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front shifting (not!)

Old 09-29-11, 11:36 PM
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greenmonstr
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front shifting (not!)

I recently got an old Burley Django SWB and noticed the shifting wasn't great on the front chainrings, especially going from middle to big ring. The bike had newish 8 speed Shimano trigger shifters and a shimano sora road 8 spd front derailleur, and a middle of the road mountain crank (with a bigger jump from middle to 44 tooth big ring than from the small 22 to middle). The FD shifting down to the small chainring was no problem....but it seemed to take forever (and considerable pressure on the trigger to get to the big ring. New chain and cassette did not improve things. I did some research.. Aha! Shimano trigger shifters were never meant to move a road FD. I had a compatible XT mountain FD and had it installed at the LBS....ack....shifting is still not great, chain only wants to move from the middle to the big ring if i'm in the higher gears of the rear derailleur when i shift the FD) Any ideas?...would it help to change the cranks to a closer range, or change the shifters to some old XTs? Or is this just a common problem with recumbents and mountain bike triples that I need to come to terms with (and plan my shifts a few kms in advance) Surely not ?
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Old 09-30-11, 06:42 AM
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Originally Posted by greenmonstr View Post
... chain only wants to move from the middle to the big ring if i'm in the higher gears of the rear derailleur when i shift the FD) Any ideas?...would it help to change the cranks to a closer range, or change the shifters to some old XTs? Or is this just a common problem with recumbents and mountain bike triples that I need to come to terms with (and plan my shifts a few kms in advance) Surely not ?
22 little ring, 44 big ring which should mean you have a 32 middle ring. Not that big a jump in my opinion, and pretty standard.

chain length too short? got to have enough chain to be able to shift to the big/big. one chain length can make all the difference in the world. easiest/cheapest to check out and fix.

short throw (i.e. road) RD? needs to be able to handle all that chain to go from the little/little to the big/big rings. hmm road trigger shifter - can it handle the long throw/mountain RD?

chain rings actually parallel and not angled? I'd think you'd have noticed that already.

older bike.... sure someone hasn't gotten the chain line wrong? return roller missing, that might affect how the chain is behaving.

Hope this gives you some ideas.
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Old 09-30-11, 08:30 AM
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Just as an observation, if it had a road derailleur and a mountain crankset, then the previous owner did some parts-swapping. There's no telling what was done incorrectly to cause the current problems.

Take the chain off and see if it shifts to the correct places. Do adjustments as necessary, including derailleur positioning on the tube. Then re-install the chain. Make sure you have enough chain to span the big/big combination.

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Old 09-30-11, 11:46 AM
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In my (very limited) experience, trigger shifters never worked very well on the front derailleur. Now I have a recumbent with twistgrip shifters and the front shift is miles better. The bike's an LWB so the chain run is much longer than earlier bikes and hence smaller chain angles, which might make a difference as well as the shifters.
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Old 09-30-11, 08:54 PM
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Jeff Wills
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Originally Posted by greenmonstr View Post
I recently got an old Burley Django SWB and noticed the shifting wasn't great on the front chainrings, especially going from middle to big ring. The bike had newish 8 speed Shimano trigger shifters and a shimano sora road 8 spd front derailleur, and a middle of the road mountain crank (with a bigger jump from middle to 44 tooth big ring than from the small 22 to middle). The FD shifting down to the small chainring was no problem....but it seemed to take forever (and considerable pressure on the trigger to get to the big ring. New chain and cassette did not improve things. I did some research.. Aha! Shimano trigger shifters were never meant to move a road FD. I had a compatible XT mountain FD and had it installed at the LBS....ack....shifting is still not great, chain only wants to move from the middle to the big ring if i'm in the higher gears of the rear derailleur when i shift the FD) Any ideas?...would it help to change the cranks to a closer range, or change the shifters to some old XTs? Or is this just a common problem with recumbents and mountain bike triples that I need to come to terms with (and plan my shifts a few kms in advance) Surely not ?
Trigger shifters and oddball arrangements like yours require considerable tweaking before they really work well. At a guess, I'd say the rotational adjustment of the derailleur is off. The tail of the derailleur needs to move a little outward, or the whole derailleur needs to move downward, or you need to back off on the cable tension a bit. Or all 3.

FWIW: I've had trigger shifters with road-style cranksets and the compatible Shimano front derailleur on my Easy Racer bikes for nearly a decade now. Once they're right, they work perfectly: https://home.comcast.net/~jeff_wills/...-grr%20008.htm
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Old 09-30-11, 11:09 PM
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Thanks for your suggestions! The shifters are Alivio mountain triggers, ok Shimano stuff from a few years ago, and the right shifter works perfectly with the Deore rear derailleur - hmmm at the risk of raising the ire of any lurking Campophiles, is there any difference between this and the Campy 10 on my road bike...? Well, I guess not much bling, more weight, and two less gears out back....still gets me down the road.....lol.
The idler is intact, in fact the rest of the bike is in perfect shape, just the chain and cassette were worn and I think they are both original stock parts (Sunrace cassette, anyone?) so the bike may have about 1000 to 2000 miles on it. The previous owner told me she couldn't get the chain up on the big ring either, and so had switched from twistshifters to triggers to try to solve the problem. You know, that may be a clue. I wonder if the chain length was too short all along...I cut it to same length that was on the bike already, so just maybe that's the explanation. Or maybe it is the rear D......
I'll have a go at it tomorrow and let you know if I have any success!
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Old 09-30-11, 11:53 PM
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The chain should be long enough to go around the big chainring and the big cog, around any idlers, without going through the rear derailleur, plus about one link. If it's too short, you'd absolutely have problems getting onto the big chainring while on the big cogs.
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Old 10-01-11, 06:01 AM
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Sheldon Brown web page has some excellent articles that may help you track down the problem. However, I differ on one point with Sheldon and Jeff Wills. When I set the chain length, I run the chain through the derailer. I've found (at least on bents I've had before) that not going through the derailer usually left me short when trying to get to the big/big cobmination - and I like to be able to use every gear combination.

https://sheldonbrown.com/gearing/index.html

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Old 10-02-11, 05:20 PM
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I tweaked the shift cable tension a bit and the front shifting is a little better now (and much better than with the Sora FD). The remaining problem seems to be the throw on the Alivio front (or left) trigger, when moving from the middle to the big ring. It isn't stuck in position, or gunked up (though I did give it a couple of squirts anyway). It does eventually click into place. But the throw is gigantic, if i didn't have big hands I would be in serious trouble! Some of that is accounted for by the size of the jump from middle to big ring. However, I have read other posts indicating that XT has a shorter throw than some lower end mountain groups. Old 8 speed XT turns up from time to time....might be worth trying! Or...maybe mix up a flatbar road shifter/FD with a mountain rear shifter/RD? Might not be too aesthetically pleasing but all i care about are quick shifts.....
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Old 10-02-11, 05:24 PM
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Originally Posted by greenmonstr View Post
I tweaked the shift cable tension a bit and the front shifting is a little better now (and much better than with the Sora FD). The remaining problem seems to be the throw on the Alivio front (or left) trigger, when moving from the middle to the big ring. It isn't stuck in position, or gunked up (though I did give it a couple of squirts anyway). It does eventually click into place. But the throw is gigantic, if i didn't have big hands I would be in serious trouble! Some of that is accounted for by the size of the jump from middle to big ring. However, I have read other posts indicating that XT has a shorter throw than some lower end mountain groups. Old 8 speed XT turns up from time to time....might be worth trying! Or...maybe mix up a flatbar road shifter/FD with a mountain rear shifter/RD? Might not be too aesthetically pleasing but all i care about are quick shifts.....
If the shifter is older, they grease inside is probably dried up and gummy. This is very, very common with Shimano trigger shifters. Try hosing out the internal parts with spray oil- WD-40 works in a pinch, but it tends to gum up on its own. Work the shifters around a bunch while spraying and it should improve.
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Old 10-02-11, 08:07 PM
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The number of teeth difference between rings does not affect how far you have to move the derailleur to shift. That is determined by the spacing between rings. I had some early SX trigger-type shifters that required a huge amount of lever movement in order to shift. Although I liked how the rear shifted, I was never happy with the front shifting and eventually went back to twisties.
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