I recently purchased a new bike (~7 weeks ago). Since day one, it has had an issue with chain slippage. I initially took it back to the bike shop from which I bought it, to be told that it was likely just down to "cables not yet being bedded in" and told to "just give it more time". (I am more than aware that cables don't need to "stretch" once installed; after a ride or two, the only thing that will change is cables/ferrules/etc being properly seated in their housing, and stable)
Given that reaction from the bike shop, I have tried to locate the problem myself.
How the problem presents itself: When pedaling normally, the cranks slip in a way at least similar to chain slippage. Typically, I hear a few single 'popping' sounds as if a part is moving back and then forth, before finally feeling the chain jumping feeling. Note that I only say "feeling" - as it could well not be the chain jumping, but something else which feels like that - the cranks rotate freely through what feels like 1 or 2 cog teeth (from experience), but perhaps it could be the freehub body?
- It doesn't happen during shifting - shifting performance is good
- It doesn't appear to matter which chainring I'm in
- It doesn't appear to matter which end of the cassette I'm in
- It is not caused by cross-chaining (I avoid cross-chaining)
- It doesn't appear to matter whether or not the system is under high load; it still happens when pedalling moderately
- It doesn't happen "regularly" - ie, it isn't every pedal stroke/every chain full revolution/etc. Sometimes it will happen multiple times in quick succession, and other times it will be 10 mins between occurences.
Here are the key facts and what I have noted to try and eliminate possible causes:
- The parts are (of course, being a new bike) all new - no wear on the chain/jockey wheels/chainrings/cassette.
- The parts match - all are part of a Shimano 105 groupset (no aftermarket/3rd party parts, including chain and quick link)
- There are no sticky links in the chain, having checked the entire chain
- The bolts on the chainrings are properly tightened
- The bolts on the derailleur hanger are properly tightened
- The derailleurs are both properly indexed and high and low limit screws are set properly
- The rear derailleur hanger does not appear to be bent
- The chainrings aren't bent and are in alignment
- The cassette cogs aren't bent and are in alignment, and secured properly on the freehub body
Frankly, I'm out of ideas. In the first instance, I am going to take the bike back to the shop to be looked at once more (now that I have "given it more time" as requested, however dubiously). That said, I would still like to understand possible causes of this in case they aren't able to or are unwilling to find the root cause.
What could cause the above-described issue which hasn't been covered off by the above checks?
EDIT: for reference (since it's now relevant having solved this issue): my bike make and model is a Pinnacle Arkose 4 (2016), the groupset is full first-party Shimano 105 and the wheel set has KT hubs.