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Utility Cycling Want to haul groceries, beer, maybe even your kids? You don't have to live car free to put your bike to use as a workhorse. Here's the place to share and learn about the bicycle as a utility vehicle.

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Old 01-20-12, 06:45 AM   #1
bendembroski
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Gear range for a cargo bike.

Just curious as to what kind of gear range (in gear-inches) people are running on their cargo bikes.

I'm particularly curious what the highest gear people usually use -- I've got a good handle on how low a gear I typically need.

The reason I ask is that I'm plotting a Madsen to replace my trailer setup, and I'm wondering if I should try to budget in a Nuvinci N360 into the equation.

On my trailer pulling bike, my GI range is about 24.7 - 79.9 (according to sheldon). I'm happy enough with the 24-ish side of things, just. With the trailer attached, even empty, I rarely go above 60-ish gear-inches. Mostly because once I get above a healthy speed (about 16-17 MPH) at around that gear, I start thinking about my ability to emergency brake without the trailer pushing the rear wheel about and back off.

With the Madsen, I suspect this is going to be less of a problem so maybe a higher gear would be used more often ? On the other hand, if not, I'd just as soon lower gear range overall to give me a little extra pulling power when I need it.

What say ye?
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Old 01-20-12, 07:21 AM   #2
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Anything below 20 or so gear inches wouldn't be usable on our tandem, because I can't keep it balanced below 4 mph or so. Of course the stoker working hard doesn't add stability, so maybe you can go a little slower with a static load. As for top end, why hurry? If the hill is steep enough to spin out in top gear, just coast and save your energy for the next climb. As for the nuVinci: all IGH have torque limitations, which will limit your lowest gear. The only safe way to get lower gearing once you are at the torque limit is to have a bike with smaller wheels.
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Old 01-20-12, 07:42 AM   #3
bendembroski
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Yes. 20 gear-inches will probably be my lower limit as well (fidgety kids in the bucket). I also would agree about coasting once spinning out down hills -- to a point. For a while I had a bike who's top end was around 50 gear-inches, and found that maddening. It's hard to say without riding the bike in the terrain, but I'm wondering what the Madsen's 'sweet spot' will be.

I'm not too worried about torque limits on the hub. My legs are skinny
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Old 01-21-12, 08:31 PM   #4
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My mtb commuter which I load up well, with panniers or trailer is geared at 17.8" -- 99.2"
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Old 01-22-12, 01:12 PM   #5
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i am at 22 to 74 on my cetma. This is around what I woul consider ideal.
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Old 01-27-12, 03:28 PM   #6
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My Yuba Mundo v4 has a gear inch range of 17 to 102.

At least that's what I calculated using this: http://home.earthlink.net/~mike.sherman/shift.html

Last edited by Chaosbarbie; 01-27-12 at 03:29 PM. Reason: Adding more info.
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Old 01-27-12, 09:05 PM   #7
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Originally Posted by bendembroski View Post
I'm not too worried about torque limits on the hub. My legs are skinny
I'm gonna guess your kidding about the size of your legs in relation to torque....you intend on hauling your kids and "stuff", that adds weight and increases the power your skinny legs will need to spin the pedals up a slight grade or even a hill if you have them...a lot of folks that have IGH's on their trikes are very aware of the torque limits they have on the IGH's just for that reason....many of them have multiple trikes - 1 with and 1 w/out an IGH.
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Old 01-27-12, 10:52 PM   #8
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According to Sheldon brown gear calculator, 43.5/54.1/65.3/80.2. It's flat where I live, so that is low enough for me. 1st is for bridges with a loaded trailer, 2nd and 3rd normal city use, 4th on the road with a tailwind.
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Old 01-28-12, 01:23 AM   #9
bendembroski
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I'm gonna guess your kidding about the size of your legs in relation to torque....you intend on hauling your kids and "stuff", that adds weight and increases the power your skinny legs will need to spin the pedals up a slight grade or even a hill if you have them...a lot of folks that have IGH's on their trikes are very aware of the torque limits they have on the IGH's just for that reason....many of them have multiple trikes - 1 with and 1 w/out an IGH.
I was half-kidding. I've done enough IGH hub cycling to know I'll fall over from lack of speed before I'll break the hub. Trikes are different, you don't fall over.

That said, I've pretty much decided to go with the Sturmey cs-rf3 that will apparently handle a 22-34 combo if I were so inclined. (pun partially intended)
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Old 01-28-12, 11:10 AM   #10
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My folding bike, 16" wheels AW3, 15t cog, in Mountain drive crank low range its like a 21.6t, ~18GI .
I have a trailer to tow , so the hauling is more than old fatso in the seat .. occasionally..
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Old 01-28-12, 01:53 PM   #11
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16-96 gear inches. If I am spinning out my highest gear I have no problem just coasting, I am never in a big hurry on this bike.

I have pretty good low speed balance and occasionally climb steep hills with a heavy load/trailer so the 22/36 is a nice gear combo. I also tend to ride with a fairly high cadence.
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Old 01-28-12, 03:20 PM   #12
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17" to 90" on my Big Dummy. Just about right.
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Old 01-29-12, 07:44 AM   #13
bendembroski
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After futzing with Sheldon's gear calculator a bit, I came up with the following solution...

If I go with CS-RF3 Sturmey Archer hub with a 12-32 cassette paired with the 38 tooth chainring that comes standard on the Madsen, I get the following ranges:

Overall, the range is going to be about (depending on tire size) 16.6 - 78.9
In the 1:1 ratio on the hub (theoretically the most efficient) the range is 22.2 - 59.2

That sounds about right to me. My most comfy cadence is round-about 80 RPM which gives me a top cruising speed of 18.8 MPH. I can't imagine I'd want much more than that on a cargo bike very often.

If I wanted to raise the range a bit, swapping the front ring for 42 tooth would raise the overall range to 18.4 - 87.2

I just hope this hub is tough as Sturmey is saying it is.
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Old 04-28-12, 08:23 AM   #14
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When I got my 1984 Grand Touring bike, I was riding and camping in mountainous terrain. I replaced the inner chain ring such that I pull 19 chain inches in granny one. Today, towing a loaded trailer from a loaded bike climbing hills, that 19 helps. I got a BD last August, so far, the stock gears are sufficient on the low end. I recently rebuilt the front end of my MTB to lower its ratios which also lowered its top end. On all three, I don't worry about top end gears. Even traveling unladen, I don't have the horsepower to max out any top gear unless I'm already going down hill. It is the bottom end and that torque that gets me around.
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Old 04-28-12, 05:00 PM   #15
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Quote:
Originally Posted by bendembroski View Post
The reason I ask is that I'm plotting a Madsen to replace my trailer setup, and I'm wondering if I should try to budget in a Nuvinci N360 into the equation.
I ended up cutting the Nuvinci from my short list, as by my calculations it almost certainly would not handle the strain of what I was going to attempt.

The Nuvinci, unlike most IGH's, uses two adjustable friction plates against ball bearings to establish gear ratio. These components are soaked in a friction-inducing fluid. Several people with higher-torque applications reported on the Nuvinci forums that the hubs could slip at high load, (which was generally agreed to be just above 100nm at the hub), and once they begin to slip, they slowly get worse.

I weigh ~140lbs, and a ring/cog ratio that would give me a safety margin when out of the saddle would put the low-end ratio at about 30 G.I. with a 26" wheel. Which, when tackling hills is nowhere near enough for a utility bike. I might use the Nuvinci for a commuter bike, but not a utility bike.

That's my $0.02 on the Nuvinci.

As for gear range in general, I'm shooting for 17 or less in first gear with my next bike. I've found the ~23 of my current bike to be barely enough for just myself and the bike when tired, forget about a trailer.
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Old 04-28-12, 08:14 PM   #16
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11x34 out back and 22/32/44 in front. That yields a range of roughly 16.8 to 104 gear inches. It is just right for me.
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