full-throttle
1 MW
Had a better look, mine is the same.LightningRods said:
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GNG, 1000W 48V BB-drive, $400
- Thread starter spinningmagnets
- Start date
bee
100 W
Does anyone know if it's possible to remove the spindle from our GNG bottom bracket? It would be super easy to heat treat it with a propane torch.LightningRods said:
skyungjae
10 kW
bee said:
I ordered a 140mm ISIS crank and ISIS freewheel cranks from Cyclone for $98 shipped. This might be an affordable solution to bending BB spindles. More info here:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=47618&p=713125#p712879
Since the crank is likely 5mm shorter on each side, it might be tricky getting the GNG chain ring adapter to work. The support bearing may need to be pressed out and I'm not sure if it can be replaced with a larger diameter bore one. The other option is putting together your own freewheel crank set up and fabricating a support bearing system.
bzhwindtalker
100 kW
It is actually quite easy to get out but I would be worried that the heat treating would make the spindle break instead of bending...bee said:
skyungjae
10 kW
bzhwindtalker said:
+1 instead of bending like the rest of ours, it could cause it to snap due to similar stress. I don't want to discourage you and it's a good idea, but please be careful if you test it out. We already know the quality of the metal is sub par.
Denisesewa
100 W
We have had a problem with trials bicycles breaking titanium BB spindles due to them being too hard and brittle, I'd rather bend one than break one and plant my foot in the ground comming off a jump, broken BB spindles have resulted in some pretty nasty injuries.bzhwindtalker said:
Denisesewa
100 W
I couldnt find the broken Titanium BB spindle but here is a pic of a broken titanium pedal spindle, you get the idea. 
justlooking
1 kW
didnt get all these problems on parts made in the 70s 
to be honest, if i could replace most parts made back then, i would use them ,, they were made to last ,,
i remember having bikes for years and never even had to change bearings and chains ,, if i had the machines and the skill, i would buy good grade metal, even buying it from scrap yards and make my own bits ,,
as for buying them , i think the threads were different,,
to be honest, if i could replace most parts made back then, i would use them ,, they were made to last ,,
i remember having bikes for years and never even had to change bearings and chains ,, if i had the machines and the skill, i would buy good grade metal, even buying it from scrap yards and make my own bits ,,
as for buying them , i think the threads were different,,
skyungjae
10 kW
justlooking said:didnt get all these problems on parts made in the 70s
to be honest, if i could replace most parts made back then, i would use them ,, they were made to last ,,
i remember having bikes for years and never even had to change bearings and chains ,, if i had the machines and the skill, i would buy good grade metal, even buying it from scrap yards and make my own bits ,,
as for buying them , i think the threads were different,,
Increase production output and quality control have changed quite a bit in the past 50 years. Also, the consumer culture that manifested lends to the "newer is better" correlation.
"They don't make them like they used to." No, they don't because, if they did, they'd put themselves out of business. :wink:
Chalo
100 TW
I work on a lot of 1970s Raleighs and a few 1970s Dawes Galaxies. Those bikes were terrible in their own ways. But the steel was pretty good, and most of their rotating components hold up a long time without decent seals.
As far as brittleness of the bottom bracket spindle and pedal spindles, it's pretty much intrinsic to the design. A square taper spindle end isn't very big, and it's under a lot of stress. A pedal spindle is almost as stressed, but it's smaller. Only a few materials are definitely strong enough to do that job (and titanium is not one of them). Of the handful of materials that are definitely strong enough, the only cheap ones are high-carbon steel and medium-carbon alloy steel. These materials can be hardened until they are strong enough to work as BB or pedal spindles without bending in normal use, but when they are that hard they generally won't bend much, or at all, before they snap. They could be tempered to a softer state to allow them to bend when they fail, but they'd do it far more often.
"Toughness" is the technical term for what we'd like to see in these parts-- the ability to bend and absorb a lot of energy in the process, without breaking. 17-4 stainless steel, used in BB and pedal spindles, is tougher than the usual stuff, but more expensive. Maraging steel (for instance Carpenter Aermet used in carrier aircraft tailhooks) is just right for the job, but even more expensive and difficult to work with.
The solution the bicycle industry has adopted for bottom bracket spindles that break is to use much larger diameter splined tubular spindles, that are big enough to work adequately when made of milder, tougher steel or even aluminum. ISIS was just a first step away from the traditional square taper. The new designs generally have minimal overhang outside the bearings, which makes them stronger but less versatile and adaptable than the square taper. There is no easy way to bodge an overrunning chainring onto an outboard bearing crank with a 24mm spindle, for example. You'd have to make a whole new crank for that. On the plus side, if you make a crank with a 24mm round spindle, it will fit into any of many bottom brackets made in that size now.
As far as brittleness of the bottom bracket spindle and pedal spindles, it's pretty much intrinsic to the design. A square taper spindle end isn't very big, and it's under a lot of stress. A pedal spindle is almost as stressed, but it's smaller. Only a few materials are definitely strong enough to do that job (and titanium is not one of them). Of the handful of materials that are definitely strong enough, the only cheap ones are high-carbon steel and medium-carbon alloy steel. These materials can be hardened until they are strong enough to work as BB or pedal spindles without bending in normal use, but when they are that hard they generally won't bend much, or at all, before they snap. They could be tempered to a softer state to allow them to bend when they fail, but they'd do it far more often.
"Toughness" is the technical term for what we'd like to see in these parts-- the ability to bend and absorb a lot of energy in the process, without breaking. 17-4 stainless steel, used in BB and pedal spindles, is tougher than the usual stuff, but more expensive. Maraging steel (for instance Carpenter Aermet used in carrier aircraft tailhooks) is just right for the job, but even more expensive and difficult to work with.
The solution the bicycle industry has adopted for bottom bracket spindles that break is to use much larger diameter splined tubular spindles, that are big enough to work adequately when made of milder, tougher steel or even aluminum. ISIS was just a first step away from the traditional square taper. The new designs generally have minimal overhang outside the bearings, which makes them stronger but less versatile and adaptable than the square taper. There is no easy way to bodge an overrunning chainring onto an outboard bearing crank with a 24mm spindle, for example. You'd have to make a whole new crank for that. On the plus side, if you make a crank with a 24mm round spindle, it will fit into any of many bottom brackets made in that size now.
Thanks, Chalo. I had been looking at the 19mm tubular cromo shafts (I am unfamiliar with these families of parts), so this is useful info for the continued search for a more complete list of viable options.
Chalo
100 TW
spinningmagnets said:
One caveat about those: They are "outboard bearing" cups; they hang the bearing just outside the BB shell. So anything that goes outside of that is another 10-12mm farther out from the bike's centerline than it would be with an internal bearing design.
19-22mm bottom brackets come in both inboard and outboard bearing varieties.
christerljung
100 W
I got this ideá inspired by bzhwindtalker:s non-pedal bike, an e-mx?
I wanna use the BB as a jackshaft and cut the pedals. Then mount footpegs ,mx-style.
The gearing is calculated to 55/9 in the first stage and 20/9 in some of the middle coggs in the cassette. That would give 2,22 x 6,11 = 13,56. A little lower (higher )than the standard GNG-gearing which aproximately would be about 12, at the rear wheel.
Biggest problem i can see is to make a strong mounting for the footpegs.
I wanna use the BB as a jackshaft and cut the pedals. Then mount footpegs ,mx-style.
The gearing is calculated to 55/9 in the first stage and 20/9 in some of the middle coggs in the cassette. That would give 2,22 x 6,11 = 13,56. A little lower (higher
)than the standard GNG-gearing which aproximately would be about 12, at the rear wheel.Biggest problem i can see is to make a strong mounting for the footpegs.
Awesome project! sounds fun. I would start by finding the absolute largest sprocket for the rear wheel. If it turns out to be a little too large for what you want with the other gears in the driveline, you could enlarge the motor-sprocket to 10T or 11T to help it run quieter.
If anyone else likes the idea of an off-road scooter (E-MX is a clever name!), John-in-CR is selling non-hubs with an extra-low 17-Kv. 2.5-kW at 72V is $285. Also, consider driving the left side of the rear wheel with a 60T chainring and a 415 chain, and am ENO freewheel on the BB-jackshaft. Hmmm, maybe mount the 7-inch diameter motor in the triangle?
http://endless-sphere.com/forums/viewtopic.php?f=28&t=48439#p713337
http://endless-sphere.com/forums/viewtopic.php?f=31&t=40859#p597310
edit: does anyone know if the GNG motor is reversable?
Plus, a "sliding bottom bracket shell"
Azonics BMX handlebar stem as a 12mm jackshaft (for anti-rotation of mount, you can run a headless set-screw through the mount into threaded bottle cage holes):
http://endless-sphere.com/forums/viewtopic.php?f=2&t=27320#p395257
If anyone else likes the idea of an off-road scooter (E-MX is a clever name!), John-in-CR is selling non-hubs with an extra-low 17-Kv. 2.5-kW at 72V is $285. Also, consider driving the left side of the rear wheel with a 60T chainring and a 415 chain, and am ENO freewheel on the BB-jackshaft. Hmmm, maybe mount the 7-inch diameter motor in the triangle?
http://endless-sphere.com/forums/viewtopic.php?f=28&t=48439#p713337
http://endless-sphere.com/forums/viewtopic.php?f=31&t=40859#p597310
edit: does anyone know if the GNG motor is reversable?
Plus, a "sliding bottom bracket shell"
Azonics BMX handlebar stem as a 12mm jackshaft (for anti-rotation of mount, you can run a headless set-screw through the mount into threaded bottle cage holes):
http://endless-sphere.com/forums/viewtopic.php?f=2&t=27320#p395257
Denisesewa
100 W
You could perhaps retain the square taper and use the crank arm with the freewheel threads with the arm itself cut off as an adapter, this way you could screw on a cog to the remaining part and have a removable gear on the left side, I think the smallest single speed cog is 11 tooth so the right side gearing would be off a bit if you used the same thing, of course alignment might be an issue but could maybe be solved by using a shorter bottom bracket.christerljung said:I got this ideá inspired by bzhwindtalker:s non-pedal make, an e-mx?
I wanna use the BB as a jackshaft and cut the pedals. Then mount footpegs ,mx-style.
The gearing is calculated to 55/9 in the first stage and 20/9 in some of the middle coggs in the cassette. That would give 2,22 x 6,11 = 13,56. A little lower (higher
Biggest problem i can see is to make a strong mounting for the footpegs.
I like the idea which ever way you get it done.
bzhwindtalker
100 kW
I reversed the motor no problem, just the usual hall/phase swap.
Christer, a very easy way to try your idea and make footpegs is to find straigth handlebars with oversise center part : you can cut it to the rigth legngth and the oversise center can be tightened between two bottom bracket cups, making very strong footpegs rigth where the BB spindle used to sit. easy, cheap. The only issue is that those are not very grippy. I tryed the setup you are describing, only on the normal chain side. I had issues with my pants getting stuck in the chain, I wasnt far from hurting myself bad.
I run 80amps and 11-92 reduction on my bike at the moment, the torque is very nice and the bike tops at 45-50kph.
Christer, a very easy way to try your idea and make footpegs is to find straigth handlebars with oversise center part : you can cut it to the rigth legngth and the oversise center can be tightened between two bottom bracket cups, making very strong footpegs rigth where the BB spindle used to sit. easy, cheap. The only issue is that those are not very grippy. I tryed the setup you are describing, only on the normal chain side. I had issues with my pants getting stuck in the chain, I wasnt far from hurting myself bad.
I run 80amps and 11-92 reduction on my bike at the moment, the torque is very nice and the bike tops at 45-50kph.
LightningRods
1 MW
Well THAT is clever. Annoyingly clever, in fact.
hillyterrain
100 W
I have a 110mm BB spindle with a 3 speed freewheel, I want to get the THUN torque sensor from ebikes.ca and the GNG, does it make sense to get a different size BB spindle for the GNG freewheel or does it not matter?
Thanks!!
Thanks!!
Samd
10 MW
Looks like the 95T belt 'ringgear' will fit on my ABS printer as well as the 19T belt pulley. If anyone wants to hit me up a few bucks for material and post I'm happy to print it at cost. Cheers.
If keeping the belt, I would definitely want one of these. thanks for doing the coding!
Chalo
100 TW
LightningRods said:
Definitely "I should have thought of that" material.
Samd
10 MW
spinningmagnets said:
Might have found a guy with a bigger printer who could do a few 125 tooth ones in a month or so - if you can keep the width below 20mm then technically I can post it as an airmail letter for about three dollars AUD!
LightningRods
1 MW
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flyinmonkie
10 kW
The stem idea is good and I was going to use it for my build, but the seat tube was to big for any stems. So be careful about what size your seat tube is. I had an extra big "steam" made to hold my jackshaft/motor bracket, but it wasn't that cheap. If you have a mill, it wouldn't be too hard if you can get a nice chunk of aluminum.
Clay
Clay
christerljung
100 W
Actually the idea was to use the wide spread 11-34 cassette with a derailleur and that small 9 tooth sprocket pulling a 8-speed HG-chain.spinningmagnets said:
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