Crashed due to chain/derailleur fault.

[Nigelnaturist]

On a different tack, I had a Gitane back in the 80's that had the gear levers on the head stock, nice idea, until you knocked the rear lever with your knee. usually went from 2nd to 5th result tarmac sandwich.

 

[HovR]

If the down tube shifters are friction, then you should be able to swap for a 7. Axel width should be 126mm, it's now 130mm for 8-11 speed systems

Not sure about OP's bike, but I know the more modern splined 7 speed freewheels are too wide for my Dawes. Might work if he can find a 2 notch version, though I'd be more inclined to stick with 5 or 6 speed.

 

[monkeylc]

yes

 

[sidevalve]

Nothing wrong with 5 speed. As many have said before it's the range of gears more than the sheer number that counts.

 

[Deleted member 1258]

Replace the freewheel and chain, but check the width of the frame first, I recon you would get a 6 speed in but you might find it difficult to get a 7 speed in. Also how worn are your chain rings?

 

[little dilbert]

Update:

Set off today and the same thing happened, fortunately I had the chance to take a picture of the problem. The problem is the chain is literally riding over the top of the cog and not meshing (as seen in the attached pictures), so it's not a problem with the freewheel mechanism.

The freewheel and the chain have been looked over at a bike shop and there is 'some' wear on them, but generally they are OK.

Does this suggest the chain is too loose, or is there anything else to consider?

TIA

 

[addictfreak]

Last time I had a similar problem it was down to wear. I changed cassette, large chainring and chain, problem solved.

 

[Deleted member 1258]

Your freewheel is worn, it shows up on the bottom photo, you may need to replace it, the only other thing to do is to have a play with the inner limit screw, it might need adjusting.

 

[little dilbert]

Your freewheel is worn, it shows up on the bottom photo, you may need to replace it, the only other thing to do is to have a play with the inner limit screw, it might need adjusting.

What's the inner limit screw?

 

[Deleted member 1258]

What's the inner limit screw?

If you look at your bottom photo there are two screws on the top of the changer, one is the outer limit screw and one is the inner limit screw, they limit how far across the freewheel the chain goes, on the inner limit screw if its too tight you wont get bottom gear, if its too loose your chain is likely to go into the spokes. Have a look at this video and see if it makes things clearer

View: http://vimeo.com/20216647

 

[little dilbert]

If you look at your bottom photo there are two screws on the top of the changer, one is the outer limit screw and one is the inner limit screw, they limit how far across the freewheel the chain goes, on the inner limit screw if its too tight you wont get bottom gear, if its too loose your chain is likely to go into the spokes. Have a look at this video and see if it makes things clearer

View: http://vimeo.com/20216647

I will certainly have a look at this, thanks!

 

[fenlandpsychocyclist]

Hmmm?? Looking at the photo i can see the chain guide is quite loaded.
I don't suppose you have the chain "crossed", with it on the largest chainweel at the front
and largest at the rear?
I know my cheap and nasty 2010 coyote everglades road bike will throw its chain off the
largest front chainwheel if i go into gears 1/2/3 on the rear, where a road bike three times
the cost like my Trek isn't bothered at all by poor gear use.

 

[little dilbert]

Hmmm?? Looking at the photo i can see the chain guide is quite loaded.
I don't suppose you have the chain "crossed", with it on the largest chainweel at the front
and largest at the rear?
I know my cheap and nasty 2010 coyote everglades road bike will throw its chain off the
largest front chainwheel if i go into gears 1/2/3 on the rear, where a road bike three times
the cost like my Trek isn't bothered at all by poor gear use.

Yes, the chain at the time of this picture was crossed (largest front and rear).

------------------------------------------------------------

EDIT - I have just been experimenting with it and you are quite right, when the chain is 'crossed', the chain guide is always in the fully loaded position, when the chain is uncrossed the chain guide moves back to an unloaded position.

I think you may have solved the problem. Simply, I was never aware that certain configurations of gears were usable, and neither did I notice the problem with a fully loaded chain guide. So, I'll see how this goes, but I think it looks promising.