105 2x12 - R7170 (R7150) / R7120 (R7100) - di2 / mechanical (MY2024)

[robertbb]

I have no problem whatsoever if people "want" pro level stuff.

Then why are you arguing and calling people stupid over it?

Because they said they "need" it. Not that they "want" it.

You are mistaken. The person you said had rocks in their head did not say they needed anything, they just expressed a preference.

He said he was "spinning out" a gravel bike (on descents) with a 46/30 and that switching to a 50/34 remedied this.

And I called BS. Because that's the equivalent of going from an 11t cog to a 12t cog. ONE single tooth cog.

Fact: He'd need to be doing circa 55k/hr and still pedalling at over 95rpm to be "spinning out" a 46x11

Fact: Changing to a 50t changes this equation by a whopping... wait for it... 2k/hr.... a spin out at 57k/hr.

Numbers don't lie. People do.

[robertbb]

And why would you ever bring up average speed? It's such an irrelevant stat that depends entirely on the route and conditions of the day.

Because in context it's actually a great reference point, being the average speed on widely varied terrain over the course of three weeks of a professional bike race.

Your average bell curve rider simply doesn't need the same gearing as a professional.

The cool thing about this sport is one can actually model and calculate this stuff.

Gain ratios, gearing, power to weight, Vo2 max, aerodynamics, stress, strain, fatigue... it's all in the numbers. And as I said earlier, the numbers don't lie.

[SystemShock]

Lots of assertions, not much data, so I offer you a 100km ride on fairly flat ground with about 800m of vertical, average speed just under 40kph. I'm a fairly average B grade rider. Long legs so spinning at more than about 100 rpm doesn't really happen. 52T on the front.

Here's my speed / cadence chart



While there's some noise of course, what you see is clustering around the rear sprocket size. I was using r8000 11-28, so from the right, you see 11T, then to the left 12T and so on.

If the cassette stopped at 12T I'd have spun out many times.
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You really can't spin faster than 100 RPM?

Condolences.
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[Mocs123]

It appears we've really gotten into the hedges as the whole last page has little to nothing to do with Shimano 7150/7100 the upcoming 105 groupset.

[Lina]

And why would you ever bring up average speed? It's such an irrelevant stat that depends entirely on the route and conditions of the day.

Because in context it's actually a great reference point, being the average speed on widely varied terrain over the course of three weeks of a professional bike race.

Your average bell curve rider simply doesn't need the same gearing as a professional.

The cool thing about this sport is one can actually model and calculate this stuff.

Gain ratios, gearing, power to weight, Vo2 max, aerodynamics, stress, strain, fatigue... it's all in the numbers. And as I said earlier, the numbers don't lie.

Average speed tells absolutely nothing. But if you're so worried about it, averaging 40 km/h isn't actually anything special for a fast group ride in flat/rolling terrain. Hell my last sweet spot ride was 90 minutes averaging 38.5 km/h. Yet that tells absolutely nothing if you don't know the route, the weather, etc.

Point to where anyone has claimed the average bell curve rider needs the same gearing as professionals do. Please do so. You're the one here acting as if no one but pros need it.

You really can't spin faster than 100 RPM?

Condolences.
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Many people can spin quite fast, if it's just going for maximum cadence, or peak maximum power. But if you're actually trying to put down consistent power while spinning super fast it becomes a whole lotta harder. And having to go above your self selected cadence is a lot more taxing than being able to use your self selected cadence.

[SystemShock]

You really can't spin faster than 100 RPM?

Condolences.
.

Many people can spin quite fast, if it's just going for maximum cadence, or peak maximum power.

But if you're actually trying to put down consistent power while spinning super fast it becomes a whole lotta harder. And having to go above your self selected cadence is a lot more taxing than being able to use your self selected cadence.
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Thing is, 100 RPM just isn't that fast. A *lot* of ppl shoot for 90 RPM as their 'standard' comfortable cadence, and the max in the efficient range (which is kinda what I think you're alluding to) is about 120-130 RPM for most.

But, to just plain not be able to go above 100 RPM? Ouch.
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[Lina]

You really can't spin faster than 100 RPM?

Condolences.
.

Many people can spin quite fast, if it's just going for maximum cadence, or peak maximum power.

But if you're actually trying to put down consistent power while spinning super fast it becomes a whole lotta harder. And having to go above your self selected cadence is a lot more taxing than being able to use your self selected cadence.
.

Thing is, 100 RPM just isn't that fast. A *lot* of ppl shoot for 90 RPM as their 'standard' comfortable cadence, and the max in the efficient range (which is kinda what I think you're alluding to) is about 120-130 RPM for most.

But, to just plain not be able to go above 100 RPM? Ouch.
.

It all depends. 130 rpm with 160 mm cranks, not a big deal. With 175 mm cranks it's a completely different thing. And people have different cadences. I know people that ride at over 100 rpm constantly. But I also know people who ride at around 80 rpm. You can't tell someone that they should just spin more if they tell you they're spinning out at some cadence. Max in efficient range definitely isn't 120 to 130 for most.

I can go over 200 rpm. But if I'm doing sustained power I don't want to go much over over 110 rpm. Just because you can do something shortly or with a different load doesn't mean you can do it while putting out sustained power. Don't believe me? It's easy to test, go do some sweet spot to VO2max efforts and test it first with whatever your natural cadence is and then with 10 rpm and then 20 rpm higher, and for the sake of testing you can also do lower. Just test it out and see which feels much more comfortable and which you can keep for longer.

[SystemShock]

Max in efficient range definitely isn't 120 to 130 [RPM] for most.

I was quoting Greg LeMond (from his book).

I'll assume he meant with training.

For myself, 120 RPM is about the limit. Beyond that, I'm not efficient or powerful. But my cranks are fairly long for my leg length (172.5mm and 81.6cm, respectively).

This isn't to say that your normal 'just riding around' cadence should be 120+, if that was not clear. Just that if you need to, you can do it, and without your efficiency and power falling off spectacularly.

Training it helps.
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[blaugrana]

I don't think I've ever seen anyone (pro or not) average 120 or 130 rpm of cadence in a TT or any kind of sustained effort in a race. Of course it's possible to do it, just like it's possible to climb at 50 rpm for hours, but there is no reason to if you can pick your gearing to avoid it. And for many people, that's slightly larger chainrings than for others, there is nothing wrong with that.

[SystemShock]

I don't think I've ever seen anyone (pro or not) average 120 or 130 rpm of cadence in a TT or any kind of sustained effort in a race.

Really? While the avg speed on a major Tour is 'only' around 40 kph, and while (as I said) 120+ RPM isn't your 'just riding around' cadence, there ARE most definitely times when the peloton is positively hauling ass.

For example:

Around 20 riders, including four-time champion Chris Froome, lay stricken and needing attention shortly after a first mass fall on the Tour de France opening stage.

Unlike the earlier crash caused by a fan, the second came as the peloton was going around 70kph some 5km from the finish line.

Btw, 70 kph in a 53x11 is 115 RPM.
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[robbosmans]

I am getting flashbacks to the Dura ace thread… Please keep it civil.

[blaugrana]

I don't think I've ever seen anyone (pro or not) average 120 or 130 rpm of cadence in a TT or any kind of sustained effort in a race.

Really? While the avg speed on a major Tour is 'only' around 40 kph, and while (as I said) 120+ RPM isn't your 'just riding around' cadence, there ARE most definitely times when the peloton is positively hauling ass.

For example:

Around 20 riders, including four-time champion Chris Froome, lay stricken and needing attention shortly after a first mass fall on the Tour de France opening stage.

Unlike the earlier crash caused by a fan, the second came as the peloton was going around 70kph some 5km from the finish line.

Btw, 70 kph in a 53x11 is 115 RPM.
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Yes, but cycling journalists tend to exaggerate speeds a bit, sustained speeds of 70km/h don't really happen on the flat under normal conditions (it's easy to see why with an aero drag calculator). And if there is a downhill with no corners where you would have a chance to pedal at these very high speeds for a relatively long time, you will see people with 55+ teeth chainrings (especially if it's close to the finish). I doubt you will find footage of some guy leading a sprint train averaging 120+ rpm over his whole turn at the front.

Also, it is worth noting that due to the non-linear relation between speed and power, the speed differentials between a well trained amateur and a professional will be a lot more similar at the top end than at the low end, so the same can be said for their gearing needs. For example, a 30% (just a somewhat reasonable example) increase in power will produce a much higher % of extra speed when both are on a very steep climb compared to when they are pedalling fast downhill on rolling terrain.

[Hexsense]

I am getting flashbacks to the Dura ace thread… Please keep it civil.

Similar, but I see the discussion to revolve more around amateur which is the target group of 105.

IMO,Reduce gearing to fit better with vast amateur make sense. Anyone need 53t can increase the budget to ride Ultegra/Dura-ace. A win for Shimano.

I don't think I've ever seen anyone (pro or not) average 120 or 130 rpm of cadence in a TT or any kind of sustained effort in a race. Of course it's possible to do it, just like it's possible to climb at 50 rpm for hours, but there is no reason to if you can pick your gearing to avoid it. And for many people, that's slightly larger chainrings than for others, there is nothing wrong with that.

Yeah, 120-130 is more like sprint cadence. But if they can do high power sprint at that cadence, they can do high power short seated-acceleration before the tuck down hill as well.

Also, it is worth noting that due to the non-linear relation between speed and power, the speed differentials between a well trained amateur and a professional will be a lot more similar at the top end than at the low end, so the same can be said for their gearing needs. For example, a 30% (just a somewhat reasonable example) increase in power will produce a much higher % of extra speed when both are on a very steep climb compared to when they are pedalling fast downhill on rolling terrain.

hmm, right. Amateur at half the power of pro (200w vs 400w) maybe 100% slower up hill (half the speed) but ~26% slower down hill? (1.26^3 ~=2.000376)
So, a scaled down pro gearing for amateur would be ~26% lower top end and 100% lower low end, right?

[spartan]

this thread is about upcoming 105 di2 NOT about gearing choices. WTF are the moderators. please delete the posts.

[Lina]

Also, it is worth noting that due to the non-linear relation between speed and power, the speed differentials between a well trained amateur and a professional will be a lot more similar at the top end than at the low end, so the same can be said for their gearing needs. For example, a 30% (just a somewhat reasonable example) increase in power will produce a much higher % of extra speed when both are on a very steep climb compared to when they are pedalling fast downhill on rolling terrain.

hmm, right. Amateur at half the power of pro (200w vs 400w) maybe 100% slower up hill (half the speed) but ~26% slower down hill? (1.26^3 ~=2.000376)
So, a scaled down pro gearing for amateur would be ~26% lower top end and 100% lower low end, right?

Okay, now do a 350 W vs 400 W comparison.