In our Tech Q&A series, we tackle cycling queries big or small, complex or simple with insights from the BikeRadar team and trusted industry experts. Next up, a reader wants to know why his gears are shifting when he pedals backwards. Im finding the chain shifts through the cogs when pedalling backwards. Whats going on? Raf, via email This isnt uncommon on both 2x and 1x systems, as anyone who has used a plastic chain-cleaning tool will know. Simon von Bromley explains that there can be a number of reasons for it. Cross-chaining may cause your gears to change when pedalling. Steve Sayers / Our Media First, if youre cross-chaining (riding with the chain on the smaller chainring and smallest sprocket, or larger chainring and largest sprocket), its likely to happen because the chain and cogs arent designed to work in those combinations. A misaligned rear derailleur could be the culprit. Scott Windsor / Our Media It could also be caused by a misaligned rear derailleur even the slightest twist in the derailleur hanger can leave the chain not sitting correctly on the cassette, making it liable to shift and move unpredictably. Next, the range of movement and chainline angles on a 1x drivetrain sometimes makes it impossible to back-pedal smoothly. Some chainlines make pedalling backwards less smooth. Stan Portus / Our Media This is particularly true if a wide-range cassette is used on a bike with short chainstays. Check your freehub to see if it spins smoothly. Ben Delaney / Our Media Finally, it can also be symptomatic of a sticky freehub. If the freehub bearings are becoming gritty and worn, it can stick, which stops the chain running smoothly especially if youre pedaling backwards. The answer is to keep an eye on all of these things and try to avoid cross-chaining. Its not usual to need to back-pedal for any length of time, except when applying chain lube.