Shimano GRX (or other): is it top pull compatible?
12-29-19, 12:18 PM
#1
Senior Member
Thread Starter
Join Date: Mar 2017
Posts: 95
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 50 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
Shimano GRX (or other): is it top pull compatible?
Hello, I have Planet X XLS bike, it has top pull and I use now FD-CX70. Want change my crankset to new GRX 46/30 and probably will have to change also FD because change in chain line.
So the question: is the new GRX FD compatible with top pull? I can't find answer on Shimano bike parts website. According to this website, FD-R8000 and FD-R7000 (so Ultegra and 105) ale dual pull, but not sure that, because didn't use them.
So the question: is the new GRX FD compatible with top pull? I can't find answer on Shimano bike parts website. According to this website, FD-R8000 and FD-R7000 (so Ultegra and 105) ale dual pull, but not sure that, because didn't use them.
12-29-19, 12:30 PM
#2
Senior Member
Join Date: Aug 2005
Location: Pittsburgh, PA
Posts: 33,656
Bikes: '96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '20 Surly Midnight Special, All are 3x10. It is hilly around here!
Mentioned: 39 Post(s)
Tagged: 0 Thread(s)
Quoted: 2026 Post(s)
Likes: 0
Liked 1,096 Times
in
742 Posts
I don't think Shimano road front derailleurs are dual pull but here's a gadget that will solve your problem: https://problemsolversbike.com/produ..._clamp_-_17312
12-29-19, 12:50 PM
#3
Senior Member
Thread Starter
Join Date: Mar 2017
Posts: 95
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 50 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
I know this - my bike had something like this in orignal configuration but I removed that and mounted CX70 with top pull because... it doesn't work. Some mud and FD never worked as should.
12-29-19, 01:23 PM
#4
Senior Member
Join Date: Jan 2013
Location: Llano Estacado
Posts: 3,702
Bikes: old clunker
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 684 Post(s)
Likes: 0
Liked 105 Times
in
83 Posts
A "top push" setup with a length of housing is a better way to convert a bottom-pull FD -- simpler, less friction, less fouling.
12-30-19, 12:05 AM
#5
Senior Member
Thread Starter
Join Date: Mar 2017
Posts: 95
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 50 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
Exactly, and with top pull CX70 it works much, much better than with bottom pull FD and pulley. So, I'm looking for information: can I use FD from GRX group using top pull?
12-30-19, 12:57 AM
#6
Really Old Senior Member
Hello, I have Planet X XLS bike, it has top pull and I use now FD-CX70. Want change my crankset to new GRX 46/30 and probably will have to change also FD because change in chain line.
So the question: is the new GRX FD compatible with top pull? I can't find answer on Shimano bike parts website. According to this website, FD-R8000 and FD-R7000 (so Ultegra and 105) ale dual pull, but not sure that, because didn't use them.
So the question: is the new GRX FD compatible with top pull? I can't find answer on Shimano bike parts website. According to this website, FD-R8000 and FD-R7000 (so Ultegra and 105) ale dual pull, but not sure that, because didn't use them.
12-30-19, 04:32 AM
#8
Senior Member
Join Date: Jan 2013
Location: South Jersey
Posts: 2,266
Mentioned: 18 Post(s)
Tagged: 0 Thread(s)
Quoted: 714 Post(s)
Liked 800 Times
in
475 Posts
GRX cranksets put the chainrings 2.5mm further outboard with the proper BB. This is not a square taper crankset.
OP - Sram makes a wide spacing braze on clamp that spaces the front derailleur out 2.5mm. If your CX70 is a braze on, you could use that clamp and continue to use the CX70 with the GRX crankset. https://www.amazon.com/SRAM-Braze-Ad...JB02TKBTY6K9ZP
OP - Sram makes a wide spacing braze on clamp that spaces the front derailleur out 2.5mm. If your CX70 is a braze on, you could use that clamp and continue to use the CX70 with the GRX crankset. https://www.amazon.com/SRAM-Braze-Ad...JB02TKBTY6K9ZP
12-30-19, 11:01 AM
#9
Senior Member
Join Date: Jan 2017
Posts: 1,064
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 350 Post(s)
Likes: 0
Liked 122 Times
in
90 Posts
If you use MTB BB cups instead of Road BB cups, you can move the cranks 1mm inward on each side. You'll have to shave the plastic water sleeve, which is easy to do. You'll have to check the splines at the end of the spindle are long enough to eat the excess 2mm that the left crank arm will have to go further into before bottoming out.
Then if you add a couple millimeters of chainring spacers, you could move both chainrings to the original chainline that you previously had.
However, these are all theoretical. I've never seen a GRX crank, so I don't know if this actually works.
Then if you add a couple millimeters of chainring spacers, you could move both chainrings to the original chainline that you previously had.
However, these are all theoretical. I've never seen a GRX crank, so I don't know if this actually works.
12-30-19, 11:12 AM
#10
Really Old Senior Member
GRX cranksets put the chainrings 2.5mm further outboard with the proper BB. This is not a square taper crankset.
OP - Sram makes a wide spacing braze on clamp that spaces the front derailleur out 2.5mm. If your CX70 is a braze on, you could use that clamp and continue to use the CX70 with the GRX crankset. https://www.amazon.com/SRAM-Braze-Ad...JB02TKBTY6K9ZP
OP - Sram makes a wide spacing braze on clamp that spaces the front derailleur out 2.5mm. If your CX70 is a braze on, you could use that clamp and continue to use the CX70 with the GRX crankset. https://www.amazon.com/SRAM-Braze-Ad...JB02TKBTY6K9ZP
OP doesn't say IF they tried.
12-30-19, 11:22 AM
#11
Occam's Rotor
Join Date: Jul 2013
Posts: 7,248
Mentioned: 61 Post(s)
Tagged: 0 Thread(s)
Quoted: 2366 Post(s)
Liked 2,331 Times
in
1,164 Posts
I didn't, with my Ultegra Di2 front derailleur. I did have to slide it down a bit, and crank on the H-limit screw to adjust for the chainline, but it has been working fine.
According to Shimano's website, the GRX front-derailleur is down-pull (only) and braze-on mount only.
So, based on my experience, I would try it with the current derailleur first. (The other option is to get a 46/30T crank that doesn't offset the chainline.)
Last edited by Cyclist0108; 12-30-19 at 12:04 PM.
