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  1. #1
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    Utility IGH hub max load?

    how much wieght can I put on an IGH hub bike before breaking the IGH?
    I like IGH hubs and would like to use them on my cargo bike (which doesnt exist yet) but ideally I could carry up to 600 lbs.
    Would that be possible? maybe 400lbs? 300?

  2. #2
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    Use a NuVinci CVT. They are slow but I hear they are pretty tough. Their maximum input torque is 130Nm, which is probably more than your legs can dish out.
    Last edited by antonyfhilliard; 03-08-10 at 12:01 AM.

  3. #3
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    Quote Originally Posted by chico1st View Post
    how much wieght can I put on an IGH hub bike before breaking the IGH?
    I like IGH hubs and would like to use them on my cargo bike (which doesnt exist yet) but ideally I could carry up to 600 lbs.
    Would that be possible? maybe 400lbs? 300?
    IIRC Rohloff recommends not exceeding about 400 pounds total bike weight with rider(s).

    Some Dutch Bakfiets are using the Shimano 8 speed hub. You might talk to Clever Cycles who import such bikes to find out their load limits. They are in Portland, OR and specialize in cargo bikes, some from Europe. Google the name.

    Per recent posts on the Rootsradicals cargo bike Yahoo group members are using the Rohloff, NuVinci and Shimano 8 speed hubs successfully but loads carried were not discussed. The general consensus seems to be that the Xtracycle conversion on an MTB frame work with a 400 pound load including the rider. That is also the limit that Surly recommendation for he Big Dummy.

    The only longtail bike I know of which lists a CARGO limit of 400 pounds, plus the rider, is the Yuba Mundo and it has not been offered in an IGH version that I know of. It lists using a 48 spoke rear wheel with a 14mm axle to withstand the weight and the maximum number of spokes a modern IGH wheel can be built with is 36.

    At the total weight you are talking about I would be as concerned about the frame, fork and other components on the bike too. Also I would worry about what would happen if the bike fell over and landed on your leg. To me 400 pounds including the rider is the practical limit. For such a bike I would build it with the NuVinci hub if doing an IGH bike.

    You are talking about loads in excess of those most riders would be willing to tackle on ANY bike so I suspect that you are on your own here.
    Gear Hubs Owned: Rohloff disc brake, SRAM iM9 disc brake, SRAM P5 freewheel, Sachs Torpedo 3 speed freewheel, NuVinci CVT, Shimano Alfine SG S-501, Sturmey Archer S5-2 Alloy. Other: 83 Colnago Super Record, Univega Via De Oro

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  4. #4
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    damn and im cheap so i dont want to break a 7-sp nexus or something... i guess i will have to stay at 300 lbs.

    The issue that im thinking of now is that I cant even use a trailer with an IGH because of the torque on the pawls, with an externally geared i really only need to worry about the 400 lb limit on the bike itself and I can add a heavy trailer.

    NB: I was thinking that I would have to have a front derailer on a cargo IGH bike, which i know is doable. So im not the hulk or anything.
    Last edited by chico1st; 03-11-10 at 10:06 AM.

  5. #5
    cyclopath vik's Avatar
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    Quote Originally Posted by chico1st View Post
    damn and im cheap so i dont want to break a 7-sp nexus or something... i guess i will have to stay at 300 lbs.

    The issue that im thinking of now is that I cant even use a trailer with an IGH because of the torque on the pawls, with an externally geared i really only need to worry about the 400 lb limit on the bike itself and I can add a heavy trailer.

    NB: I was thinking that I would have to have a front derailer on a cargo IGH bike, which i know is doable. So im not the hulk or anything.
    There are two issues with cargo weight and IGHs:

    1) axle capacity
    2) torque loading of the hub

    The Big Dummy, for example, is rated for 200lbs of load + a 200lbs rider...that's probably 300lbs on the rear wheel axle given the weight distribution of a longtail. If you stick with that you'll be okay on any of the IGHs. Beyond that there is some risk depending on the hub, the load and the terrain you traverse. Obviously the shock loading of a pothole or something similar is going to be the sort of impact that will damage your axle....so going slow, fat tires and smoother roads will be necessary as you increase your cargo weight. At some point your going to have to worry about failure of other components [frame, spokes/rims] and your ability to brake the bike.

    As far as torque loading goes there are two variables: 1) rider power 2) input gear ratio....Rohloff has a minimum gear ratio [38T x 16T] to limit the input torque...you can vary this depending on how strong you are and how gently you pedal and how much risk you want to take.

    You idea of a trailer is a good one. Most of the time you aren't going to need to haul 200lbs+ of cargo so no point compromising the cargo bike for that occasional need. If you built up a BD with an IGH using a sensible low gear you'll have a very versatile rig. When you need to haul a massive load use a trailer....ideally loaded so it doesn't add a huge load to the rear wheel of your cargo bike. You'll be able to share the cost/storage of the trailer with friends since one will probably be enough for several households.
    safe riding - Vik
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  6. #6
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    Quote Originally Posted by chico1st View Post
    damn and im cheap so i dont want to break a 7-sp nexus or something... i guess i will have to stay at 300 lbs.

    The issue that im thinking of now is that I cant even use a trailer with an IGH because of the torque on the pawls, with an externally geared i really only need to worry about the 400 lb limit on the bike itself and I can add a heavy trailer.

    NB: I was thinking that I would have to have a front derailer on a cargo IGH bike, which i know is doable. So im not the hulk or anything.
    IGH bikes can handle trailers. The maker of BOB trailers offers adapters to allow installing it on IGH axles. A two wheel heavy duty trailer with a frame or axle mount, properly balanced, should put little more weight on the hub axle. Torque on hub pawls is far more dependent on rider strength and how hard you pedal than on weight being carried. BTW the latest Shimano 8 speed hubs do not use pawls, they use rolller clutches.
    Gear Hubs Owned: Rohloff disc brake, SRAM iM9 disc brake, SRAM P5 freewheel, Sachs Torpedo 3 speed freewheel, NuVinci CVT, Shimano Alfine SG S-501, Sturmey Archer S5-2 Alloy. Other: 83 Colnago Super Record, Univega Via De Oro

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  7. #7
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    oh so by just limiting the gear ratio, which effectively limits the max torque I can exert then I can use an IGH ... neat

  8. #8
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    Quote Originally Posted by chico1st View Post
    oh so by just limiting the gear ratio, which effectively limits the max torque I can exert then I can use an IGH ... neat
    How low a low gear do you want?

    Staying within factory recommendations you can get down to about 17 gear inches with the Rohloff hub and 26 gear inches with the NuVinci using a 26" rear wheel. On the NuVinci some people have gone considerably lower than that w/o reported problems as have some mountain bikers using the Shimano 8 speed hub.

    A limitation to going for low gears using an IGH is, unless you use the Rohloff with the wide range it has, you are limited on the high gear you have for unloaded riding. Some people have solved this by using two chainrings up front with a front derailleur and a dual pulley chain tensioner (or a rear derailleur used as a tensioner) at the rear but this increases the drivetrain complexity.

    I have six IGH bikes but also have three with derailleur drivetrains. The modern derailleur MTB drivetrain can be built with a wider range than a wide range IGH one and a lot less expensively usuallly. My Big Dummy cargo bike is a derailleur drivetrain with a gear range of about 21 to 113 gear inches. My personal philosophy is to use the drivetrain that fits the requirements and my own pocketbook at the time.

    BTW per information from several people NuVinci is coming out sometime soon with a lighter hub to replace the current one which will not be recommended for cargo use.
    Gear Hubs Owned: Rohloff disc brake, SRAM iM9 disc brake, SRAM P5 freewheel, Sachs Torpedo 3 speed freewheel, NuVinci CVT, Shimano Alfine SG S-501, Sturmey Archer S5-2 Alloy. Other: 83 Colnago Super Record, Univega Via De Oro

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  9. #9
    Senior Member stevevance's Avatar
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    Quote Originally Posted by tatfiend View Post
    How low a low gear do you want?

    A limitation to going for low gears using an IGH is, unless you use the Rohloff with the wide range it has, you are limited on the high gear you have for unloaded riding. Some people have solved this by using two chainrings up front with a front derailleur and a dual pulley chain tensioner (or a rear derailleur used as a tensioner) at the rear but this increases the drivetrain complexity.
    I haven't thought about a front chain ring size for the Yuba Mundo with IGH I want to build soon.

    My plan right now is to use the Shimano Alfine. But what would be the best size front chain ring?

  10. #10
    Senior Member stevevance's Avatar
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    Quote Originally Posted by tatfiend View Post
    How low a low gear do you want?

    A limitation to going for low gears using an IGH is, unless you use the Rohloff with the wide range it has, you are limited on the high gear you have for unloaded riding. Some people have solved this by using two chainrings up front with a front derailleur and a dual pulley chain tensioner (or a rear derailleur used as a tensioner) at the rear but this increases the drivetrain complexity.
    I haven't thought about a front chain ring size for the Yuba Mundo with IGH I want to build soon.

    My plan right now is to use the Shimano Alfine. But what would be the best size front chain ring? I don't want to use a front derailleur.

  11. #11
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    Quote Originally Posted by stevevance View Post
    I haven't thought about a front chain ring size for the Yuba Mundo with IGH I want to build soon.

    My plan right now is to use the Shimano Alfine. But what would be the best size front chain ring?
    Very dependent on the terrain you want to handle with a cargo bike and your own strength. It wil also vary with what size rear cog you install. Shimano offers rear cogs from about 16 to 23 teeth per the Harris Cyclery web site.

    A 2:1 input ratio on a 26" wheel, say 44 tooth chain ring and 22 tooth rear cog, would give a gear inch range from 27" to 84". Up to you though whether this is a low enough gear for your riding conditions and strength on a cargo bike application.
    Gear Hubs Owned: Rohloff disc brake, SRAM iM9 disc brake, SRAM P5 freewheel, Sachs Torpedo 3 speed freewheel, NuVinci CVT, Shimano Alfine SG S-501, Sturmey Archer S5-2 Alloy. Other: 83 Colnago Super Record, Univega Via De Oro

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  12. #12
    cyclopath vik's Avatar
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    Quote Originally Posted by stevevance View Post
    I haven't thought about a front chain ring size for the Yuba Mundo with IGH I want to build soon.

    My plan right now is to use the Shimano Alfine. But what would be the best size front chain ring? I don't want to use a front derailleur.
    As a data point - I've been running a 32T x 21T setup on my Surly Pugsley [effective 29" wheel] with an Alfine incl. some fully loaded dirt touring in the mtns. I'd want at least that low of a gear on a dedicated cargo bike unless you live somewhere uber flat. I haven't had any issues with my Alfine even though it's been abused quite a lot for 16 months+ as one of my most used bikes.

    Alfine cogs are cheap so I'd try a ratio that seems sensible to you and buy one or two extra cogs as needed to dial in the gear range.

    Keep in mind I'm not a monster so the amount of torque I can apply to the pedals is limited.
    Last edited by vik; 03-13-10 at 08:12 AM.
    safe riding - Vik
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  13. #13
    Senior Member stevevance's Avatar
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    Good tips. Thanks.
    I live in Chicago, where our hills our called "highway overpasses" or "bridges over the river." I could move, though

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