I had some issues with my gears on the road bike yesterday, while climbing in the smaller front chainring the chain kept skipping and wouldn’t stay in gear on the cassette in rings 2-4(ish), but was fine in the largest ring and 5-11. the chain stayed put, but was a bit noisy when in the larger front ring (I suspect the increased chain tension helps). When I put the bike on a stand the gears all work fine so it’s not a simple indexing issue. The chain and cassette aren’t overly worn so what are the possible issues and where should I start (could it be the cable/outer or is it likely to be more sinister/expensive)? Thanks

Id say double check everything. If there is no physical damage visible to the cassette, or links in the chain (doubtful given the symptoms), it could be something really daft. Are the components standard or have you swapped anything? It might be an indexing issue caused by you being on the bike and pedaling, check everything for damage and the hanger is not banged. Check chain alignment too

I’d check the hanger