To save you hunting, here's the relevant section - I had it grabbed before, just in case Rym challenged my 2% efficiency loss assertion from before, and yes, it's the same paper, as I expect that Scott and I both sourced it from the wiki page on hub gears:
"Hub gears are generally about 2% lower in efficiency than derailleur-type gears. But there are exceptions. This is illustrated by figures 3, 6, 7, and 12. Figure 12 shows that the efficiencies of the Shimano 4, Sachs 7, Shimano 7, Sturmey 7 and the Rohloff 14 all cluster about two percent lower than the Browning 4, Browning 12, or the Shimano 27. However, two of the 3-speed hub gears did not follow this trend. The grease in the Sachs 3 and the Sturmey Archer 3-speeds was replaced with light oil, and unlike the other hub gear transmissions, the efficiencies of the Sachs 3 and Sturmey 3, compare well with the best of the derailleur transmissions (figs. 7, 9, and 12).
Also, these transmissions were worn in, whereas many of the others were new. Manufacturers would do well to replace heavy grease in their hub gears with light oil. Although oil wouldn’t last as long as grease, the energy savings would be significant. Unfortunately commuters have a tendency to ignore maintenance until something breaks, so light oil probably wouldn’t be a popular choice.
Also, with the Shimano 4, the first gear (a 1.0 ratio) had a higher efficiency than the derailleur transmissions, even though gears 2, 3, and 4 had a lower efficiency (see fig. 6). In a planetary transmission (also called epicyclic), even when the hub ratio is 1.0, the planet gears are still in motion [12]; however, all of the planetary transmissions we tested had high efficiency at 1.0 gear ratios."
And to cut Scott off before he has the chance, here's the section of the introduction he'll quote if you challenge him regarding the rather unimpressive numbers for efficiency loss (with bolding placed on the most likely subsection for him to pick as his extract):
"In a bicycle, small losses can mean large performance differences—especially in competition [3, 4]. For example, suppose Christopher Boardman, the present holder of the bicycle world hour record (56.375 km; Manchester, England, 1996), were to use a bicycle with a drive that lost 2% more energy than his record machine. Boardman would travel almost 0.5 km less in one hour [3]. The hour record has been broken several times in the past 30 years by less than 0.5 km. If an Olympic 4000-meter pursuit team were to use bicycles that were 2% less efficient, they would be about 2 seconds slower in the 4000-meter team-pursuit race, which would have moved them from first place to fourth place in the 1996 Atlanta Olympics (4 min 8 sec vs . 4 min 6 sec) [4]. By using the wrong fixed gearing, differences of 2% are easily possible."
Because a world record attempt for the longest distance cycled in an hour is clearly relevant and an excellent analog to your average bicycle commute.
But, Fair's fair, and credit where credit is due - At least he put something from a third party forward instead of just pulling it out of his arse. And of course, do keep in mind, this is a Journal Article is 13 years old, and the technology has advanced since then on both sides of the fence. How much and what gains or losses this might lead to, I don't know, but I'm sure Scott can come up with something. This doesn't make it good or bad inherently, but it is something to consider.
So after 60km of cycling in perfect conditions, the two percent can save me two minutes?
And, to be clear, picking the wrong gear on a derailleur bike can make more than a two percent difference? And picking the wrong make of derailleur gear can make more of a difference? And having different oil in my hub gear can make more difference too?
It seems that at the top levels of competition, every two percent saved makes the difference between winning and losing or breaking a record or not. As I'm cycling in the real world, knowing not to cycle on cobblestones will make more difference than which gear technology I chose.
Oh, and to be fair, I'd also read the same paper, as it was the only real science study I could find. I'm not going to say there wasn't a difference 13 years ago, but there is no way Scott can use this study to back up his "way less efficient" when the difference would be indistinguishable from noise.
That study only gives you the difference in efficiency of the drivetrain only. Which is kind of interesting. That efficiency is how much effort you put into pedaling that actually makes it to the wheel and isn't lost as friction, heat, etc. in the gears.
I'm still trying to find out how much these different drivetrains weigh, also taking into account things like the weight of the thicker chain, the weight of the chain guard, etc. We won't need a study for that because Newton's Second Law, F=MA. More M means less A with the same F.
You also have to take into account available gears for efficiency at different speeds and efficiency of the maximum gear.
2% means that every 100 pedal rotations, I waste two of them. I pedal at about 70-80rpm for long periods when I'm riding. Each rotation is tiring, as I'm always pushing to maintain cadence.
That's a lot of cycles to lose on even a short half-day trip.
You also have to take into account available gears for efficiency at different speeds and efficiency of the maximum gear.
2% means that every 100 pedal rotations, I waste two of them. I pedal at about 70-80rpm for long periods when I'm riding. Each rotation is tiring, as I'm always pushing to maintain cadence.
That's a lot of cycles to lose on even a short half-day trip.
Yes. Only the fancy speedhub has even close to enough gears, and it was really the only choice that had serious efficiency issues.
I find the best rough guide would be a comparable set of either middle of the range or top-end gear, or average out a few of them in a range and with comparable gear ranges, do the same with a full set of external gears. The best you can to compare like to like, basically.
For the Hub, you need to take into account - if you want truly everything in the system required to function - Hub, Cabling, shifter, Crankset, chain. You seem to want to add the chainguard too, so fair enough, but it's not essential to function.
For the External gears, you need the Cassette, Crankset, derailleurs(front and rear), chain, cables, shifter(two.)
From what I can remember about industrial brushless chain, the weight difference is going to be negligible - You're talking a 2mm whole difference total breadth, spread between links and pins(mostly pins), but the chain is rather shorter than a derailleur chain, since you don't need slack or much length for lateral flexibility. Per meter, you're looking at a difference of well under ten grams.
As for bike cable, steel cable of that size will run you on average about 14 grams per meter. You tend to have approximately double the amount of cable on a derailleur bike, with the need for two derailleurs, whereas a hub bike requires only one cable for shifting.
While I appreciate you doing all this work, and I'm happy to help with average weights, I feel you're getting a little too caught up in your own argument, and you're forgetting the case of Precision vs Accuracy.
Guys fixies is where its at! One gear no brakes its like the best thing ever!
On another note I've been BMXing more and more, partly as physio and partly exersise and partly to prove that I am not an old fart who's past it. Starting to look at down hill mountain biking soon as there are some sweet corse near my house. Anyone else ride off the beatten track?
I've biked in woods and trails FAR more than I've biked on streets. I used a small hardtail schwinn for a long, long time and gave it quite a pounding on rough terrain trails.
Hell yeah. With all this readily available bushland, and living near a bunch of decent enough really big hills that are named mountains for some reason, I got plenty of riding in back in the day. Not to mention that pre-car, I rode my bike almost everywhere, and idolised the speed and skill of bike messengers and allycat racers.
Being that Chicago's public transit amenities, street width, bike path structure, and overall topography are pretty much the same as Berlin's, I'm probably going to join the Glorious City Bike Master Race. I do some mountain and road riding in Wisconsin, and when I make enough money to do that regularly, I'll buy a God-of-Gods crosstrail from Specialized.
Bikes are like cars. Roadsters/City Bikes are the Honda Fits, 21-speed crosstrail touring bikes and road racers are the Porsche 911s. It's more practical to get a Honda Fit first and then invest in a 911 when you start autocrossing. ~_^
Maybe? If it works for you and you don't see any reason to change, it doesn't really matter what you ride.
That said, you are going to be losing a lot of stroke efficiency to a full-suspension frame in any terrain where it's unnecessary, and mountain bikes are too heavy for day-to-day city use. A hardtail with a suspension fork is the most you need for city riding, but a hardtail with fat road tires and no front fork will handle most city streets quite admirably.
I'm not nearly as hardline as Scott, but there is such a thing as the right tool for the job.
Mountain bikes aren't so bad in the city, just a little slower. I ride mine around for 2 hours all the time. It's not like I have a lightweight either. I think the frame is steel.
Mountain bikes aren't so bad in the city, just a little slower. I ride mine around for 2 hours all the time. It's not like I have a lightweight either. I think the frame is steel.
That's actually a problem for me. Two reasons:
1) I live in a second-story walkup, and it's probable that I will be living in a higher-storey (but still walkup) apartment in the next two years. It's only sane to store a nice bike indoors, so that translates to carrying the bike upstairs whenever I go home. I want my frame to be as light as possible.
2) Every bit of energy I spend moving a heavy frame is energy I can't spend moving cargo. That's a big deal when I'm doing all my groceries for the week.
Mountain bikes aren't so bad in the city, just a little slower. I ride mine around for 2 hours all the time. It's not like I have a lightweight either. I think the frame is steel.
That's actually a problem for me. Two reasons:
1) I live in a second-story walkup, and it's probable that I will be living in a higher-storey (but still walkup) apartment in the next two years. It's only sane to store a nice bike indoors, so that translates to carrying the bike upstairs whenever I go home. I want my frame to be as light as possible.
2) Every bit of energy I spend moving a heavy frame is energy I can't spend moving cargo. That's a big deal when I'm doing all my groceries for the week.
Buy a $10 bike. Buy a new $10 bike at the new place. DONE.
Hell yeah. With all this readily available bushland, and living near a bunch of decent enough really big hills that are named mountains for some reason, I got plenty of riding in back in the day. Not to mention that pre-car, I rode my bike almost everywhere, and idolised the speed and skill of bike messengers and allycat racers.
When I lived in Cashmere there was a shitload of trails around everywhere. I didn't get very far past that area with a bike though. We never took our bikes anywhere for the most part unfortunately.
When I lived in Cashmere there was a shitload of trails around everywhere. I didn't get very far past that area with a bike though. We never took our bikes anywhere for the most part unfortunately.
Hi guys it's been a long time since my last post, but I need an opinion on this bike http://www.specialized.com/us/en/bikes/multi-use/sirrus/sirrussport It's at the very top of my price range I cannot go any higher then that. In Brazil I will pay about 1.100 dollars for it. The use will be strictly to commute, it will be tough because I'm gonna have to do a lot of riding on high speed streets. There isn't anyone riding a bike to were I work but beeing a nerd I have to set the example.
The Vanmoof 3.7 arrived, and I've put about 50 miles on it across the last three days.
Having now ridden both a Rubin Bike and a hub-geared City Bike in city conditions, I can say that the bike I chose is a lot better for my purposes. Little things (being able to shift back to low gear at a standstill, being able to pull the brakes hard without losing stability, the Hebie Chainglider) really make commute riding and errands easier. I want to get some go-fast shoes and some hybrid pedals so I can make effective use of my highest gear.
Still get a teensy bit jealous when the dudes on Rubin Bikes tear past me in gearings I don't have. That said, most of the guys who do that wear sponsor jerseys and have legs like tiny jackhammers, so I'm not sure we're the same class of cyclist. ~_^
I went to a different bike shop at lunch and the guy offered me this khsbicycles.com/12_vitamin_c_11.htm I don't know much but it seems this has better parts compared to the specialized sirrus sport. The geometry of the frame looks a lot different too, the frame on the khs vitamin C is much lower to the ground. Can anyone tell me which one of these is better? Also the khs bike is 150 dollar cheaper.
Comments
"Hub gears are generally about 2% lower in efficiency than derailleur-type gears. But there are exceptions. This is illustrated by figures 3, 6, 7, and 12. Figure 12 shows that the efficiencies of the Shimano 4, Sachs 7, Shimano 7, Sturmey 7 and the Rohloff 14 all cluster about two percent lower than the Browning 4, Browning 12, or the Shimano 27. However, two of the 3-speed hub gears did not follow this trend. The grease in the Sachs 3 and the Sturmey Archer 3-speeds was replaced with light oil, and unlike the other hub gear transmissions, the efficiencies of the Sachs 3 and Sturmey 3, compare
well with the best of the derailleur transmissions (figs. 7, 9, and 12).
Also, these transmissions were worn in, whereas many of the others were new. Manufacturers would do well to replace heavy grease in their hub gears with light oil. Although oil wouldn’t last as long as grease, the energy savings would be significant. Unfortunately commuters have a tendency to ignore maintenance until something
breaks, so light oil probably wouldn’t be a popular choice.
Also, with the Shimano 4, the first gear (a 1.0 ratio) had a higher efficiency than the derailleur transmissions, even though gears 2, 3, and 4 had a lower efficiency (see fig. 6). In a planetary transmission (also called epicyclic), even when the hub ratio is 1.0, the planet gears are still in motion [12]; however, all of the planetary transmissions we tested had high efficiency at 1.0 gear ratios."
And to cut Scott off before he has the chance, here's the section of the introduction he'll quote if you challenge him regarding the rather unimpressive numbers for efficiency loss (with bolding placed on the most likely subsection for him to pick as his extract):
"In a bicycle, small losses can mean large performance differences—especially in
competition [3, 4]. For example, suppose Christopher Boardman, the present holder of the bicycle world hour record (56.375 km; Manchester, England, 1996), were to use a bicycle with a drive that lost 2% more energy than his record machine. Boardman would travel almost 0.5 km less in one hour [3]. The hour record has been broken several times in the past 30 years by less than 0.5 km. If an Olympic 4000-meter pursuit team were to use bicycles that were 2% less efficient, they would be about 2 seconds slower in the 4000-meter team-pursuit race, which would have moved them from first place to fourth place in the 1996 Atlanta Olympics (4 min 8 sec vs . 4 min 6 sec) [4]. By using the wrong fixed gearing, differences of 2% are easily possible."
Because a world record attempt for the longest distance cycled in an hour is clearly relevant and an excellent analog to your average bicycle commute.
But, Fair's fair, and credit where credit is due - At least he put something from a third party forward instead of just pulling it out of his arse. And of course, do keep in mind, this is a Journal Article is 13 years old, and the technology has advanced since then on both sides of the fence. How much and what gains or losses this might lead to, I don't know, but I'm sure Scott can come up with something. This doesn't make it good or bad inherently, but it is something to consider.
And, to be clear, picking the wrong gear on a derailleur bike can make more than a two percent difference? And picking the wrong make of derailleur gear can make more of a difference? And having different oil in my hub gear can make more difference too?
It seems that at the top levels of competition, every two percent saved makes the difference between winning and losing or breaking a record or not. As I'm cycling in the real world, knowing not to cycle on cobblestones will make more difference than which gear technology I chose.
I'm still trying to find out how much these different drivetrains weigh, also taking into account things like the weight of the thicker chain, the weight of the chain guard, etc. We won't need a study for that because Newton's Second Law, F=MA. More M means less A with the same F.
2% means that every 100 pedal rotations, I waste two of them. I pedal at about 70-80rpm for long periods when I'm riding. Each rotation is tiring, as I'm always pushing to maintain cadence.
That's a lot of cycles to lose on even a short half-day trip.
I also shift regularly in order to maintain cadence, and downshift fully to 2-1 any time I must stop for traffic.
For the Hub, you need to take into account - if you want truly everything in the system required to function - Hub, Cabling, shifter, Crankset, chain. You seem to want to add the chainguard too, so fair enough, but it's not essential to function.
For the External gears, you need the Cassette, Crankset, derailleurs(front and rear), chain, cables, shifter(two.)
From what I can remember about industrial brushless chain, the weight difference is going to be negligible - You're talking a 2mm whole difference total breadth, spread between links and pins(mostly pins), but the chain is rather shorter than a derailleur chain, since you don't need slack or much length for lateral flexibility. Per meter, you're looking at a difference of well under ten grams.
As for bike cable, steel cable of that size will run you on average about 14 grams per meter. You tend to have approximately double the amount of cable on a derailleur bike, with the need for two derailleurs, whereas a hub bike requires only one cable for shifting.
While I appreciate you doing all this work, and I'm happy to help with average weights, I feel you're getting a little too caught up in your own argument, and you're forgetting the case of Precision vs Accuracy.
On another note I've been BMXing more and more, partly as physio and partly exersise and partly to prove that I am not an old fart who's past it. Starting to look at down hill mountain biking soon as there are some sweet corse near my house. Anyone else ride off the beatten track?
On the other hand.... no mountains in Berlin!
Bikes are like cars. Roadsters/City Bikes are the Honda Fits, 21-speed crosstrail touring bikes and road racers are the Porsche 911s. It's more practical to get a Honda Fit first and then invest in a 911 when you start autocrossing. ~_^
That said, you are going to be losing a lot of stroke efficiency to a full-suspension frame in any terrain where it's unnecessary, and mountain bikes are too heavy for day-to-day city use. A hardtail with a suspension fork is the most you need for city riding, but a hardtail with fat road tires and no front fork will handle most city streets quite admirably.
I'm not nearly as hardline as Scott, but there is such a thing as the right tool for the job.
1) I live in a second-story walkup, and it's probable that I will be living in a higher-storey (but still walkup) apartment in the next two years. It's only sane to store a nice bike indoors, so that translates to carrying the bike upstairs whenever I go home. I want my frame to be as light as possible.
2) Every bit of energy I spend moving a heavy frame is energy I can't spend moving cargo. That's a big deal when I'm doing all my groceries for the week.
Brakes, check
All good.
Having now ridden both a Rubin Bike and a hub-geared City Bike in city conditions, I can say that the bike I chose is a lot better for my purposes. Little things (being able to shift back to low gear at a standstill, being able to pull the brakes hard without losing stability, the Hebie Chainglider) really make commute riding and errands easier. I want to get some go-fast shoes and some hybrid pedals so I can make effective use of my highest gear.
Still get a teensy bit jealous when the dudes on Rubin Bikes tear past me in gearings I don't have. That said, most of the guys who do that wear sponsor jerseys and have legs like tiny jackhammers, so I'm not sure we're the same class of cyclist. ~_^