of shifting action worked.

When I disassembled, the jockey pulley's torsion spring had broken at
its end. It was a close wound helical spring made of square wire, ending
in a short axial tang that plugged into a hole or slot. The tang had
broken off at the 90 degree angle to the main coil. I just bent a few
millimeters of the coil out to make a new tang, and all was well.

That pivot motion should be smooth and consistent, AFAIK. I wonder if
gravel dust, etc. jammed that pivot? Would cleaning and lubricating fix it?



I have seen a rear derailer that the spring that moves the cage
sideways was weak and the bike shifted normally when the cable was
pulling the derailer and didn't shift as well when the shifter moved
under spring power. But, if I recollect that was a no name 7 speed
derailer on a $100 bike.
--
Cheers,

John B.


Yes, I had the same - a SunTour Cyclone GT (i.e. the long-cage, original
cyclone version). The parallelogram return spring did, um, /something/.
I never figured out if part of it had broken off or if it had just
gone soft - neither of which really make sense to me. Even with the
derailleur taken completely off the bike it was clear that the return
spring just didn't have the oomph required to do its job.

I believe it was a coil spring with ends that extended out from the
coil, wrapped around one of the parallelogram pivots; the ends pushed
against adjacent sides of the parallelogram. Couldn't really see it
clearly without pushing out the press-fit pivot, so I never did figure
out how it "failed."

Mark J.
  #30  
Old August 1st 20, 01:20 PM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 11,994
Default Gravel bikes

On 7/31/2020 10:05 PM, Mark J. wrote:
On 7/31/2020 5:26 PM, John B. wrote:
On Fri, 31 Jul 2020 12:10:15 -0400, Frank Krygowski
wrote:

On 7/31/2020 2:34 AM, wrote:
On Thursday, July 30, 2020 at 4:52:38 PM UTC-5, Lou
Holtman wrote:
On Thursday, July 30, 2020 at 11:14:59 PM UTC+2,
wrote:
On Wednesday, July 29, 2020 at 5:53:08 PM UTC-5, John
B. Slocomb wrote:
On Wed, 29 Jul 2020 15:39:48 -0700 (PDT),
"
wrote:

On Tuesday, July 28, 2020 at 4:09:31 PM UTC-5, AK
wrote:
What do you think of a gravel bike?

Does anyone have one?

https://www.youtube.com/watch?v=XC_xFpg_UmA

Andy

I've done a few rides recently on gravel roads.
They were fun with the group. Not sure
riding them by myself would be any fun. I used a
Nashbar cyclocross
bike. Heavy steel. 38mm tires. STI ten speed.
Cantilever. Shimano
105 rear derailleur died at the end of one ride and
had to be
replaced. So I'm not sure gravel riding is good or
not. Not sure
what a gravel bike means. I've ridden many different
bikes on gravel
roads just fine. Most gravel roads have two or three
perfectly smooth
strips on them that you ride on. Much smoother than
many potholed
roads. Less wear and tear on the bike. But you do
have to run over
loose rocks when making turns. Those are the rough
pothole portions
of gravel roads. Pros ride the cobblestone classics
each year on road
racing bikes converted to gravel by putting huge 28mm
tires on them.
They ride 150 miles at 30 mph.

Out of curiosity "Shimano 105 rear derailleur died"
What actually
happened?

Cheers,
John B.

It stopped shifting with the STI levers. I replaced
it with another new 105 long cage rear derailleur and
the shifting works perfectly again. It happened a few
months ago so I cannot remember exactly what
happened. But shifting was bad, not precise, move the
STI one click and the derailleur did not shift the
chain. Move it two or three clicks and it would sort
of move the chain. Everything imprecise. New
derailleur, no change to cable, and everything shifts
perfectly again. So I am pretty sure it was the
derailleur, not the cable or shifters. Perfect
shifting for several years before the one gravel
ride. End of gravel ride bad shifting. New
derailleur perfect shifting again with no other
changes. So I assume the 20 miles of gravel riding
killed the derailleur somehow.

A RD being a spring loaded lever, what can possibly
went wrong. What could have happened is a cracked
pulley cage plate (inner or outer). My brother had that
once causing also weird shifting. Replacing the cracked
outer cage plate was less than 10 euro:
https://www.bike-components.de/en/Sh...8-grey-GS-type


Lou

I went down to the basement and cleaned up, looked at
the bad Shimano 105 rear derailleur. I took the plate
and pulleys off. No broken cage/plate. Pulleys and
their bushings looked OK. About the only thing that
might be wrong is the spring to pull the cage backwards
was not really consistent over the whole travel. Can't
remember if all rear derailleurs have that varying
spring tension for pulling the pulley cage backwards.
The side to side spring in the derailleur was strong and
consistent. No problem with it. Everything looks OK on
the derailleur. It still looks new. And it sort of is
new. But it died on me at the end of the gravel ride.
Would not shift. And the new 105 long cage derailleur I
installed now works perfectly. So...

Odd.

I had a rear derailleur whose jockey pulley spring
failed. But IIRC the
symptom was no takeup of chain slack. The shift cable
still moved the
derailleur side to side, so that main part of shifting
action worked.

When I disassembled, the jockey pulley's torsion spring
had broken at
its end. It was a close wound helical spring made of
square wire, ending
in a short axial tang that plugged into a hole or slot.
The tang had
broken off at the 90 degree angle to the main coil. I
just bent a few
millimeters of the coil out to make a new tang, and all
was well.

That pivot motion should be smooth and consistent, AFAIK.
I wonder if
gravel dust, etc. jammed that pivot? Would cleaning and
lubricating fix it?



I have seen a rear derailer that the spring that moves the
cage
sideways was weak and the bike shifted normally when the
cable was
pulling the derailer and didn't shift as well when the
shifter moved
under spring power. But, if I recollect that was a no name
7 speed
derailer on a $100 bike.
--
Cheers,

John B.


Yes, I had the same - a SunTour Cyclone GT (i.e. the
long-cage, original cyclone version). The parallelogram
return spring did, um, /something/. I never figured out if
part of it had broken off or if it had just gone soft -
neither of which really make sense to me. Even with the
derailleur taken completely off the bike it was clear that
the return spring just didn't have the oomph required to do
its job.

I believe it was a coil spring with ends that extended out
from the coil, wrapped around one of the parallelogram
pivots; the ends pushed against adjacent sides of the
parallelogram. Couldn't really see it clearly without
pushing out the press-fit pivot, so I never did figure out
how it "failed."

Mark J.


Nothing smaller than 'body assembly'[1] is shown in the
drawing and I can't recall the body return spring format for
those. However similar designs of the era can bind when
smacked and sometimes respond well to working the two end
castings a bit until the roll pins are freed up. It's more
likely that than an actual spring failure IME.

[1]Same body for both long & short models

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


 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
A real reason for gravel bikes? Frank Krygowski[_4_] Techniques 83 February 24th 20 12:39 AM
Gravel rash anyone? Mrcheerful[_2_] UK 5 July 23rd 10 12:06 AM
Sand and Gravel Nick Jackson Racing 1 October 14th 09 02:00 AM
Why do some walk their bikes across gravel? Mike Reed Techniques 80 June 12th 06 02:20 PM
Hit gravel, broke leg Ron Teplitz Recumbent Biking 199 June 28th 05 10:43 AM


All times are GMT +1. The time now is 09:25 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Copyright 2004-2020 CycleBanter.com.
The comments are property of their posters.