[TiCoyote]

Are you faster on a compact or faster on a standard?

 

[Roland44]

Are you faster on a compact or faster on a standard?

Interesting poll! I'm actually a lot faster on a standard 53/39.

 

[spectastic]

the question doesn't make sense, considering the difference between compact and standard are the gearing range, which only varies slightly. compact lets you climb mountains. standard makes sure you don't spin out on the flats or descents. aside from that, there is absolutely no difference, unless you want to argue the minuscule savings from bigger sprockets of a standard, resulting in less chain wrap..

 

[Blue CheeseHead]

^^^

Spot on. Gears are gears. The difference in chainrings only shows up at the far ends of the spectrum.

One thing a standard may do is force one to use a harder gear in some situations which may make one stronger over time (just before blowing out one's knees. )

 

[TiCoyote]

I know it's a strange question, and it makes me look like I don't understand gearing. But I have played with HTML5 Gear Calculator ad nausium, and what I've found on paper doesn't match what I've found IRL.

Here's the deal. I'm 5'8" 140lbs. I'm way faster in the saddle than out of it. I used to be a 65 RPM cranker, but at some urging from my brother out of concern for my knees, I'm now a 95 RPM spinner.

As a result, on a standard, I was always in the big ring and the second-largest sprocket. This meant a pretty extreme chain angle. I figured a compact would allow me to move over one or two sprockets. I tried out a compact, and it allowed me to stay in the saddle longer on bigger climbs. As a result, I PR'd on the biggest hill I regularly climb.

So I swapped out the standard for a compact, but I've been slower this season. However, there are lots of variables. It's been a long, cold winter. I had surgery in the fall. I was off the bike for 5 months. It's been windy here. I sprained my ankle.

Then, yesterday, it was warm but wet. I took out my old bike, which has a standard, and it was my fastest solo-ride of the season. In fact, I was as fast as I had been last Sept. Maybe it was because I had a few days of rest. Maybe it was because the old bike is Ti and the thinner tubes are more aero. Maybe it's because I just cleaned the chain. Maybe it was just a good day for me. Maybe it's because it was raining and I wanted to get home sooner.

Anyway, I felt like I was getting more power out of the 53 than I normally get out of the 50. I'm trying to eliminate variables.

 

[ibericb]

I know it's a strange question, and it makes me look like I don't understand gearing. But I have played with HTML5 Gear Calculator ad nausium, and what I've found on paper doesn't match what I've found IRL.

Here's the deal. I'm 5'8" 140lbs. I'm way faster in the saddle than out of it. I used to be a 65 RPM cranker, but at some urging from my brother out of concern for my knees, I'm now a 95 RPM spinner.

As a result, on a standard, I was always in the big ring and the second-largest sprocket. This meant a pretty extreme chain angle. I figured a compact would allow me to move over one or two sprockets. I tried out a compact, and it allowed me to stay in the saddle longer on bigger climbs. As a result, I PR'd on the biggest hill I regularly climb. ...

Keep playing with the gear calculator and here's what you'll find --

- most of the gear ratios are equivalently available on either setup with a change in the rear sprocket.

- the differences in what's available come at the ends or the extremes.

- the spacing between adjacent gears may be different, which depending on your preferred riding cadence, may lead to a particular combination being more preferable, reflecting a subtle difference in the exact gearing.

- combining the second and third point, you may be able to better adjust to your most used or most preferred gearing changes with a change in cassette; for example using Shimano 6800 cassettes , the widely used 11-28 provides singular gear tooth changes through 15 teeth, then jumps to 2-tooth changes from 15 through 25, whereas the 11-25 gives 1-tooth changes trough 17, then moves to 2-tooth from 17 on, and the 12-25 gives 1-tooth changes from 12 through 19.

If you feel like you're getting more power out, it's because you're putting more power in. There are two input variables in the power equation, pedal torque, and cadence. If you ride by the feel of cadence in a fairly narrow range, then the changes in gear spacing can make a difference around your sweet zone.

 

[TiCoyote]

My old setup was 53/39 in the front with a 12-25 in the back 10 spd. The gear calculator tells me that a 53 up front with a 23 in the back pedaling at 95rpm puts me at 17mph. That's the 2nd largest sprocket. On a 50/34 with a 12-25 11 spd I would hit 17mph with the 50/21 combination. That's the 3rd sprocket. So it should move me over by 1 sprocket.

Ive also read that a 53 is more efficient than a 50 bc the chain is engaged on more teeth, so there's less friction less loose chain to stretch and more of the chain is being pulled. Is it enough of a difference that I would feel it and notice an increase in speed?

 

[Mandeville]

I'm the same as I don't generate enough power to ever really use the tallest gears. The highest power I can sustain or average on a long climb or on the flats is about 200 watts maximum. The maximum watts for a one minute or less hardest effort is between 400 and 500 watts.

 

[mikerp]

My old setup was 53/39 in the front with a 12-25 in the back 10 spd. The gear calculator tells me that a 53 up front with a 23 in the back pedaling at 95rpm puts me at 17mph. That's the 2nd largest sprocket. On a 50/34 with a 12-25 11 spd I would hit 17mph with the 50/21 combination. That's the 3rd sprocket. So it should move me over by 1 sprocket.

Ive also read that a 53 is more efficient than a 50 bc the chain is engaged on more teeth, so there's less friction less loose chain to stretch and more of the chain is being pulled. Is it enough of a difference that I would feel it and notice an increase in speed?

IMO based on your info gearing and the speeds you are looking at you should be in the small chainring. 39/17, with a bit more effort you can be in 39/16 and 39/15. I wouldn't get into the large chainring until 53/19 (maybe 53/21 if you can't make it to 39/15).

 

[Lelandjt]

^Exactly. You're using a crossed up gear in the big ring when you should be using a cog with a straighter chainline in the small ring. Both will have the same gear ratio but the small ring will have less friction and not require trimming the front derailleur.
I have 39/53 11-23 9spd. I use the small ring for 23,21,19,17,15,14 and the big ring for 11,12,13,14,15,17. The front derailleur doesn't have to be trimmed, just shift up or down. I use a lower cadence than you and don't use my big ring below 18mph.

P.S. The way the poll is worded the answer is "standard". We all have a built in rev limit and obviously you can go faster at that rpm in a taller gear.

 

[spectastic]

agreed on using the 39 instead of the 53. this is one of the main reasons I choose shimano over sram. the front shifting on the shimano is so much better.

it's up to you whether you like to stay in the big ring on your compact, and be able to accelerate in the big ring right after, or shift from the small ring to the big ring, after a climb. it sounds like you would prefer the 50, which is totally fine.

 

[ibericb]

Hey Mandeville - before I can respond the your PM you need to clean out your PM mailbox. It's full and can't accept anymore messages.

 

[ibericb]

Are you faster on a compact or faster on a standard?

Power determines speed, not gearing. Gearing defines the cadence that coincides with a given power. If you produce the same power, the bike will go the same speed, regardless of gearing, but the pedaling cadence for that power will be different.

 

[Lelandjt]

Power determines speed, not gearing. Gearing defines the cadence that coincides with a given power. If you produce the same power, the bike will go the same speed, regardless of gearing, but the pedaling cadence for that power will be different.

Except that we all have a rev limit. Higher gearing = more speed. You just need the power or downhill to use it.

 

[ericm979]

You just need the power or downhill to use it.

Aero drag rises with speed. Most riders can tuck in a more aero position when they are coasting. Beyond a certain speed it is faster to coast and tuck than to pedal.

You can experiment on your own with a speedometer, or in a group ride where you can see your speed relative to others (remembering that being in the draft is a large advantage). I'm usually faster coasting and tucked above about 37 mph.

 

[ibericb]

Except that we all have a rev limit. Higher gearing = more speed. You just need the power or downhill to use it.

Higher gearing doesn't increase speed. More power increases speed (all other factors consuming power, like drag, being equal). Gearing allows you to adjust angular velocity of cranking at a given power. If you hit an upper physical angular velocity limit (cadence), then increasing gear ratio will allow you to bring that velocity back down and, if you can apply more force to the pedals increase power. Speed is entirely about power, which is the product of torque applied to the pedal and cadence.

 

[myhui]

Does using a larger freewheel decrease friction at the hub at the same overall power output when measured at the hub ?

If it does, then we should all be riding at least 14 in the back instead of 11.

I don't think it does.

 

[ericm979]

Friction increases with smaller sprocket size.
It's not a huge difference but it's there. It's why riders doing the hour record use relatively large cogs (14t, 15t) and larger chain rings.

However it would be impractical to have the desired spread of road bike ratios with a 14t small cog.

 

[TiCoyote]

I wonder if I'd be happier with a 52/36 than a 50/34 or a 53/39. I wonder if it would be worth adding a 52/36 to my parts drawer, and then I could swap back and forth between the compact and mid-compact. I wonder if a different chain length would be required.

 

[ibericb]

Aero drag rises with speed. Most riders can tuck in a more aero position when they are coasting. Beyond a certain speed it is faster to coast and tuck than to pedal.

You can experiment on your own with a speedometer, or in a group ride where you can see your speed relative to others (remembering that being in the draft is a large advantage). I'm usually faster coasting and tucked above about 37 mph.

The drag force increases as the square of speed, so everything else being equal, if you double your speed the drag force at the higher speed increases by 4X over that at the slower speed. But here's the real killer - the power consumed by drag is the drag force X velocity. That means that the power consumption from aerodynamic drag goes as the cube of velocity. So in an otherwise sterile and perfect world with everything else being equal, to double your speed would take nearly 8-times the power (discounting the other demands for power, like grade, rolling resistance, friction, etc.).