Recommend a 3 speed hub w/ disc brake
- Thread starter GasX
- Start date
A human makes far less than 1 HP, so I don't think any bicycle hub manufacturer will tell you that their rear hub is durable enough to support 4 or 5 HP. Just buy the 3 speed hub with the best reputation. Plenty of reviews of 3 speed hubs on MTBR.com They also have an internal geared hub section in their forum.
My 2 cents- Broken derailleurs and gear clusters are easily replaced when damaged or worn out. Repairing an internally geared hub (Nexus, Sturmey-Archer, Sachs, SRAM) is very difficult and expensive for the novice.
My 2 cents- Broken derailleurs and gear clusters are easily replaced when damaged or worn out. Repairing an internally geared hub (Nexus, Sturmey-Archer, Sachs, SRAM) is very difficult and expensive for the novice.
I agree with wheelbender if you are going to go with gears the deraileur is prob your best bet. I think a 4 or 5 hp and add a few mods will tear up an i ternal probabally the extern
Nal gears as well. If you are looking for tbe stopping power just go with a moped hum 135 mm they have drum brakes and already have a sprocket set up. Plus you can massage alot of power out of a 4 or 5 hp and get a good topnspeed.
Nal gears as well. If you are looking for tbe stopping power just go with a moped hum 135 mm they have drum brakes and already have a sprocket set up. Plus you can massage alot of power out of a 4 or 5 hp and get a good topnspeed.
I just had a thought... What if you used a single speed rear hub & a FRONT derailuer with a shifter kit??
I don't know if there would be any mechanical advantage, but it shure would keep the rear of the bike looking clean. (& it would certainly take the power)!
You would definately have to let off the throttle to shift gears.
I don't know if there would be any mechanical advantage, but it shure would keep the rear of the bike looking clean. (& it would certainly take the power)!
You would definately have to let off the throttle to shift gears.
The problem with derailleurs is that the chain often isn't straight in the lowest or highest gears. This can be a big problem in high-torque situations.
One would still need to retain the rear derailleur or replace it with with a sprung tensioner to accommodate the front derailleur, tho.I just had a thought... What if you used a single speed rear hub & a FRONT derailuer with a shifter kit??
I don't know if there would be any mechanical advantage, but it shure would keep the rear of the bike looking clean. (& it would certainly take the power)!
You would definately have to let off the throttle to shift gears.
Asthetics is part of the consideration. Also, chain alignment and a cassette is not a problem I want to tinker with. It's 3 speed or single speed...
I use a jack-shaft arrangement with a nexus inter3 . I spin that bastard up to 2000 RPM on my way to my 40mph cruise speed. No danger of breaking them if you spin them up faster.
If you notice the equation above, with the same HP value of your engine, solve for torque at any given RPM.
You will find that increasing the RPMS transmitted by the jack-shaft, the load it deals with lowers.
I recommend the nexus over a sturmey-archer due to my experience with the reliability of the nexus. Dont listen to the nay-sayers.
I recommend this hub as a jackshaft.
http://www.niagaracycle.com/product_info.php?products_id=5522
BEST VALUE FOR MOTORIZED BIKE SHIFTER APPLICATIONS PERIOD!
I have thousands of miles to back me up on this We're working on a 4.2 HP engine mount for my ride that will couple to the tranny.
We are betting on hitting 55-60mph. Right now we get 43 mph with a 1.5 HP engine.
Code:
HP = TORQUE x RPM ÷ 5252You will find that increasing the RPMS transmitted by the jack-shaft, the load it deals with lowers.
I recommend the nexus over a sturmey-archer due to my experience with the reliability of the nexus. Dont listen to the nay-sayers.
I recommend this hub as a jackshaft.
http://www.niagaracycle.com/product_info.php?products_id=5522
BEST VALUE FOR MOTORIZED BIKE SHIFTER APPLICATIONS PERIOD!
I have thousands of miles to back me up on this
We're working on a 4.2 HP engine mount for my ride that will couple to the tranny. We are betting on hitting 55-60mph. Right now we get 43 mph with a 1.5 HP engine.
I might pick one of these up because it solves the rear brake problem too. For the price it's worth it, and if the shimano dies and you want to try a sturmey, the same website has a sturmey with the same dimensions which I know is good for about 3 hp electric.
If you wanted to get real crazy lol www.amazon.com/Sturmey-Archer-3x9-speed-alloy-disc/dp/B007X4FPRO/
It really comes down to torque in the end, on what hub can handle what. A 200lb man standing on 175MM cranks can generate over 150lb/ft to the crank, times the pedal reduction. A good IGH should handle 100lb/ft at least IMO. I've broken Nexus 3-speeds twice with nothing but leg power so I wouldn't trust one with leg+engine power!
Figuring out how much torque you'll be adding from engine power is as easy as multiplying engine's peak torque by the overall ratio. An engine that makes 5lb/ft will be ~100lb/ft itself with a 20:1 ratio. With a 12:1 it will be ~60lb/ft. Figure it all in to your math before getting the best idea of what you need. If you need a hub that can handle over 300lb/ft reliably, you may need a Rohloff.
It really comes down to torque in the end, on what hub can handle what. A 200lb man standing on 175MM cranks can generate over 150lb/ft to the crank, times the pedal reduction. A good IGH should handle 100lb/ft at least IMO. I've broken Nexus 3-speeds twice with nothing but leg power so I wouldn't trust one with leg+engine power!
Figuring out how much torque you'll be adding from engine power is as easy as multiplying engine's peak torque by the overall ratio. An engine that makes 5lb/ft will be ~100lb/ft itself with a 20:1 ratio. With a 12:1 it will be ~60lb/ft. Figure it all in to your math before getting the best idea of what you need. If you need a hub that can handle over 300lb/ft reliably, you may need a Rohloff.
