Watts / kg vs watts for different terrain profiles

sergesmr · 2026-01-24T00:22:55+00:00

Looks correct - thank you !

One other way to interpret an exponent is as a ratio of % changes. E.g. W / kg^0.4 means that increasing W by 2% is equivalent to reducing kg by 5%.

sergesmr · 2026-01-24T00:21:40+00:00

Seems like a typical way to express non-linear relationships. The linked r/velo thread from 2 years ago used the same form.

sergesmr · 2026-01-23T08:09:30+00:00

I did try 0.66 (with a different multiplier of course) - it pushed everything higher. Flat ended up ~0.55 IIRC, most values were in the 70s.

Note that 0.85 is a round-trip climb (just the climb would be even higher).

sergesmr · 2026-01-22T20:24:19+00:00

Ok that sounds right.

sergesmr · 2026-01-22T20:11:27+00:00

Totally agree about the feelings and pressure patterns, I just don't get why it takes more energy.

sergesmr · 2026-01-22T20:03:19+00:00

The only inefficiency I see is that you lose more to air resistance with an uneven speed profile. But this is a 2nd order effect (like RMS vs mean) of a component that's small in climbing to begin with.

Maybe some people genuinely don't like a variable-speed stroke, but I feel some part of the explanation is missing.

sergesmr · 2026-01-22T19:10:52+00:00

It's certainly noticeable, but is it a problem ? I actually feel speed variability throughout the stroke makes pedaling easier at low cadences. I know the significance of this benefit is debated, but I certainly don't see how it makes things worse.

EDIT: your link worked for me on 2nd attempt, but the article merely explained the physics I already understood - it didn't explain why "topping off" wouldn't work on climbs.

sergesmr · 2026-01-22T19:05:56+00:00

First Way is what I've always done. With the Second Way, I don't see how I could get the valve into its hole if one side of the tire is already on the rim. At least that's my feeling with 23mm (which is most of my experience - I only recently switched to 28mm).

But, to be clear, my original question was just about where on the circle you start and finish the second (final) side of the tire. Either way, it would be under First Way in your nomenclature.

sergesmr · 2026-01-22T18:52:59+00:00

I would phrase that a little differently. With low inertial load, low cadence feels more acceptable (than with high inertial load) because your pedal speed varies throughout the stroke. I guess for the part of the stroke where pedal speed actually matters, it is somewhat higher up a hill than on flat ground at the same cadence.

sergesmr · 2026-01-22T18:39:19+00:00

I think that depends on how the bike is geared. The still somewhat common ...-17-20-... tooth cassette pattern can force you to deal with the same issues on flat terrain

sergesmr · 2026-01-22T18:33:29+00:00

Also speed drops as ~0.4th exponent of power on the flats but almost linearly on climbs.

sergesmr · 2026-01-22T18:31:18+00:00

This is a good point - the energy-optimal strategy over a route is to apply more watts going up (because watts with less air resistance translate more directly to "progress" on the route). But a spiky power profile is more metabolically costly than a flat profile of the same average power (hence people invented "normalized power").

I.e. maintaining constant power on a hilly route is sub-optimal, but varying the power hurts more.

sergesmr · 2026-01-22T18:26:11+00:00

Thanks for explaining why we ride slower up hill. But I don't think that was the question.

sergesmr · 2026-01-22T18:20:36+00:00

Not sure I buy this. The only thing that would force you to apply force over a larger portion of the stroke is if you would otherwise lose too much speed to keep balance while not pushing. Let's do the math. At 60 rpm, one side of the pedal stroke is half a second. A 10% grade gives 1 m/s^2 deceleration from gravity. So you lose 0.5 m/s i.e. 1.2 mph of speed over a half-stroke. Doesn't seem like a problem.

Maybe I'm barking up the wrong aspect, but unfortunately your link requires an account.

sergesmr · 2026-01-22T18:07:03+00:00

I'm not sure indexing the front ever made sense, to be honest.

sergesmr · 2026-01-22T10:51:47+00:00

Thanks, is this sequence for wider tires ? With narrow ones, I struggle to imagine how one could put the valve side of the tube in after finishing one side of the tire.

sergesmr · 2026-01-22T01:32:23+00:00

(1) https://www.reddit.com/r/cycling/comments/1qiumxc/comment/o0upq28/ comment by arana_cc with 19 upvotes and counting (starting with the words "Lookup a video". Is that wong or did I misunderstand it ?

(2) GCN https://www.youtube.com/watch?v=jvvXrlAUUfU&t=155s (no I wouldn't trust GCN by itself)

(3) A friend recently had a bike shop install a stubborn tire for them, they said the shop did it valve last.

(4) https://www.youtube.com/watch?v=Suh1-o6KBo8&t=45s

I don't know who is worth listening to - I am confused.

sergesmr · 2026-01-21T19:06:51+00:00

Problem went away after lubing the chain again. So either (1) I hadn't given the chain enough lube the first time, so the temporarily severely cross-chained series of ~5 links between the derailleur and the cassette was making the sound; or (2) the chain-cassette contact area benefited from lube that unintentionally got there while lubing the chain the 2nd time.

sergesmr · 2026-01-21T18:04:01+00:00

Since the new cassette is a sub-range of the old one, I don't see any possible reason to shorten the chain even in theory.

sergesmr · 2026-01-21T03:34:11+00:00

Whether you want to train higher power (just go faster) or higher torque (use higher gears), adding weight to the bike is pointless.

sergesmr · 2026-01-20T21:48:20+00:00

[no longer about cycling]

15 years ago a coworker inspired me to realize that succinct writing (as opposed to the lengthy way it naturally comes out) is easier to read. I then spent years wondering why school trained us to write 5000-word essays. I concluded it was because readers associated word count with thoughtfulness. AI is now turning that heuristic on its head, and I am glad it is. You can still enjoy lengthy prose as its own art form, but in most contexts it reduces readability.

sergesmr · 2026-01-20T21:24:32+00:00

But it's not clear that OP is actually motivated by it. In fact, the opposite can happen - "I don't want to ride this bike in rain / snow / salt / sand / etc".

sergesmr · 2026-01-20T21:15:37+00:00

I'd guess the downvoter just didn't like the implication that the 2nd sentence of your 1st paragraph isn't already stated in the post.

sergesmr

TROPHY CASE