Cycling UK Forum

I’m going to suggest something different here as this:

and the whole system goes slack for a slightly more than a split second and then clicks itself back into place.

doesn’t sound like chain suck to me. When it happens is the chain riding on the top of the small chainring’s teeth, before finally dropping into place properly? This is most frequently a problem when shifting down at the front while still using the smaller sprockets at the back. It is quite different to chain suck where the cranks will lock solid.

In terms of suitability the Schwalbe G One Allround Performance tyres I bought a couple of months back would be a good match for that. I am hesitant to fully recommend them though as try as I might I cannot get them to run straight on the rims. Might be me, my 17mm internal width rims or a quality control issue that doesn’t affect you.

You could do the ‘rim transplant’ yourself and then take the wheel to your LBS for them to do the final tensioning and trueing. It would save them a fair bit of labour and hence cut the cost to you. Have a search for how it’s done - as basically you tape he new rim to the old and move the spokes over 1 at a time.

I read, but haven’t checked, that Shimano’s GRX single chainsets are simply double chainsets with the inner ring removed. Meaning, as Brucey says, that the chainline must be wrong in at least one configuration.

Did you change anything else at the same time? I ask as a GRX chainset has a wider ‘q factor’ (distance apart) than a 105 so the opposite should be happening ie your feet should be further from the chainstays.

https://productinfo.shimano.com/#/spec/Gravel/Crankset
https://productinfo.shimano.com/#/spec/ROAD/Crankset

Also, how well is the shifting working at the front - as specifications say you would have needed a new front mech to work with that chainset?

If otherwise good/maintained BBs fail regularly in a bike could it be an issue with the frame? If you can stand the swearing have a look at some of Hambini’s videos on this topic.

Yes, I usually refer to them as ‘specifications’, not standards. And avoid most of them.

Is that tyre inflated in the photos? It might be the way the picture was taken but for a familiar Continental tyre there’s very little sidewall showing - making me wonder if there isn’t something odd about the setup that makes it prone to impact punctures/damage.

BTW the only confusing thing about top swing and bottom swing is how anyone could possibly get it wrong.

It’s confusing because it doesn’t specify what it’s in relation to - the band or the thing being swung (the cage).

Mick’s reference to the RN makes me realise that we could use ‘Port’ and ‘Starboard’, but I guess that’s not useful to everybody...

‘Inside and outside’ might have been a better description. But it might have just led to a different confusion. For L and R you should imagine being stood behind the bicycle looking forwards

It was always ‘top swing’ and ‘bottom swing’ on front mechs that got me. Found it utterly meaningless.

When I was a lad we were taught not to shift to the small ring when in the small sprockets as the chain won’t engage on the small ring. Surprised that the OP wants to make this shift, but also surprised that it doesn’t work on modern high end kit.

This sounds more like it - at least I can see why a manufacturer might choose DOT 5.1 over mineral now. I've used both and, presumably like most others, not had a problem with either. But if I had I can imagine it being sufficiently frightening to want to swap.

Thanks Jd. As cost doesn’t appear to be an issue for the small quantities involved in bicycle brakes I think mineral oil remains my favourite. History and tradition definitely don’t swing it, even though they may explain it.

Is the top jockey wheel too close to the sprocket - meaning the b tension screw needs tightening?

Another thought: how feasible is it to temporarily put some of the sprockets on the freehub in the wrong order, so you can try and isolate whether it’s something about the sprocket, the chainline or the twisting forces on the freehub? I know this means that some down shifts will give you a bigger gear (and vice versa) but it’s just for diagnostic purposes. Incidentally I knew someone who did his once by accident, but he was on day 3 of a stage race so can be forgiven for being a bit tired.