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  1. #1
    Senior Member bud16415's Avatar
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    14t-40t (9 sp) cassette / Crazy idea? (Touring)

    Not sure what forum to post in but I know most cross read so I will stick it in the Bicycle Mechanics and hope the Touring guys find it.

    I’m pretty sure there isn’t a 40t cog out there yet and this is a hypothetical question for the most part. 36t is available in a 12-36 and that is what I’m now running on my touring bike. For whatever reason a lot of these touring bikes come with a road triple up front like a 52-42-30 and more mountain bike gears in the back like an 11-32 (9) The conventional fix for heavy loaded touring is to switch out the triple crank to a mountain bike triple or some of the in between triples. For me the mtn triple like a 44-32-22 was great at getting a super low range but left me not liking the center ring with my gears split between the center and large rings and then not a half step pattern.

    It is safe to drop the granny gear on the road triple a bit and I dropped mine from 30 to 26 and there is little issue with that shift from 26 to 42 and no FD changes were required. The back saw no issues with RD going from 11-32 to 12-36.

    So my question is if there was a 14-40 available with the tooth count of 14,16,18,21,24,28,32.36,40 and I kept my front of 52,42,26 I would have a total range of 17 GI to99 GI I would have 5 very useful gears off the granny ranging from 17 GI to 29 GI. My center ring would cover a very nice range of normal touring for me of 28 GI to 80 GI. My large ring would give me two more higher gears of 87 and 99 GI and the pattern for the 87 down to say 49 GI would stay in a nice half step. Many say half step is not that important with the 9 speed cassettes and I do agree but these mountain cassettes are wider spaced and I personally like having the in between gears if I can And gives a purpose to the big ring other than one or two higher gears only.

    The drawbacks I see are chain length and RD capacity issue. I’m not sure how it would work but I would tend to set it up so the big, big combo wouldn’t self-destruct and the small, small combo would just go slack if needed. I could never see myself going deeper than 4 or 5 cogs off the granny ring anyway. I would say the same for the big ring but I could see that maybe happening when daydreaming or something.

    I would think cassettes might last a bit longer with more teeth and yes bigger might weigh a little more. I have played around with all the known sizes I see around and got pretty close to what would be perfect for me with the 12-36. A little bit of this for me is about looks also a very little bit but the bike looked funny when I had that mtn crank on there. I really like the look of the 52. But sure didn’t need a 120 GI on a loaded touring bike.

    What do think?

    Last edited by bud16415; 03-30-12 at 10:31 AM.
    What's not in your legs needs to be in your gears.

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    One problem is that, AFAIK, no one makes a rear derailleur with a jockey pulley that will clear a 40T cog. Even long cage MTB derailleurs are rated for 36T max. I know Sun Tour made a 38T cog freewheel in the past but I have no idea which of their rear derailleurs they matched it with and, that was before indexing and cassettes.

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    Easier solution would be to get the mountain triple up front and find a middle ring with more plausible half-step gearing.

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    Senior Member bud16415's Avatar
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    Quote Originally Posted by HillRider View Post
    One problem is that, AFAIK, no one makes a rear derailleur with a jockey pulley that will clear a 40T cog. Even long cage MTB derailleurs are rated for 36T max. I know Sun Tour made a 38T cog freewheel in the past but I have no idea which of their rear derailleurs they matched it with and, that was before indexing and cassettes.
    I’m no expert and when I put the 36 on I could see I was getting close. I don’t know if the mounting point for the RD could be moved down on the dropout seeing as how the small cog it’s designed around is an 11 and would be going to a 14. I know it’s not one for one. I’m pretty sure I could make a 40t cog that would work but I don’t think I want to build a new RD though.
    What's not in your legs needs to be in your gears.

  5. #5
    Low car diet JiveTurkey's Avatar
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    Quote Originally Posted by mconlonx View Post
    Easier solution would be to get the mountain triple up front and find a middle ring with more plausible half-step gearing.
    E.g. a 44/32/22T, then swap the 32T for a 38T.
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    Senior Member bud16415's Avatar
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    Quote Originally Posted by mconlonx View Post
    Easier solution would be to get the mountain triple up front and find a middle ring with more plausible half-step gearing.
    Well that’s where I was heading and ran the numbers on a lot of the combinations I see guys using here. In most cases I didn’t get the spread of gears on the center ring and or the half step drifted off after a couple cogs. It’s pretty easy finding the 17 to 100 thing there are a million ways to get that and I’m not that unhappy with the 12-36 right now and I could drop to a 24 granny and get a bit more push, if I wanted to go that route. When I saw how much I liked the jump to the 36 from the 32 I thought what would the 40 do?
    What's not in your legs needs to be in your gears.

  7. #7
    Senior Member bud16415's Avatar
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    Quote Originally Posted by JiveTurkey View Post
    E.g. a 44/32/22T, then swap the 32T for a 38T.
    That was one I see lots using and it gives me a nice range off the center but the large ring is duplication all but the smallest cog pretty much.

    One combination that did look pretty good was the 22,38,46 I’m sure that might be a smarter way to go.
    What's not in your legs needs to be in your gears.

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    coprolite fietsbob's Avatar
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    I have a Schlumpf Mountain drive 2 speed crankset,
    it's planetary reduction gear
    really drops the equivalent chainring size a lot .

    Mine is on my Brompton, others have fitted them on bigger wheel bikes
    and used 2 chainrings.

    On My Brommy I have what is a wide range 6 speed ,
    the 3 hub gears are used twice.

    It's chainring a 54t, the low range is as if a 21.6 tooth,
    [50 divides evenly, so a 20t in low range]

    and with both gears planetary, double.. gear/range shifts happen,
    even bogged down on hills.
    Last edited by fietsbob; 03-30-12 at 12:15 PM.

  9. #9
    Senior Member bud16415's Avatar
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    Quote Originally Posted by fietsbob View Post
    I have a Schlumpf Mountain drive 2 speed crankset,
    it's planetary reduction gear
    really drops the equivalent chainring size a lot .

    Mine is on my Brompton, others have fitted them on bigger wheel bikes
    and used 2 chainrings.

    On My Brommy I have what is a wide range 6 speed ,
    the 3 hub gears are used twice.

    It's chainring a 54t, the low range is as if a 21.6 tooth,
    [50 divides evenly, so a 20t in low range]

    and with both gears planetary, double.. gear/range shifts happen,
    even bogged down on hills.
    I have looked at the planetary drives and they look like a great solution. A must if you live in very mountainous area for sure. Not sure if I want to take that big of a plunge into gearing yet.
    What's not in your legs needs to be in your gears.

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    This is sort of a "raise the bridge or lower the water question".

    Increasing cassette size and decreasing chainring size have the same practical effect. Discounting the issue of sprocket and RD reach limitations, why do this the hard way? The identical gearing can be achieved by reducing chainring size (or reducing wheel size, but let's not go there).

    You'll notice by driving around the country that when spanning rivers and leaving clearance for tall boats, the tendency is to build a higher bridge rather than putting in a lock system to lower the water. You'd be wise to think the same way.
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    There is one advantage to having bigger gears in the same ratio,they will wear longer.
    Everything should be as simple as possible...But not more so.---Albert Einstein

  12. #12
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    I've got a 26, 36 , 46 on my tourer. 32-12 out back, works for me.

  13. #13
    Senior Member bud16415's Avatar
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    Quote Originally Posted by FBinNY View Post
    This is sort of a "raise the bridge or lower the water question".

    Increasing cassette size and decreasing chainring size have the same practical effect. Discounting the issue of sprocket and RD reach limitations, why do this the hard way? The identical gearing can be achieved by reducing chainring size (or reducing wheel size, but let's not go there).

    You'll notice by driving around the country that when spanning rivers and leaving clearance for tall boats, the tendency is to build a higher bridge rather than putting in a lock system to lower the water. You'd be wise to think the same way.

    Kind of the water over the dam problem, as they say. I did say in the OP that it was a hypothetical problem. They seemed to stop getting smaller with chain rings at 20t and cassettes at 11t for some reason. I think the 36t cog must have come about with the desire for larger wheels and off road usage. Who would have ever thought they would even have 36’s
    If I was to do a 38 center I think I could keep my road crank and do that with a 24,38,46 and be in the sweet spot also with the 12,36 cassette.
    What's not in your legs needs to be in your gears.

  14. #14
    Senior Member Bill Kapaun's Avatar
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    I think I'd take a different approach and swap between 2 cassette.
    IF you're doing "LOADED" touring, what's the extra weight penalty for an extra cassette, chain whip & 1" wrench.
    You could use a "mountain" cassette where needed and a close ratio "road" cassette for the flat lands.
    IF you wanted to spend a couple extra minutes on a cassette change, you could carry only the loose cogs needed.

  15. #15
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    Quote Originally Posted by bud16415 View Post
    They seemed to stop getting smaller with chain rings at 20t and cassettes at 11t for some reason. I think the 36t cog must have come about with the desire for larger wheels and off road usage.
    The sizes offered are based on logical mechanical and marketing considerations.

    You don't see smaller sprockets than 11t which itself id IMO too small for heavy use. Going smaller with a derailleur drive causes fast wear, and begins to run into limitations of cassette body and axle diameters. I've seen some smaller sprockets used for small wheel bikes, but I think that was because they were because of maximum chainring constraints.

    Likewise increasing the largest rear sprocket begins so call for some added bracing, not to speak of needing longer arms on RDs. I've seen more than a few 36t sprockets bent in use, so would expect more of this with a 40t.

    If you accept that a 13" final drive ratio is mechanically equivalent to walking, then we can accept this as the lower limit of required gearing for the real world. That ratio is easily achieved using a 20 or 22t granny, with a 32t or 36t rear sprocket, so there's no practical need to go bigger, and re-engineer the entire drivetrain.

    IMO if can't make it with a 24/32 combination (20" gear) for a low gear, you're not going to make it anyway, no matter how much lower you go, but as I say that's just an opinion.
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  16. #16
    Insane Bicycle Mechanic Jeff Wills's Avatar
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    Quote Originally Posted by FBinNY View Post
    The sizes offered are based on logical mechanical and marketing considerations.
    <snip>
    If you accept that a 13" final drive ratio is mechanically equivalent to walking, then we can accept this as the lower limit of required gearing for the real world. That ratio is easily achieved using a 20 or 22t granny, with a 32t or 36t rear sprocket, so there's no practical need to go bigger, and re-engineer the entire drivetrain.
    The low gear on my touring bike is about 18 gear inches (24 front/34 rear). I've used that while loaded touring, while climbing a 15% slope. I was just barely faster than my wife, who was pushing her bike up the same hill.
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    Low car diet JiveTurkey's Avatar
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    Quote Originally Posted by bud16415 View Post
    That was one I see lots using and it gives me a nice range off the center but the large ring is duplication all but the smallest cog pretty much.

    One combination that did look pretty good was the 22,38,46 I’m sure that might be a smarter way to go.
    On my MTB turned commuter/tourer with 26 x 1.5" tires, I started with a 48/38/28T crank and 11-34T cassette. I was having trouble with the road FD and MTB crank and decided I really didn't need the outer chainring. At 100 RPM, I top out at 26 MPH. I can't imagine feeling the need to pedal to go any faster. By the time I'm hitting that speed on that bike, I'm coasting downhill.

    Anyway, 44T may be redundant, but it's only there to give you a couple more gears beyond what the 38T can provide.
    Quote Originally Posted by slopvehicle View Post
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  18. #18
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    Quote Originally Posted by Jeff Wills View Post
    The low gear on my touring bike is about 18 gear inches (24 front/34 rear). I've used that while loaded touring, while climbing a 15% slope. I was just barely faster than my wife, who was pushing her bike up the same hill.
    My point exactly, if the gear were a bit lower she's pass you walking.
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  19. #19
    Senior Member bud16415's Avatar
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    Quote Originally Posted by Bill Kapaun View Post
    I think I'd take a different approach and swap between 2 cassette.
    IF you're doing "LOADED" touring, what's the extra weight penalty for an extra cassette, chain whip & 1" wrench.
    You could use a "mountain" cassette where needed and a close ratio "road" cassette for the flat lands.
    IF you wanted to spend a couple extra minutes on a cassette change, you could carry only the loose cogs needed.
    Bill

    I had similar ideas when I was first thinking about this. If I was just using the bike for touring I would maybe have a different idea ofwhat I wanted, but I do use the bike for commuting with a light load and also pleasure riding unloaded. I had also thought about building another wheel withthe big cogs just for touring. Similar to what you suggested.

    I liked the 42 center ring a lot for all my non tour ridingand being able to get a 26 / 36 gave me a good low granny gear I could stillshift down to without too much trouble.
    What's not in your legs needs to be in your gears.

  20. #20
    Senior Member bud16415's Avatar
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    Quote Originally Posted by FBinNY View Post
    The sizes offered are based on logical mechanical and marketing considerations.

    You don't see smaller sprockets than 11t which itself id IMO too small for heavy use. Going smaller with a derailleur drive causes fast wear, and begins to run into limitations of cassette body and axle diameters. I've seen some smaller sprockets used for small wheel bikes, but I think that was because they were because of maximum chainring constraints.

    Likewise increasing the largest rear sprocket begins so call for some added bracing, not to speak of needing longer arms on RDs. I've seen more than a few 36t sprockets bent in use, so would expect more of this with a 40t.

    If you accept that a 13" final drive ratio is mechanically equivalent to walking, then we can accept this as the lower limit of required gearing for the real world. That ratio is easily achieved using a 20 or 22t granny, with a 32t or 36t rear sprocket, so there's no practical need to go bigger, and re-engineer the entire drivetrain.

    IMO if can't make it with a 24/32 combination (20" gear) for a low gear, you're not going to make it anyway, no matter how much lower you go, but as I say that's just an opinion.



    When I had the mtn crank on I had time to experiment both loaded and unloaded and I found I limited out at 17 GI. I felt I could climb just about anything but was spinning my legs off just to keep enough speed to stay upright. I also noted for me 20 GI still had room to ask for a lower gear.So I must be one of those riders that if I couldn’t make it with 20 GI I would never make it then. Walking may well be around 13 GI if done without load but when I measured my stride pushing a loaded rig up hill I would guess for me I was sub 10 GI when pushing. Everyone has different cadence and torque abilities and that will factor in. About 3 MPH is my slowest speed climbing.
    What's not in your legs needs to be in your gears.

  21. #21
    Senior Member bud16415's Avatar
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    Quote Originally Posted by JiveTurkey View Post
    On my MTB turned commuter/tourer with 26 x 1.5" tires, I started with a 48/38/28T crank and 11-34T cassette. I was having trouble with the road FD and MTB crank and decided I really didn't need the outer chainring. At 100 RPM, I top out at 26 MPH. I can't imagine feeling the need to pedal to go any faster. By the time I'm hitting that speed on that bike, I'm coasting downhill.

    Anyway, 44T may be redundant, but it's only there to give you a couple more gears beyond what the 38T can provide.

    Everyone uses their gears differently and with a closer cluster of 9 or 10 speed I wouldn’t worry about half step. I personally have jumps of about 10 GI and if I can work it out where I can get another 5 or 6 in there at the half way points I will use them to fine tune when I know I will be in that gear for a while. Having one or two higher gears is also nice. I do like to keep my legs moving rather than coast on a downhill. Sometimes to build some speed sometimes to keep legs warm.
    What's not in your legs needs to be in your gears.

  22. #22
    Senior Member bud16415's Avatar
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    It sounds like the general consensus is that the status quo is about all we will ever see in touring gearing systems for touring and has no room for improvement with still larger cogs than what we now believe to be the biggest we will ever see.

    From my limited knowledge of what goes into designing a touring bike it looks like other than frames the market is driven by what parts are widely used on road and mountain bikes. The good quality of those parts are driven by racing needs and weight. I don’t see any reason as FBinNY said that a 36t cog needs to be frail on a touring bike. He also mentioned that an 11t cog was most likely too small to stand up to the demands of touring. I also agree with him there both the 11 and 12t seemed small to me on a bike loaded with a heavy rider lots of gear and a heavy frame, thus my idea of an overall larger drive train for loaded touring. The upper class racer with an overall weight difference of about one fourth of what I have seen many people tour with has an additional benefit after a few races he can replace his gearing as needed. Someone touring IMHO doing thousands of miles unsupported wants to be on the other end of the strength to weight durability curve. Yes there are weight penalties in touring also but I feel the discretion is of a magnitude lower in touring in the market place in favor of a more robust product.

    That was my thoughts in posting the thread really. I have seen lots and lots of gearing threads related to touring and most are dealing with getting a lower gear ratio or getting a stronger drive train. There has been a lot of great things developed for road and mountain bikes that have greatly improved touring bikes. I just wondered if there was a place for tour specific innovation. Whenever I find 12-36 cassettes they always say “Designed for 29ers but is also a new option for touring bikes” http://harriscyclery.net/product/shi...sette-3054.htm
    I never have seen where it says designed for a touring bike also a new option for (fill in the blank).
    What's not in your legs needs to be in your gears.

  23. #23
    Senior Member Bill Kapaun's Avatar
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    Quote Originally Posted by bud16415 View Post
    Bill

    I had similar ideas when I was first thinking about this. If I was just using the bike for touring I would maybe have a different idea ofwhat I wanted, but I do use the bike for commuting with a light load and also pleasure riding unloaded. I had also thought about building another wheel withthe big cogs just for touring. Similar to what you suggested.


    I liked the 42 center ring a lot for all my non tour ridingand being able to get a 26 / 36 gave me a good low granny gear I could stillshift down to without too much trouble.

    I'd still get a 2nd cassette, chain whip, lock ring tool and 1" wrench (Crescent).
    Cassette change can be done in about 5 minutes with a bit of practice. Just leave the chain sized for the largest big cog.

  24. #24
    Charles Ramsey
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    A standard Shimano mega range derailer will climb a 48 tooth rear cog. http://share.ovi.com/media/currentre...resident.10073 The derailer in the photo has been replaced by a tourney TX it is working fine on the 39 tooth cog I'm running now though I estimate 40 teeth is it's limit. Shimaono derailers will only climb a 10 tooth difference so I recomend something like I'm using now 12 13 15 17 20 24 30 39 Action Tec makes 39 tooth rear cogs for $78
    Last edited by Charles Ramsey; 04-02-12 at 02:28 PM.

  25. #25
    coprolite fietsbob's Avatar
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    Old Chuck who hand makes the eyeglass mirrors, that Hub Bub sells, using stainless spokes,
    had a wild drive train on an old bike .
    he fabricated the alterations himself.

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