Converting a 9 speed to a SS
- Thread starter TForan
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indianajo
Well-Known Member
Fine if you live in a pancake flat area with no traffic lights or wind. You must also ride short distances. Say Houston, TX?
I ride in traffic and use 4 speeds out of most traffic lights. I can pull different gears on the flats depending on how strong the headwind is. The various speeds also improve the efficiency of the motor at using electricity. Faster lightly loaded motors use less energy than motors heavily lugging at slow rotational speed.
I ride in traffic and use 4 speeds out of most traffic lights. I can pull different gears on the flats depending on how strong the headwind is. The various speeds also improve the efficiency of the motor at using electricity. Faster lightly loaded motors use less energy than motors heavily lugging at slow rotational speed.
indianajo
Well-Known Member
My 1000 W DD hub motor accelerates fine. I don't use it if I'm not trying to get across a 6 lane street in a 5 second green light from the 3rd position.
Unlike a mechanical motor, the more I use my heart & muscles, the longer they last. More wear & tear, more T-cells. (see bbcnews.com/health) I'm hoping for 38 more years of riding.
TForan
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TForan
Well-Known Member
What's beating on it ?
TForan
Well-Known Member
You're missing the point. I often ride around in the highest without any struggle. i like the idea of a more simple and efficient single speed setup. When I'm back on the road Tuesday, I'll ride strictly in high gear and see how it goes.
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indianajo
Well-Known Member
Simple, yes. Efficient, no. Read audel's motor book about 3 phase AC motor performance. 90-100% of full speed is best efficiency. If you're not going very far you can waste the battery watthours by lugging, but the waste comes out as heat in the motor.
The reason trucks are going to 6 and 8 speed automatic transmissions is that it provides better fuel efficiency. 40 ton truck auto transmissions have been 6 speed for 50 years. Ie more range per fuel tank. Gallons of fuel is equivalent to X battery watthours.
BTW about riding a bafang mid drive, the nearest bike shop that has multiple brands for test riding is 160 miles away near Chicago. It is hub drives (pedego) or nothing in this state, and the next one too. I'm happy for you that you live somewhere civilized. Enjoy your tax rate.
In terms or practicality, I doubt if you can find a single speed sprocket that will fit in the holes of the 9 speed chain. Single speed chain is wider than 9 speed chain.
The reason trucks are going to 6 and 8 speed automatic transmissions is that it provides better fuel efficiency. 40 ton truck auto transmissions have been 6 speed for 50 years. Ie more range per fuel tank. Gallons of fuel is equivalent to X battery watthours.
BTW about riding a bafang mid drive, the nearest bike shop that has multiple brands for test riding is 160 miles away near Chicago. It is hub drives (pedego) or nothing in this state, and the next one too. I'm happy for you that you live somewhere civilized. Enjoy your tax rate.
In terms or practicality, I doubt if you can find a single speed sprocket that will fit in the holes of the 9 speed chain. Single speed chain is wider than 9 speed chain.
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TForan
Well-Known Member
From Sheldon Brown's site
Paradoxically, a singlespeed is, in another sense, more efficient than a multispeed bike! While the single gear ratio will not be the "perfect" gear ratio for all conditions, in the conditions which fit the single gear, it is considerably more efficient mechanically than the drivetrain of a derailer bike.
A singlespeed bike dispenses with the weight of the derailers, shifters, cables, extra sprockets and longer chain. In addition, a singlespeed gear train runs the chain in a perfectly straight line from sprocket to chainwheel, and avoids the serpentine wind through the pulleys of a derailer. You can really feel the difference! A singlespeed is noticeably quicker and easier to pedal than a multispeed bike in the same gain ratio.
Singlespeed bikes are also considerably more sturdy and reliable than multispeed bikes. There's no derailer to bash if the bike falls over, catch on the underbrush or get overshifted into the spokes. The rear wheel itself is a lot stronger than one made with off-center (dished) spoking to make room for a whole bunch of sprockets on one side.
I know he's talking about a analog bike but many aspects are applicable. I also have a 48volt 21aH battery, so I'm not worried about range.
harryS
Well-Known Member
Hi TF, seems to me the posts above me discuss beating on an engine. Why increase the load on the internal gears and bearings?
Suppose you were a lot stronger than you are now. Would you like to beat yourself up with a single speed bike.
Well, it's your bike to do as you wish. I think you'll need a chain tensioner. SIngle speeds usually have the axle sliding horizontally to keep chain tension. And it's not like this is forever. You can change it back,
Suppose you were a lot stronger than you are now. Would you like to beat yourself up with a single speed bike.
Well, it's your bike to do as you wish. I think you'll need a chain tensioner. SIngle speeds usually have the axle sliding horizontally to keep chain tension. And it's not like this is forever. You can change it back,
TForan
Well-Known Member
I think you're missing the point.
Sure, getting rid of all the components (longer chain, extra sprocket on derailleur, weight of derailler, etc.) may be more efficient on the particular gear.
In real life, in real cycling, you will be constantly accelerating, decelerating, ascending, descending, etc.
You will be riding in the inefficient wrong gear with mechanically efficient set up.
Which is not efficient overall, because the disadvantage outweighs the benefit.
You said "simplicity is tempting" but Juggernaut Ultra? That's hardly a minimalist bike, hard tail or full suspension.
I know it's your bike and my opinion is irrelevant, but still.. I would personally like to be able to change gear for the best gear ratio.
We all have seen single speed bikes, and they don't look anything like Juggernaut..
No, your opinion is valued. I'm in one gear (the top one) 95% of the time. Even from a dead stop, it just plain goes. Mine is stripped down quite a bit. No fenders, no suspension fork.
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TForan
Well-Known Member
They also have these dual sprockets.
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TForan
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No, you have to manually move the chain from one sprocket to the next. No shifting.
TForan
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It simply gives you two different ratios to choose from.
TForan
Well-Known Member
Double Sprocket Freewheel from White Industries
This double freewheel fits in the same space a single freewheel would normally fit in, allowing you to change gears on your singlespeed just by loosening the axle and moving the chain, without any need to reverse the wheel as with a flip-flop hub.
If you were still using a tensioner, couldn't you easily change sprockets ?
Personally, I never understood why people want single speed.
You're not the first one asking about single speed conversion.. and I personally don't understand the problem.
You're spending money, time and effort on something that is not really upgrading.
What's next? lose ability to select assist mode?
With enough power from a rear hub motor there is certainly no reason for gearing or even assist modes. Just go with something like a 48T front and 14T or 16T rear (depending on your preference for cadence and typical riding speed) and a throttle for essentially infinite assist modes via direct control and you have a simple, reliable, and effective ebike.
I personally think there is a lot of defensive development that happens in the ebike industry that will eventually be revealed by bikes that get rid of the unnecessary complexity.
I would acknowledge that if you want the bike to be very ridable without battery power this would not be a good idea but for urban mobility most riders are going to always have battery power.
I'm the opposite of the OP.. My Haibke w/ Yamaha drive has a 10 speed cassette and dual chainrings up front. I love all the gears and enjoy shifting and being in the "right" gear or predicting what the correct gear will be for any given incline. W/O shift detect it's important to ease off the pedals before shifting (duh) and I'm always trying to make the perfect shift w/o stressing the components. I also enjoy keeping the drive train perfectly tuned and lubed My wife is the opposite and hates shifting. Armed with that knowledge, we got her a nexus IGH 8 speed on her e-bike and she loves it. Her Gazelle also has an enclosed chain case so less maintenance for me. She still bangs the gears though and I wince every time I hear her shift under load. Perhaps a single speed would be the best for her but it would require a more powerful motor. If I remind her that she needs to let off before shifting she gets mad at me
I think the idea would be to have a gear ratio that would make the ebike more ridable if you ever find yourself with battery power. Then you are only using the 2nd sprocket for those emergency purposes. It's never going to be easy to shift mindsets in the bike industry just like it's hard for the ebike industry to convince more people they should get out of the cars more often and ride.
I'm like the idea of fixie ebikes (with enough motor power it makes great sense) but I'm going to bring up something no one seems to be mentioning. When you do a fixie with a mid-drive motor you are locking yourself into a gear ratio that dramatically reduces the torque transmitted to the rear wheel (this is where hub drives shine because at high speed they are more efficient and all the torque is directly applied to the rear wheel). It's simple math...let's say you ride with a 48T front and a 16T rear fixie ratio, only 1/3rd of the motor torque is every utilized. This is why mid drives are much much better for mtn biking and climbing then they ever will be on urbam mobility bikes.
This in not up for debate but the marketing people at the mid drive manufacturers will try to tell everyone I'm wrong but how many of them have a clue about physics and mechanics.
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