Please help me out of a senior moment?..Hi/Lo limit screws.......

[Widge]

..............front derailleur? My mtb threw the chain past the small chainring into the frame/BB today.
It hasn't done this for ages. No big deal except cursing and swearing, oily hands and (now) smelly gloves trying to unjam it and sit it back on the ring.

I would like to back up the limit screw a tiny amount to prevent it overshooting again.........

Trouble is....I never know WHICH of the 2 limit screws to turn or which way!!

By the time I've turned them both enough to SEE any movement I've thrown the whole mech out of whack and what should be a 2 minute job becomes a frustrating hour.

Is there any logic to these blessed screws. Is the one nearest the frame the one I need to turn? Which way??

My life would become easier if only I knew.

Thanks in Advance-

w

 

[Rickshaw Phil]

The screws should be marked H and L so you can identify them. Turn the low one clockwise to move the limit closer to the low gear (away from the frame).

I hope this helps. If it continues to throw the chain off when changing down to low range it could be a sign the chain is getting worn.

 

[derrick]

You need one of these,http://www.ebay.co.uk/itm/Deda-Dog-...sure_cycling_bikeparts_SR&hash=item564ecc2013 it won't stop chain coming of but it will help if it does, stops it all getting jammed up.

 

[Widge]

Many thanks......in the event, there were no H or L marks on or near the screws that I could see but I plumped for the screw nearest the frame and turned it c/wise about 1/4 or 1/2 a turn as you suggest and (I think) the cage has moved out a few hairs width.....maybe be enough to prevent the chain falling off in future. Haven't had a chance to properly ride it since yet.

The 'Chain-Dog' looks like a good wheeze - but there is absolutely zero room to mount it below the mech on my bike owing to the rear suspension pivot mount directly above the BB. The derailluer cage (a large plate XT top swinger) takes up the little remaining space. I can see it working well in other scenarios though......perhaps my road bike - although I have not had any problems with dropping the chain on that.

Thanks again

w