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Hubs, Gearboxes, Sprockets and Chains Can't find 'em, grind em - hubs and transmissions, problems and modifications to make your motorized bicycle run smooth and trouble free


internal gear hub or derailer gearing system???

Can't find 'em, grind em - hubs and transmissions, problems and modifications to make your motorized bicycle run smooth and trouble free


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  #1  
Old 09-13-2012, 02:37 AM
ozilew ozilew is offline
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Question internal gear hub or derailer gearing system???

hi , just purchased 2nd bike a 26" single speed cruiser .about to purchase 66cc rock solid engine, dellorto carb, expansion chamber, hp cdi with lead and later on down the track high compression head with ceramic piston etc..
my big dilema is that i love the idea of the shift kit, (1st bike i ran a 36t rear sprocket and stop starting around town annoying). so deciding as to what to do on this cruiser would love to run an internal geared hub(either nuvinci or shimano alfine) or wether i should just place a cassette on the back and have a derailer changing my gears???
i'm wondering if anybody else has used or runs the internal geared hubs and wether or not they are worth it and also any unforseen problems they may arise. any thoughts or help would be greatly appreciated.
ps.. this bike is going to be my pride and joy so its not about the money to me, just the best outcome.. cheers!!
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Old 09-13-2012, 05:04 PM
turbo1889 turbo1889 is offline
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Default Re: internal gear hub or derailer gearing system???

Internally geared hubs are not known for their strength and even with human power only certain minimum gear-up ratios are required between the rear gear hub sprocket and the chain ring on the pedals especially with tandem bikes where there are two people pedaling together and putting twice the torque on the hub.

The older heavier Nu-Vinci variable hubs that were built heavier and had a 350% range instead of the lighter built newer Nu-Vinci hubs with their slightly wider 360% range (new N360 model) have been used in both electric and internal combustion builds successfully but the motors used were of the smaller lower power weed-eater type that were less then 50cc and less then 2-hp. I'm not familiar with anyone using the newer N360 hubs for gasoline engine powered bikes and I don't think they would stand up to it, this based on that fact that electric powered builds above 500-watts are not recommended for the new lighter built N360 hubs and failures have been reported with 1,000-watt and higher set-ups using them which is about 1.34 horsepower. A supped up 66cc like you have in mind is probably going to put out 3 horsepower or more and is probably too much for a Nu-Vinci even the older heavier duty ones (assuming you could pick one of them up) and the Nu-Vinci hub is considered one of the best internal gear hubs that can take the most torque by those in the electric assisted bike world (do some reading on the endless sphere forum if you really want to figure out what works and what doesn't for high power builds and then just apply what those guys learned to your internal combustion powered build).

If I were going to try to do a build like you suggest I think I would go either one of three ways:

Option #1 ----- Use a heavy duty rear cassette free-hub specifically built for use on a tandem bike that is compatible with the Shimano rear cassette hub splines and then put an 8 speed cassette on it that used a lock ring rather then a lock cog. An 8 speed cassette is as many cogs as you can go in the back without having to switch to a narrow and weaker chain then a normal bike chain (9, 10, & 11 speed cassettes all use progressively thinner and weaker chains and sprockets). Then I would use a good quality mountain bike derailer on the rear, not one of those junky cheap rear derailers a good quality one.

Option #2 ----- Order a "Yuba Mondu" rear wheel and hub assembly (a heavy duty long tail cargo bike rated to haul up to a 1/4 ton of weight on the rear wheel that has a hybrid hub that uses the thicker heavier duty axle and bearings of a BMX trick bike hub on a 48 spoke rear wheel with the right drop out spacing to allow the use of a multi-speed freewheel) and then look real hard on e-bay for one of the 80's era high end heavy duty race bike English threaded freewheel assemblies preferably one of the fully serviceable ones and screw that onto the heavy duty Yuba rear wheel assembly and then once again use a quality derailer.

Option #3 ----- Truth be told for an internal combustion motorized bicycle you really only need two gears provided both the pedals and the motor work through those gears together with the motor and pedals geared to match their disassociate RPM operating range. One low gear for starting from a dead stop and climbing steep hills and a high gear for traveling at speed on the flat. Take a good look at the model #200 bike on the top of the bike page at sportsmanflyer.com notice how the rear wheel has two heavy duty sprockets using heavy chain on it. One smaller diameter one on the right hand side and one larger diameter one on the left side of the wheel. As it is the right side is driven by the pedals and the left side is driven by the motor through a double reduction. What if both sides were driven by both the motor and the pedals with a double clutch assembly to switch drive sides in the bottom bracket so that when in low gear both the pedals and the motor drove the large sprocket on the left side of the tire and gave a low strong gear and then when in high gear the pedals and the motor drop the smaller sprocket on the right side of the tire giving a high speed gear? Wouldn't that make a sweet set-up? And using two thick strong sprockets with heavy weight chain would be a lot stronger and less problem prone then any gearing system that used lighter weight bicycle chain and sprockets.
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Old 09-13-2012, 11:58 PM
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Default Re: internal gear hub or derailer gearing system???

I have been looking this up on endless sphere(they know their stuff!) and apparently the best that I could see was a Shimano Sram i-motion 3. That's what I'm looking for now as I want to switch my bike from single speed.
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Old 09-14-2012, 12:50 AM
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Exclamation Re: internal gear hub or derailer gearing system???

I know for a fact that a Shimano Nexus 3-speed internal hub will not hold up on a tandem with a 124cc Kawasaki 4-stroke engine. Blew it up after one day of racing and was not even power shifting it. I'd go with a derailleur in this case.

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Last edited by scotto-; 09-14-2012 at 02:00 AM.
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Old 09-14-2012, 12:57 AM
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Default Re: internal gear hub or derailer gearing system???

Are the nexus and the i-motion hubs the same? I don't want to spread the rear dropouts if I don't have to. And I'm using the washing machine w/4G.
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Old 09-14-2012, 01:00 AM
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Default Re: internal gear hub or derailer gearing system???

Quote:
Originally Posted by d_gizzle View Post
Are the nexus and the i-motion hubs the same? I don't want to spread the rear dropouts if I don't have to. And I'm using the washing machine w/4G.
They are not the same but either one should hold up ok to the 49cc engine.
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Old 09-14-2012, 01:11 AM
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Default Re: internal gear hub or derailer gearing system???

Quote:
Originally Posted by The_Aleman View Post
There's several members here with 3-speed IGH (myself included) and one member I know of with a 5-speed. The 8-speed has wonky gearing (2-8 are internally overdriven). Most of us use Sturmey Archers and the 3-speed has proven to be up to the task, with the 5-speed so far on it's way to proven reliability...
http://motorbicycling.com/showthread.php?t=41796

I've the Sturmey Archer X-RD3 & it's worked flawlessly for over 5000 miles so far, despite my abuses. I would however recommend the XL-RD3 if you're considering a 3sp w/a drum brake as it has the larger 90mm drum (vs the X-RD3's 70mm);

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Old 09-14-2012, 01:31 AM
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Default Re: internal gear hub or derailer gearing system???

Thank you Scotto,that's exactly what I needed to know.

Barely,I don't need the rear drum option as I don't run a rear brake on the "Suicide". Keeps me on my toes. Maybe a disc brake IGH?

But thanks for the info,just the same.
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  #9  
Old 09-14-2012, 01:42 AM
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Default Re: internal gear hub or derailer gearing system???

The SA 3sp disc variant is the SX-RK3, Sturmey's 3sp hub list can be found here: http://www.sturmey-archer.com/products/hubs/cid/3
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Old 09-14-2012, 01:44 AM
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Default Re: internal gear hub or derailer gearing system???

Thank you again Barely. I just found This on amazon.com:

http://www.amazon.com/gp/aw/d/B004YI...604834&sr=8-12

Not too bad for $100 ,right?
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