pbcsd

Have a really old but almost brand new (hardly used) Diamondback Topanga at our cottage equiped with SRAM shifters and Shimano parts.

Have an issue where I can't get the bike to shift onto the larger gear. If I shift and hold the shifter down,the derailleur properly shifts the chain to the larger gear. However,as soon as I let go of the shifter the derailleur loosens and the chain gets pushed back to the smaller gear.

Can't seem to figure how out to fix this issue? Any assistance would be greatly appreciated!

J.Higgins 

Sounds like you need to tighten the tension on the shifter. Google your shifter brand/model, and it should lead you to the process of adjusting that.

maddog34

describe the type of shifter on your bike, please... one lever with clicks, or no clicks? two click type levers? twist type, around the bars?

pbcsd

Just got home so will get back to it Saturday.

Each shifter has 2 levers. No clicks. Around the bars. Shifters do not show what gear the bike is on.

cny-bikeman

There should be a wingnut or screw going through the pivot of the shift lever. Just tighten that down enough so that the derailleur stays in place. If the lever does not stay tensioned there may be a part missing, broken or assembled incorrectly.

dedhed

If it's an old "click" shifter spray some WD-40 inside and work it back and forth. Often the old grease hardens up and the pawl that should catch is sticking.

If it's a friction (no clicks) shifter, you need to tighten the pivot.

Eririn07

try to adjust the cable on the front derailleur. if it still happen, maybe your shift cable already worn out

fietsbob

return spring pulls to the inside, so cable is slipping.

pbcsd

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pbcsd

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pbcsd

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pbcsd

So tighten the cable attached to the derailleur in the first pic?

cny-bikeman

The pics help. It could well be that you just have to increase the cable "tension" by turning the adjustment knob on the lever that the cable housing is inserted into so that the cable is tighter before you shift. Also, your front derailleur may be mounted too high, and you should also make sure the cage is parallel to the chainrings when viewed from the top down. Finally, it's possible there's a problem with the shifter itself.

theunartist

If no clicking on your shifters hopefully this is the problem...

youtube.com/watch?v=AKLejn7f_Po

I'm really not allowed to post links etc. but this might work, the related videos are also helpful...

Bill Kapaun

So your pics show a FRONT DER and a REAR shifter?
You might elaborate on the supposed connection.

pbcsd

Front and rear shifters look the same to me?

Tried cleaning it per the video, same issue. Tightened the cable, didn't work.

The rear shifter does have clicks, while the front one doesn't click. Maybe that's the issue as it just won't stay when I shift to the middle or highest gear.

So maybe the shifter is just shot?

pbcsd

Sorry, deleted the additional posts I spammed this thread with and now can't post pics again until I hit 10..

pbcsd

Will post the front shifter pic shortly, but looks identical to the rear shifter.

Bill Kapaun

Just trying to make sure we're talking about the FRONT is all.

Repeat flushing up to 2 more times before giving up.
Sometimes it takes that long to get enough grease dissolved to release things.
After flushing, work the lever up as far as you can push and then-
SLOWLY let it back down. Repeat 5-6 times.
That gives the pawl more "time" to engage. Once it starts, things get better fast.

dedhed

^^^^^ Be generous. Get the red tube in as many spots as you can. If the shifter has a cover you can pop off so much the better. I've been known to use half of big can on a shifter.

Trevtassie

Yep, that grease has been in there for more than 20 years. It'll take a while to soften. Drown it in spray. Keep going, because those shifters are better than any new 7 speed you will buy nowadays.

pbcsd

Okay, will keep trying. Top doesnt pop off unfortunately.

Have done it about 4 times now, front shifter in particular just has zero catch/clicking to it.

Trevtassie

Undo the top allen bolt. The shifter will drop off the brake perch. Then undo the screw holding the plastic cover on the bottom. This will expose the innards. You should be able to see the pawl and manipulate it with a little screwdriver. It should flick freely. I have had to pull the circlip off and remove the pawl to grease the shaft it pivots on. Fiddly, but possible.

xenologer

Tip:
rather than undo the circlip and remove the pawl (risk of tiny parts going flying)
I've had luck heating the pawl with a lighter to liquefy the solidified old grease jamming it up, then wicking new oil into it.

onbike 1939

This is sometimes caused by the "H" screw on the FD being a little too tight to allow the chain to remain on the large ring. Unscrew the "H" a quarter of a turn usually fixes this.