Mixing Tiagra and 105 - but not your standard mixup

[Holio cornolio]

So, possibly not the usual groupset mixing question, but earlier this year I snagged a Tiagra mini groupo from ebay for quite cheap. It was in as new condition and worked fine for a couple of thousand km. However unfortunately the front (left) shifter failed after a long stint of towpath riding in Birmingham, when I was constantly shifting from big ring to little ring over the canal bridges. I managed to fix it (they're tricky little buggers those 4700 shifters) but the tiny pawl that engages with the upshift ratchet is sticky and no amount of lube will loosen it. Anyway, I could go on at length about it, but the upshot is, I need to replace my left lever because I can't keep hitting the lever with the heel of my hand every time I want to shift back to the big dog (the other option would be to never leave the big ring, but I've tried that, and it hurts).
Being a man of meagre means, I have been trawling ebay for a suitable left lever, and there are scores of 105 levers available (many fewer tiagra levers and I'm wary of them now). I have no problem with mixing a tiagra right lever and a 105 left lever, I'm not a princess, but my only reservation is that tiagra 4700 on the right will feel different under my hand than the 105 (5700 or 5800) on the left. I don't mean in terms of action, I mean dimensionally. I ride on the hoods 90% of the time so would want them to be the same shape...
So does anyone know if tiagra 4700 is the same shape lever hood as 105 5700 or 5800?
Thanks in advance

(that was a very roundabout way to ask a very simple question...)

 

[Pumpkin the robot]

It looks a similar shape to the 5700. I will try it later on as I have 5700, and the bike shop next door has a genesis vapour fitted with 4700.

 

[Holio cornolio]

Thanks. Just been doing a bit more reading, not sure if 5700 FD is compatible with 4700, since 4700 has the longer arm on the front derailleur and so maybe different cable pull?

 

[Pumpkin the robot]

I was just thinking the same thing.

 

[Racing roadkill]

Thanks. Just been doing a bit more reading, not sure if 5700 FD is compatible with 4700, since 4700 has the longer arm on the front derailleur and so maybe different cable pull?

They are exactly the same

 

[smutchin]

From the official Shimano compatibility chart...

...which suggests you probably also need a new front mech (FD4600) if you're changing the shifter from 4700 to 5700.

Full document here: http://productinfo.shimano.com/download/pdf/com/1.8/en

 

[Pumpkin the robot]

They are exactly the same

Not according to shimano. The pull is closer to the new 11 speed than the old 10 speed.

 

[smutchin]

As for the look and feel of the Tiagra lever compared to the 105, I've used both but couldn't honestly tell you if they're any different. They look close enough to me that I wouldn't worry about the swap on aesthetic grounds.

I would, however, warn you that the 5700 LH lever is known for having problems of its own - I had to replace one after a pawl snapped during regular use. I tried taking the lever apart to see if I could fix it myself but it's just a tiny plastic piece, and spares are not available. My reading tells me I'm far from being the only person who has suffered this problem. I replaced it with a 6700 Ultegra lever, which is still going strong several years later. If you can pick up a secondhand 6700 lever reasonably cheaply, I would advise going for that instead of the 105.

 

[Holio cornolio]

Interesting. A bit more research suggests that there's nothing technical to distinguish 5800 and 4700 left levers at all...
The pawl in mine hasn't snapped, but the teeny spring that returns it against the ratchet isn't strong enough to overcome the friction of the pawl on it's pin (or spindle or whatever its called). A tonne of lubricant kept is shifting over the summer, but the first wet ride of the winter had it back to non shifting status. If 105 and Tiagra have the same internals it sounds like the sensible option would be to buy new and hope that I can rely on a warranty.

 

[Racing roadkill]

As for the look and feel of the Tiagra lever compared to the 105, I've used both but couldn't honestly tell you if they're any different. They look close enough to me that I wouldn't worry about the swap on aesthetic grounds.

I would, however, warn you that the 5700 LH lever is known for having problems of its own - I had to replace one after a pawl snapped during regular use. I tried taking the lever apart to see if I could fix it myself but it's just a tiny plastic piece, and spares are not available. My reading tells me I'm far from being the only person who has suffered this problem. I replaced it with a 6700 Ultegra lever, which is still going strong several years later. If you can pick up a secondhand 6700 lever reasonably cheaply, I would advise going for that instead of the 105.

Bang on. All the Shimano brifters are a bit cack, but the Ultegra 6800 isn’t quite so cack.

 

[Holio cornolio]

^ well this is frustrating. It seems that as far as compatibility goes, Tiagra 4700 is exactly the halfway house between 105 5700 and 5800, so broadly compatible with neither. I suspect that the Tiagra 4700 FD will work with 105 5800, and probably ultegra 6800, but not 5700 or 6700. So if 4700 and 5800 front levers are the same, and only 6800 represents a step up in reliability then that would be the (expensive) way forward. It's almost like Shimano planned it that way...

Seriously though, there must be a lot of bikes out there running tiagra 4700 and 105 5800, are failures really that common? Am I being unnecessarily paranoid about the likelihood of a second lever failing? I want to believe I'm just unlucky with this one lever.

 

[Racing roadkill]

^ well this is frustrating. It seems that as far as compatibility goes, Tiagra 4700 is exactly the halfway house between 105 5700 and 5800, so broadly compatible with neither. I suspect that the Tiagra 4700 FD will work with 105 5800, and probably ultegra 6800, but not 5700 or 6700. So if 4700 and 5800 front levers are the same, and only 6800 represents a step up in reliability then that would be the (expensive) way forward. It's almost like Shimano planned it that way...

Seriously though, there must be a lot of bikes out there running tiagra 4700 and 105 5800, are failures really that common? Am I being unnecessarily paranoid about the likelihood of a second lever failing? I want to believe I'm just unlucky with this one lever.

I’ve got four levels of Shimano Brifters / GS on various bikes, from Sora, through 4700 Tiagra, then 105 5700, and finally Ultegra 6800, The fragility of the Brifters is uniformly poor, except for the 6800, which hasn’t let me down as yet.

 

[smutchin]

Seriously though, there must be a lot of bikes out there running tiagra 4700 and 105 5800, are failures really that common? Am I being unnecessarily paranoid about the likelihood of a second lever failing? I want to believe I'm just unlucky with this one lever.

No, I don't think failures are common, but the problem with my lever was AIUI a known design flaw that made breakage more likely. Something to do with the high tension involved in front gear changes, which meant you were putting a lot of stress through the mechanism with each upshift. I imagine solving that problem is one of the reasons for changing the cable pull ratio, so it's probably not an issue with the latest Tiagra.

As it happens, I have just realised that I made a mistake - my lever that broke was the 5600, the first generation of 10-speed 105, which had the 'clothes line' cable (coming out of the side of the lever). And it would have been the 6600 Ultegra lever that I replaced it with - which is still performing flawlessly.

I generally think Shimano STIs are very good and always have been. My first experience of STIs was with the original 4400 Tiagra, which were a bit agricultural but worked well. The latest Ultegra R8000 are just lovely by comparison, with a notably light action, but if I were spending my own money on a new bike, I would be perfectly happy with the latest 4700 Tiagra, which is excellent (and streets ahead of the 4400). I think you probably have just been unlucky with yours.

 

[smutchin]

Tiagra 4700 is exactly the halfway house between 105 5700 and 5800

10.5 speed?