2016 Tiagra 4700 and 105 hydraulic disc brakes

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biker jk
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2016 Tiagra 4700 and 105 hydraulic disc brakes

Postby biker jk » Fri Apr 03, 2015 11:05 am

Tiagra remains 10-speed but gets new four arm crankset, shifter cables along bars, better brakes, 34 tooth cassette option with long-cage derailleur. 105 hydraulic brakes and shifters provide cheaper option for moving to disc brakes.

http://www.bikeradar.com/road/news/article/shimano-2016-tiagra-4700-groupset-and-105-disc-brakes-announced-43962/

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Tim
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Re: 2016 Tiagra 4700 and 105 hydraulic disc brakes

Postby Tim » Fri Apr 03, 2015 12:06 pm

Mmm, thanks for that.
Could be just the stuff for a budget winter bike build I'm considering.

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Re: 2016 Tiagra 4700 and 105 hydraulic disc brakes

Postby Duck! » Wed Jun 10, 2015 1:15 am

An Update:

Went to the Shimano dealer launch today & saw these goodies in the flesh. New Tiagra is a very slick-looking package that belies its budget market sector. While still 10-sp, it draws very heavily from the 11-sp. groups above it, notably in the shifters (thus skipping trickle-down of the underwhelming 1st-generation hidden cabled models), and the 4-arm crank. Two double options are offered, regular compact 50/34 and "pro" compact 52/36, and unlike its big brothers, a triple 50/39/30 remains on offer, with ST-4703 "brifter" and SL-4703 flat-bar shifters, and FD-4703 front derailleur to suit. A 12-34 cassette is offered, but I doubt even the GS medium cage RD will have enough wrap to pair this cassette with the triple crank. One glaringly odd lack of logic is that the shift system apparently uses a unique pull ratio, which renders these very nice shifters incompatible with any other 10-sp. gear. Bizarre. I shall do some investigative fiddling when I get my hands on a set & see what really happens.....

Disc brakes..... Yes there are some new models, but they are NOT 105; as with the existing models they're listed as "non-series" parts. They're a new "flat mount" design specifically designed for road bikes; more compact than the existing MTB-derived calipers, with closer mount bolt spacing, so will only fit compatible frames & forks. A big feature is that the front brake is now compatible with a 140mm rotor, where the MTB-derived models are resticted to a 160mm disc at minimum. Two models are offered, Ultegra-level RS805, and 105-level RS505. A new RS-805 lever to suit is also introduced; 11-sp. mechanical shifting with the hydro brake system. To be honest, it's a rather bulky unit; where the current RS785/685 levers are taller in the peak but otherwise similar to cable-braked models, these are rather bulbous & just.... well... fat. Although it wasn't stated in the presentation, I don't think these new calipers will work nicely with the older RS 785/685 levers; the smaller caliper body brings with it smaller pistons & slave cylinders, and the fluid flow from the other levers would make the brake application far too aggressive. Even with the introduction of these new levers, there is still no hydro brake/mechanical shifting option available for 10-sp; only the Di2 RS785 offers 10-sp. compatibility.
I had a thought, but it got run over as it crossed my mind.

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Re: 2016 Tiagra 4700 and 105 hydraulic disc brakes

Postby MichaelB » Wed Jun 10, 2015 9:24 am

Hi Duck,

The comments re the new brake levers are interesting. I wonder what the differences are to make the lever a very different shape (i.e. what is the advantage in the new shape vs the RS685 ?), as it seems a bit of a departure from something that already received good support ?

RS805 lever
Image

RS685 lever
Image

Hmmmm, the RS805 looks phat (and not in a good way ...)

w.r.t. to the new flat mount caliper, I gotta admit I'm a bit over the new standard, and whilst I can see some merits, I just don't see the overall benefit being sufficient just yet. I'm also curious as to the changes to the caliper piston size, as Shimano have been so consistent in the past. I wonder if they do a different F & R piston size as per the SRAM road calipers ?

The different master/slave piston sizes also seem to be a potential conflict area, but I've teamed up the RS685 with Zee calipers and that should yield all sorts of troubles, but it doesn't. Mind you, if you go the other way (putting smaller slave piston size on a set master - opposite to the RS685/Zee combo that I have), it could be very different.

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Re: 2016 Tiagra 4700 and 105 hydraulic disc brakes

Postby 2wheels_mond » Wed Jun 10, 2015 12:56 pm

Duck! wrote:An Update:

Went to the Shimano dealer launch today & saw these goodies in the flesh. New Tiagra is a very slick-looking package that belies its budget market sector. While still 10-sp, it draws very heavily from the 11-sp. groups above it, notably in the shifters (thus skipping trickle-down of the underwhelming 1st-generation hidden cabled models), and the 4-arm crank. Two double options are offered, regular compact 50/34 and "pro" compact 52/36, and unlike its big brothers, a triple 50/39/30 remains on offer, with ST-4703 "brifter" and SL-4703 flat-bar shifters, and FD-4703 front derailleur to suit. A 12-34 cassette is offered, but I doubt even the GS medium cage RD will have enough wrap to pair this cassette with the triple crank. One glaringly odd lack of logic is that the shift system apparently uses a unique pull ratio, which renders these very nice shifters incompatible with any other 10-sp. gear. Bizarre. I shall do some investigative fiddling when I get my hands on a set & see what really happens.....


Well, the change in pull ratio would be to bring it in line with the groups above (DA 9000, Ult 6800, 105 5800) rather than keeping it in line with the current 10 speed stuff. Pretty sure it's necessary to take advantage of the new longer armed front derailleur. There's a guy on the Weight Weenies board who's used a Tiagra 4600 FD with an Ultegra 6800 shifter and says it works, but feels 'forced':

http://weightweenies.starbike.com/forum ... a#p1134472

No idea if it'd work for RD, can't really see anyone that's tried it yet.

Are they sticking with the 12-28 and 12-30 ratio cassettes from 4600? IMO they're the best cassettes (in terms of ratios) for all the 10 speed Shimano offerings.

Nice to see that there's no 53/39 offered any more though - these are coming on entry level bikes, I remember my first bike came with a 52/42 and 13-26, and as someone learning to cycle in quite a hilly area it's pretty demoralising for a beginner when you get off and walk. At least this way Shimano more or less forces manufacturers to follow suit (there's no 130 BCD option in Claris or Sora I'm fairly sure) and it looks like they have, most entry level options now have a 50-34 at the front and at least an 11-28 at the back.

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Re: 2016 Tiagra 4700 and 105 hydraulic disc brakes

Postby Duck! » Wed Jun 10, 2015 1:33 pm

When I get a 4700-specced bike in the workshop I'll sub in both a current 10-sp & 11-sp. derailleur & see what happens. The rear derailleur geometry looks very similar to the 11-sp. models, so I kinda suspect it will have the same leverage ratio. I have worked on a bike with a 5800 FD in an otherwise 5700 setup, and it worked better than expected, so expect similar compatibility between 4600 & 4700 at least at this end. Maybe not quite as slick as the correct pairings, but quite acceptable/

MichaelB wrote:
The comments re the new brake levers are interesting. I wonder what the differences are to make the lever a very different shape (i.e. what is the advantage in the new shape vs the RS685 ?), as it seems a bit of a departure from something that already received good support ?

I suspect the primary driver to be the the dimensions of the master cylinder. Only non-functioning plastic lever mock-ups were on display, so I'm unable to offer any actual observations of the specifics.

I'm also curious as to the changes to the caliper piston size, as Shimano have been so consistent in the past. I wonder if they do a different F & R piston size as per the SRAM road calipers ?

The different master/slave piston sizes also seem to be a potential conflict area, but I've teamed up the RS685 with Zee calipers and that should yield all sorts of troubles, but it doesn't. Mind you, if you go the other way (putting smaller slave piston size on a set master - opposite to the RS685/Zee combo that I have), it could be very different.
Pistons in the calipers are the same at both ends, but the considerably smaller pads (little more than half the area of M/R/RS785 pads) suggest smaller pistons, possibly similar to Shimano's lesser-spec MTB brakes.
I had a thought, but it got run over as it crossed my mind.

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Re: 2016 Tiagra 4700 and 105 hydraulic disc brakes

Postby Calvin27 » Wed Jun 10, 2015 1:59 pm

Duck! wrote:They're a new "flat mount" design specifically designed for road bikes; more compact than the existing MTB-derived calipers, with closer mount bolt spacing, so will only fit compatible frames & forks.


I got excited and then, *sigh* another new standard - the brakes won't fit on my bike or pretty much anything on sale at the moment.

Not sure what's going on here because the change in standard doesn't actually beenfit shimano imo. Unless they are genuinely convinced there are benefits. Shimano already has the hydro brake market cornered and all they need to do was deliver something that works. Sram already shot themselves with their woeful avid reputation and s700 recall, not to mention a lot of people simply hate dot fluid. Also, it's a strange move from shimano to be introducing new standards at the 105 range. It's a risky strategy because they are probably going for early market share by providing a decent hydro brake groupset at a value range. The tradeoff is that buyers might snuff it and not take the risk for a new standard (keep in mind discs brake roadie discussions are still going on and the uci are not running discs yet). At the very least it kills off an entire chunk of the market that may be purchasing a full hydro set-up (me) for upgrade, not the end of the world if they continue their existing hydros but they are a bit pricey - a 105 full kit would be more appealing. It would make more sense for them to pitch a bit higher seeing that this segment of the market is probably more receptive to new stuff.

Anyways, I'll be keeping an eye out to see if the exsting hydros get phased out, if they intend to I might have to pull the trigger.
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Re: 2016 Tiagra 4700 and 105 hydraulic disc brakes

Postby MichaelB » Wed Jun 10, 2015 2:58 pm

Duck! wrote: Pistons in the calipers are the same at both ends, but the considerably smaller pads (little more than half the area of M/R/RS785 pads) suggest smaller pistons, possibly similar to Shimano's lesser-spec MTB brakes.


Smaller pads ? Say What ?

Unless the new compound is better than the current, this can only benefit the WW and small statured, and I don't fit into that category !!!

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Re: 2016 Tiagra 4700 and 105 hydraulic disc brakes

Postby Duck! » Wed Jun 10, 2015 8:18 pm

OK, disregard my earlier comments & assumptions on new/old brake compatibility.... Got my hands on the detailed charts to see what goes where and with what else, and here's the correct version:

The new flat-mount calipers are fully compatible with the existing R785 Di2 & RS685 mechanical shift levers; the new ST-RS505 is a cheaper 105-level (NOT part of the 105 series) model. I suspect most buyers will prefer to stump for the RS685. Why the new lever looks so hideous only Shimano can answer.... Apologies for previous misinformation.

Calvin27 wrote:
Not sure what's going on here because the change in standard doesn't actually benefit Shimano imo. Unless they are genuinely convinced there are benefits. Shimano already has the hydro brake market cornered and all they need to do was deliver something that works. SRAM already shot themselves with their woeful Avid reputation and S700 recall, not to mention a lot of people simply hate DOT fluid. Also, it's a strange move from Shimano to be introducing new standards at the 105 range. It's a risky strategy because they are probably going for early market share by providing a decent hydro brake groupset at a value range. The tradeoff is that buyers might snuff it and not take the risk for a new standard (keep in mind discs brake roadie discussions are still going on and the uci are not running discs yet). At the very least it kills off an entire chunk of the market that may be purchasing a full hydro set-up (me) for upgrade, not the end of the world if they continue their existing hydros but they are a bit pricey - a 105 full kit would be more appealing. It would make more sense for them to pitch a bit higher seeing that this segment of the market is probably more receptive to new stuff.

Anyways, I'll be keeping an eye out to see if the exsting hydros get phased out, if they intend to I might have to pull the trigger.


It's a bit naive to solely blame Shimano for the new mounting; why would they introduce something that won't fit on anything? The frame manufacturers do consult with the component manufacturers (sometimes exclusively, but often the designs become open standards) to develop new versions of things. Road disc brakes are still a very new sector of the market, and you could be pretty certain that at least one manufacturer would have approached Shimano with suggestions that given the different demands of road bikes, that an alternative to the comparitively bulky MTB-derived current models would be desirable. Flat-mount may in time become the industry-preferred design for road bikes, but I don't see post-mount going away any time soon. To use MTB as a reference, in 15-odd years of development, post mount has pretty well become the standard caliper design, but many frames & forks still come with IS tabs & use adaptors to fit the calipers. I wouldn't be surprised to see adaptors to fit post mount calipers to flat mount frames & forks down the track if the design takes hold.
I had a thought, but it got run over as it crossed my mind.

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Re: 2016 Tiagra 4700 and 105 hydraulic disc brakes

Postby Calvin27 » Wed Jun 10, 2015 10:44 pm

Duck! wrote:It's a bit naive to solely blame Shimano for the new mounting; why would they introduce something that won't fit on anything? The frame manufacturers do consult with the component manufacturers (sometimes exclusively, but often the designs become open standards) to develop new versions of things. Road disc brakes are still a very new sector of the market, and you could be pretty certain that at least one manufacturer would have approached Shimano with suggestions that given the different demands of road bikes, that an alternative to the comparitively bulky MTB-derived current models would be desirable.


I wasn't really blaming shimano. I actually can't see how this improves over PM. I might have missed something but it seems all that has changed is narrower spacing between the bolts to house a smaller caliper.

I suspect the move to 140mm discs is because they have a hunch on where the UCI will go with regards to disc specs. But the spacing makes no sense. I can't see how the 'flat' can't be replicated with PM and why the smaller caliper can't just use the PM spacing. Seems like a whole new standard just to loose a few mm of material - the flipside is it completely looses 160mm capability without an adaptor whereas you could design a 140mm caliper piece to fit PM.

Maybe I'm missing something, but I'm sure you'll fill me in duck. :D
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Re: 2016 Tiagra 4700 and 105 hydraulic disc brakes

Postby Duck! » Wed Jun 10, 2015 11:41 pm

The angle at which the rotor passes through the caliper is the primary reason why PM can't work with 140mm rotors on the front (although is possible with IS tabs via an adaptor, if you can find one); different angles at the critical part of the frame allow it to work on the rear end though. Reducing rotor size on the front also reduces the stress on the fork, but on the other side does bring potentially more heat-related issues (smaller rotors don't dissipate heat as well as bigger ones). Maybe what they're finding is that seeing it's the tyres that limit how efficiently the braking force can get to the ground they just don't need as much braking up front.

At the back, the slimline profile certainly moves critical components further away from large feet at the back sector of the crank cycle; we've already seen the change from R785 to RS785 caliper with its revised hose entry & bleed nipple placement, due in large part from feedback of riders kicking the earlier design calipers. Tighter race frame geometry would bring the rear caliper more into potential conflict with stray heels, so every bit of extra clearance helps.

The thing is, it's not losing 160mm compatibility; as with existing mounts, design to the smallest option, and use adaptors to step it out to the larger ones.

Road disc brake development is still in its infancy; as with IS/PM on the dirt, I expect we'll see both mounts for some time to come.
I had a thought, but it got run over as it crossed my mind.

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Re: 2016 Tiagra 4700 and 105 hydraulic disc brakes

Postby 2wheels_mond » Fri Jun 19, 2015 9:49 am

For anyone curious about the cable pull ratios of 4700, for further evidence it will be the same as the 11 speed stuff, the dealers' manuals for 4700 shifters, rear derailleurs and front derailleurs all list them as being in the 9000/6800/5800 family.

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