Look at the speeds: when are those relevant, unless either you have really good tailwind on a false flat or are going downhill? I’m above-average fit and don’t go above 50 km/h where I live now (which is pancake flat).
When I lived near mountains, it’d take said false flat or me going downhill. In the latter case, I would spin out any gear (50:11, 52:11, you name it).
Of course, you could be faster and really need the extra gearing very often. But in my experience the vast, vast majority of riders have too few easy gears and too many hard gears. You only very occasionally use the really tall gears, but you tend to use the easy gears a lot more often.
Most people use large chainrings to improve efficiency. My next chainring will have 46 teeth (on a 10–33 cassette, up from 42 teeth). I won’t need the hardest gear, I just want to see for myself if I can feel and measure any impact.
adding my single N here. I am 6’1" with weird proportions. Short inseam super long torso and long arms.
I have ridden 175/172.5’s for almost my entire life (52 and have been riding road since I was 16). I jumped on the bandwagon and converted most of my bikes to 165. I really didn’t like the sensation is the only way I can describe it. It was easier to maintain a 100+ cadence in all positions, is all I can say. Power really didn’t change much at all. But for climbing and sprinting I also REALLY hated it. But I’m a sprinter so I may just be used to what I’m used to.
Digging deeper into the literature into the “why” they may not be working for me I hit upon a nugget of efficiency and body proportions I realized why they aren’t working for me. The UofU studies in particular cite two separate proportions of crank length.
The first is obviously let length. But buried in a chart and a paragraph there is a mention of a percentage of tibial length determining ideal crank length. So given my inseam, I should be riding 164.5’s. However because of my freakishly long tibias the rough estimation for ideal crank length puts me at something more like 173-174. It may have been mentioned already above but my recommendation is that if you have longer tibias consider staying where you are. Regardless I would make both the inseam % calculation as well as the tibial % calculation (which if memory serves is 41% of tibia length).
If you have the desire to accelerate a downhill, good luck trying to do that with a high cadence. You’re already dealing with a sliver of pedaling circumference (with resistance) so I need a harder gear ratio, at a lower cadence, to actually put any meaningful power down.
Yup, along with better efficiency from being in the middle of the cassette more this is why a lot of racers are using bigger chainrings. Being able put out power on fast sections without having to spin >100rpm is very helpful for getting/maintaining/closing a gap in a race. On a 48-11 you’re getting above 100rpm at about 34.7mph, on a 54-11 it’s 39mph.
Outside of a race situation it doesn’t matter - you’re likely just coasting when you get to those speeds.
I’m not sure how gearing came into play here but also with shorter cranks I can pedal with great control much faster, like beyond 120rpm while still making good power whereas with my 170s I’m flopping around like a fish out of water past 110rpm just tryin to make circles. And it’s not a matter of short legs..
People oversimplify things and make the problem about leverage and not total power. So they assume shorter cranks need lower gears to compensate. But John Cobb, who has been fitting shorter cranks maybe longer than anybody, has found that people need to gear up. Recently Barry Anderson, who fits Keegan Swenson and other top pros, also said he gears people up when they go shorter.
I think everyone on here is assuming total power doesn’t change unless there is some physical issue where a shorter or longer crank is solving a specific problem on a small subset of people.
Swapped about a month ago on my TT bike , moving from 175 mm to 165 mm, keeping the same 56/42 set up and bumping the saddle up by 10 mm to cater for the change. I’m 6ft 4 with long legs.
Initially the 165mm felt ok, but I’ve found that since then I struggle to get the power down as it were, RPE increases quickly and I start to struggle to hold powers. I’ve “failed” repeated VO2 workouts on the bike and really struggled on threshold/sweetspot, returning to my 175 mm road bike this week, it was back to normal (completetion of VO2 with relative ease).
While there may be a positional aspect, in the past I’ve had no difficultly with threshold/sweetspot on the TT bike and have matched my road bike performance. I put it down to having spent many years with a cadence of ~85-90 that having to spin faster at 90-95 to maintain the power puts up my RPE and then I start to struggle. Not entirely given up on the idea but I’m certainly not sold its for me.
I do wonder if I need to alter my position more but strikes me I could disappear down a rabbit hole with that one
I might not be a native speaker so bear with me. But if you mean higher gear as in with the same power you ride with a lower cadence at the same speed can you explain me how that would work? I.e. you would get lower cadence and would need to produce higher force on the pedal (shorter crank). That seems nice if you have over-gear session scheduled otherwise not so much.
What’s the logic of this? Gearing up would only make sense if shorter cranks either allowed you to generate more power and therefore could push a higher gear at same cadence and/or if shorter cranks meant you were self selecting a lower cadence.
I don’t think either of these things is normal. Shorter cranks don’t lead to higher power unless they’re solving significant fit issues which wouldn’t normally be the case for pro riders. And they normally lead to higher cadence, not lower, as smaller circles mean lower foot speed for any given cadence.
Yes, they must get more power and have lower aerodynamic losses. They end up going faster. Prematurely undergearing the bike because of an oversimplification turns out to not work in the real world.
In my case they solved a fit issue: I wouldn’t be able to hold an aero hoods position as my knees would massage my breakfast with the standard cranks. That’s no longer an issue now. I might even get even shorter cranks next time.
I was wondering the same. I geared down (slightly easier gears) by choosing a chainring with less teeth to compensate for the slightly quicker cadence I anticipated. My experience bears that out, my self-selected cadence is 3–4 rpm higher, and the difference is basically the ratio of the crank lengths.
I’m not sure why you’d want to gear up
Why would they make more power, though? What is the rationale behind that?
Theories I’ve heard: better recruitment of larger posterior chain muscles, lower waste metabolite generation from shorter muscle contraction, better oxygen intake from less restriction of the diaphragm, less double-taxing of calves, better concentration of effort over the pedal stroke.
Not quite what you asked for but reasons I haven’t gone for it yet:
I already have a 34 at the back, don’t really want anything bigger, and shorter cranks would require that given how much I climb (because the shorter crank means less leverage means different feel to climbing with the same gears).
Do you really have such big issues? I realised I don’t, not really. If it ain’t broke…
I feel like my saddle to bar drop is already fairly high. I don’t particularly want to increase, which I would have to if I moved to a shorter crank (because the saddle needs to go up to compensate and I already have max spacers).
. 1980’s?
Well halfway there I guess. The cranks were a mail order from perhaps 2007, & the chainring about 2021.
