Brompton derailleur problem
#1
Senior Member
Thread Starter
Join Date: Jan 2007
Posts: 58
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Brompton derailleur problem
Hi, need a little help here from the Brompton experts. I have just upgraded my Brompton 2-speed to a 6-speed. The 3-speed BWR hub is working fine, but I can't get the 2-speed derailleur to run smoothly in the lower gear (larger sprocket). The shifting from the small cog to the big cog works ok, but during pedalling it feels rough. I could feel vibrations through my feet. It doesn't happen in the small sprocket though.
I have already tried adjusting the derailleur, and even tried out a newish one, with no difference. It was working well before I upgraded to 6-speed. Does anybody have the same experience, and if so, how did you solve the problem? Any suggestion will be most appreciated. Thanks.
I have already tried adjusting the derailleur, and even tried out a newish one, with no difference. It was working well before I upgraded to 6-speed. Does anybody have the same experience, and if so, how did you solve the problem? Any suggestion will be most appreciated. Thanks.
#2
Senior Member
Join Date: Jul 2007
Posts: 361
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
Hi, need a little help here from the Brompton experts. I have just upgraded my Brompton 2-speed to a 6-speed. The 3-speed BWR hub is working fine, but I can't get the 2-speed derailleur to run smoothly in the lower gear (larger sprocket). The shifting from the small cog to the big cog works ok, but during pedalling it feels rough. I could feel vibrations through my feet. It doesn't happen in the small sprocket though.
I have already tried adjusting the derailleur, and even tried out a newish one, with no difference. It was working well before I upgraded to 6-speed. Does anybody have the same experience, and if so, how did you solve the problem? Any suggestion will be most appreciated. Thanks.
I have already tried adjusting the derailleur, and even tried out a newish one, with no difference. It was working well before I upgraded to 6-speed. Does anybody have the same experience, and if so, how did you solve the problem? Any suggestion will be most appreciated. Thanks.
#3
Senior Member
Join Date: May 2005
Location: Albany, WA
Posts: 7,393
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 321 Post(s)
Likes: 0
Liked 7 Times
in
6 Posts
Unfortunately I can't give specific help... but what I would do in your situation, is first establish, is the roughness felt in all BWR gears? Sometimes geared hubs may impart a rough feeling especially more so in some gears. If that draws a blank, backpedal or pedal on some sort of back wheel off the ground setup and try to spot what rubs to find the culprit. The only one I can think of is the derailer actuator rubbing against the chain but you have already eliminated that, I understand.
#4
smallwheelsonly
Join Date: Jan 2009
Location: Ca.
Posts: 279
Bikes: SmallWheelOnly
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I have a Brompton six speed with the Stram T3 instead of Sturmey-Archer hub and of course dual cogs and derailleur system and I can tell you that its prone to skipping and some roughness if the cogs are dirty or the chain is dirty and requires some attention to that area of the drivetrain but I don't think this is the case with your newly installed system. Clownbike might be right that a slightly narrower chain might be required.
where did you get the cogs ? where they from Brompton ? IF so did the vendor help at all in the situation or solutions?
where did you get the cogs ? where they from Brompton ? IF so did the vendor help at all in the situation or solutions?
#5
Senior Member
Thread Starter
Join Date: Jan 2007
Posts: 58
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I haven't tried swapping out the chain yet. It's the same chain that is on the 2-speed system before I upgraded, so the width shouldn't be an issue. May try using a different length to see what happens.
#6
Senior Member
Thread Starter
Join Date: Jan 2007
Posts: 58
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Unfortunately I can't give specific help... but what I would do in your situation, is first establish, is the roughness felt in all BWR gears? Sometimes geared hubs may impart a rough feeling especially more so in some gears. If that draws a blank, backpedal or pedal on some sort of back wheel off the ground setup and try to spot what rubs to find the culprit. The only one I can think of is the derailer actuator rubbing against the chain but you have already eliminated that, I understand.
#7
Senior Member
Thread Starter
Join Date: Jan 2007
Posts: 58
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I have a Brompton six speed with the Stram T3 instead of Sturmey-Archer hub and of course dual cogs and derailleur system and I can tell you that its prone to skipping and some roughness if the cogs are dirty or the chain is dirty and requires some attention to that area of the drivetrain but I don't think this is the case with your newly installed system. Clownbike might be right that a slightly narrower chain might be required.
where did you get the cogs ? where they from Brompton ? IF so did the vendor help at all in the situation or solutions?
where did you get the cogs ? where they from Brompton ? IF so did the vendor help at all in the situation or solutions?
Anybody here has a six-speed BWR?
#8
Senior Member
Join Date: Jan 2010
Posts: 142
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Have you tried adjusting the limit screws on the thing that pushes the chain over? Is the chain rubbing against it?
The chain is the original one used on the SL-2, with the two gears. Isn't that already the correct width? I ordered the BWR and new cogs online from a Brompton supplier. I haven't asked them for advice yet, as they are only a parts supplier.
Anybody here has a six-speed BWR?
Anybody here has a six-speed BWR?
#9
Senior Member
Join Date: Jul 2007
Posts: 361
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
The chain is the original one used on the SL-2, with the two gears. Isn't that already the correct width? I ordered the BWR and new cogs online from a Brompton supplier. I haven't asked them for advice yet, as they are only a parts supplier.
Anybody here has a six-speed BWR?
Anybody here has a six-speed BWR?
Best thing to do is pick up Park Tool's Big Blue Book. It will help you understand bicycle engineering and how it relates to maintenance and modification. Which comes in handy even if you're not going to be performing the actual work.
#10
Banned
Odd, blissfully ignorant in the early 60's I ran an 1/8" chain 3 cogs in a 3 speed hub,
with a triple chainring set, and never noticed an issue, 40~ 50 years ago.
with a triple chainring set, and never noticed an issue, 40~ 50 years ago.
#11
Senior Member
Thread Starter
Join Date: Jan 2007
Posts: 58
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
#12
Senior Member
Thread Starter
Join Date: Jan 2007
Posts: 58
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Let me put it this way...an 8 speed derailleur system uses a different chain than a 9 speed, etc. And every bike I've ever purchased had a too long chain, which leads to chain slap and possibly funky gear changes. When changing chainrings and cogs/cassettes, the chain length should be adjusted to fit the combo.
Actually, I'm not a newbie; been doing my own bike maintenance for years. I'm very familiar with road and mtb derailleur systems. The Park Tool's Big Blue Book doesn't say anything about Brompton's unique 2-spd derailleur design. :-)
#14
Senior Member
Join Date: Jul 2008
Posts: 1,984
Bikes: Brompton, Dahon Vitesse D5
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 55 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
I've read posts about the 1/8 chain plus derailleur combination being noisy, the reason being the chain isn't laterally flexible enough.
Ah, it was here:
https://www.foldsoc.co.uk/bromptont6.html
Ah, it was here:
https://www.foldsoc.co.uk/bromptont6.html
#15
Senior Member
Thread Starter
Join Date: Jan 2007
Posts: 58
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I've read posts about the 1/8 chain plus derailleur combination being noisy, the reason being the chain isn't laterally flexible enough.
Ah, it was here:
https://www.foldsoc.co.uk/bromptont6.html
Ah, it was here:
https://www.foldsoc.co.uk/bromptont6.html
#16
Senior Member
Thread Starter
Join Date: Jan 2007
Posts: 58
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Thread
Thread Starter
Forum
Replies
Last Post
Training.Wheels
Folding Bikes
3
10-28-12 06:10 PM
chagzuki
Folding Bikes
11
02-12-12 01:11 PM