Shimano triple front derailleur will not shift to large sprocket
#1
Senior Member
Thread Starter
Shimano triple front derailleur will not shift to large sprocket
Hi Folks,
I need some mechanical advice. I am working for a non profit bike group and have run into a problem with a Trek or Gary Fisher mountain bike. It appears to have a Shimano C050 , possibly Allivio, front derailleur that clamps on the seat tube just above the bb, with the derailleur cage above the clamp. So, it appears to be a top swing cage, since there is no evidence of a bb cable guide. There is a black plastic cable routing piece next to the vertical cable clamp. So it appears that the cable comes down from the top tube and attaches straight to the clamp, cirucumventing the entire black plastic routing piece. I cannot get the left triple shifter ( a Shimano shift/brake combo) to shift the cage up to the largest sprocket. There is a new cable, the shifter will click up to the #3 high position, the L and H adjuster screws are OK- but no go. All other parts - crankset, shifters, rear derailleur appear stock with the bike. I tried running the new cable around the black routing piece but absolute no go. Can't figure this one out.
?Not enough tension on the cable wire through the shifter tension adjuster piece ? Wrong front derailleur ? Help !
I need some mechanical advice. I am working for a non profit bike group and have run into a problem with a Trek or Gary Fisher mountain bike. It appears to have a Shimano C050 , possibly Allivio, front derailleur that clamps on the seat tube just above the bb, with the derailleur cage above the clamp. So, it appears to be a top swing cage, since there is no evidence of a bb cable guide. There is a black plastic cable routing piece next to the vertical cable clamp. So it appears that the cable comes down from the top tube and attaches straight to the clamp, cirucumventing the entire black plastic routing piece. I cannot get the left triple shifter ( a Shimano shift/brake combo) to shift the cage up to the largest sprocket. There is a new cable, the shifter will click up to the #3 high position, the L and H adjuster screws are OK- but no go. All other parts - crankset, shifters, rear derailleur appear stock with the bike. I tried running the new cable around the black routing piece but absolute no go. Can't figure this one out.
?Not enough tension on the cable wire through the shifter tension adjuster piece ? Wrong front derailleur ? Help !
#2
Senior Member
Join Date: Feb 2012
Location: Golden, CO and Tucson, AZ
Posts: 2,837
Bikes: 2016 Fuji Tread, 1983 Trek 520
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 676 Post(s)
Liked 741 Times
in
430 Posts
That sounds like a dual pull set-up. With top pull, you don't use the pulley.
Have you tried manually pulling the cable, see if you can get it to shift?
If the high limit is adjusted all the way out and it's not shifting, maybe the chain line was messed up with an improperly sized bottom bracket or spindle. Does it look like excessive clearance between the crankset and the chain stay?
Have you tried manually pulling the cable, see if you can get it to shift?
If the high limit is adjusted all the way out and it's not shifting, maybe the chain line was messed up with an improperly sized bottom bracket or spindle. Does it look like excessive clearance between the crankset and the chain stay?
#3
Senior Member
Thread Starter
Hi
Yes, when you pull the wire on the top tube by hand it does shift up to the large sprocket. Will check the shifter, bb,etc, again today.
Yes, when you pull the wire on the top tube by hand it does shift up to the large sprocket. Will check the shifter, bb,etc, again today.
#4
Senior Member
Join Date: Feb 2012
Location: Golden, CO and Tucson, AZ
Posts: 2,837
Bikes: 2016 Fuji Tread, 1983 Trek 520
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 676 Post(s)
Liked 741 Times
in
430 Posts
I think the best way to diagnose shifting problems is to check all components separately. As obvious as this sounds, it seldom gets done. An easy way is to manually shift into the large chain ring, stop pedaling, click the shifter into low, then you should be able to pull a cable housing out of a slotted frame stop. Now everything is separated and you haven't messed up the current cable adjustment. You can move housings to inspect and clean the cable, manually check limit screws, and check the shifter operation with no load on it.
Make sure your shifter is making two firm clicks with an equal pull on the cable.
Make sure your shifter is making two firm clicks with an equal pull on the cable.
#5
Junior Member
Has the shifter been replaced. Have you inspected it for issues?