I only use the big chain ring on the front so I went without a front derailleur for a bit. Then I noticed the chain would fall out (to the pedal side) if I hit a bump or shifted a couple of gears. It seems that the front derailleur also helps in guiding the chain on the ring when not shifting. So it seems I need some sort of light chain guide as I would rather not keep the derailleur there. Does anyone have any recommendations?