I just came across this thread and thought I'd chime in. I've been riding on a Nexus 3-speed hub for a year now with zero problems. My engine is rated at 3.5HP and the hub handles it just fine. Unlike other hubs, the Nexus is designed to handle shifts under a mild load without damaging the internal gears. The new bellcrank makes it easy to adjust the cable for sure shifting, I use a vintage Shimano indexed jockey shifter which adds a little to the fun factor. The range is adequate for light duty motorized biking, .733 in low, 1.0in second, and 1.364 in third. Geared for final ratios of 25:1 in first, 18:1 in second, and 13:1 in third, I have plenty of pick up from the line and good high end. I'm thinking about swapping my 48 tooth sprocket with a 44 to see how well the bike performs with ratios of 21:1 in first, 15:1 in second, and 11:1 in third, but I'm not quite sure if I want to give up my crisp acceleration for a better top end. With this set up the bike feels more like a nimble motorcycle than a motorized bicycle.
internal gear hub or derailer gearing system???
- Thread starter ozilew
- Start date
My major gripes with the Nexus 3-speed hubs with a 3+ HP motor are:
1. The darn wheel won't stay in place, the power just pulls the right side towards the JS sprocket especially on a big heavy bike like like the Felt MP with a Skyhawk 66 with all the performance modes that matter.
It is tough to see from this pic but I solved the problem with a little flat 'eyelet' bolt that goes over the axle before the axle nut and point out the back where you put a U shaped piece of metal around the back of the horizontial dropout with a hole in it and just screw a nut on to keep the axle from moving forward.
You can just see it peeking out the back here.
I don't know what they are actually called and always have a hard time finding them but a 'molly bolt' eyelet can work if you pound the eyelet itself thin so the shifter will still fit on the axle and be able to be adjusted.
2. The Nexus crappy pot metal housing the set screw goes in to hold it on strips out in a heartbeat. The good news is don't take much torque to keep the shifter on so just go real easy on it and you'll be OK.
Other than that I have beat the crap out of several of those cheap Nexus 3-speeds hubs, 2 on my personal rides, and never seen one internally fail but I am all for a better quality hub like an SA when budget allows.
I do like the new SA's with a drum brake however, that Felt MP could have used it but the bike came with the 3-speed Nexus wheel so there ya have it.
1. The darn wheel won't stay in place, the power just pulls the right side towards the JS sprocket especially on a big heavy bike like like the Felt MP with a Skyhawk 66 with all the performance modes that matter.
It is tough to see from this pic but I solved the problem with a little flat 'eyelet' bolt that goes over the axle before the axle nut and point out the back where you put a U shaped piece of metal around the back of the horizontial dropout with a hole in it and just screw a nut on to keep the axle from moving forward.
You can just see it peeking out the back here.
I don't know what they are actually called and always have a hard time finding them but a 'molly bolt' eyelet can work if you pound the eyelet itself thin so the shifter will still fit on the axle and be able to be adjusted.
2. The Nexus crappy pot metal housing the set screw goes in to hold it on strips out in a heartbeat. The good news is don't take much torque to keep the shifter on so just go real easy on it and you'll be OK.
Other than that I have beat the crap out of several of those cheap Nexus 3-speeds hubs, 2 on my personal rides, and never seen one internally fail but I am all for a better quality hub like an SA when budget allows.
I do like the new SA's with a drum brake however, that Felt MP could have used it but the bike came with the 3-speed Nexus wheel so there ya have it.
Not these, they are called something like 'axle stays' or something like that and hard to find but a Google on 'Chainstay tensioner' will get you to those cool $14 tensioners I sometimes use on the pedal side on direct drive builds I just can't quite get chain matched and don't want a tensioner on the drive side.
Don't ya hate it when you can't remember a term that will get you what you want?
The sad part is none my local bike stores carry them either but they sure work well on open back horizontal dropout's, if the open side is on the front they are useless so I end up putting a bolt and cut washer and nut in front of the right side axle nut. It's not pretty and it makes it a pain in the butt to take the wheel off but keeps it from moving forward when I lay on the power ;-}
One other note on Internal shifters, be sure that yellow tabbed and slotted washer that goes on the left side fits perfect in the dropout. Unlike every other wheel an internal shifter is not a solid shaft and that left side washer is what keeps the two different axle pieces from spinning separate from each other. Been there, done that, the right side axle spun and darn near ripped the shifter controller off when I left it off or used the wrong one, can't remember but it was nasty and to be avoided ;-}
I don't hate it when I can't think of a term cuz I don't open my mouth less I know what's coming out of it.
http://m2.sourcingmap.com/smapimg/e...e-parts-metal-chain-tensioner-pcs-146002n.jpg
These are what your talking about,right? They are called chain tensioners.
http://m2.sourcingmap.com/smapimg/e...e-parts-metal-chain-tensioner-pcs-146002n.jpg
These are what your talking about,right? They are called chain tensioners.
KC, chain adjusters are a good idea on any bike. Not only do they keep the wheel in place, they make it easier to center the wheel when you are adjusting the chain tension. I've seen several versions, mostly vintage, for sale on Ebay and elsewhere, or you can buy motorcycle adjusters and modify them for a bike. BTW, the metal piece you refer to is not pot metal, it's aluminum and it's called a bell crank. You only need enough torque on the set screw to keep the bell crank in place since it does not hold the axle in place. I've ridden mine nearly 2000 miles without a hiccup. I'm excited about riding it in the "Spirit of Christmas" parade with several Cushmans, Vespas, and California Scooters on December 8.
Thanks soup, that is the style that has helped keep a hub shifter wheel from moving when power shifting a powerful motor, that is just too fat however as I mention below.
Thanks Scootmeister and I agree if you have one put one on the motor drive side.
It just gets tricky with the Nexus 3-speed motor drive side because you don't have the luxury of changing how close the axle nut is to end of the hollow axle shaft or you won't be able to get your shifter aligned on the end of the shaft and you can't butt anything up against it.
I'll take some pics on my next one.
I searched around some more and came up with this for horizontal open back dropouts.
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MKS Chain Adjuster 5mm x 10mm Hex
http://www.euroasiaimports.com/productcart/pc/MKS-Chain-Adjuster-5mm-x-10mm-Hex-334p484.htm
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That bolt and plate should fit right inside the 10mm slot so it comes out the of middle of the back slot and the washer fits snug to the frame with the cup over the back openings to take some motor torque against.
Granted that one is overkill for a motorized bike but pretty simple in overall design, a washer attached to a nut and bolt that will fit in a grove for you creative guys.
Anyway that should work for that Nexus hub issue.
This SA 3-speed sure looks like a good hub and you won't have to mess with a hollow axle or where the lug nut goes as the shifting mech is vertical.
http://www.sturmey-archer.com/products/hubs/cid/9/id/23
---
MKS Chain Adjuster 5mm x 10mm Hex
http://www.euroasiaimports.com/productcart/pc/MKS-Chain-Adjuster-5mm-x-10mm-Hex-334p484.htm
---
That bolt and plate should fit right inside the 10mm slot so it comes out the of middle of the back slot and the washer fits snug to the frame with the cup over the back openings to take some motor torque against.
Granted that one is overkill for a motorized bike but pretty simple in overall design, a washer attached to a nut and bolt that will fit in a grove for you creative guys.
Anyway that should work for that Nexus hub issue.
This SA 3-speed sure looks like a good hub and you won't have to mess with a hollow axle or where the lug nut goes as the shifting mech is vertical.
http://www.sturmey-archer.com/products/hubs/cid/9/id/23
I have tried 3 IGH(Internal Gear Hub). 1st was an 8 speed Sturmey Archer which lasted for a year. The 2nd was an 8 speed Shimano Alfine, which was really good until the bike got stolen. My 3rd and currently riding with is the 11 speed Shimano alfine. And this is what I think, the 8 speed Shimano alfine seem to be more durable since it was not designed to be in an oil bath, and seems to shift more smoother than than the 11 speed. The thing about IGH is that you can use BMX chains which are more durable than the thinner ones used on derailers or rear mech to some.
In terms of cost, I'd rather break a chain than an IGH.
On my MX1000 my Sturmey SRK-3, which shares internal construction with the SRF-3, withstood 1000+ watts or about 1.5 hp with mad torque from stall by using Mobil1 75-90LS gear oil, just don't get wheel hop under power or it'll machine gun the guts. I'm on my second set of guts because of broken pawls and cracked driver.
I'm interested in hearing how that Alfine 8 speed roller clutched hub works out. The only others that don't have pawls (the enemy!) are the S3X and the Nuvinci AFAIK.
The S3X has ISO threads instead of 3 splines and a lockring, much better for longevity.
On my MX1000 my Sturmey SRK-3, which shares internal construction with the SRF-3, withstood 1000+ watts or about 1.5 hp with mad torque from stall by using Mobil1 75-90LS gear oil, just don't get wheel hop under power or it'll machine gun the guts. I'm on my second set of guts because of broken pawls and cracked driver.
I'm interested in hearing how that Alfine 8 speed roller clutched hub works out. The only others that don't have pawls (the enemy!) are the S3X and the Nuvinci AFAIK.
The S3X has ISO threads instead of 3 splines and a lockring, much better for longevity.
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