>>1201424You really shouldn't need a guide on a road bike but if you do it's just a little piece of carbon with a negligible aero effect. Pro DH riders are doing 2000w out of the gate and yes they constantly mash and shift under power. Shifting the rear under load should never make the chain come off the chainring. I usually go out and intentionally try to destroy me cassette and it's almost impossible for the rear derailleur to knock the chain off.
