Page 3 of 4 FirstFirst 1 2 3 4 LastLast
Results 51 to 75 of 77
  1. #51
    Join Date
    Nov 2007
    Location
    Eburg
    Posts
    11,024
    Quote Originally Posted by Alaskan Rover View Post
    Rethinking your statement...it turns out your high speed, low torque (your average small engine) vs low speed, high torque (your average cyclist or mtn biker) is more accurate than my high speed, high torque vs. Low speed, low torque... because I'd underestimated just how much torque the leg muscles can apply to the crank!
    I was speaking in relative terms, of course. The distinction is more about rotational speed of motor and lever length: Contrast bicycle @ 100 RPM w/ 175mm cranks (300mm stroke) vs. 5HP engine @ 2,500 RPM w/ 50mm stroke.

  2. #52
    Join Date
    Nov 2005
    Posts
    1,792
    High torque (relatively) is quite correct.

    I've ridden a few belts and I'm convinced. I have a very old bike that is very close to falling apart and needs to be replaced. I like the new bikes. And yet I wait. I don't want to buy another bike with a chain.

  3. #53
    Join Date
    Feb 2012
    Location
    Missoula
    Posts
    1,030
    Belt plus IGH seems like a good thing for a fatbike. I've had my RD/cassette get all gunked up with snow/slush and start skipping.

    Also this is pretty sweet:

    http://www.raleighusa.com/rxs

  4. #54
    Join Date
    Nov 2007
    Location
    Eburg
    Posts
    11,024
    Internal gear hub comes at the cost of significant energy loss in all but the direct drive gear (11th gear on a Rohloff hub). The question is whether the energy loss per planetary gear transmission is setoff by the superior protection from weather and dust.

    IGH bikes can also be awkwardly heavy in the rear, can be an issue when carrying your bike.

  5. #55
    Join Date
    Nov 2005
    Posts
    1,792
    Total efficiency for the Rohloff is reported (quite believably, given typical planetary gear efficiencies) as 95-99% depending on which gear you're in. Doubt the Shimanos or the dual-shaft style Pinion does nearly as well, but if a dirty chain falls to 85-90% as some claim they're probably all fine for filth duty.

    Weight in the rear hub is noticeable when riding. I got on a Rohloff-equipped bike at Outerbike and followed it immediately with one with the Pinion and even in a hardtail the light rear wheel with the Pinion mounted at the BB is very noticeable. I'm surprised Rohloff hasn't offered their internals in a casing for frame-mounting yet, because that seems like the best answer so far. (Still a bit heavy, but I'd take it.)

  6. #56
    Join Date
    Nov 2007
    Location
    Eburg
    Posts
    11,024
    Quote Originally Posted by jono View Post
    Total efficiency for the Rohloff is reported (quite believably, given typical planetary gear efficiencies) as 95-99% depending on which gear you're in. Doubt the Shimanos or the dual-shaft style Pinion does nearly as well, but if a dirty chain falls to 85-90% as some claim they're probably all fine for filth duty.
    A chain would need to get so dirty to the point of very stiff links to lose that kind of efficiency. Don't get me wrong: Rohloff hub is remarkable engineering and would be a great choice for many. Also note that a Rohloff hub requires maintenance, which can be a bit trickier than lubing a chain, although needs to be done much less often.

    Non-Rohloff IG hubs are indeed less efficient, some more than others.
    Last edited by Big Steve; 11-16-2016 at 01:56 PM.

  7. #57
    Join Date
    Mar 2010
    Location
    Electric Larry Land
    Posts
    5,258
    How do the belt-driven bikes deal with replacing the belt? Splicing?

  8. #58
    Join Date
    Dec 2010
    Posts
    1,011
    You open up the notch on your frame, take the belt off, and install a new one.

  9. #59
    Join Date
    Nov 2005
    Posts
    1,792
    Quote Originally Posted by Big Steve View Post
    A chain would need to get so dirty to the point of very stiff links to lose that kind of efficiency. Don't get me wrong: Rohloff hub is remarkable engineering and would be a great choice for many. Also note that a Rohloff hub requires maintenance, which can be a bit trickier than lubing a chain, although needs to be done much less often.

    Non-Rohloff IG hubs are indeed less efficient, some more than others.
    Have you ever seen a dirty chain tested for efficiency? I'm assuming that the low end of the range includes a mud-filled jockey wheel or two and horrible chain line at both ends, but I've actually seen claims as low as 80% for a badly maintained drive train. It's been a long time though, and I don't recall the source so the veracity is totally questionable. I'd be very interested in seeing an actual worst-case (or even average-case) scenario tested.

  10. #60
    Join Date
    Nov 2007
    Location
    Eburg
    Posts
    11,024
    Quote Originally Posted by jono View Post
    Have you ever seen a dirty chain tested for efficiency? I'm assuming that the low end of the range includes a mud-filled jockey wheel or two and horrible chain line at both ends, but I've actually seen claims as low as 80% for a badly maintained drive train.
    No, I haven't. What does efficiency mean in that context? Is the chain isolated or is it a test of overall efficiency of the drive train? If the former, how does the chain efficiency number relate to the overall efficiency of the drive train?

    As you know "efficiency" is an ambiguous term that gets thrown around alot but can be measured in many ways, even on the same systems. I have ridden Rolhoff-equipped bikes and I cannot recall ever "feeling" that a dirty chain approached the "feeling" of drag of a Rohloff hub in the gears with the most drag (ETA except when I've had a derailleur drive train gets fouled with snow and ice, and I don't know whether or not belt drive would have solved that problem). Yeah, I know that's not scientific. But neither is comparing apples efficiency vs. oranges efficiency. And I can tell you with reasonable certainty that a sorta clean and sorta lubricated derailleur-equipped drive train is more efficient than a Rohloff drive train in everything but 11th gear.

    And so, again, the question is whether the constant additional drag (in all but 11th gear) of a Rohloff hub is offset by the effects of dirt and weather on a derailleur drive train. Surely there are some circumstances where that is so. FTR, I have little MTB experience although I have ridden thousands of miles of dirt roads, e.g., from Missoula MT to Anchorage AK in 34 days, 31 of which were rainy. It would have been nice to have had a Rohloff hub for a few of those 34 days.

    ETA: I acknowledge other advantages of IG hubs, e.g., the ability to shift while sitting still at a traffic light.

  11. #61
    Join Date
    Nov 2005
    Posts
    1,792
    In an engineering or scientific context efficiency is defined as the ratio of power coming out of a system divided by the power going in. So unless it'smeasured wrong it's actually well defined, but with that said, I don't know how you could reliably separate chain drag from all other losses in a standard drive train. So to answer your question, I believe the only good test is drive train vs. drive train.

    With respect, I can't believe anyone can actually feel the difference between the efficiencies in different gears through your legs because your legs only feel torque and speed on the input side. It's easy, with training, to notice a lot about the input side, but feeling the resistance you're overcoming (wind, rolling, slope up/down) with adequate precision is a lot harder. Actually comparing efficiencies requires feeling both sides and comparing from gear to gear, so the machines tend to come out for that kind of stuff. Of course, with the machines come the question of whether the real world has been lost, too.

  12. #62
    Join Date
    Dec 2007
    Location
    Hell Track
    Posts
    6,885
    Quote Originally Posted by jono View Post
    Total efficiency for the Rohloff is reported (quite believably, given typical planetary gear efficiencies) as 95-99% depending on which gear you're in. Doubt the Shimanos or the dual-shaft style Pinion does nearly as well, but if a dirty chain falls to 85-90% as some claim they're probably all fine for filth duty.

    Weight in the rear hub is noticeable when riding. I got on a Rohloff-equipped bike at Outerbike and followed it immediately with one with the Pinion and even in a hardtail the light rear wheel with the Pinion mounted at the BB is very noticeable. I'm surprised Rohloff hasn't offered their internals in a casing for frame-mounting yet, because that seems like the best answer so far. (Still a bit heavy, but I'd take it.)
    I had a Truvativ Hammerschmidt Crankset for a while - two internally shifted gears that used a planetary arrangement. Supposedly those things were between 90-95% efficient, but the extra drag was super noticeable. It was far worse than any dirty chain I've encountered (not counting old ones that were rusted solid). And that efficiency loss was only in the "big" chainring - the climbing gear was direct drive. I ended up selling it because the extra drag was so annoying.

  13. #63
    Join Date
    Nov 2005
    Posts
    1,792
    A 10% drag I can see noticing, for sure (and those would have to be some seriously crappy gears compared to Rohloff's, but that definitely happens). And I'm speculating a bit about how bad a Rohloff might get--obviously if a bearing starts to drag a little that would change things. I'm just saying a 2% efficiency change from one gear to the next is less noticeable than the difference between a 13% upshift and a 13.5% step, for example.

    Eta: point being: efficiency can get lost in step differences, especially since they're not quite even.

    To walk that back yet a step further, I found a ratio in the Pinion that I was less pleased with than the others. I attributed that to shift performance and sound change, but it's possible that with more time on it I could hate that gear in earnest. Hard to say.

  14. #64
    Join Date
    Aug 2007
    Location
    Bottom feeding
    Posts
    4,451

    Belt drive. Why not?

    Quote Originally Posted by Alaskan Rover View Post
    How do the belt-driven bikes deal with replacing the belt? Splicing?


    The belt shows zero wear after 2 whole seasons of riding. I now prefer to ride this bike in my Seattle location, (because it's so muddy), and I don't have to maintain the chain.

    Now go ahead and factor in that efficiency.
    Well maybe I'm the faggot America
    I'm not a part of a redneck agenda

  15. #65
    Join Date
    Nov 2007
    Location
    Eburg
    Posts
    11,024
    Quote Originally Posted by jono View Post
    I don't know how you could reliably separate chain drag from all other losses in a standard drive train. So to answer your question, I believe the only good test is drive train vs. drive train.
    FTR, I rode Rohloff-equipped and derailleur-equipped bicycles back to back to back to back (2 x 2 laps) on the same (hilly) course and the latter was measurably faster for me and for the other guy participating in this rough experiment. (He owned both bikes.) We timed each other. The bicycles were not otherwise identical, although they were equipped similarly, e.g., tires, tire pressure, seat height, crank length. No, I wasn't wearing a HR monitor, so it wasn't scientific, but I'm pretty certain that the derailleur-equipped bicycles were indeed faster. FTR, we had a few beers.

    As you know, drive train drag (and other drag, e.g., brake drag, binding wheel bearings) can be noticed with a bike in a repair stand. When I was a shop rat I diagnosed lots of problems by noting drag while the bike was on a bike stand. Anybody would notice the drag of a Rolhoff hub in the least efficient gears on a bicycle stand, just as they would notice the drag associated with a dirty chain. I am not suggesting that one could make any meaningful measurements that way.

    I agree that one might not notice 2% drive train efficiency difference by feel while riding, but it sure seems that the difference in drag between a clean well-lubed derailleur transmission and the least efficient Rohloff gears is more than 2%. (ETA: The article I linked in ETA2 below confirms this.)

    ETA: The final sentence above assumes a new Rohloff hub. I've read and heard that the seals loosen up after a few thousand miles and as a result a well-used hub might have less drag.

    ETA2: IHPVA Journal: The mechanical efficiency of bicycle derailleur and hub-gear transmissions
    Last edited by Big Steve; 11-16-2016 at 07:26 PM.

  16. #66
    Join Date
    Nov 2005
    Posts
    1,792
    That article is interesting, and some of the observations look useful, but as they noted, it leaves more questions than answers. I don't trust their specific measurements very far, for several reasons, but I'm not sure anyone here is interested in diving into the weeds. Suffice it to say, the data they show in their final table does not show a greater than 2% difference between the Shimano 27-speed and the Rohloff, if the data is taken at face value. But they did use a very well-oiled chain, which is really the problem: how to compare a nice clean belt with a chain that started out wet and collected gunk? Also, how would a 1x11 (or 12) compare in its extreme gears--especially since 15 years on we're using 10 or 11 as the small cog instead of 12?

    I guess I'm willing to assume that an IGH would be more efficient for a while if, like a derailleur system, it had no contact seals. But the seals are worth it so they seal these systems because they can.

    This is the answer:

    Quote Originally Posted by plugboots View Post

    The belt shows zero wear after 2 whole seasons of riding. I now prefer to ride this bike in my Seattle location, (because it's so muddy), and I don't have to maintain the chain.

    Now go ahead and factor in that efficiency.

  17. #67
    Join Date
    Nov 2007
    Location
    Eburg
    Posts
    11,024
    That's the answer to a different question. That plug has the belt on his W-side bike confirms my statement that the Rohloff hub -- in this case together with belt drive -- loss of efficiency via friction of many spinning gears is setoff by environmental factors, in this case muddy W-of-crest conditions.

    Quote Originally Posted by jono View Post
    the data they show in their final table does not show a greater than 2% difference between the Shimano 27-speed and the Rohloff, if the data is taken at face value.:
    Huh? 3rd gear: 92.8 - 87.8 = 5.0. 7th gear: 92.6 - 86.1 = 6.5. And, no, I'm not cherry picking because the issue is the loss of efficiency with Rohloff hub's least efficient gears (3, 5, 7, 12, 14), i.e., when the most IGH gears are spinning resulting in more loss of energy via friction.

  18. #68
    Join Date
    Nov 2005
    Posts
    1,792
    Quote Originally Posted by Big Steve View Post
    Huh? 3rd gear: 92.8 - 87.8 = 5.0. 7th gear: 92.6 - 86.1 = 6.5. And, no, I'm not cherry picking because the issue is the loss of efficiency with Rohloff hub's least efficient gears (3, 5, 7, 12, 14), i.e., when the most IGH gears are spinning resulting in more loss of energy via friction.
    I'm sure that feels like it's not cherry picking, but of course 3rd, 7th etc are not the same in a sequential 14 speed vs. a 3x9, so there's no reason to compare those. The relevant comparison is between least efficient gears on each system, since both systems will see use in those gears. The fact that they occur at different ratios isn't meaningful to any rider I know. As such, note the 89.5, 89.4 and 90.0--to say nothing of 86.9% in 24th (a currently common 32x12) on the Shimano. I will admit to shifting to the big ring for a sense of higher efficiency on a 3x9, but how many people would keep the big ring just for that purpose? (Although a 7% gain certainly starts to justify it.)

  19. #69
    Join Date
    Aug 2007
    Location
    Bottom feeding
    Posts
    4,451
    Another year of absolutely no maintenance on the belt. The bike is just so fun to ride hard and put away wet and not care about it.
    Well maybe I'm the faggot America
    I'm not a part of a redneck agenda

  20. #70
    Join Date
    Oct 2003
    Location
    Banff
    Posts
    18,647
    skibee is on 5+ years with her belt drive spot rocker SS. I have had to do exactly nothing to it

    Email me at dave@fatskideals.com for boot fitting questions,
    read where I'm skiing at http://www.fatskideals.com/blog.html

  21. #71
    Join Date
    Mar 2010
    Location
    Electric Larry Land
    Posts
    5,258
    Quote Originally Posted by plugboots View Post
    I'm buying a new 29er SS and the guy building it suggested a belt drive. I missed the boat on that, but after some research, it seems like the way to go.
    http://www.carbondrivesystems.com/index.php?lang=us
    Quiet, light, no stretch, no fucking lube.
    If belt drives were so great, they would be all over the racing circuit, because I can't actually see mechanical reasons in favor of them, unless these carbon fiber belts(?) have a much better transfer of energy, and I can't really see that as being the case. Less weight would be a plus, though.

    Now belt drives for commuter bikes, that I would love to see more of. I'm sick and tired of ruining my good street pants with chain grease when I forget to wear a right leg band. Plus you have too tuck your pants just right, or it screws up the crease in slacks. Yes...if Iceman skis in jeans, I sometimes ride bikes in slacks!!

  22. #72
    Join Date
    Oct 2003
    Location
    Banff
    Posts
    18,647
    Quote Originally Posted by Alaskan Rover View Post
    If belt drives were so great, they would be all over the racing circuit, because I can't actually see mechanical reasons in favor of them, unless these carbon fiber belts(?) have a much better transfer of energy, and I can't really see that as being the case. Less weight would be a plus, though.

    Now belt drives for commuter bikes, that I would love to see more of. I'm sick and tired of ruining my good street pants with chain grease when I forget to wear a right leg band. Plus you have too tuck your pants just right, or it screws up the crease in slacks. Yes...if Iceman skis in jeans, I sometimes ride bikes in slacks!!
    skibee has one because it takes no maintenance work. no chain stretch, no broken chain, just pedal

    Email me at dave@fatskideals.com for boot fitting questions,
    read where I'm skiing at http://www.fatskideals.com/blog.html

  23. #73
    Join Date
    Aug 2007
    Location
    Bottom feeding
    Posts
    4,451
    Quote Originally Posted by Alaskan Rover View Post
    If belt drives were so great, they would be all over the racing circuit, because I can't actually see mechanical reasons in favor of them, unless these carbon fiber belts(?) have a much better transfer of energy, and I can't really see that as being the case. Less weight would be a plus, though.

    Now belt drives for commuter bikes, that I would love to see more of. I'm sick and tired of ruining my good street pants with chain grease when I forget to wear a right leg band. Plus you have too tuck your pants just right, or it screws up the crease in slacks. Yes...if Iceman skis in jeans, I sometimes ride bikes in slacks!!
    What mntlion said, plus, you really can only compare to other SS bikes, and igh bikes. In that case, the percentages are swinging in beltís favor, (slowly). One cyclocross racer I follow says that if itís a hilly course and itís raining his belt drive is way faster.
    Well maybe I'm the faggot America
    I'm not a part of a redneck agenda

  24. #74
    Join Date
    Feb 2008
    Location
    Summit North
    Posts
    4,402
    Quote Originally Posted by Alaskan Rover View Post
    If belt drives were so great, they would be all over the racing circuit
    I would have to imagine that the limited number of manufacturers that make a frame with spliced stays has to factor in to that equation.
    Alpental Indigenous

  25. #75
    Join Date
    Mar 2010
    Location
    Electric Larry Land
    Posts
    5,258
    I think they would work great for a simple single speed stainless steel folding bike though. No rust! And no grease to muss up your sail covers. And yes, they actually make a stainless steel folding bike for boats. It folds into a leather monogrammed suitcase and costs about a gazillion dollars.....but STILL has a greasy chain.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •