Tiagra 4700: triple, under tape routing & 34T sprocket

[keyboardmonkey]

Is this getting dangerously close to being a (light) touring group set?

http://road.cc/content/news/147338-shim ... 0-groupset

[Brucey]

I think it looks pretty good. It looks quite a lot like a 'greatest hits' from the older 105 and Ultegra 10s groups which means it can't be that bad. I'm still a bit conflicted about under-bar-tape cables for the shifters but there is no doubt some folk will welcome them with open arms.

However I bet they don't have long reach brakes on the menu. Still, I would expect the levers to work high MA cantis or mini-Vs OK and that will suit many, Cable discs are another option I guess.

They talk of a revised 'cable pitch' to the rear mech which I suppose is what others would call 'shift ratio'. My secret hope is that they have made it so that it will be easy to run 9s from these shifters, but I'm not holding my breath.

Another secret hope is that the inside chainring is mounted in such a way as to allow something smaller than 30T to be fitted. But again, I'm not holding my breath....

First impressions are that if it works out the right price and the right weight, it'll do well. If it easily runs a more durable 9s chain and cassette (by virtue of a revised 10s shift ratio), that is even better....

cheers

[honesty]

2 questions:
1. Is it still compatible with rear 9 speed mountain derailleurs
2. Will the medium cage rear derailleur handle the triple AND the 34 tooth cassette.

Other than that looks good. Basically rebadged ultegra 6700 stuff?

[Brucey]

actually looking at the pictures of the rear mechs I think they are using a much different shift ratio in the rear mech; more like dyna sys or that used on 11s. If so, it won't allow the use of a 9s rear mech for high capacity 10s use; for that you will need a 10s shimano MTB rear mech or something similar. It also means that setting the system up for 9s (rather than 10s) may be tricky too.

As it is I guess we'll have to wait and see for sure but for a shimano medium cage mech to have a total capacity of 43T (30-39-50 and 11-34T) isn't that big an ask, is it?

cheers

[honesty]

The rear mech looks suspiciously like my current 9 speed XT one... Though that could be just company design coming through.

Edit: Just actually looked and its not that close and looking at photos its more like the previous 105 mech.

[Brucey]

yeah that is what I thought to start with and then I looked at the cable mounting. The shift ratio has to be miles different with a cable mounting like that.

cheers

[foxyrider]

rear mech doesn't look much different to the Sora/Claris stuff and the non group 10 speed stuff on some Giant Anyroad models

[Brucey]

except the shift ratio is obviously different; compare at the cable mounting.





cheers

[keyboardmonkey]

The brake calipers on my mid-eighties Shimano 600 (6207) are listed on Velobase as being ‘short reach’ at 49mm max – the 57mm max are listed as ‘standard reach’. So we could have decent brake caliper clearance and 52/42T chainset back then, but 30 years later and a group set has a more forgiving 50/34T chainset as standard but no ‘standard’ 57mm calipers. Hmm.

I don’t expect the four-arm triple chainset will have provision for a smaller inner chainring either.

I do prefer the under tape routing for the cleaner lines as well as easier fitting for a bar bag.

The 34T sprocket is welcome, just not sure about this revised cable pitch business.

[Brucey]

For brakes shimano will still do the non-groupset longer reach calipers I hope.

I suspect that the new rear mech shift ratio could be the same as the 11s mechs. For comparison here is a 105 RD-5800 11s mech;



cheers

[keyboardmonkey]

For brakes shimano will still do the non-groupset longer reach calipers I hope.

I suspect that the new rear mech shift ratio could be the same as the 11s mechs. For comparison here is a 105 RD-5800 11s mech;



cheers

Re the brakes I have the BR650 calipers on my 'Audax' bike. I rate them, but as you say they are not part of a GROUP set. Or rather, they may have once been - IIRC the are the 'long reach' version of the Ultegra 6500 series. So getting a bit elderly nowadays. So Shimano were still doing brakes for larger clearances some time ago. With all the choices of chainsets, derailleurs, cassettes etc that can be specced when getting a group set it seems a pity that a matching set of calipers can't be had. (Will this group set be available in the silver finish of the BR650 calipers?)

Re cable pull - a confession: what am I looking for, please?

[Brucey]

you can (just) with this kind of mech see what the shift ratio might be. Just imagine how much cable to would take to shift the parallelogram a given distance. To a first approximation (for any given parallelogram type) this is related to the distance from the pinch bolt to the outer rear pivot in the parallelogram. In this respect the 4700 mech looks like the current 11s mechs more than the older 8s/9s mechs.

Hopefully some kind soul will measure the cable pull required and we will then know if we can mix and match or not.

If some adaptation is required, I note that extending an '11s' style cable mount (inwards to reduce the shift ratio of the mech) is easy enough to do.

cheers

[keyboardmonkey]

Cheers for that. Will keep an eye out for updates/reviews etc.

[cycleruk]

you can (just) with this kind of mech see what the shift ratio might be. Just imagine how much cable to would take to shift the parallelogram a given distance. To a first approximation (for any given parallelogram type) this is related to the distance from the pinch bolt to the outer rear pivot in the parallelogram. In this respect the 4700 mech looks like the current 11s mechs more than the older 8s/9s mechs.

If some adaptation is required, I note that extending an '11s' style cable mount (inwards to reduce the shift ratio of the mech) is easy enough to do.
cheers

So would you expect the 4700 mech' to work with the 105 10 speed STI.

[pete75]

I think it looks pretty good. It looks quite a lot like a 'greatest hits' from the older 105 and Ultegra 10s groups which means it can't be that bad. I'm still a bit conflicted about under-bar-tape cables for the shifters but there is no doubt some folk will welcome them with open arms.


cheers

Campag Ergos have been working well since about 1992 with all cables under the tape. Why should Shimano be any different?