I suppose my question is actually ‘what is the point’ of Top Swing front mechs.

IME they are more finicky to set up, go sloppier more quickly and, most importantly, harbour clag much more than a conventional front mech.

So, what advantages to they bring that I’m missing?

would it not be down to routing options…?

No, that’s top v bottom PULL.

Top swing is to fit some full sussers and the like where there are clearance issues. If you have plenty space above the level of the mech cage bottom swing is much better.

some frame designs, particularly full sus mean that the clamp needs to be lower, so you’re limited to either a top swing or e-type.

No, that’s top v bottom PULL.

And most mechs can handle both

Top swing is to fit some full sussers and the like where there are clearance issues.

That’s the theory isn’t it, but they seem to be standard on most new bikes. My Mrs’s new bike came with one, and it’s a bog standard hardatil frame (hence the mild rant, as it kept getting bunged up when we were riding in the mud yesterday)

Piss poor design IMO neccesitated by piss poor FS designs that don’t allow a normal mech to be used.

No reason for it to be used on a hardtail though, but I imagine you’d have trouble trying to get the dealer to change it.

full sus frame design or hardtail bottle mount location.

top swing is a lot neater and the top pull cable routing is nicer to, so it looks better on a showroom bike, hardtail or otherwise.

some are evidently essential due to frame design

however they are disabled by a bit of mud or a beechnut.

I have had a few frames that can only accept top swing – which is obviously why they exist. As a result I have got used to them and always use them – never had any trouble.

I did wonder if the mechanically simpler bottom swing setup might actually work better and bought one when I built up a hardtail recently – but god knows how the allegedly “dual pull” M961 I bought would actually work for top pull, I gave up in the end and went top swing M952 – back to what I know…

Are bottom swing really that much better?

Some hardtail frames need a top swing. Boardman 18″ hardtails (pre 2011 ones anyway) need a Shimano top swing as the band clamp on a conventional needs to sit right where the lower water bottle boss is. SRAM must have a lower drop on conventional swing as they seem to fit a treat!

Cable runs can affect as well – a scandal has a front mech cable stop which is angled towards the right hand side of the bike – if the cable clamp is on the left (as on most top swings I’ve seen), the cable pulls at a crazy angle out of the end of the outer/stop. Hence need to use a conventional swing dual pull front mech.

EDIT – also meant to add that I prefer to use conventional whenever possible – the cage is stiffer and they last FAR FAR longer than top swing. I find top swing do have a lighter feel at the shifter end of things though.

Also, there are probally more top swing about now as for the companies making mechs, they can make a whole pile of top swing mechs with shims to fit different size seatposts (like most lower end shimano) and thus sell cheaper thru economies of scale, and bike shops only have to stock a couple models.

Otherwise you get the situation of “I need a new XT mech”

“certainly sir, top swing or conventional? And what seatclamp size?” = many many combos!

the last few conventional swings i’ve had have been dual pull and come with adaptors for difference seat tube sizes.

Conventionals are far far better. The design is simpler, and the spring prevents any pivot slop manifesting itself as a rattle. The shape of the swing means they stay closer to the rings, so shifting granny to middle is far better. And they never ever get clogged.

Beats me why any manufacturer would use a top swing mech for a hardtail. Guess it just leaves more space for writing on the frame..

I’ve tried both types on my (new!) hardtail and cannot tell any difference. So I think I’ll stick with top swing as it makes everything nice and neat.

I don’t get why there’s so many standards here, so I guess that Giant will come up with a new one very shortly.

Some hardtail frames need a top swing. Boardman 18″ hardtails (pre 2011 ones anyway) need a Shimano top swing as the band clamp on a conventional needs to sit right where the lower water bottle boss is.

Surely that’s down to poor design/siting of the bottle bosses? It’s hardly like they’re a structural component that needs millimeter perfect positioning.

indeed

Surely that’s down to poor design/siting of the bottle bosses?

Indeed it is. But as an end user it means you have to use a top swing. It would be great if everything in the world could be cross compatible….