Front derailleur won't stay in big ring - it just springs back

I've been trying to sort out this issue with my front shifter/derailleur (not sure which is the problem really) to no avail.

For reference: They're Sachs New Success, downtube shifters, 6 speed, don't know if that matters since it's the front I'm having issues with. I've got a double chainwheel. I have the limit screws adjusted to what looks like the right limits; it shifts into the big ring fine, but it just won't stay there. It springs right back as soon as I let go of the shifter, putting me back in the smaller ring. Is my spring too springy? Cable too tight? Any other ideas?

Thanks!

tighten the nut holding the shifter/lever to the down tube to increase the friction. This is what stops the spring in the derailleur from pulling the cable back

Hmm, alright... it hasn't got a nut, but one of these jobbies:

Was already finger tight, so I stuck an allen key through and used that for a bit more leverage, and uh, now it's sheared off. Am I completely fucked?

that would be the correct technical term, yeas

still, at least the chain won't be jumping from the big to little ring anymore

win!

you can get a new d-wing by buying cheap shifters, or buy a new shifter set. Simplex retrofriction are great and will probably sort out the initial front mech problem too. Sachs, Suntour, Shimano 105. all are cheap. You probably need a new set anyway.

you can get a new d-wing by buying cheap shifters, or buy a new shifter set. Simplex retrofriction are great and will probably sort out the initial front mech problem too. Sachs, Suntour, Shimano 105. all are cheap. You probably need a new set anyway.

Well, yeah... but it'll probably be a right job getting the rest of bolt out of the... whatever you call it, the inside of the thing that sticks out of the downtube.

oh that's what's sheared off!!

will need drilling out, if you drill the inside of the stuck in bolt the outer edge of it will come to bits hopefully saving the thread of the frame braze on

Bit late now but downtube shifters need to be taken off and cleaned every so often. The accumulated dirt can act as a lubrication and reduce the friction.

oh that's what's sheared off!!

will need drilling out, if you drill the inside of the stuck in bolt the outer edge of it will come to bits hopefully saving the thread of the frame braze on

Yeah. Observe:

Did you know a NOS pair of these costs £60? Cause I didn't. I mean, I don't need a new pair, just to sort that bolt out, but I thought I'd check it out. Anyway, is it possible to get at that bolt from the other side of the frame?

Doubt it. Even if the end of the sheared bolt is accessible from the other side of the frame, you're unlikely to be able to do anything with it. Looks to me like it'll have to be drilled out, and the threads re-tapped. If you're really lucky you might be able to get the sheared bolt out using an Easy-Out stud extractor, if the remains of the bolt aren't seized, although Easy Outs tend not to work in most cases in my experience.

or drill a slot on the part bolt and screwdriver it out

try using a screwdriver, tweezers...anything that you might give you a bit of purchase on the sheared end......once the bolt has snapped there's no tension ....and sometimes sheared bolts come out very easily....try before doing anything else.

In the meantime I've also botched my bar tape job. What a shit day. I'm going to ditch this "fixing my own bike" business for the time being and go to the fucking shop.

Sheared bolts will come out easily if it's simply been overtightened. However, it's more common in my experience for them to shear because they're corroded into place, and so won't turn in the threads. And because they won't turn in the threads, they shear when you try and turn them. In that case, quite a lot of effort can be required to get them out.

It's impossible to say whether that's the case here - you can't tell until the bolt's out - but given where it sheared I'd say it's a distinct possibility.

you need a small dia hss drill bit that will drill easily into the remaining diameter with a mm to spare all round, then a stud extractor, like > http://www.screwfix.com/p/screw-extractor-5-piece-set/18643 < this has a counter thread, so as it bites in it starts to wind out the remainder of the bolt.

Well, I'm not doing anything else with it. The mechanic I took it to was of the opinion that easy-outs don't work a lot of the time and thought he'd try the same idea as Hilly Ben, drill a slot for a screwdriver.

And in the meantime, I'll have to source a new bolt, or pair thereof I guess. I have a full New Success group and would like to keep it that way. :/ Seems a bit much to buy a new pair of shifters when all I need is one bolt.