Cranks
10-19-08, 06:17 PM
#26
Grumpy Old Bugga
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Hey, were'd that come from?
Not fighting mate, just carrying on the discussion. Sorry you took it the wrong way but there was nothing intended in it. Gearing is something I find fascinating and people's choices are part of that.
Richard
Not fighting mate, just carrying on the discussion. Sorry you took it the wrong way but there was nothing intended in it. Gearing is something I find fascinating and people's choices are part of that.
Richard
10-19-08, 09:00 PM
#27
Senior Member
Tigrrrtamer,
Do you have a compact on your recumbent? Exactly what gears are you using? What kind of hills do you ride? Also, when you're not climbing hills, how fast do you ride? I think the answers will give us some insight into why you're advocating losing gearing range for what I see as no good reason.
Do you have a compact on your recumbent? Exactly what gears are you using? What kind of hills do you ride? Also, when you're not climbing hills, how fast do you ride? I think the answers will give us some insight into why you're advocating losing gearing range for what I see as no good reason.
10-19-08, 10:38 PM
#28
Senior Member
Thanks for the question.
Section 1: WHY
I'm not losing "gearing range". The tables are showing a range far wider than I need. I'll repeat myself, I'm not advocating that Richard reduce his gearing range (he needs his just the way it is). I merely used his setup as a starting point to make a simple comparison with a double-compact, because of the challenge that his unusually low gear represented. I had to compare with something... His smallest gear is far smaller than what is standard on most triple cranksets (how many triples do you see with an inner chainring of 26, huh?). So I figured that if I could come close to his extremely low gearing with a double, and still have a good range, from a high top gear to a low low, with good increments, I'll have proven the merits of a double. And my tables also offer a smallest geat just shy of Richard's smallest, but smaller than what is standard issue on most road bikes with triples... all this while offering reasonable and very useful incrementations between gears. Good highest gear, good lowest gear, good increments, good landing spot (gearing-wise) when shifting on the front. I'm sorry to diverge in opinion, but in my book, it's great!
Section 2: WHAT I USE
I currently have a Shimano Tiagra triple crankset on my recumbent. The small inner chainring has zero wear on it, so I may as well have a double. My smallest gear with the middle chainring could be one gear smaller, but I don't ever bother to shift onto the smallest chainring to get a smaller one, because I KNOW I'd have to shift a few spaces over on the rear just to get the right gear I'm looking for. So my front derailleur stop screw is set to not be able to accidentally shift onto the smallest chainring and potentially derail and end up between it and the frame. My setup will be changing (more on that later).
Section 3: WHERE
I live in Montreal. In the center of the city, is a mountain. Not as big as in the rockies, but a small mountain nevertheless. Around the mountain is a plateau, and around that, a lower level. The geography affects most streets in the city's center. I can't get anywhere without encountering steep hills on the way. 2 decades ago, I used to go up and down the mountain itself for half a day, every day, to train, when I wasn't doing a 100 mile loop bringing me north of the city, towards the Laurentians (part of the Apalachians mountain chain).
Here I find that everytime I hit a hill, I'm fussing with gears, front and back, more than I should have to. There is no simple crossover from the large chainring to the middle one, where I can just do one shift in the front and keep going without shifting the back too. Nope... I have to shift the front, then start messing around with the back... and in doing that, I slow down, and often have the frustration of having to downshift again because I've lost my inertia. ...and with the slowing down, while shifting at ever lower speed, I hear the rear sprockets bang and crack, and I wonder when one of them is just going to break.
I find that I have way too many gears than I need... that aren't in the right places.
Section 4: WHAT I WANT
A cadence within 10% of our ideal is easy to handle. a 15% gear spacing gives us small enough increments so that when we go out of our sweet-spot range of RPM, we have a gear waiting for us thre. So, what I want, is for them to be spaced with a 15% difference, and have a wide enough range to handle anything the topography dishes out at me... that means, for me, having a 53x11 or 53x12 as highest (I'll go with 11 and 12 just in case my derailleur doesn't make it onto 11), and a lowest gear of say, 39x26, is fine for me. I can go up ANY incline with this. (I've been doing that on a 42x23 I think prior to that).
So I ordered myself a Shimano Ultegra crankset, 167.5mm arms, 53T/39T, and a SRAM 11-28 cassette. I think I will be very happy with that. And a new chain... because, even after swapping out my Deore derailleur for an SRAM X.7, it still rarely shifts onto x11.
Two chainrings give me a reasonably wide range with each, and when I shift from 53 to 39 I'll have downshifted just the right amount to take a hill without having to shift on the rear right away, and it's the same the other way round, 39 to 53 while staying on the same rear sprocket will put me in a gear taller enough to benefit right away from a changing slope without having to shift on the rear right away.
When I do the gearing calculations, and transpose this into my riding situations, a compact double is much better for me.
And this gearing should work where well over 80% of the north american population lives. Just not where those grueling hills are, like where Richard lives... those people will have to put up with messing with three chainrings instead of just two. But then again, maybe 11 speeds (see Campy), or 12 speeds, will change things for them too.
Section 5, SPEED
I have no idea how fast I go. I put a speedometer on my recumbent last week, but have had some problems and haven't tested it in the hills yet. On the flats I've approached 50km/h, top speed 58 on some small inclines. But I don't know yet how fast on a real downhill. Plus, I have some problems... the lousy Z chain, standard issue on an Actionbent, doesn't shift onto x11. Or on x12 half the time... not even after I swapped out the rear derailleur from a Deore to an SRAM X.7. I'm not changing the chain, because I'll be selling the recumbent.
The new recumbent, I'll be building out of carbon fiber in a couple of weeks, just as soon as my ex moves her daycare out of my place, so when I can reclaim the space, in other words.
The new one will have the folowing setup: Shimano Ultegra double with 167.5mm crankarms, 53/39 chainrings, SRAM 9 speed cassette, 11-28.
Section 1: WHY
I'm not losing "gearing range". The tables are showing a range far wider than I need. I'll repeat myself, I'm not advocating that Richard reduce his gearing range (he needs his just the way it is). I merely used his setup as a starting point to make a simple comparison with a double-compact, because of the challenge that his unusually low gear represented. I had to compare with something... His smallest gear is far smaller than what is standard on most triple cranksets (how many triples do you see with an inner chainring of 26, huh?). So I figured that if I could come close to his extremely low gearing with a double, and still have a good range, from a high top gear to a low low, with good increments, I'll have proven the merits of a double. And my tables also offer a smallest geat just shy of Richard's smallest, but smaller than what is standard issue on most road bikes with triples... all this while offering reasonable and very useful incrementations between gears. Good highest gear, good lowest gear, good increments, good landing spot (gearing-wise) when shifting on the front. I'm sorry to diverge in opinion, but in my book, it's great!
Section 2: WHAT I USE
I currently have a Shimano Tiagra triple crankset on my recumbent. The small inner chainring has zero wear on it, so I may as well have a double. My smallest gear with the middle chainring could be one gear smaller, but I don't ever bother to shift onto the smallest chainring to get a smaller one, because I KNOW I'd have to shift a few spaces over on the rear just to get the right gear I'm looking for. So my front derailleur stop screw is set to not be able to accidentally shift onto the smallest chainring and potentially derail and end up between it and the frame. My setup will be changing (more on that later).
Section 3: WHERE
I live in Montreal. In the center of the city, is a mountain. Not as big as in the rockies, but a small mountain nevertheless. Around the mountain is a plateau, and around that, a lower level. The geography affects most streets in the city's center. I can't get anywhere without encountering steep hills on the way. 2 decades ago, I used to go up and down the mountain itself for half a day, every day, to train, when I wasn't doing a 100 mile loop bringing me north of the city, towards the Laurentians (part of the Apalachians mountain chain).
Here I find that everytime I hit a hill, I'm fussing with gears, front and back, more than I should have to. There is no simple crossover from the large chainring to the middle one, where I can just do one shift in the front and keep going without shifting the back too. Nope... I have to shift the front, then start messing around with the back... and in doing that, I slow down, and often have the frustration of having to downshift again because I've lost my inertia. ...and with the slowing down, while shifting at ever lower speed, I hear the rear sprockets bang and crack, and I wonder when one of them is just going to break.
I find that I have way too many gears than I need... that aren't in the right places.
Section 4: WHAT I WANT
A cadence within 10% of our ideal is easy to handle. a 15% gear spacing gives us small enough increments so that when we go out of our sweet-spot range of RPM, we have a gear waiting for us thre. So, what I want, is for them to be spaced with a 15% difference, and have a wide enough range to handle anything the topography dishes out at me... that means, for me, having a 53x11 or 53x12 as highest (I'll go with 11 and 12 just in case my derailleur doesn't make it onto 11), and a lowest gear of say, 39x26, is fine for me. I can go up ANY incline with this. (I've been doing that on a 42x23 I think prior to that).
So I ordered myself a Shimano Ultegra crankset, 167.5mm arms, 53T/39T, and a SRAM 11-28 cassette. I think I will be very happy with that. And a new chain... because, even after swapping out my Deore derailleur for an SRAM X.7, it still rarely shifts onto x11.
Two chainrings give me a reasonably wide range with each, and when I shift from 53 to 39 I'll have downshifted just the right amount to take a hill without having to shift on the rear right away, and it's the same the other way round, 39 to 53 while staying on the same rear sprocket will put me in a gear taller enough to benefit right away from a changing slope without having to shift on the rear right away.
When I do the gearing calculations, and transpose this into my riding situations, a compact double is much better for me.
And this gearing should work where well over 80% of the north american population lives. Just not where those grueling hills are, like where Richard lives... those people will have to put up with messing with three chainrings instead of just two. But then again, maybe 11 speeds (see Campy), or 12 speeds, will change things for them too.
Section 5, SPEED
I have no idea how fast I go. I put a speedometer on my recumbent last week, but have had some problems and haven't tested it in the hills yet. On the flats I've approached 50km/h, top speed 58 on some small inclines. But I don't know yet how fast on a real downhill. Plus, I have some problems... the lousy Z chain, standard issue on an Actionbent, doesn't shift onto x11. Or on x12 half the time... not even after I swapped out the rear derailleur from a Deore to an SRAM X.7. I'm not changing the chain, because I'll be selling the recumbent.
The new recumbent, I'll be building out of carbon fiber in a couple of weeks, just as soon as my ex moves her daycare out of my place, so when I can reclaim the space, in other words.
The new one will have the folowing setup: Shimano Ultegra double with 167.5mm crankarms, 53/39 chainrings, SRAM 9 speed cassette, 11-28.
Last edited by Timmi; 10-19-08 at 11:15 PM.
10-20-08, 12:01 AM
#29
Grumpy Old Bugga
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Ahh, the personal touch. THAT's where gearing gets interesting because to my mind, the engine driving the gear box is more interesting than the gear ratios. I find gear charts interesting but personal quirks can distort the information.
I'm guessing you're younger than me but no youngster either.
It seems you've been on a bike and working those hills for many years.
You've probably a reasonable body shape too.
Just guess work, correct me if I'm wrong (without embaressing yourself).
This suggests that you've built up some genuine strength in those legs and your body is well tuned to the hills you're climbing. This would suggest an ability to ride through a large jump between chainrings. I don't have that and so notice the jump.
Am I also right in imagining that you're either climbing or on flatish roads? ie, there's two distinct styles of riding without much transition between them? In that case, if you get your ring size right and one ring will serve you for some distance.
For example: On my Jamis, I get onto a ring and stay there for some time because the three rings are pretty much right (you're right about the ultra small ring - that took some thought and looking at charts). Rolling country on the other hand, has me wearing out both shifters. On the other hand, the very low middle ring on my commuter has me swapping rings on a frequent basis even on the flat unless I can stick to a steady speed.
Just trying to understand why it works for you in the hope that I'll learn more about making my own choices.
The other thing that comes into the equation these days is the widening number of gears and the skinny chains to suit. I'm still wary of the need to go to 10 gears or beyond, particularly as it increases the amount of cross chaining we do. However, I read recently where someone commented on the flexibility of the new, very thin chains. He claimed that cross chaining just isn't an issue now, something I still regard as marketing hype, however there is probably some truth in it and maybe it is okay to use the full cassette from any chain ring (if your front dr allows it).
Richard
I'm guessing you're younger than me but no youngster either.
It seems you've been on a bike and working those hills for many years.
You've probably a reasonable body shape too.
Just guess work, correct me if I'm wrong (without embaressing yourself).
This suggests that you've built up some genuine strength in those legs and your body is well tuned to the hills you're climbing. This would suggest an ability to ride through a large jump between chainrings. I don't have that and so notice the jump.
Am I also right in imagining that you're either climbing or on flatish roads? ie, there's two distinct styles of riding without much transition between them? In that case, if you get your ring size right and one ring will serve you for some distance.
For example: On my Jamis, I get onto a ring and stay there for some time because the three rings are pretty much right (you're right about the ultra small ring - that took some thought and looking at charts). Rolling country on the other hand, has me wearing out both shifters. On the other hand, the very low middle ring on my commuter has me swapping rings on a frequent basis even on the flat unless I can stick to a steady speed.
Just trying to understand why it works for you in the hope that I'll learn more about making my own choices.
The other thing that comes into the equation these days is the widening number of gears and the skinny chains to suit. I'm still wary of the need to go to 10 gears or beyond, particularly as it increases the amount of cross chaining we do. However, I read recently where someone commented on the flexibility of the new, very thin chains. He claimed that cross chaining just isn't an issue now, something I still regard as marketing hype, however there is probably some truth in it and maybe it is okay to use the full cassette from any chain ring (if your front dr allows it).
Richard
10-20-08, 12:18 AM
#30
Grumpy Old Bugga
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Here I find that everytime I hit a hill, I'm fussing with gears, front and back, more than I should have to. There is no simple crossover from the large chainring to the middle one, where I can just do one shift in the front and keep going without shifting the back too. Nope... I have to shift the front, then start messing around with the back... and in doing that, I slow down, and often have the frustration of having to downshift again because I've lost my inertia. ...and with the slowing down, while shifting at ever lower speed, I hear the rear sprockets bang and crack, and I wonder when one of them is just going to break.
As you noted, I've got a change of about two gears between big and middle ring (which is the appropriate comparison here). Nearly all my hills have a gradual entry and so moving down onto the middle ring, then working down through the gears is pretty normal. I do often use the double shift function on my shifters (ie, two rear cogs at a go) and it's true that I'll often find myself going down through the gears pretty quickly, but it's change and ride, change and ride, not bang bang bang bang bang through the gears such as you get when stopping from high speed.
With a larger change between big and middle (as you get in a compact), you'd change off the big ring and find yourself in too low a gear for a period until the bike slows a bit - I'm well experienced with this going from the middle to the granny though in those cases, the hill is usually steep enough to make shifting up to compensate an annoyance - it's easier to just relax for 10m and let the bike slow under gravity.
In fact Tim, the more I think about your experience, the more I'd address that with a narrower gap between the rings rather than a wider gap. What am I missing?
I find that I have way too many gears than I need... that aren't in the right places.
... that aren't in the right places.
Richard
10-20-08, 12:37 AM
#31
Senior Member
I'm guessing you're younger than me but no youngster either. It seems you've been on a bike and working those hills for many years. You've probably a reasonable body shape too. Just guess work, correct me if I'm wrong (without embarassing yourself). This suggests that you've built up some genuine strength in those legs and your body is well tuned to the hills you're climbing. This would suggest an ability to ride through a large jump between chainrings. I don't have that and so notice the jump.
Just trying to understand why it works for you in the hope that I'll learn more about making my own choices.
The other thing that comes into the equation these days is the widening number of gears and the skinny chains to suit. I'm still wary of the need to go to 10 gears or beyond, particularly as it increases the amount of cross chaining we do. However, I read recently where someone commented on the flexibility of the new, very thin chains. He claimed that cross chaining just isn't an issue now, something I still regard as marketing hype, however there is probably some truth in it and maybe it is okay to use the full cassette from any chain ring (if your front dr allows it). Richard
Just trying to understand why it works for you in the hope that I'll learn more about making my own choices.
The other thing that comes into the equation these days is the widening number of gears and the skinny chains to suit. I'm still wary of the need to go to 10 gears or beyond, particularly as it increases the amount of cross chaining we do. However, I read recently where someone commented on the flexibility of the new, very thin chains. He claimed that cross chaining just isn't an issue now, something I still regard as marketing hype, however there is probably some truth in it and maybe it is okay to use the full cassette from any chain ring (if your front dr allows it). Richard
Please do take a moment to examine the gear charts I've come up with. And read my reasoning behind it in my previous post (the ~15-17% jump from one gear to the other). You should be able to see that it's pretty good. You can get a 50/34, 50/36, 53/39, depending on if you like to push hard (like me) or spin more (like you), in conjunction with one of those gear ranges in the charts I provided. You know, even with your terrain over there, you might actually like it. I'm not saying change all your bikes... they're probably not all geared the same... but maybe a change to the one that has gearing the least suited for you.... it might be worth a try. It won't replace your bike that has gearing so well adapted for your needs, but it might make a bike under-used more polyvalent.
About the new extra speeds... I totally agree with you. With China gone global and mainstream in manufacturing, and Shimano regularly obsoleting products, prices have nowhere to go but down. I had a sigh of relief when I started getting back into cycling and discovered I missed the wave of 8 speed stuff, so short lived - that's when I finally "upgraded" to 7 speed! LOL Currently, I buy 9 speed, it's cheap - because everything in manufacturing is switching over to 10 and 11 speed now. If 9 was good a year ago, it's good enough for me today! When 12 speeds hit the market, I'll be buying 10, maybe even 11 if it also comes down in price enough at that time.
Regarding mechanical strength, shortening the rivet has no effect on chain strength, since it's strength is dependent on material (the steel alloy used and consistency thereof), and thickness of the plates used. If you're just shortening the pin, no difference... or is there? Well there is actually. When the chain is not in a straight line, but crossing over, then pins and plates on opposing sides on each end are supporting way more than if the chain was taught in a straight line where everything would be suported 50-50 on each side. This discrepancy caused with deflection is reduced with narrower pins being used (simple basic trigonometry). So yes, I believe the theory that a chain can be a bit stronger if it is narrower (for a same plate thickness).
Now one thing that is definitely a nice feature of the new narrower chains, is cramming an ever increasing number of gears into the same space... not that we actually need to increase the total number of gears, now, but rather, the usable amount before your chain deflection starts to affect chain strength or mechanical efficiency (through more rubbing on the cogs), you can shift among more gears before that happens. With 11 speed, I think that compact double cranksets will serve every need.
You see, the probability of having this debate decreases with every extra gear they add on the back.
I mean, on my cirrent 9 speed setup, if I decide to not use the last smallest 2-3 gears with the large chainring, or the largest 2-3 gears with the small chainring, I have 6-7 gears left on each that I use. With a 10, that increases to 7-8, with an 11 it's 7-9. I mean... it seems that not that long ago, I was running a 6 speed freewheel where I was reduced to just 5 useable cogs with each chainring.
Last edited by Timmi; 10-20-08 at 01:03 AM.
10-20-08, 01:18 AM
#32
Senior Member
On a compact double, in the configurations proposed, it is 14% in the first example, and 16% in the latter. Not a dramatic change! Our cadence sweet spot is well in excess of a 10% variation, so all of these are quite comfortable. You do not have an extra gear lower after shifting with a double... look at the tables... it is quite similar actually. Maybe a quarter of a gear lower at worse, but not one full one.
10-20-08, 08:02 PM
#33
Senior Member
This person is an expert on short cranks. He has some for sale and will also shorten your present cranks if they meet certain criteria. Give him a call or email. https://bikesmithdesign.com/
How in the world did this thread get sucked into the recumbent forum? The OP is not a bent rider and the subject of short cranks is not bent-specific.
I use 155mm cranks on my latest lowracer. Not that I'm a convert, it's just that I need the short cranks because otherwise I can't adjust the bike short enough to reach the pedals. Short cranks give up a little bit in torque but the advantage is that you don't need to bend your knees as much at the top of the pedal stroke, meaning less strain and higher output in the first 1/4 of the circle. To compensate for the torque, you have to spin better, which may mean lower gears.
My 155s are made by Thorn. Current searches don't show any made by them that are that short. Whereas 165 are easy to find, 160 are a bit harder and 155 are very hard. Well, maybe that's an exaggeration - you can always get cheap short cranks that are made for kids' bikes. You may be able to get your current set shortened, depending on what you've got.
https://bikesmithdesign.com/Short_Cranks/shorten.html
I use 155mm cranks on my latest lowracer. Not that I'm a convert, it's just that I need the short cranks because otherwise I can't adjust the bike short enough to reach the pedals. Short cranks give up a little bit in torque but the advantage is that you don't need to bend your knees as much at the top of the pedal stroke, meaning less strain and higher output in the first 1/4 of the circle. To compensate for the torque, you have to spin better, which may mean lower gears.
My 155s are made by Thorn. Current searches don't show any made by them that are that short. Whereas 165 are easy to find, 160 are a bit harder and 155 are very hard. Well, maybe that's an exaggeration - you can always get cheap short cranks that are made for kids' bikes. You may be able to get your current set shortened, depending on what you've got.
https://bikesmithdesign.com/Short_Cranks/shorten.html
Look up item number 130263594187
Closes in a little over 5 days. Looks like it's in good shape!
PS: no, I'm not spamming - I'm not the seller. My seller ID on eBay is "Super-Timm". I'm posting this because some mentioned needing shorter cranks.
Last edited by Timmi; 10-20-08 at 08:06 PM.
10-21-08, 01:21 PM
#34
Senior Member
For those who don't want to deal with E-Bay, Harris Cyclery sells Bulletproof cranks.
https://harriscyclery.net/itemdetails.cfm?id=1215
They come in 140-170mm sizes. They're 110 BCD for a single or double chainring system, so will take pretty much whatever size chainrings you want, from 34T up to 60+. To make it a triple, you'd need to get a triplizer, which is a middle chainring with additional holes for mounting a 58T granny ring.
https://www.interlocracing.com/triplizer.html
https://harriscyclery.net/itemdetails.cfm?id=1215
They come in 140-170mm sizes. They're 110 BCD for a single or double chainring system, so will take pretty much whatever size chainrings you want, from 34T up to 60+. To make it a triple, you'd need to get a triplizer, which is a middle chainring with additional holes for mounting a 58T granny ring.
https://www.interlocracing.com/triplizer.html
10-21-08, 01:32 PM
#35
Senior Member
For those who don't want to deal with E-Bay, Harris Cyclery sells Bulletproof cranks.
https://harriscyclery.net/itemdetails.cfm?id=1215
They come in 140-170mm sizes. They're 110 BCD for a single or double chainring system, so will take pretty much whatever size chainrings you want, from 34T up to 60+. To make it a triple, you'd need to get a triplizer, which is a middle chainring with additional holes for mounting a 58T granny ring.
https://www.interlocracing.com/triplizer.html
https://harriscyclery.net/itemdetails.cfm?id=1215
They come in 140-170mm sizes. They're 110 BCD for a single or double chainring system, so will take pretty much whatever size chainrings you want, from 34T up to 60+. To make it a triple, you'd need to get a triplizer, which is a middle chainring with additional holes for mounting a 58T granny ring.
https://www.interlocracing.com/triplizer.html
BTW, while we're on the topic of talking about sources, I had ordered some nice 20" rims and the matching spokes from Cascade Cyclery, which were hard to find elsewhere.
Last edited by Timmi; 10-21-08 at 01:46 PM.
10-22-08, 11:53 PM
#36
Grumpy Old Bugga
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For those who don't want to deal with E-Bay, Harris Cyclery sells Bulletproof cranks.
https://harriscyclery.net/itemdetails.cfm?id=1215
They come in 140-170mm sizes. They're 110 BCD for a single or double chainring system, so will take pretty much whatever size chainrings you want, from 34T up to 60+. To make it a triple, you'd need to get a triplizer, which is a middle chainring with additional holes for mounting a 58T granny ring.
https://www.interlocracing.com/triplizer.html
https://harriscyclery.net/itemdetails.cfm?id=1215
They come in 140-170mm sizes. They're 110 BCD for a single or double chainring system, so will take pretty much whatever size chainrings you want, from 34T up to 60+. To make it a triple, you'd need to get a triplizer, which is a middle chainring with additional holes for mounting a 58T granny ring.
https://www.interlocracing.com/triplizer.html
I haven't had a chance to follow things through this week - big uni assignments due, I'm not touching the bike to do anything except ride it
Richard
10-23-08, 06:07 AM
#37
Senior Member
As I read my last post, I realized I wrote "58T granny ring." That is incorrect. I think that's the BCD for the inner ring on a 110mm crank, so the BCDs would be 110/58.
