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  1. #1
    All Lefty's, all the time Moderator
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    Noob questions, be gentle with me please?

    Hey all, just built a Moonlander for a customer, and they speced a Rohloff.

    By the time I was done figuring the whole thing out, I was in love.

    I'm planning on putting one on my recently acquired Krampus, and have a few questions before I drop some serious coin.

    They mention chainring size minimums. A 40t or so ring sounds HUGE for typical northeast MTB riding. I mean, I run a 2x9 and so my biggest is a 32t, just for reference sake.

    Please don't start in with gear inches and ratios, I'll just glaze over, it's meaningless to me, and I'm too stubborn to go out and learn that which will be a purely intellectual exercise for me.

    If you say a 40t with the 16 cog will net me low gearing anywhere near a 22/34, I'd be okay with it.

    My customer found info in several places where folks with fatbikes were running 34t as a preferred ring size, which is outside the limits Rohloff sets out. Actually, he just stopped in and said that Rohloff has now approved use down to a 34t with the 16. So now the question is, what ring would likely give the closest feeling ratio to my 22/32 with an 11/34 out back?


    Shifting under load. They say it can be done, but toss a caveat out about it possibly going to a neutral position so be cautious. It certainly feels like it will work fine, but I only had a parking lot test. On par with a Hammerschmidt, or a bit less trustworthy?

    Thanks! Pretty stoked to play around with this thing!
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



    www.mendoncyclesmith.com

  2. #2
    1*14*29*2.1 & 1*1*29*2.4
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    36/16 for me on my 29er. I have to have it for the steep gradients here 20-25% and loose consistently. Really low gears just mean tyre slip to me. I think 34 would be closer to the trad drivetrain 22/34, but for me it is close enough. I would guess for a heavy bike with gobs of traction you may want lower but I am not familiar with your use. I don't use 1st gear much but mainly try to keep to 2nd. 1st for me is a bailout when I am sick, unfit or really flogged. Like you said, it's been mentioned recently the chainring size has been lowered I think to 36 now (from 38). If you want to run a 32 chainring you'll need to use a 13t cog, but I'd stick with the larger chainring. You shouldn't need to have a 40t chainring unless your clilent is 100kg+ I would think. I think the cranklength may play a part but sticking to 175 should be good. Shifting under load is possible but from my point of view not great withthe Rohloff. Some gears do it better than others and I can't be bothered remembering where I am all the time. Also it isn't hard to change gear without load given the other shifting benefits and also if like me you still remember the days of friction shifters.

  3. #3
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    Front 34T and rear 16T and Rohloff is pretty close to Front 22T and rear 36T in a 29er wheel according to Sheldons gear calculator and within the revised limits from memory. Approx 17 to 90 inches. This is good as otherwise I'd have not bothered with a Rohloff but gone with a Sram Dualdrive. I'd advise not shifting under load but a momentary pause or lightening on the pedals during changes.

    Love the look of the Krampus but will go with an Ogre due to a bit more tyre selection even though the 29 selection is still a little woeful compared to 26". At times I find myself looking at the Troll because of the wonderful tyre selection up to 2.7 wide but I'm hoping the 700c 2.35's offer a happy comfort level for a variety of touring conditions here in Australia..
    Last edited by rifraf; 01-18-2013 at 08:36 PM.

  4. #4
    Cycle Psycho
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    You have a Krampus?!?! In the flesh?! When did you get it? Today?

    I'm building an Ogre with Alfine 11, so I will look up to your rig. I would love to see pics!
    '10 Rocky Mountain Metropolis (rigid 2x10)
    '10 SURLY 1x1 (rigid SS)
    '13 SURLY Ogre (rigid SS)
    '13 SURLY Troll (rigid 2x10)

  5. #5
    All Lefty's, all the time Moderator
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    Thanks all, I really appreciate the input. Just the info I wanted to get.

    Gritter, yes, they showed up Thursday, part of the preseason I did this past Fall. I should have it mostly built by next weekend, assuming things go well.

    Scored the last Rohloff QBP had in stock!
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



    www.mendoncyclesmith.com

  6. #6
    Music & Bikes
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    Rohloff advise 2,1 as the minimum torque input

    SPEEDHUB 500/14 revised permitted transmission factor now 2.1!: www.rohloff.de

    Been running 36/16 on my 1FG for the last 8 years and it was perfect balance for my type of riding (26er) , got a new frame and put a 46/20 belt setup (2,30)

    As for shifting under load , there are certain speed wich are harder to shift under load , some are very easy like 1-2 / 8-9 , you have to learn to shift on the "dead spot" of your circular pedal motion.
    It shifts better as it ages.
    I now know what speed I'm in just by the feel and the sound.
    Shifting under pressure is not prohibited by Rohloff.

    It's the best piece of bike equipement I ever bought , even better than my Lefty , can you imagine !
    "There is a big difference between kneeling down and bending over" -FZ

  7. #7
    Unhinged Aussie on a 29er
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    Rohloff owner's manual online link

    Quote Originally Posted by MendonCycleSmith View Post
    Hey all, just built a Moonlander for a customer, and they speced a Rohloff.

    By the time I was done figuring the whole thing out, I was in love.

    I'm planning on putting one on my recently acquired Krampus, and have a few questions before I drop some serious coin.

    They mention chainring size minimums. A 40t or so ring sounds HUGE for typical northeast MTB riding. I mean, I run a 2x9 and so my biggest is a 32t, just for reference sake.

    Please don't start in with gear inches and ratios, I'll just glaze over, it's meaningless to me, and I'm too stubborn to go out and learn that which will be a purely intellectual exercise for me.

    If you say a 40t with the 16 cog will net me low gearing anywhere near a 22/34, I'd be okay with it.
    Firstly, you shouldn't discount understanding gear inches, ratios and roll out.

    Ref: Pg 21 of the Rohloff owner manual:
    22/34 compared to Gear 1 of the speedhub:
    Equivalent ratios on the Rohloff are
    32/13
    36/15
    38/16
    40/17

    Because these are ratios, that has no bearing on the tire size. It could be a 20" or a 29" tire; they will have the same climbing ratio - if you were to have 22/34 on a 20" bike, it would be comparable to a 38/16 rohloff on a 20" bike.

    Quote Originally Posted by MendonCycleSmith View Post
    My customer found info in several places where folks with fatbikes were running 34t as a preferred ring size, which is outside the limits Rohloff sets out. Actually, he just stopped in and said that Rohloff has now approved use down to a 34t with the 16. So now the question is, what ring would likely give the closest feeling ratio to my 22/32 with an 11/34 out back?
    fokof mentioned the revised ratio, so I'll just point at that and say, "look there".

    REF: Pg 22, 3rd box down.
    38/16
    22/34 gear 1
    38/11 gear 14

    This is why I say you shouldn't discount learning about ratios; even if you can't do the math, having a basic understanding will help a lot. What you described will have what is referred to as a 450% range on your gearing, calculated as: (32/11) / (22/34)* 100 = 449.59% (2 dp). Rohloff's have 526% range.

    In theory, you should be able to gear 1 about the same, and gear 14 slightly higher, or gear 1 slightly lower, and gear 14 the same, or some mix of the two.

    Personally, on a 29'er I would gear it slightly lower and have the same top gear, lower climbing gear.

    REF: Derived from definition given on Rohloff owner manual pg. 19, eqn. 2. 526% is also defined on pg. 19, can also be calculated but no one gives a **** about that.

    Quote Originally Posted by MendonCycleSmith View Post
    Shifting under load. They say it can be done, but toss a caveat out about it possibly going to a neutral position so be cautious. It certainly feels like it will work fine, but I only had a parking lot test. On par with a Hammerschmidt, or a bit less trustworthy?
    Less trustworthy IMO. One is designed to do it under load, the other is not.

    You have two issues that you'll hit with the Rohloff. Under certain gears, the internal mechanisms will have trouble shifting under load. This is especially noticeable shifting from 8 to 7; if you do so under load, the mechanisms can't cope, and you'll temporarily shift in to gear 14. The second, as you describe, is "neutral" positions. Generally I find that the temporarily shifting to the wrong gear is the bigger problem.

    Shifting under load and shifting in general has improved after the first 1000 miles.

    REF: Rohloff owner's manual, pg 5 paragraph 4.
    Last edited by hunter006; 01-19-2013 at 10:54 AM. Reason: added owner manual link

  8. #8
    All Lefty's, all the time Moderator
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    Thanks for all the detailed info, much appreciated.

    Having never been a higher math guy, the stuff just goes over my head. Combined with being too busy as it is, and trying to jam that stuff into my head, and have it make sense, is just beyond a low priority.

    That little admission being made, I am very grateful for the breakdown.

    fokof, yeah, I'm thinking it'll be pretty high up in my list of awesome additions to my bike, first ever IGH, so it'll outshine my forks for sure.

    "REF: Pg 22, 3rd box down.
    38/16
    22/34 gear 1
    38/11 gear 14"

    So, what you're saying with this is, with a 38/16, gear one gives me an equivalent 22/34, and gear 14, a 38/11 equivalent?

    I did say be patient with me! Wow, so I can have my cake and eat it too? Wider than my 2x9? That's cool!

    So a 34 ring will be even lower than 22/34. Curious. I'm a seat of the pants guy, I'll buy a few rings and play. I guess drag comes into it too, might be valuable to have a bit lower gearing because of that....
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



    www.mendoncyclesmith.com

  9. #9
    dru
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    Having never been a higher math guy, the stuff just goes over my head.
    Mendon, it's so easy using Sheldon's calculator.

    I am not a 'math guy' either and I can use it fine.

    You want 22/34 equivalent right? So you go to SB and put in that gearing. You can choose whatever wheel size/tire combo you want. You can choose whatever measurement you want, be it gear inches, cadence vs mph/kmh, or gain ratios.

    It doesnt matter, just get the output for 22/34.

    When you know that, use the same input info (wheel size, etc.) for the rohloff and pick your gear choices (such as the 34/16 combo you are interested in) and then look at your results.

    It doesn't matter what measurements you use as long as the units are the same. (I always use cadence/mph)

    If your 22/34 equals 4.7 mph, then a 34/16 equipped Rohloff 1st gear gives you 4.3 mph.

    The rest of the gears are as follows, 4.9, 5.5, 6.3, 7.1, 8.1, 9.2, 10.5, 11.9, 13.5, 15.4, 17.4, 19.8, 22.5 mph.

    I also did the conventional top gear 32/11 you run, which will give you 21 mph.

    The Rohloff has a nice wide range that's for sure.

    Drew
    Last edited by dru; 01-21-2013 at 03:51 PM.
    occasional cyclist

  10. #10
    Unhinged Aussie on a 29er
    Reputation: hunter006's Avatar
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    Quote Originally Posted by MendonCycleSmith View Post
    "REF: Pg 22, 3rd box down.
    38/16
    22/34 gear 1
    38/11 gear 14"

    So, what you're saying with this is, with a 38/16, gear one gives me an equivalent 22/34, and gear 14, a 38/11 equivalent?

    I did say be patient with me! Wow, so I can have my cake and eat it too? Wider than my 2x9? That's cool!

    So a 34 ring will be even lower than 22/34. Curious. I'm a seat of the pants guy, I'll buy a few rings and play. I guess drag comes into it too, might be valuable to have a bit lower gearing because of that....
    1st part: yes, that is what the table is trying to express - 38/11 would be your high gear. or a 22-38 double up front, with a 34-11 rear cassette would approximate the same spread, but you wouldn't have the even spacing between each gear.

    Good point on the drag; efficiency is higher in the higher gears in general, so yes, perceived drag would be lower on the higher gears.

    Quote Originally Posted by dru View Post
    Mendon, it's so easy using Sheldon's calculator.

    I am not a 'math guy' either and I can use it fine.

    You want 22/34 equivalent right? So you go to SB and put in that gearing. You can choose whatever wheel size/tire combo you want. You can choose whatever measurement you want, be it gear inches, cadence vs mph/kmh, or gain ratios.

    It doesnt matter, just get the output for 22/34.

    When you know that, use the same input info (wheel size, etc.) for the rohloff and pick your gear choices (such as the 34/16 combo you are interested in) and then look at your results.

    It doesn't matter what measurements you use as long as the units are the same. (I always use cadence/mph)

    If your 22/34 equals 4.7 mph, then a 34/16 equipped Rohloff 1st gear gives you 4.3 mph.

    The rest of the gears are as follows, 4.9, 5.5, 6.3, 7.1, 8.1, 9.2, 10.5, 11.9, 13.5, 15.4, 17.4, 19.8, 22.5 mph.

    I also did the conventional top gear 32/11 you run, which will give you 21 mph.

    The Rohloff has a nice wide range that's for sure.

    Drew
    ^^^ This is why understanding the core concepts is good, even if you can't do the math. FWIW, that's how I "tuned" my ride, using Sheldon's calculator and other things I knew about my personal riding style - I cruise at ~80-90 RPM, and I planned to run 29x2.0" tires - changed chainring specs until I had a low end, top end and gear 11 that I was happy with. It's a lot cheaper than buying lots of chain rings.

    FWIW, while it doesn't matter if you use gain ratios or gear inches, etc. I would select gear inches to be a little more accurate. Ratios 0.1 going to 0.2 could be really close or really far, depending on how the rounding function works on the calculator. Gear inches will give you a much better idea (24 to 25" for example represents a 4% increase, which may not register on a ratio based calculation that was rounded).

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