7100 105 12s mechanical

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7100 105 12s mechanical

Postby warthog1 » Mon Mar 11, 2024 2:59 pm

https://road.cc/content/review/shimano- ... set-307155

Yep that'd probably do me.
If I am to buy a new bike it doesn't need to be as expensive as a car.
Sounds like good capacity on the rear derailleur to cope with lower gearing as my legs age.
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Re: 7100 105 12s mechanical

Postby Dave_rh » Tue Mar 12, 2024 10:33 am

My next bike WILL be 12 speed 105 R7100 mechanical. This is a smart move by Shimano which I think will be popular choice.

Riders 35+ (like me) are a big customer base. They may not have the budget or interest in di2 but they are very interested in lower gearing which the 36 tooth cassette (CS-HG710-12) provides.

However there is one big concern for 105 mechanical - Stupid modern headset cable routing or more specifically the negative impact headset routing has on cable movement.

Many modern bikes with 105 12s mechanical (e.g. 2024 Defy) gear cables are being forced through several 90 degree bends to fit under the stem, inside fork spacers and through the headset. This terrible cable routing will accelerate cable and hosing wear, accelerate bad shifting and cost more to replace in future.

Ironically, the best bikes for 105 12 speed mechanical are older bikes WITHOUT headset routing of cables.

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Re: 7100 105 12s mechanical

Postby AndrewCowley » Tue Mar 12, 2024 10:51 am

Am I reading it correctly that there is only one size RD, meaning there is no longer any need to worry about which version you need?

Also related, if you want a 105 cassette, the only options are 32T and 34T versions. This is a big change from Shimamo.

Also it's heavy. And expensive.

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Re: 7100 105 12s mechanical

Postby biker jk » Tue Mar 12, 2024 11:15 am

AndrewCowley wrote:
Tue Mar 12, 2024 10:51 am
Am I reading it correctly that there is only one size RD, meaning there is no longer any need to worry about which version you need?

Also related, if you want a 105 cassette, the only options are 32T and 34T versions. This is a big change from Shimamo.

Also it's heavy. And expensive.
Yes, only one size rear derailleur but the 105 cassettes are 34T and 36T.

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Re: 7100 105 12s mechanical

Postby AndrewCowley » Tue Mar 12, 2024 11:24 am

Offering only 34T and 36T is a bit weird. Likely a decision based around wanting to force a percentage of people into buying more expensive Ultegra cassettes. Shimano are getting increasingly shonky IMO.

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Re: 7100 105 12s mechanical

Postby g-boaf » Tue Mar 12, 2024 2:48 pm

Maybe they are just looking at what the majority of the 105 customers actually want and then figuring they can also make a quick dollar here and there to go with it.

I've long ditched Shimano and happy to be free of them. Only thing I use is their cleats and pedals.

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Re: 7100 105 12s mechanical

Postby familyguy » Tue Mar 12, 2024 3:45 pm

AndrewCowley wrote:
Tue Mar 12, 2024 11:24 am
Offering only 34T and 36T is a bit weird. Likely a decision based around wanting to force a percentage of people into buying more expensive Ultegra cassettes. Shimano are getting increasingly shonky IMO.
Perhaps also catering to people who think 34T rings look dinky on bigger bikes so you can run a 52/36 or 50/36 and a 34T rear and not suffer the ignominy of having a 1:1 drivetrain?
(only mild sarcasm here)

Is there an argument of efficiency or longevity of a drivetrain doing more of a 1:1 ratio as there is more chain overlapping teeth each end therefore something something reduced wear etc whatever?

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Re: 7100 105 12s mechanical

Postby MichaelB » Tue Mar 12, 2024 4:17 pm

I'll worry about it when the current setup wears out.

Have several key 11sp consumable products, especially for the 11sp Di2.

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Re: 7100 105 12s mechanical

Postby warthog1 » Tue Mar 12, 2024 8:30 pm

AndrewCowley wrote:
Tue Mar 12, 2024 10:51 am
Am I reading it correctly that there is only one size RD, meaning there is no longer any need to worry about which version you need?

Also related, if you want a 105 cassette, the only options are 32T and 34T versions. This is a big change from Shimamo.

Also it's heavy. And expensive.
Expensive compared to which other current groupsets?
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Re: 7100 105 12s mechanical

Postby blizzard » Tue Mar 12, 2024 8:37 pm

Looks fine, but as pointed out a lot bikes coming with this spec'd have fully internal routing which seems like a poor combination due to potential for worse shifting due to tight bends and added complications in replacing cables.

Makes more sense for older bikes with fully external or semi internal routing, like my SL6 Tarmac and the outgoing TCR, however for me, I am going to keep replacing my existing 11sp gear with new 11sp until I can't.

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Re: 7100 105 12s mechanical

Postby warthog1 » Tue Mar 12, 2024 8:42 pm

I want a disc braked roadie so it means a new bike and groupo.
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Re: 7100 105 12s mechanical

Postby Duck! » Tue Mar 12, 2024 9:19 pm

I'm not going to pick out multiple quotes to post, 'cos I'll get lost trying to answer them specifically, so here's a general view from an ex-industry insider.....

105 has always been targetted as an "enthusiast"-level groupset rather than a competitive-level one, so it has never had the same extent of cassette choices as its superiors, however, only offering one option of 34 or 36T is a new low for restriction, hence only one derailleur type. Over the last fair few years, the demographic of bike buyers in that market sector has been getting older, and looking for lower gearing, in combination with a broader understanding that mashing high ratios up hills is not good for long-term joint health. However only offering low-ratio, wide-range cassettes is a fair snub to flat-land riders who don't need super-low gears and would prefer a narrower range with closer steps between ratios. Even the extra choices offered in Ultegra and Dura-Ace are bordering on too big a range for real flat-landers, but there's only so tight the range can go with that many gears.....

On a technical efficiency/longevity perspective, bigger sprockets & chainrings mean there is more contact between chain & sprockets, which for a given power input means there is less point loading on each chain link and sprocket/chainring tooth, so durability will improve in an ideal world (but considering some of the horrendously filthy drivetrains I've seen over the years, the world is often not ideal).
I had a thought, but it got run over as it crossed my mind.

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Re: 7100 105 12s mechanical

Postby Duck! » Tue Mar 12, 2024 9:29 pm

Dave_rh wrote:
Tue Mar 12, 2024 10:33 am

However there is one big concern... (snip, because it's not specific to this group).... Stupid modern headset cable routing or more specifically the negative impact headset routing has on cable movement.
Disregard groupset. Headset cable routing is quite probably the most phuqed-up design "innovations" the bike industry has ever invented. It's bad for mechanical cables (friction). It's bad for electronics (pinch points that can cut wires), bad for hydraulics (can kink hoses, blocking fluid flow), and just makes services that should be relatively simple processes a lot harder than they should be. It's just a plain dumb and potentially dangerous idea.
Last edited by Duck! on Tue Mar 12, 2024 9:33 pm, edited 1 time in total.
I had a thought, but it got run over as it crossed my mind.

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Re: 7100 105 12s mechanical

Postby warthog1 » Tue Mar 12, 2024 9:33 pm

Could you not just run a 32-11 or even a 30-11?
My understanding is the clearance between cassette teeth and cage pulleys is the main limiting factor, as found on larger sized cassette gears like the 34 and 36.
Run a smaller cassette and at the top of the cassette there will be more clearance so shifts will be less crisp but it will still shift.
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Re: 7100 105 12s mechanical

Postby MichaelB » Wed Mar 13, 2024 9:54 am

Duck! wrote:
Tue Mar 12, 2024 9:29 pm
Dave_rh wrote:
Tue Mar 12, 2024 10:33 am

However there is one big concern... (snip, because it's not specific to this group).... Stupid modern headset cable routing or more specifically the negative impact headset routing has on cable movement.
Disregard groupset. Headset cable routing is quite probably the most phuqed-up design "innovations" the bike industry has ever invented. It's bad for mechanical cables (friction). It's bad for electronics (pinch points that can cut wires), bad for hydraulics (can kink hoses, blocking fluid flow), and just makes services that should be relatively simple processes a lot harder than they should be. It's just a plain dumb and potentially dangerous idea.
10,000% agree

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Re: 7100 105 12s mechanical

Postby warthog1 » Wed Mar 13, 2024 9:57 am

It looks pretty, so sells.
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Re: 7100 105 12s mechanical

Postby Dave_rh » Wed Mar 13, 2024 10:32 am

I note some people who ride in flatter terrain understandably prefer a cassette with closer ratios, I suggest the 11-34. Its not a perfect solution. However, it's basically the same close ratios as the old dura-ace 11-30 11 speed cassettes.

I live in a hilly area and suggest it needs to go the other way... Why not wider 105 cassettes? Why are 11-38 or 11-40 12 speed cassettes not offered at the 105 entheausist level?

  • The target market (entheausist) is typically NOT racing crits using 105. Therefore slightly wider ratio gaps and cadence changes are less of a problem.
  • This offers a lower range or, a better top speed with same low gears if you go for bigger chainrings.
  • Many people would take extra grams of cassette weight to make hills easier and give their knees a break.
  • I think we're past the whole "needing to be a roady hero pushing tiny corn-cob cassettes and big chainrings".

    There is no law saying road cassettes need to be small. For all we know, Shimano may have engineered a tolerance into the 105 RD that it can take a larger cassette. Someone will probably test it eventually.

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Re: 7100 105 12s mechanical

Postby AndrewCowley » Wed Mar 13, 2024 10:41 am

Dave_rh wrote:
Wed Mar 13, 2024 10:32 am
I note some people who ride in flatter terrain understandably prefer a cassette with closer ratios, I suggest the 11-34. Its not a perfect solution. However, it's basically the same close ratios as the old dura-ace 11-30 11 speed cassettes.

I live in a hilly area and suggest it needs to go the other way... Why not wider 105 cassettes? Why are 11-38 or 11-40 12 speed cassettes not offered at the 105 entheausist level?

Which is exactly why Shimano have traditionally offered a decent range of cassettes for each groupset. As you acknowledge above, there are people who ride in flatter terrain and there are others who ride in hilly terrain.

Sorry but this is just a pathetic cash grab from Shimano.

Nobody will argue that 25T max cassettes are a thing of the past. Shimano could stop selling those in a heartbeat and hardly anyone would care. But offering only 34T and 36T max cassettes and thinking it will cater for a wide audience is ridiculous. 105 is now finding its way onto more and more mid and even high end bikes because of the stupid pricing of the groupsets above it, so 105 is no longer numpty level only. This is simply going to force people to purchase Ultegra cassettes at a higher price.

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Re: 7100 105 12s mechanical

Postby blizzard » Wed Mar 13, 2024 12:49 pm

AndrewCowley wrote:
Wed Mar 13, 2024 10:41 am
Dave_rh wrote:
Wed Mar 13, 2024 10:32 am
I note some people who ride in flatter terrain understandably prefer a cassette with closer ratios, I suggest the 11-34. Its not a perfect solution. However, it's basically the same close ratios as the old dura-ace 11-30 11 speed cassettes.

I live in a hilly area and suggest it needs to go the other way... Why not wider 105 cassettes? Why are 11-38 or 11-40 12 speed cassettes not offered at the 105 entheausist level?

Which is exactly why Shimano have traditionally offered a decent range of cassettes for each groupset. As you acknowledge above, there are people who ride in flatter terrain and there are others who ride in hilly terrain.

Sorry but this is just a pathetic cash grab from Shimano.

Nobody will argue that 25T max cassettes are a thing of the past. Shimano could stop selling those in a heartbeat and hardly anyone would care. But offering only 34T and 36T max cassettes and thinking it will cater for a wide audience is ridiculous. 105 is now finding its way onto more and more mid and even high end bikes because of the stupid pricing of the groupsets above it, so 105 is no longer numpty level only. This is simply going to force people to purchase Ultegra cassettes at a higher price.
I think you will find the majority of people buying 105 have no idea what gearing they have. Most guys I ride with don't care too much about tech side of riding.

I very much doubt Shimano are trying to force people into buying Ultegra cassettes, more likely they looked at R7000 sales and probably found the 11-28 and 12-25 sales were less than 10% of cassettes sold so only bothered with the equivalent 12sp cassettes.

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Re: 7100 105 12s mechanical

Postby AndrewCowley » Wed Mar 13, 2024 12:51 pm

blizzard wrote:
Wed Mar 13, 2024 12:49 pm
I think you will find the majority of people buying 105 have no idea what gearing they have. Most guys I ride with don't care too much about tech side of riding.

You might be right. But 105 is being used on more expensive and higher end bikes than it used to be. So in that sense, the type of rider on 105 will be changing in these next few years.

Agree that sales of 25T and 28T cassettes have probably tanked. But moving to only 34T and 36T seems extreme. 30T and 32T still have a place, even taking into account all the modern day thinking about gearing.

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Re: 7100 105 12s mechanical

Postby Dave_rh » Wed Mar 13, 2024 1:25 pm

blizzard wrote:
Wed Mar 13, 2024 12:49 pm
I very much doubt Shimano are trying to force people into buying Ultegra cassettes, more likely they looked at R7000 sales and probably found the 11-28 and 12-25 sales were less than 10% of cassettes sold so only bothered with the equivalent 12sp cassettes.

Of interest. A comparison between Shimano 12 speed 11-30 vs 11-34 cassettes. I lined equivalent ratios up. Looks like the 11-34 has one 15t cog removed from the middle of the 11-30, replaced by the 34t at the end.

11-30: 11-12-13-14-15-16-17-19-21-24-27-30-XX
11-34: 11-12-13-15-XX-16-17-19-21-24-27-30-34

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Re: 7100 105 12s mechanical

Postby Dave_rh » Wed Mar 13, 2024 2:18 pm

Hypothetical upgrade options for 12speed 105 mechanical:

Can swap in 12 speed Ultegra/Dura Ace crankset and/or 11-34 cassette.

Can swap to Ultegra 12 speed Brake callipers but they seem identical to 105. Probably the same part with different paint job.

The 105 12 speed Front Derailleur seems identical to the older 11 speed mechanical models (105 FD-R7000 and Ultegra FD-R8000). Therefore if cable pull ratio is the same, it be possible to "upgrade" to Ultegra?


It may? be possible to swap Ultegra 11 speed carbon brake lever blades onto the 105 12 speed Shifter bodies?
  • The 12 speed 105 ST-R7120 shifter bodies look identical to the 11 speed 105 ST-7020 ones. (levers blades are shaped slightly differently but same mechanism)
  • The 12 speed cable-pull ratchet mechanism is part of the shifter body, not part of the shifter blades, which can be replaced if damaged.
  • If, 11 speed shifter blades fit 12 speed bodies, then an 11 speed Ultegra blade might fit the 12 speed 105 shifter body!
I think the part numbers for 11s Ultegra replacement lever blades are ‎Y0DL98010 "Left lever assembly" and Y0DK98020 "Right lever assembly"

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Re: 7100 105 12s mechanical

Postby warthog1 » Wed Mar 13, 2024 4:17 pm

AndrewCowley wrote:
Wed Mar 13, 2024 12:51 pm



You might be right. But 105 is being used on more expensive and higher end bikes than it used to be. So in that sense, the type of rider on 105 will be changing in these next few years.

Agree that sales of 25T and 28T cassettes have probably tanked. But moving to only 34T and 36T seems extreme. 30T and 32T still have a place, even taking into account all the modern day thinking about gearing.
If that is your preference what is stopping you putting one on?
Buy an ultegra or one from a third party manufacturer.
Using Sunrace on all my 11s shimano groupos. Works fine. I assume they will make 12s cassettes too, if they dont already.
They do.
https://sunrace.com/product/csrz800-wat ... Mi4wLjAuMA..
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Re: 7100 105 12s mechanical

Postby Duck! » Wed Mar 13, 2024 4:35 pm

warthog1 wrote:
Tue Mar 12, 2024 9:33 pm
Could you not just run a 32-11 or even a 30-11?
My understanding is the clearance between cassette teeth and cage pulleys is the main limiting factor, as found on larger sized cassette gears like the 34 and 36.
Run a smaller cassette and at the top of the cassette there will be more clearance so shifts will be less crisp but it will still shift.
No reason not to; fitting a smaller cassette than the derailleur's capacity is far less problematic than fitting an oversized one.
I had a thought, but it got run over as it crossed my mind.

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Re: 7100 105 12s mechanical

Postby warthog1 » Wed Mar 13, 2024 6:52 pm

Duck! wrote:
Wed Mar 13, 2024 4:35 pm
warthog1 wrote:
Tue Mar 12, 2024 9:33 pm
Could you not just run a 32-11 or even a 30-11?
My understanding is the clearance between cassette teeth and cage pulleys is the main limiting factor, as found on larger sized cassette gears like the 34 and 36.
Run a smaller cassette and at the top of the cassette there will be more clearance so shifts will be less crisp but it will still shift.
No reason not to; fitting a smaller cassette than the derailleur's capacity is far less problematic than fitting an oversized one.
Ta Duck! :)
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