Cross chaining and shifting between chain rings advice

robdabank666

I recently had my rear derailleur get mangled by my back wheel on a ride.

I was approaching a slight hill and after trying to shift down a gear on my rear cassette I realised i had no more gears left on the back and that I was in fact cross chaining. Riding along with my biggest cog on the back and the biggest chain ring on the front. This is not a gear combination I usually find myself in

To get the lower gear that I needed I attempted to shift onto my lower chainring. Immediatly the chain fell off which I heard and sensed immediately, i stopped pedalling straight away and was letting my bike run to a stop at the side of the road to correct this. Whilst slowing down I heard the painful crunching sound of my rear derailleur being caught in the wheel and ripped off the hanger.

This has been an expensive incident for me and I want to as far as possible retrospectively learn from anything I may have done wrong. The gears were serviced before the ride and were changing perfectly smoothly when I tested them and for 40 miles of the ride!

I ride a standard chainset (53-39) on the front and (11-26) cassette on the back.

I don’t believe the gears were set up wrong but I want to try and better understand if it was bad technique or plain bad luck that that caused the chain to come off.

Question 1 - Is changing between your front gears on your chain rings when they are at their extremes (Big chain ring front - Big cog back) and (small chain ring front - small cog back) bad practice. My thoughts are that the angle makes it more likely for the chain to drop off? But is this angle so severe/dangerous that other cyclist completely avoid it by first adjusting the rear derailleur.

Question 2. Although I know cross chaining is something to be avoided on a triple chain set as it causes unnecessary strain and chain wear my understanding was that every gear combination on a standard chain and a compact chainset were available to be used. - is this correct?

Thanks in advance for you input

sungod

1) i'd avoid it, on big-big the chain is a highest tension, shifting at this point increases tension even further as the chain rides up over the teeth before it can drop to the small ring

2) normally best to avoid the two biggest cogs when on the big ring, though if the rd has enough travel and the chain length is ok they can be used without problems - it causes a smidge more wear and is less efficient


depends on the rear mech, but with the chain tension lost the cage may have moved clockwise (seen from driveside), so that the edge moves closer to the wheel axis and of course the spokes - a sram red rear mech with no chain can reach this position

desweller

Sounds like the limit screws on both derailleurs could have done with winding in a bit.

Monty Dog

The fact that your chain unshipped from the front mech and that the rear mech was close enough to get caught in the spokes suggests that neither was set-up correctly. I expect that if you were pushing the gears i.e. high tension means that the chain will take the straight-line option e.g. fall-off.