RChung

Two things:

1. It shouldn't surprise you that I've actually done the calculations. No matter what gear you're in, if you drop your cadence (which, of course, drops your speed) your pedal force will decrease. But that's a small effect; you're right that the main effect is in terms of gearing.

2. My main point was that cadence matters little; the main point was that instead of thinking about this as a cadence problem, think of this as a pedal force (or crank torque) problem. Right now, unless you're sitting at one of those cycling desks, your legs probably have cadence = 0. Do your legs hurt? If not, it's not the cadence, it's the pedal force (or crank torque).

By the same token, if you could maintain 80 rpm on a steep hill in that same gear, the pedal force (or crank torque) wouldn't be any lower (in fact, it would be slightly higher). Pedal force is pretty much insensitive to cadence under those conditions, so even if you could pedal faster the pedal force wouldn't decrease.

DaveLeeNC

I don't know how others could know my personal cadence tolerance. That is why I did not ask that question.

You made a very clear statement regarding what happens to you in low cadence situations. I am curious as to what that point is for you.

Dave

DaveLeeNC

I am also convinced that force (too much of it) is the important parameter here. But, even though force is the fundamental measurement being made by my power pedals, that number is not reported to me. But I can see power and cadence and can imply a relative force from those numbers. So power and cadence is how I look at this.

I could have asked 'how many newtons of force can you apply long term to your pedals before you fatigue excessively in long climb', but probably would not have gotten a useful response :-)

dave

Road Fan

Dave, are you saying you would like to try pedaling on your uphills in 85 to 95 rpm range? If so, plan to reduce you deepest granny by a factor about 20% and see what happens. If you don't sell the old parts you can always change it back if you don't like it. You may or may not actually maintain ftp, but you will pedal faster going up the hills. Faster cadence may require some acclimation.


I've found lower gears do help me maintain uphills for longer time with more comfort - not being so close to the edge.

Exactly how much lower I need is a matter of trial and error. Sometimes it's easy to re-equip the bike, and sometimes it's not.

Carbonfiberboy 

Butting in again . . . Actually, my legs do hurt sitting at my desk, but that's a good thing. At my age, if my legs don't hurt, I'm doing it wrong.

Higher cadence in the same gear increases pedal force due to wind resistance, which in Dave and my case, it probably insignificant - as you say, a small effect. Are there other increased resistances I'm not thinking of?

The reason to use a lower gear is to pedal higher cadence and get almost the same power as using a higher gear at the same speed. Power in a lower gear will, for us duffers out here, usually be a little lower due to metabolic effects, i.e. higher oxygen cost from wiggling the legs more. I'm using "oxygen cost" as shorthand, because that's easy to feel, doesn't require instrumentation. Offsetting that slightly lower power is the increased endurance over a long day due to lower pedal force = decreased glycogen cost. The balance between oxygen and glycogen is individual and can only be assessed through individual experience. That balance will always be slightly different for each course and length, which really complicates the issue. Just trying to simply things by recognizing their complexity.

DaveLeeNC

My sense of things is that I need to stay at/above around 75 rpm (at my estimated climbing power of 240 Watts). And that is a roughly 15% gear reduction from the status quo. It is alot of speculative analysis, 'climbing simulation' on a spin bike that has power measuring capability, and judgment as there are no long climbs (or even long flat places) where I live/ride.

dave

DaveLeeNC

The next opposing force 'factor on the list' would be rolling resistance. And rolling resistance looks much like gravity in that it is pretty constant WRT speed.

Next I guess would be drive train efficiency which is (again I am guessing here) probably a function of applied power. RChung probably has a good handle on that.

dave

Dean V

In my area the climbs don't get any bigger that cat 3 or 4. Those I can get up ok with almost any gearing.
The few times that I have done a HORS category climb I found that having the right gearing was critical if you want to get up it well.
Basically climbing a mountain is a lot different to climbing a hill.
So if you just want to have a crack at this ride and see how it goes take your bike and gearing as is.
If you want to prepare and do what you can to get the best result. Gear it down.

Carbonfiberboy 

The only thing I know about drive train losses is that running the largest ring up front that gives you the cadence you want reduces chain wear.

BengalCat

It seems to me that cadence is very individually specific. I'm old and heavy and reasonably fit with low power to weight ratio. Nevertheless over the course of the past five years despite getting fitter but losing power my cadence remains the same until I run out of gears to maintain what I would normally do. On the flats for workout cruising is around 95 and if pushing it at a constant pace about 105 average. On climbs of significance to me, my optimal cadence whether going max or just working hard is about 86 on average. All that changes at 86 is my gearing depending on how much power at a given point that I need or my legs are capable of providing depending on freshness or fatigue level.

IMO weight is very important but increasing your maximum or FTP level of power produces better performance in endurance and speed up climbs than dropping weight. Naturally, if you can do both that's best!

redlude97

The pedal force and cadence can be the same in two different gears resulting from two different power outputs

HTupolev

That would imply two different speeds, not two different power outputs. Power is essentially force*cadence, so if force and cadence are the same, power is the same.

DaveLeeNC

The one case that I can think of where the same pedal force and cadence would result in a different power, is when a portion of the pedal force is not inline with the pedal motion. I don't know if that was redlude's point or not.

dave

ps. I have Garmin Vector pedals measuring power, and the ONLY data that they have is cadence and force (and crank length plus a sensor angle to deduce torque, but these are fixed values for a given installation).

redlude97

whoops i meant same force and different cadence, meaning that pedal force alone doesn't determine fatigue

redlude97

Sorry i made a mistake in my post
Was trying to answer this question

ridethecliche

It would appear to me that there's a psychological element at play here as well.

Wilmingtech

This thread got me thinking. I've got quite a few good hill climbs on my daily rides. Anywhere from 1-5 miles going up around 800 to 1200' of vertical gain.

I'm a bigger guy for a cyclist in the 185lb range. Good legs and built like a sprinter. I am usually out of the saddle at the top of climbs pulling and pushing on pedals to sprint up over to the descent.

My cadence on steady climbs is usually 70-75rpm. I try to keep it above 70 anything below 60 is mashing and ineffective.

Reading through this thread has me thinking. I should go back through my Strava segments and see what gear I would have to be in at 90 rpm on these climbs to keep the same speed as I did at 70rpm on previous attempts and see if it is harder or easier for me with the higher cadence.

This will be interesting.

-Sean

woodcraft

Maybe some folks don't have much in the way of hills, but theorizing about your ideal cadence is pointless

when the grade is much above 10%. Unless you are cat 1, you're not going to be much over 5 mph, and even with 1:1 gears

that means around 60 rpm. Different with a mountain bike, but we're talking road here.

HTupolev

There's no reason you can't stick sub-1:1 gears on a road bike. I certainly would if I was climbing 5mph all day.

colnago62

This is very true. Your cadence will be what it will be based so many factors. How much riding you have done that week. The kind of riding you have been doing previously to the climb. Of course there are more variables, but I hopefully made my point clear. I think it is always good to have a gear a few teeth lower than you think you will need just in case.

DaveLeeNC

Your optimal cadence is certainly an interesting discussion and this thread is as good a place as any for that.

But for the record, that is NOT the issue that I raised when I started this thread. For me I would guess that, for a long and steady (and hard) effort, somewhere around 95 rpm would be my ideal cadence. But if I were limited to 85 I don't think it would matter much. My sense of thing is that at some point as RPM drops your ability to put out the same power for the same period of time falls dramatically. That was my question, but no reason not to talk about the other side of the curve as well.

dave

woodcraft

After overcoming the embarrassment, I've come to really like the 34/48, 11/34 gearing that I often ride currently.

The gaps on the small end of the cassette are not that different, so the penalty in a fast group is not much,

but much more time is spent in the big ring overall w/ few double shifts.


Interestingly, 1:1 gearing makes figuring speed easy- 7' circumference wheel= 754 revolutions per mile so, for example, 60rpm= 12.6 minutes= 4.76mph

and 85rpm= 6.76mph which for me would be 7%- 12% grades, although I would probably shift to stay below 85 rpm.


I hardly ever see an average cadence of as high as 90 on Strava, 'tho I imagine it happens more where it very flat,

which suggests that above that is not the fastest/most efficient/etc. in practice.

terrymorse 

I haven't seen many riders doing climbs at 95 cadence.

A cadence of 90 is a rough average for flat time trials or flat road races, but for mountain stages, the average is closer to 70.

Here's a decent article about "optimal cadence", with references.

DaveLeeNC

That would be Lance/Froome country - which doesn't exactly make it right for me (even if I had the gearing and/or strength to pull it off).

I came to that conclusion (for me) based on an observation of what I do when I am riding indoors on a spin bike (with power pedals) trying to ride for 15 to 30'ish minutes at 95% to 105% of my ftp. On a spin bike you kind of have infinite gears and when I do those rides I tend to gravitate toward 95 or so rpm.

But that is hardly a scientific analysis. Even though Froome and Armstrong climbed at high cadence, I believe that Quintana is more of a 75 RPM guy.

Of course I was not looking for the optimum cadence, but looking for the cadence (when pedaling in the vicinity of your ftp) that things kind of fall apart.

dave

woodcraft

Well really you have one gear & variable resistance. Crank that thing down another 5 or 10 turns, and something will fall apart.


Now for an interlude- quote from "The Hardmen":

"Lance Armstrong said, 'Pain is temporary, quitting lasts forever', proving that even *******s can be insightful."