I've personally had so many questions about the whole weight issue between internal and external gears that I thought it would be helpful to start a thread where people could actually put down some standard weight differences in hubs. All I could find was for some of the Shimano hubs. If anyone knows the standard weights on the SRAM hubs, please post.
Keep in mind that internally geared hubs don't need deraillers or multi cog cassettes. A cassette and derailleur will generally add anyware from 1-1.5 lbs combined depending on the quality of said components. For example, a 10 speed ultegra setup in the rear would run you a little less than 1.75 lbs total (That includes the hub, cassette, and derailleur). That's a savings of more than 2 lbs over a Nexus Red Band 8 speed! That may not be a big deal to some, but that definitely makes me stop and think.
I am personally interested in the weight of the sram dual drive hubs.
Juan
randya
02-27-07, 10:27 PM
IMO your being a bit of a weight weenie. Personally, I like internal hubs but recognize the tradeoffs, both ways. Also, more gears = more weight with either system. The Nexus 7 seems like the best deal for the weight; I've used this hub and like it; 5-speed internal might be another consideration, IMO 3 to 5 is enough speeds to work in most situations. Although I don't have the specs, I've got a few Sram internal hubs in 5 and 7 and the weights seem comparable to the Sturmeys. The dual-drive also seems like a good compromise. Have you considered the new Sturmey hubs? I saw a recent post somewhere on the forums w/ link to whole range of newer Sturmey stuff in 3 to 7 or 8 speed.
Wavshrdr
02-28-07, 12:43 AM
Don't forget you also need a longer chain with a derailleur too. Those links aren't light weight. You also have shorter spokes on an internal hub and it tends to be a very strong hub as well. Also your weight is incorrect for the 8R25 aka redlabel (high efficiency according to Shimano). It is actually 1550grams.
One other big benefit on small wheeled bikes that nobody seems to use, is the option of going with a roller brake. This makes a lot of sense given the accelerated rim wear I've seen on some of my bikes and especially the Bromptons. These small rims are definitely eroded more quickly by the brakes due to the fact they turn more rpms and have less swept area.
I am not saying there isn't a weight disadvantage with the internal hubs as there is. I do love their benefits on a folder. Nothing hanging down to get all over your pant leg. I can shift at a stop. No low chain that sucks in dirt and debris. Very quiet gear changes. The Shimano shifts great under load. I could go on and on. A pound or so weight penalty isn't going to kill me. It is a folder, not a race bike. I can lose the pound in a day if I want.
jur
02-28-07, 02:18 AM
It would be fair if you listed the exact tradeoff weights, as you yourself have mentioned about cassettes, derailers and the extra chain length. Just to day I looked at an XT hub setup, and it came to 910g without the extra chain, but I don't know what that amounts to.
The SA 8-speed hub, no brakes, no disc, amounts to 1480g. Not sure if that includes the cog.
caotropheus
02-28-07, 03:24 AM
A pound or so weight penalty isn't going to kill me. It is a folder, not a race bike. I can lose the pound in a day if I want.
Hello W. I totally agree with your description of internal gear hubs, and I would like to give one more vote for the advantages of internal gear hubs for folding bicycle. The desadvantage of 0.5 kg or one more kg is not relevant in a bicycle if you are not competing. Now about losing 0.450 kg is easy for you but a guy like me weighting 54 kg is a bit difficult! :D
Dahon.Steve
02-28-07, 05:34 AM
Keep in mind that internally geared hubs don't need deraillers or multi cog cassettes. A cassette and derailleur will generally add anyware from 1-1.5 lbs combined depending on the quality of said components. For example, a 10 speed ultegra setup in the rear would run you a little less than 1.75 lbs total (That includes the hub, cassette, and derailleur). That's a savings of more than 2 lbs over a Nexus Red Band 8 speed! That may not be a big deal to some, but that definitely makes me stop and think.
I am personally interested in the weight of the sram dual drive hubs.
Juan
Weight is only one of the problems. The major issue with the Nexus 7 or AW-3 is the inefficiency from the internals. This makes it feel like the hub is much heavier than the actual weight and the SRAM dual drive when shifted in 3rd gear is very inefficient.
I also happen to believe when the weight is all shifted to the rear hub, it feels like you're carrying an additional two water bottles!
caotropheus
02-28-07, 05:56 AM
Weight is only one of the problems. The major issue with the Nexus 7 or AW-3 is the inefficiency from the internals. This makes it feel like the hub is much heavier than the actual weight and the SRAM dual drive when shifted in 3rd gear is very inefficient.
I also happen to believe when the weight is all shifted to the rear hub, it feels like you're carrying an additional two water bottles!
From the scientific point of view, indeed internal gear drivetrains are less efficient than derrailleur drivetrains. But, I use internal gear drivetrains for several years and I didn't notice a difference on efficiency. From the bicycling science book a scientific comparison gave an average difference of 4 to 5 percentual points between derraileur drivetrains an internal gear drive trains.
EvilV
02-28-07, 07:11 AM
Maybe you weight sensitive guys are built lean 'n mean yourselves. For me, the fourteen pounds of extra fat I'm carrying over my younger days are a much greater problem. Too much red wine and beer in my early fifties. Still, I'm on the case now. Maybe when I've shed the fat, I'll worry about the three speed SA being a few ounces heavier than a derailleur. I might not feel the need to uprate my brakes either if I wasn't flinging quite so many pounds downhill!!
Seriously though, and racing aside, when you consider the all up weight of a rider and bike, does the odd pound make much difference? If you take my 172 pounds, add it to my Merc at about 27 pounds we come to 199 pounds of fat, muscle, bike and brain.... So how much am I going to notice a 1% weight reduction, and how would that compare with (to put it crudely) taking a dump or emptying my pockets of change before going out on the bike?
:)
Tony
geo8rge
02-28-07, 08:02 AM
If you are carrying the bike it is important. You might look at the ultra light weight Brompton projects. An interesting question is: does the extra 1.5 lb, and $100, you get from going from 3 to 8 gears get you much extra?
Bacciagalupe
02-28-07, 08:04 AM
Seriously though, and racing aside, when you consider the all up weight of a rider and bike, does the odd pound make much difference?
It does, if it's right on the wheel or if you have to carry it up and down stairs.
Long story short is that an internal hub will be a little heavier, a little less efficient, and generally more robust than a derailleur setup. I'm not sure why you'd need to know anything else....
folder fanatic
02-28-07, 11:21 AM
Never mind the ounces/grams differences between internal hubs and derailleurs. Concern yourselves with the insistance of carrying around huge packages on collapsable or folding bikes which turn into another package eventually.
invisiblehand
02-28-07, 12:20 PM
I've personally had so many questions about the whole weight issue between internal and external gears that I thought it would be helpful to start a thread where people could actually put down some standard weight differences in hubs. All I could find was for some of the Shimano hubs. If anyone knows the standard weights on the SRAM hubs, please post.
Keep in mind that internally geared hubs don't need deraillers or multi cog cassettes. A cassette and derailleur will generally add anyware from 1-1.5 lbs combined depending on the quality of said components. For example, a 10 speed ultegra setup in the rear would run you a little less than 1.75 lbs total (That includes the hub, cassette, and derailleur). That's a savings of more than 2 lbs over a Nexus Red Band 8 speed! That may not be a big deal to some, but that definitely makes me stop and think.
I am personally interested in the weight of the sram dual drive hubs.
Juan
I think that the efficiency, weight, and robustness matter. An individual's need will determine the best tradeoff.
I was talking with Peter Reich one day. He said that there is about a one pound difference between the SRAM Dual Drive and Nexus 8 drivetrains with the Nexus-8 being heavier.
WAV ... how much does a link in a chain weigh? And how many links less does an internal hub use?
Note that there have been comments on the location of an internal hub's weight. That is, it puts a lot of weight further back on the bike relative to a gear driven drivetrain.
rhm
02-28-07, 12:37 PM
... Although I don't have the specs, I've got a few Sram internal hubs in 5 and 7 ....
Speaking of which, can anyone tell me anything about the current SRAM Spectro P5 five-speed hub? I see from merchants' websites that it has five evenly spaced gears with a wide (303%?) range, but it's not on Sheldon Brown's online gear calculator. What I'm wondering is: which gear is the direct drive?
randya
02-28-07, 01:34 PM
All Sheldon's got is the 7 speed: http://www.sheldonbrown.com/seven_speed.html#sachs7
My links to SRAM tech info no longer work...
Here's some product info on the SRAM P5: http://www.universalcycles.com/shopping/product_details.php?id=10697
edit: here's links to SRAM's new tech info site:
http://www.sram24.com/newtechdoc/english/manufacturers/technicalnews/NewTechSpecifications_MY06.pdf
http://www.sram24.com/newtechdoc/english/consumers/ghs/pdf/spectro/Ins_sram_P5_8_2005.pdf
Wavshrdr
02-28-07, 06:23 PM
I think that the efficiency, weight, and robustness matter. An individual's need will determine the best tradeoff.
I was talking with Peter Reich one day. He said that there is about a one pound difference between the SRAM Dual Drive and Nexus 8 drivetrains with the Nexus-8 being heavier.
WAV ... how much does a link in a chain weigh? And how many links less does an internal hub use?
Note that there have been comments on the location of an internal hub's weight. That is, it puts a lot of weight further back on the bike relative to a gear driven drivetrain.
First I've never been a fan of any Nexus other than the 8speed ones. They are far more efficient than the other Nexus models and the 8R25 (red label) is the most efficient. Last I read they better internal hubs are now closer to 95-98% efficient. A chain isn't light. Each link can add up pretty quickly when you have an extra 10-20 or so (depends a lot on your biggest chain ring on the back). Keep in mind that this is all rotating mass which requires more energy to move it. You also have additional drag through the little derailleur. Don't forget to add the effects of the chain not being in a straight line.
At first glance it looks like the derailleur should kill the internal hub but it isn't quite as lopsided as you might imagine. I think the vast majority of riders would be very well suited by an internal hub but they are so derailleur centric that they don't think about it. What might be best for a racer might not be best for your normal usage unless you are mostly concerned about speed.
Here is an interesting new Shimano hub, the Alfine, that looks interesting if you haven't already heard about it.
For a good introduction to internal hub efficiency from the perspective of Rohloff see the link at the end. I've owned the Rohloff and still have several 8R25's and I can tell you that in most situations the Nexus feels more efficient and is definitely quiter.
[QUOTE=WavshrdrAlso your weight is incorrect for the 8R25 aka redlabel (high efficiency according to Shimano). It is actually 1550grams.
.[/QUOTE]
Wavshrdr - I pulled the weight off of the Shimano site. They do say it's "about" this weight...I don't exactly understand what that means, but that might explain the difference in your weight, as opposed to what I found at their site.
randya - I AM being a weight weenie, and happily. :) I haven't ruled out an internal hub nor do I think they are a bad idea, for all the reasons listed in this thread and others. However, rolling weight is a big deal and losing 2 or more lbs from the rotating mass is a huge difference. I currently am running a dual drive on my Twenty. While I'm not planning any changes in the immediate future, I have been thinking of converting my Twenty to a 105 drivetrain. While I know I can't get the weight down anywhere near 20lbs, it currently weighs 32-33 lbs. If I change the drivetrain over to 105 componants and build a lighter set of wheels (I'm also running a 42 spoke front wheel, which is way overbuilt for my style of riding), I can definitely get it south of 30lbs - maybe even 27-28lbs. While this isn't light, It's a whole heck of alot better than 32+lbs. I haven't made up my mind yet.
I have a crescent folder that I currently have set up as a single speed, but would like to change to a multi speed. I will probably go with an internal 7 or 8 speed. It's currently around 24lbs with an all steel front wheel. I figure if I build up a lighter weight front wheel and go with an internal 7 speed shimano hub, I should only pick up an extra 1.5-1.75lbs.
Juan
juan162
02-28-07, 07:56 PM
It's me again, Juan.
I thought I might add that one of the big reasons I've been thinking of changing my Twenty set up is because I use it regularly on my climbing route, where I have definitely felt a difference in efficiency and weight. I climbed the same hill on my old mountain bike, and it was definitely easier on the mountain bike. I'm trying to find the best compromise for my riding needs.
Juan
jur
02-28-07, 08:21 PM
Well this is another can of worms.
Why do you ride hills? I assume for general fitness purposes. So from that perspective it doesn't really matter, with the R20 you will be getting slightly more exercise for your money. If this is a commute and you would like to cut the time, well that's different. Perhaps you may need to consider a Swift because the R20 has a 5kg frame and nothing you can do will make it into a lightweight speedbike.
But who cares anyway? Go for it. It's fun, that's why.
invisiblehand
02-28-07, 08:25 PM
Don't forget to add the effects of the chain not being in a straight line.
Supposedly, the efficiency loss from cross-line offset and poor lubrication are negligible ... at least in a lab.
http://www.ihpva.org/HParchive/PDF/hp50-2000.pdf
Regarding the Nexus-8 internal hub weight, I find 1550 grams too.
invisiblehand
02-28-07, 08:28 PM
Well this is another can of worms.
Why do you ride hills? I assume for general fitness purposes. So from that perspective it doesn't really matter, with the R20 you will be getting slightly more exercise for your money. If this is a commute and you would like to cut the time, well that's different. Perhaps you may need to consider a Swift because the R20 has a 5kg frame and nothing you can do will make it into a lightweight speedbike.
But who cares anyway? Go for it. It's fun, that's why.
Hah! That probably is the best solution ... get a lighter bike! Soooooo many choices relative to the R20. :p
Although if you go that route then you might consider Bike Friday, Airnimal, as well as the Swift.
Jur ... that is some commute. Doubt that I would do it everyday.
By the way, this is in regards to an old post, why are you limited in chainring sizes on your Raleigh 20?
jur
02-28-07, 08:59 PM
Re my commute: Thanks! It may seem far but I got thoroughly used to it. Then when I was away for 2 weeks without riding, I bonked on the way home a few times before I got the old form back.
Re chainring: I can implement the solutions that exist, but I like the look of the genuine R20 crankset, so I had it replated. So I am kinda "stuck". :p Plus I am now satisfied I can tour Tasmania with the existing setup, so at his stage I foresee that it will stay that way. Plus I now need any spare money to build my new Swift frame into a bike. :D
Wavshrdr
02-28-07, 10:29 PM
Wavshrdr - I pulled the weight off of the Shimano site. They do say it's "about" this weight...I don't exactly understand what that means, but that might explain the difference in your weight, as opposed to what I found at their site.
Juan
The weight you listed is for the 8R20, the NON redlabel version. The 8R25 is the redlabe high efficiency hub that weighs 200 grams less. To a weight weenie that is a huge difference. Go here to see the weight for the 8R25:
invisiblehand - everything is perfect in a lab where everything is well maintained and pristine. Keep in mind that a folder has a shorter chain run, therefore the relative angles between the gears are more significant. They still measured a 0.5% degredation on a normal bike. Additionally any lateral stress on the chain will accelerate chain and sprocket wear.
That report also made hub gears look quite attractive as well. Based on their information, the larger sprockets often used on the internal hub gears would quite likely offset the mechanical losses of the internal hub to a great extent and in some circumstances if I extrapolate their date, the internal hubs could be MORE efficient if you choose the appropriate sprocket sizes front and rear.
I have bikes with both and internal hubs and derailleurs, for 99% of my riding I'll stick with the hub gears.
jur
02-28-07, 10:51 PM
I have bikes with both and internal hubs and derailleurs, for 99% of my riding I'll stick with the hub gears.Which begs the interesting question, what sort of riding is the 1%?
Wavshrdr
02-28-07, 11:11 PM
When I go riding with a club and they all want to ride their wannabe racebikes. So I keep one wannabe racebike just for these purposes and since they frown on recumbents on these rides. Then it goes back in the garage. I will likely sell it this year and just forget about the club rides. I get tired of people who agonize over every gram as if they could win the Tour by just shaving another 50 grams off their bike.
I have nothing to prove, I just want to have fun. A ride on a recumbent is more enjoyable for me as I can go faster on the flats and not have to deal with a paceline and all the hassle that entails.
DVC45
02-28-07, 11:39 PM
When I go riding with a club and they all want to ride their wannabe racebikes. So I keep one wannabe racebike just for these purposes and since they frown on recumbents on these rides. Then it goes back in the garage. I will likely sell it this year and just forget about the club rides. I get tired of people who agonize over every gram as if they could win the Tour by just shaving another 50 grams off their bike.
I have nothing to prove, I just want to have fun. A ride on a recumbent is more enjoyable for me as I can go faster on the flats and not have to deal with a paceline and all the hassle that entails.
That's me too! I'm giving my road bike to my brother and just keep my folder as my main bike. I like riding on my own pace and not worry about keeping up with anyone.
SesameCrunch
03-01-07, 07:50 AM
Which begs the interesting question, what sort of riding is the 1%?
I ride my folders and recumbents on groups rides which are more social, in organized rides and by myself.
There are times when I need my 16.4 lb carbon, DA roadie, though. These are rides which are very hilly, or when I am going out hammering with a bunch of younger riders. Gotta have the right weapon for the situation :) .
invisiblehand
03-01-07, 11:31 AM
invisiblehand - everything is perfect in a lab where everything is well maintained and pristine. Keep in mind that a folder has a shorter chain run, therefore the relative angles between the gears are more significant. They still measured a 0.5% degredation on a normal bike. Additionally any lateral stress on the chain will accelerate chain and sprocket wear.
That report also made hub gears look quite attractive as well. Based on their information, the larger sprockets often used on the internal hub gears would quite likely offset the mechanical losses of the internal hub to a great extent and in some circumstances if I extrapolate their date, the internal hubs could be MORE efficient if you choose the appropriate sprocket sizes front and rear.
I have bikes with both and internal hubs and derailleurs, for 99% of my riding I'll stick with the hub gears.
That thought did cross my mind ... that the larger sprockets on internal hubs might lessen the efficiency loss relative to certain gear combinations. Although a subsequent article in the Journal of Human Power is also relevant.
Has anyone actually tested the Nexus-8 (redband) for its efficiency? Presummably its efficiency varies across gears as well.
invisiblehand
03-01-07, 11:33 AM
When I go riding with a club and they all want to ride their wannabe racebikes.
...
I have nothing to prove, I just want to have fun. A ride on a recumbent is more enjoyable for me as I can go faster on the flats and not have to deal with a paceline and all the hassle that entails.
Maybe you should find another club. ;)
randya
03-01-07, 03:15 PM
So I'm still failing to see the advantage of the 8 speed nexus over say a 5 speed Sturmey or SRAM hub; the range on all of them are pretty close - 307% for the nexus8 and ~303% for the five speeds. Essentially, all the 8-speed hub is giving you is closer spaced gears, not more range.
juan162
03-01-07, 04:08 PM
Well this is another can of worms.
But who cares anyway? Go for it. It's fun, that's why.
That's exactly why I started this thread. If I wanted a pre-assembled, high end folder I would have bought one (I've maybe spent $700 total on my Twenty, including the original bike cost). There is nothing wrong with buying a high end folder, I'd just rather tinker. While I know I can't get the Twenty super light, I think eventually switching over to a 105 drivetrain with a double up front, I can get the "best" bike out of the Twenty for me! :) I already have a front derailleur fitted onto the front chainring to combat the dreaded chain jumps, so I might as well use it. I also just got an ultegra double crankset off of ebay for about $20 it's a square taper and if the alignments right, I can even use the same BB. Now all I need is to build up a new rear wheel!
BTW, I wouldn't say no to a high end folding road bike. Anyone want to give me one from that Japanese site Littlepixel posted on here? I'm afraid those are a little out of my price range!
Juan
juan162
03-01-07, 04:22 PM
Wavshrdr - Thanks for the weight correction on the redband. Also, the whole thing about extra link weight and the larger sprocket on the internal geared hubs are things I had never even considered.
randya - If you like to spin or do lots of long rides, the extra 3 gears in the middle really help you dial in your cadence. For some it's not a big deal. For others it is. That redband is looking very interesting for my Crescent!,
Juan
jur
03-01-07, 04:46 PM
So I'm still failing to see the advantage of the 8 speed nexus over say a 5 speed Sturmey or SRAM hub; the range on all of them are pretty close - 307% for the nexus8 and ~303% for the five speeds. Essentially, all the 8-speed hub is giving you is closer spaced gears, not more range.I just checked the SA 5-sp hub's range at the co site and it is only 225%. I wish it were 303%.
Wavshrdr
03-01-07, 10:16 PM
For me there is one MAJOR reason for the 8R25 (red label), well maybe two. It has very high efficiency and it shifts like a hot knife through butter. Hands down there is not a nice shifting internal hub I've ever ridden. Nor have I ever heard a quiter hub. The only one even close is a well broken in 3 speed SA. No other internal hub shifts as well under load. I can be standing on the pedals going up a hill and it will easily downshift to a lower gear.
SA = agricultural tractor shift feel
Nexus 8R25 = Honda S2000 gearbox or BMW M3 6 speed
If you've ever ridden a sportbike motorcycle where the tranny just "snicks" through the gears, that is how the 8R25. Even cooler when you go with the push button gear selector for the Nexus.
One last big plus for me, whatever lube the uses works well in cold temps. It doesn't feel near as stiff as the other hubs I've ridden in the cold. Last winter I was out riding in below 0 temps and the Nexus shifted almost like it was summer time.
randya
03-02-07, 11:45 AM
I just checked the SA 5-sp hub's range at the co site and it is only 225%. I wish it were 303%.
My apologies, it's the SRAM P5 which is 303%.
For me there is one MAJOR reason for the 8R25 (red label), well maybe two. It has very high efficiency and it shifts like a hot knife through butter. Hands down there is not a nice shifting internal hub I've ever ridden. Nor have I ever heard a quiter hub. The only one even close is a well broken in 3 speed SA. No other internal hub shifts as well under load. I can be standing on the pedals going up a hill and it will easily downshift to a lower gear.
SA = agricultural tractor shift feel
Nexus 8R25 = Honda S2000 gearbox or BMW M3 6 speed
If you've ever ridden a sportbike motorcycle where the tranny just "snicks" through the gears, that is how the 8R25. Even cooler when you go with the push button gear selector for the Nexus.
One last big plus for me, whatever lube the uses works well in cold temps. It doesn't feel near as stiff as the other hubs I've ridden in the cold. Last winter I was out riding in below 0 temps and the Nexus shifted almost like it was summer time.
Now this makes sense to me. My experience is that SA AW 3-spds shift and perform quite well when properly lubed and adjusted; OTOH I've been somewhat unhappy with the smoothness of several nexus 7s I've owned, but I've never ridden the 8R25.
invisiblehand
03-02-07, 11:59 AM
While I know I can't get the Twenty super light, ...
I recall reading that someone got theit Twenty down to something in the mid-20s with regards to weight. If I can find that page, I will post it later.
With regards to the big sprocket on the back, as the subsequent Journal of Human Power suggests, it isn't so simple.
http://www.ihpva.org/HParchive/PDF/hp51-2001.pdf
In the original study, the front chainring RPM and power was held constant. Under these conditions, big sprockets are more efficient. The second finding was that chain tension is the second big determinant of efficiency. But notice that if the front chainring RPM is held constant, then the velocity at the rear wheel will be slower with a larger rear sprocket.
Turns out that if you want to keep rear-wheel velocity and power constant, that using a smaller sprocket increases chain tension. Long story short, according to their results, the increase in tension more than offsets the loss in efficiency due to using a smaller sprocket. That is, using a smaller sprocket in the back is more efficient keeping velocity constant.
Note that I am not an physicist/engineer like WAV or several other members of the forum. So I know that terms like "power" have specific meanings that may or may not correspond to a layman's understanding of the word. My conclusion is that the whole issue is pretty complicated. But my understanding is that when push comes to shove, the (well-maintained) chain-driven drivetrain is still more efficient and "considerably" lighter than the best internal hubs.
From that same conversation with Peter and similar conversations with the Bike Friday guys, they suggested that there is essentially a one pound difference in the following steps
(1) Chain drivetrain (I think rear derailer only ... but I do not recall)
(2) SRAM Dual Drive
(3) Nexus 8 Redband.
WAV's point of the shorter chain makes it difficult to look up the specs and add up the weight. But presummably these people built bikes with several different configurations and weighed them to compare their gross weights. Considerably was is quotes since it is a matter of opinion whether one or two pounds are important.
Anyway, efficiency and weight we not the driving factors in our decision to go with a standard triple chain driven drivetrain (although they can still be important). Basically it was what we were familiar with and we already knew how to fix and maintain it. I think that the human motor is still the most important chunk of performance between the drivetrain alternatives.
EDIT: Note that I am building a commuter with an internal hub. So there are definitely reasons to consider them.
Wavshrdr
03-02-07, 04:57 PM
I forgot some GREAT reasons for an internal hub on a folder, no derailleur hanger to get bumped and bent and less chan gunk on my legs. My first 2 DT's with derailleurs had their hangers bent in shiipping pretty badly. Yan replaced them promptly but it was still a drag.
I honestly doubt if most people could even tell a 4% loss or less. I did a paper years ago on people's "butt dyno". A dynamometer is a device that will measure the output of motors and typically used in building high performance cars. I took and ran it on the dyno. I set up several different power combinations so that the acceleration of the vehicle would vary from config to config.
I didn't gradually increase but randomly increased or decreased the acceleration and using an accelerometer to measure the actual changes. Out of about 20 people I tested, only about 8 could discern any changes less than 7-8% with any repeatability. Only ONE could tell less than 5% change consistently.
My point is this, unless we were gradually to decrease or increase your efficiency while riding, most of you would be hard pressed to tell the difference in efficiency if I randomly stuck you in a blind test and tried each bike without seeing if it was internal hub or derailleur. It is fun to talk about the sometimes more esoteric points and of course the differences are measurable but how many of you ride far or fast enough for it to really make a difference? OTOH, I can appreciate the minimal upkeep of the internal hub almost every day.
juan162
03-02-07, 08:22 PM
Invisiblehand - thanks for the info on the weight savings between the different drive setups.
Wavshrdr - Your comments on the redband make me lean toward it for my Crescent folder, which is currently a single speed (It's actually a take apart bike and I thought it would be perfect as my pack and fly bike of choice.). My other question would be what kind of rear brake do you use? Drum, coaster, V-brake?
Juan
BTW, I still think I'd like to try out a conventional drivetrain on my Twenty.
juan162
03-02-07, 08:29 PM
Though I'd repost this link to Bill Milam's Twenty which he got down to 23lbs:
http://www.fixedgeargallery.com/milam.htm
Maybe I can get mine to 25lbs?
Juan
invisiblehand
03-02-07, 10:38 PM
I forgot some GREAT reasons for an internal hub on a folder, no derailleur hanger to get bumped and bent and less chan gunk on my legs. My first 2 DT's with derailleurs had their hangers bent in shiipping pretty badly. Yan replaced them promptly but it was still a drag.
I honestly doubt if most people could even tell a 4% loss or less. I did a paper years ago on people's "butt dyno". A dynamometer is a device that will measure the output of motors and typically used in building high performance cars. I took and ran it on the dyno. I set up several different power combinations so that the acceleration of the vehicle would vary from config to config.
I didn't gradually increase but randomly increased or decreased the acceleration and using an accelerometer to measure the actual changes. Out of about 20 people I tested, only about 8 could discern any changes less than 7-8% with any repeatability. Only ONE could tell less than 5% change consistently.
My point is this, unless we were gradually to decrease or increase your efficiency while riding, most of you would be hard pressed to tell the difference in efficiency if I randomly stuck you in a blind test and tried each bike without seeing if it was internal hub or derailleur. It is fun to talk about the sometimes more esoteric points and of course the differences are measurable but how many of you ride far or fast enough for it to really make a difference? OTOH, I can appreciate the minimal upkeep of the internal hub almost every day.
I agree with many of your points.
I think the only time you will notice the efficiency and weight differences is when one pushes the "envelope" during long and/or fast rides. So if you like to do a lot of centuries, then that 4% probably matters.
Wavshrdr
03-03-07, 11:30 PM
@juan162 - actually my choice would be a drum brake for basically one reason, rim wear. I love disk brakes but on a folder they are easy to bend when handling the bike. I also like that drum(or band) seem to be less affected by rain and debris. I can honestly say that if you asked me about 3 years ago, I would have laughed about using drum or band brakes. I now have a few bikes with them and my appreciation for them has grown markedly. After owning a Brompton I learned how crappy normal bike brakes can be. If you go with the V or any other type the grabs the rim, I HIGHY suggest going with the Koolstop pads!
@invisiblehand- I agree that for pushing the enevelope people will want to any loss elminate loss. I put on a solid week when I was putting on over a 60-100 miles a day and I never felt like my internal hub was really costing me anything in efficiency. I am sure the luggage on my bike cost me far more than the internal hub.
In general I am not saying a hub gear is great for everybody. I do think that if more people tried them without any preconcieved bias, they might be more likely to buy them. I notice when going into a bike store in Germany or Holland there are hub geared bikes everywhere. About the only ones that don't have hubs are the hard core MTB and Road bikes. Almost every "commuter" bike has hub gears. There is one exception also and that is for the ultra cheap bikes where they are trying to make a certain price point.
It is almost like the people who want to drive stick shift cars (der.) and those who like automatics (hub gears). For the longest time I'd only buy a car with a manual gearbox. I have to honestly admit that the best automatics are in some ways even better than manuals and the manuals have stolen features from the autos. Years ago I would have never bought a bike with hub gears, now the last bike I bought with totally a derailleur was a Downtube if memory serves correctly.
invisiblehand
03-04-07, 03:31 PM
@juan162 - actually my choice would be a drum brake for basically one reason, rim wear. I love disk brakes but on a folder they are easy to bend when handling the bike. I also like that drum(or band) seem to be less affected by rain and debris. I can honestly say that if you asked me about 3 years ago, I would have laughed about using drum or band brakes. I now have a few bikes with them and my appreciation for them has grown markedly. After owning a Brompton I learned how crappy normal bike brakes can be. If you go with the V or any other type the grabs the rim, I HIGHY suggest going with the Koolstop pads!
Are coaster brakes like a car's drum brakes? Are they the same thing you are referring to above?
If so, given Juan is hitting the hills, I just read that coaster brakes heated up quickly and suffered poor performance as a result.
Mind you, I have not ridden a bike with coaster brakes in 30 years. So I don't even know what they are. I just read a short blip on them in Effective Cycling.
juan162
03-04-07, 05:33 PM
Invisiblehand,
Drum brakes are a different animal all together from coaster brakes. However, I was also wondering if there is anything to worry about (similar to the coaster's overheating problem), since I do hit the hills regularly.
Juan
spambait11
03-04-07, 05:52 PM
The old Sachs drum brake on our tandem is actuated with a frictionless bar end shifter. On flat ground, that drum brake alone is enough to stop the whole rig. Yet when I apply the drum brake going down hills, we're still moving albeit a lot more slowly such that using our v-brakes in conjunction will stop everything without making the rims hot. From what I understand, this is how they're supposed to be used on tandems.
On the other hand, some Greenspeed trikes exculsively use(d) drum brakes and I've not read any complaints about their stopping ability or wear. In fact, most people seem to brag that drum brakes take a long time to wear out in general. I think most people don't use them because they think they're heavy, but I've not found this to be a problem. Yeah, you also take a little more time when changing a tire because you have to remove the cable completely and refit the torque arm when putting it back, but these issues are not difficult to overcome. Again though, they're probably best in all other situations except when you're trying to put together a lightweight speed machine.
One other thing, I think someone (Sturmey-Archer?) now has a combo drum brake/generator front hub which will give you the clean looks and efficiency of the drum brake plus provide a source to hook up some lights. That, to me, is my hub front hub of the future, weight be damned.
rhm
03-05-07, 10:44 AM
One other thing, I think someone (Sturmey-Archer?) now has a combo drum brake/generator front hub which will give you the clean looks and efficiency of the drum brake plus provide a source to hook up some lights. That, to me, is my hub front hub of the future, weight be damned.
Yep, I put one of those on a Raleigh Twenty; it seemed a good way to combine the original fender and fork with a brake that actually works. I'm pretty happy with it. Sturmey Archer also makes an 8-speed hub / drum brake combo, and I'd like to try one of those, but nobody seems to have them.
juan162
03-05-07, 11:10 AM
Sturmey Archer also makes an 8-speed hub / drum brake combo, and I'd like to try one of those, but nobody seems to have them.
Gaerlan has a 7 speed SA listed on their site with drumbrakes. It might be worthwhile to ask them if they are stocking the 8 speed ones yet,