Need some help with internal geared hubs

[Kevinator]

Hi guys, I'm thinking about getting an internal geared hub but my main concern is reliability and performance. I have a new Dahon Boardwalk S1 that I've modified for a 7 speed freewheel and a cyclone 900w motor.

I was considering a Sturmey Archer 8 speed so that I could also get a drum brake with it. The problem is, seems like internal geared hubs aren't meant for torque....ie: not for offroad use, not for motors, not for heavy loads. The exceptions being nuvinci (too bulky/heavy), rohloff (too expensive, unless they start selling them with a bike attached for the same price), SRAM P5 Cargo (too unavailable).

I read through GGoodrum's 1000w cyclone thread regarding his 3 speed, but I need more gears! More gears, and the ability to shift under power...moderate to heavy pedal-power at the very least.

Anyone have experience running a cyclone with a 5, 7, 8, or 9 speed internal hub? I'd be very interested in specifics about performance. I wa also looking at IGH's because a drum brake be much nicer than the sidepull bmx brake I currently have in the rear.

1- can you shift under hard pedal-power (standing), or motor power?
2- any problems with reliability?
3- how's the feel? Does your hub feel like its built well, or like the case and internal gears are made of weak materials? Do you baby it because you are constantly concerned of breakage, or do you go at it?

 

[rkosiorek]

not a 5 speed but i did use a Shimano Nexus Auto-D 4 speed. it held up very well. i also liked the fact that it was fully automatic. i didn't need to shift at all. it did it all by itself. it often shifted under power without issue.

needing a gazillion gears is needed for muscle power only. humans have a limited power band. the power band of a motor is so wide that even 3 speeds is plenty. you simply just do not need 7 or 8 gears. unless you just want to brag about how many gears you have.

since you likely can find a 3 speed hub at a junk yard, meaning it will be cheap, why not give it a try first before you write it off. if it turns out that you really need to brag about how many gears you have, you can always upgrade later.

rick

 

[Kevinator]

not a 5 speed but i did use a Shimano Nexus Auto-D 4 speed. it held up very well. i also liked the fact that it was fully automatic. i didn't need to shift at all. it did it all by itself. it often shifted under power without issue.

needing a gazillion gears is needed for muscle power only. humans have a limited power band. the power band of a motor is so wide that even 3 speeds is plenty. you simply just do not need 7 or 8 gears. unless you just want to brag about how many gears you have.

since you likely can find a 3 speed hub at a junk yard, meaning it will be cheap, why not give it a try first before you write it off. if it turns out that you really need to brag about how many gears you have, you can always upgrade later.

rick

Our automobiles technically don't need a bunch of gears either with their gas engines and big horsepower, but they have them right? I wish I had a 6 or 7 speed there too.

Thanks for the suggestion about the junkyard. Thats worth a go. Maybe I can find used 3-5 speed for cheap on ebay.

I think having more gears is a personal preference much like auto or manual transmission in a car. I prefer driving a manual transmission car, so naturally I went with a chain driven cyclone motor. This means, the more gears, the better. My purpose for having more gears is to minimize the current used by my motor to ultimately maximize my battery, or my legs when necessary. Would 7 gears really be a thing to brag about anyways? Maybe....until the kid next door rides up with his 27 speed, $70 Walmart bike and laughs at my 7 speed.

Others may prefer the simplicity of single speed gearing or hub motors. I can only guess that they would prefer to just sit down, push a button and steer.

 

[Kevinator]

Any recommendations on which Sturmey 3 speeds to AVOID? I might have trouble figuring out which used hub to get since a quick search on ebay came up with hubs manufactured anywhere from 1930's-present.

 

[John in CR]

Kevinator,

Yes, your car does need a range of gears much more than an electric motor does. Try starting from a dead stop with your car in 5th. Big rig trucks have many more gears.

If you want gears just to need to shift, then have at it. Maybe having that many gears can come in handy to optimize motor rpms up shallow inclines, and into the wind. I need a gears for hills, and maybe performance starts, and I'm hoping the 2:1 range of a Nexus3 will prove sufficient and durable. Gary said he only used 2nd and 3rd on his 3 speed, leaving 1st as a billy goat mountain climber.

 

[MitchJi]

Hi,

Gary has a friend who builds cruisers with big Etek motors. He uses Nexus 3 speeds and 7 speeds and has never had a problem. Gary thinks the Nexus 8 is stronger than the Nexus 3 speed.

Gary said he only used 2nd and 3rd on his 3 speed, leaving 1st as a billy goat mountain climber.

For Gary's 5kw builds 3 speeds is more than enough.

With 900 watts more than 3 speeds might be good. I rode a 500 watt ebike with an 8 speed and more than 3 speeds was definitely good. That was on the flat. On hills the need would be greater. The builder said with a 14 speed Rohloff the performance is almost twice as good.

The other consideration is if you want to contribute by pedaling at startup and at top speed (depending on how fast your top speed is) 3 speeds might not cut it.

Why don't you test this with your existing 7 speed. Figure out which speeds correspond (if they are not close it should be easy and cheap to tweak the sprockets) to the ratios of a 3 speed or 7 speed and try it out.

 

[boostjuice]

There is a reliable source for brand new SRAM P5-Cargo hubs. I contacted them myself and got a quick positive response on pricing/availability - but then decided against getting one last minute.

Should be a tad under 200USD for one delivered from Europe.

http://endless-sphere.com/forums/viewtopic.php?f=28&t=13208&p=196198&hilit=SRAM+P5+cargo#p196188

Even with the 5 speed though, the gear range isn't terrific....

SRAM P5-Cargo ----------------Shimano Nexus-3--------------11>34T Cassette
Total range 224%---------------Total range 186%--------------Total range 309%
Speed 1 67%---------------------Speed 1 73%
Speed 2 78%---------------------Speed 2 100%
Speed 3 100%------------------- Speed 3 136%
Speed 4 128%
Speed 5 150%

 

[spinningmagnets]

I searched Google image, is this it?

Would it be possible to use a hub as a mid-drive transmission, like some trikes do?

 

[def215]

ive done the intermediate shaft drive with the hub as my transmission before. Well it's a scooter and not a bike.

nonetheless, it works. i found it to be useless for me because i was underpowered. i guess it will be way more useful with higher outputs like in the +500watt range(i only had around 200 watts on my setup)

 

[MitchJi]

Hi,

Even with the 5 speed though, the gear range isn't terrific....

SRAM P5-Cargo ----------------Shimano Nexus-3--------------11>34T Cassette
Total range 224%---------------Total range 186%--------------Total range 309%

But a range of 224% vs 186% is substantial difference. Using this calculator:
http://www.sheldonbrown.com/gears/internal.html

With a cadence of 100, tire size of 20" nominal and a 50t chainring:
The Nexus 3, with a 20t rear sprocket the speeds are (low and high) 10.9 mph and 20.2 mph.
The SRAM 5, with a 17t rear sprocket the speeds are (low and high) 11.0 mph and 27.6 mph.

(The 17t with the SRAM comes closest to matching the low range of the Nexus 3 with the 20t.)

To match the low end of the Nexus 3 with the Nexus 8 requires 55t/16t and we get 10.8 mph and 33 mph.

 

[Kevinator]

thanks again for all the help everyone. I finally made a decision and ended up ordering a Nexus 8 premium (8R36), Alfine trigger shifter, and roller brake. If it shows up by the end of the week, I might be able to build my new wheels this weekend.

 

[Kevinator]

I searched Google image, is this it?

quote]


Yeah, thats the one. Here's a picture of it with the cyclone mounted, bike folded.