My common sense tells me that rotating weight is a factor that affects acceleration and deceleration more than steady state. Are you finding different?
Blue Dream: Maxarya Ray 2 Semi Recumbent w/high eff mid drive
- Thread starter neptronix
- Start date
I'm not finding different. Low weight makes the bike easier to spin from a stop, that's about it.
Less acceleration on a recumbent when descending and less deceleration when climbing would be very beneficial.
Found an interesting blog on this, done on a 700c wheel:
Rotating Weight
That's a very substantial difference from 270g of rotating weight.
Maybe i actually want a carbon front wheel.
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It also affects the gyroscopic forces and is an unsuspended mass, so interacts with the suspension; though it mostly matters for traction rather than comfort.
Gyroscopic precession is largely a non-issue on bicycles, when compared too, say, motorcycles - more wheel mass and higher RPM. You can alleviate a portion of unsuspended wheel mass by careful tire selection and inflation.
PaPaSteve
10 kW
Back when winning races with aerodynamic streamlined bicycles was important to me . . .
Coast down testing was an immensely informative source.
Using a Cateye HB 100 cycle speedometer that can download a .csv file to a spreadsheet.
This speedo has a spoke magnet with reed switch so can be quite accurate measuring device.
It takes some time to calibrate the tire roll out as I would take the average of 5 revolutions at correct tire pressure on a straight line.
Me on the bike as ridden using a carpenters square to find axle center lined up on valve core center and then mark the ground.
Always needed a helper for this task.
I'd start at the same place on a bowl shaped hill where it rolls down one side then transitions up the other side.
How far it rolled up the other side completed total distance.
The most valuable data was comparing the time and distance for each wheel revolution in the spreadsheet.
This revealed any advantage in acceleration or losses from deceleration.
Super useful for tires and wheel measuring as well.
Also have a couple of PowerTap power meter wheels but found them to be most useful for strength monitoring.
Probably too much info . . .
Coast down testing was an immensely informative source.
Using a Cateye HB 100 cycle speedometer that can download a .csv file to a spreadsheet.
This speedo has a spoke magnet with reed switch so can be quite accurate measuring device.
It takes some time to calibrate the tire roll out as I would take the average of 5 revolutions at correct tire pressure on a straight line.
Me on the bike as ridden using a carpenters square to find axle center lined up on valve core center and then mark the ground.
Always needed a helper for this task.
I'd start at the same place on a bowl shaped hill where it rolls down one side then transitions up the other side.
How far it rolled up the other side completed total distance.
The most valuable data was comparing the time and distance for each wheel revolution in the spreadsheet.
This revealed any advantage in acceleration or losses from deceleration.
Super useful for tires and wheel measuring as well.
Also have a couple of PowerTap power meter wheels but found them to be most useful for strength monitoring.
Probably too much info . . .
SlowCo
1 MW
Just a thought when I saw the photo with the long cranks. Maybe you've done this already or it isn't possible but:
PapaSteve, that's awesome.
I think now that i have NVH down to a low roar, aerodynamics come next and i may need to reference that post..
Ah, the real win is to actually point it forward, that moves the pedal up ~5mm and might allow me to remove the ring.
Pointing it forward doesn't push me backwards on the bike, which is a huge plus. Moving it all the way upward would.
I think now that i have NVH down to a low roar, aerodynamics come next and i may need to reference that post..
Ah, the real win is to actually point it forward, that moves the pedal up ~5mm and might allow me to remove the ring.
Pointing it forward doesn't push me backwards on the bike, which is a huge plus. Moving it all the way upward would.
The Toecutter
100 kW
- Joined
- Feb 8, 2015
- Messages
- 1,476
Where do you see a frame kit for sale?
I only see a bare frame, and not a full-on frame kit that has the spindles, tie rods, ect. I want another one to make a quad with!
ZeroEm
1 MW
It's just a frame! No spindles.
Did a ton of research.
I've always known that a downside of this bike was that it has two chains. This means i probably have double the friction.
With the mid drive installed, we have 3 chains. And chain #2 and #3 spin ~25% faster than the front chain, so they have more friction.
Looks like high end lubrication could improve the efficiency of each chain by about 1.5%. Since these chains are in series, these gains in efficiency get compounded 2-3 times.
If these friction losses multiply up as the power goes up, and i move to an ideal lubricant, i may be looking at ~50w of extra power, which is pretty substantial and worth doing due to the low cost.
Rims?
Reducing crosswinds by going to a more aero shape is more important than absolute low weight.
So here's what i picked after looking at rim weights and shapes for hours.
Front rim ( 20" )
~40g less, 8mm wider, ideal aero shape for crosswinds: LOWPRO RIMS - $70
Front TPU tube
100g less: https://www.amazon.com/RideNow-Fatbike-Ultra-Light-Puncture-Resistant/dp/B0DDXHLWJV?th=1&psc=1
Rear rim ( 21.75" )
~120g less, carbon, rated for 300lbs rider, slightly less width, slightly better crosswind/forward aero: Speedline Parts | Slashers OS/20 451 20x1.75 Carbon Fiber BMX Rims - $240
Rear tire ( 21.75" x 1.85 )
335g less: https://www.danscomp.com/tioga-powe...ck-20-1.85-451-iso-r9za1351/p1417923?v=943540
Should make for a 595g or 1.31lbs less rotating weight, better aero, the better rim to tire size match should improve rolling resistance a hair too. The bike should accelerate significantly faster.
Increased NVH on the rear makes me nervous. 1.31lbs less weight, a carbon rim, and a smidge larger tire diameter might not completely make up for the effects of a ~19% air volume loss. I think a 10mm taller rear shock and the pendulum pedals pushing me 7mm forward on top of this should fix it. So maybe this is not such a big deal.
What i don't like about this plan is that there's no tire larger than 1.85" for the 21.75" tire size. I'm walled in.
in 22" land, i have way more choices, including motorcycle tires.
The next move up to a 22" wheel looks like:
Rim: +60g: https://www.modernbike.com/alienation-vandal-tcs-g69-22-tubeless-rim-457-x-31-36h-black
Tire ( 2.3" ): -70g: We The People 22''overbite tire
This should give me equivalent air volume to my current 20" x 2.5" and improve rear NVH due to the diameter.
All additional tricks stack on that and could provide a surplus of comfort to explore speeds beyond 35mph.
But the extended swingarm is a requirement.
Ultimately i think this bike could use a boost in speed rather than a surplus of NVH so i think the 21.75" is the way to go.
I also think it would be a bad idea to improve NVH too much because then i'd be tempted to build a 40mph machine instead of a 35mph machine
Any thoughts?
I've always known that a downside of this bike was that it has two chains. This means i probably have double the friction.
With the mid drive installed, we have 3 chains. And chain #2 and #3 spin ~25% faster than the front chain, so they have more friction.
Looks like high end lubrication could improve the efficiency of each chain by about 1.5%. Since these chains are in series, these gains in efficiency get compounded 2-3 times.
If these friction losses multiply up as the power goes up, and i move to an ideal lubricant, i may be looking at ~50w of extra power, which is pretty substantial and worth doing due to the low cost.
Rims?
Reducing crosswinds by going to a more aero shape is more important than absolute low weight.
So here's what i picked after looking at rim weights and shapes for hours.
Front rim ( 20" )
~40g less, 8mm wider, ideal aero shape for crosswinds: LOWPRO RIMS - $70
Front TPU tube
100g less: https://www.amazon.com/RideNow-Fatbike-Ultra-Light-Puncture-Resistant/dp/B0DDXHLWJV?th=1&psc=1
Rear rim ( 21.75" )
~120g less, carbon, rated for 300lbs rider, slightly less width, slightly better crosswind/forward aero: Speedline Parts | Slashers OS/20 451 20x1.75 Carbon Fiber BMX Rims - $240
Rear tire ( 21.75" x 1.85 )
335g less: https://www.danscomp.com/tioga-powe...ck-20-1.85-451-iso-r9za1351/p1417923?v=943540
Should make for a 595g or 1.31lbs less rotating weight, better aero, the better rim to tire size match should improve rolling resistance a hair too. The bike should accelerate significantly faster.
Increased NVH on the rear makes me nervous. 1.31lbs less weight, a carbon rim, and a smidge larger tire diameter might not completely make up for the effects of a ~19% air volume loss. I think a 10mm taller rear shock and the pendulum pedals pushing me 7mm forward on top of this should fix it. So maybe this is not such a big deal.
What i don't like about this plan is that there's no tire larger than 1.85" for the 21.75" tire size. I'm walled in.
in 22" land, i have way more choices, including motorcycle tires.
The next move up to a 22" wheel looks like:
Rim: +60g: https://www.modernbike.com/alienation-vandal-tcs-g69-22-tubeless-rim-457-x-31-36h-black
Tire ( 2.3" ): -70g: We The People 22''overbite tire
This should give me equivalent air volume to my current 20" x 2.5" and improve rear NVH due to the diameter.
All additional tricks stack on that and could provide a surplus of comfort to explore speeds beyond 35mph.
But the extended swingarm is a requirement.
Ultimately i think this bike could use a boost in speed rather than a surplus of NVH so i think the 21.75" is the way to go.
I also think it would be a bad idea to improve NVH too much because then i'd be tempted to build a 40mph machine instead of a 35mph machine
Any thoughts?
50W is the difference I get, in my bicycle, between a battery that's 100% charged and 75% charged, at max power. While it's noticeable, I can't say I care much as long as the bike still accelerates well. If you get enough battery capacity, it's hardly going to matter, imho.
Well, you do you!
For me, 50w is the cheapest extra 1mph / 1.5kph i've ever attained.
How the bike performs on pedal power matters a lot to me; even if this only translates to 15w of power in acoustic mode, that is nice and worth it.
Most importantly, it turns out that drip lube is the worst lube for my area due to it being dusty.
I have 3 times the drivetrain parts of an upright bike, so it's imperative that the drivetrain(s) last.
For me, 50w is the cheapest extra 1mph / 1.5kph i've ever attained.
How the bike performs on pedal power matters a lot to me; even if this only translates to 15w of power in acoustic mode, that is nice and worth it.
Most importantly, it turns out that drip lube is the worst lube for my area due to it being dusty.
I have 3 times the drivetrain parts of an upright bike, so it's imperative that the drivetrain(s) last.
ZeroEm
1 MW
Peddling is the best way that I have to extend the distance that my trike. I'm not like everyone else that can do 400w, i'm more like 50-75w so if someone offered me 50w of power just by making my chain last longer would not pass it up. Always checked my tire pressure before riding. Bet I have more time in checking tires than waxing my chain.
Decided to do an experiment today and set the seat all the way back and did 8 miles of hill climbing up an average 2%.
Because i know this will rear bias my weight, i also let approx 5psi out of the front tire and shock.
I took off the front bag and crosswind stability improved massively. I need to rethink my storage.
I was able to pedal from a stall and hold 23mph for half a mile. I only gained 1 mph.
I think my loose clothing is holding me back from realizing higher speed. But that speed is pretty good for a clydesdale
Down a 0.5-1% grade, the bike is terrifyingly fast. I'm riding the brakes a bit and not daring to pedal, keeping it below 35. Maybe a little too aerodynamic
NVH was barely tolerable on a 90PSI rear tire. The front was quite jittery. This is no surprise, but it's improved notably since i went to a semi fat front tire.
A few serious irregularities on the sidewalk at a mere 15mph felt like they nearly pinch flatted both tires, and actually upset the rear ( this is hard to do ).
Super concerning.
The bike needs better bump compliance, especially in the rear, where drama is more dangerous than on the front. This experience cements my choice to use 22" x 2.4" in the rear over the lighter 21.75"
I'll see if i can get some more weight off the front wheel. I believe it's possible, and a lot easier knowing that an aerodynamic shape doesn't matter as much for defeating crosswinds. 200g still matters, and it is worth doing.
Regardless of the issues, it was a fun ride. I was climbing 7-13mph the entire time,
Going downhill in fully laid back mode without regenerative braking and poor NVH is for psychos, so i'll be moving the seat back to the middle position so that i have less of both problems.
Another problem with maximum recline is that the handlebar doesn't have enough reach.
You can't lean back fully due to this, otherwise it's too hard to steer the bike.
Yet another problem with maximum recline is that the bike is hilariously unstable until you hit 7mph. You have to hold the outer edges of the bar to get good stability... or you are not getting started from a stop.
The idea is the same on semi recumbents as mountain bikes. The wider the handlebar position, the more leverage, the better the control at slow speed.
During this ride, i had really long handlebar grips that forced my hands inwards, which caused me to hold the edges of the bar for slow speed stability, at the expense of not being able to grip the brake.
I cut a little over half an inch off, and now with my hands on the edge, i can access the brakes and also the ideal leverage point.
Should improve low speed stability in maximum recline, and slightly improve it in medium recline ( not that it needs it )
I think maximum recline is only unlockable with a +13mm rear shock upgrade, the pendulum pedals getting me 7mm forward, and the longer swingarm reducing drama in the rear end.
Because i know this will rear bias my weight, i also let approx 5psi out of the front tire and shock.
I took off the front bag and crosswind stability improved massively. I need to rethink my storage.
I was able to pedal from a stall and hold 23mph for half a mile. I only gained 1 mph.
I think my loose clothing is holding me back from realizing higher speed. But that speed is pretty good for a clydesdale
Down a 0.5-1% grade, the bike is terrifyingly fast. I'm riding the brakes a bit and not daring to pedal, keeping it below 35. Maybe a little too aerodynamic
NVH was barely tolerable on a 90PSI rear tire. The front was quite jittery. This is no surprise, but it's improved notably since i went to a semi fat front tire.
A few serious irregularities on the sidewalk at a mere 15mph felt like they nearly pinch flatted both tires, and actually upset the rear ( this is hard to do ).
Super concerning.
The bike needs better bump compliance, especially in the rear, where drama is more dangerous than on the front. This experience cements my choice to use 22" x 2.4" in the rear over the lighter 21.75"
I'll see if i can get some more weight off the front wheel. I believe it's possible, and a lot easier knowing that an aerodynamic shape doesn't matter as much for defeating crosswinds. 200g still matters, and it is worth doing.
Regardless of the issues, it was a fun ride. I was climbing 7-13mph the entire time,
Going downhill in fully laid back mode without regenerative braking and poor NVH is for psychos, so i'll be moving the seat back to the middle position so that i have less of both problems.
Another problem with maximum recline is that the handlebar doesn't have enough reach.
You can't lean back fully due to this, otherwise it's too hard to steer the bike.
Yet another problem with maximum recline is that the bike is hilariously unstable until you hit 7mph. You have to hold the outer edges of the bar to get good stability... or you are not getting started from a stop.
The idea is the same on semi recumbents as mountain bikes. The wider the handlebar position, the more leverage, the better the control at slow speed.
During this ride, i had really long handlebar grips that forced my hands inwards, which caused me to hold the edges of the bar for slow speed stability, at the expense of not being able to grip the brake.
I cut a little over half an inch off, and now with my hands on the edge, i can access the brakes and also the ideal leverage point.
Should improve low speed stability in maximum recline, and slightly improve it in medium recline ( not that it needs it )
I think maximum recline is only unlockable with a +13mm rear shock upgrade, the pendulum pedals getting me 7mm forward, and the longer swingarm reducing drama in the rear end.
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ZeroEm
1 MW
This is where recumbents outshine other bikes. They go down hill faster, no one talks about that unless it's a race.Down a 0.5-1% grade, the bike is terrifyingly fast. I'm riding the brakes a bit and not daring to pedal, keeping it below 35. Maybe a little too aerodynamic
Chalo
100 TW
That's okay, they more than make up for it by being soul-crushingly slow on uphills.
Yup... but the issue you speak has little to do with the bike's geometry.
According to the Centers for Disease Control and Prevention (CDC), as of 2021-2023, approximately 40.3% of adults in the United States are obese. This translates to about 100 million people.
The numbers:
- Severe obesity (BMI of 40 or higher) affects 9.2% of adults.
- Obesity rates are highest among adults aged 40-59. (the core age group of most recumbent owners)
- The number of obese adults in the United States has been increasing steadily since the 1980s.
I'm honestly surprised at how close my climbing speeds are to my upright bike thanks to the BMX racing tire in the rear + high PSI.
I will measure them in a bit once i've fully redeveloped my upright and recumbent muscles. I think the difference is 1-2 mph.
The real benefit of a recumbent is higher speed on the flat and being mostly impervious to pedaling against the wind. On today's ride i was up against a ~10mph wind for a mile of it and only dropped 20% of my speed. On my upright, i'd be dropping more like 50% of my speed.
Conversely, a tailwind provides an equally small benefit. But i'm still going faster than the upright rider taking advantage of one.
I will measure them in a bit once i've fully redeveloped my upright and recumbent muscles. I think the difference is 1-2 mph.
The real benefit of a recumbent is higher speed on the flat and being mostly impervious to pedaling against the wind. On today's ride i was up against a ~10mph wind for a mile of it and only dropped 20% of my speed. On my upright, i'd be dropping more like 50% of my speed.
Conversely, a tailwind provides an equally small benefit. But i'm still going faster than the upright rider taking advantage of one.
My point was that if you feel you need/want more speed, using more motor power and more battery is by far the easiest and cheapest way to get there.
The chain lubricant you posted has a 5.5W / 250W improvement to a stock lube and 2.7W improvement to a ceramic lube (I imagine regular stuff such as finish line). For a 600W total system (500W motor + 100W human), that's closer to 6.5W than 50W. (I'm assuming you'd be using a good quality lube to begin with).
For reference, a single p45b has a continuous power output of ~80W.
Pedaling and efficient power transfer to the optimally rolling wheels is an interesting challenge, but when it comes to actually moving things around, human muscles and chemical energy storage in our bodies just aren't very good. That's one of the things I love about electric bicycles (not motorbikes) - you can keep however much exercise you want, but move at speeds at distances that are completely separate and dependent really only on the electric system capabilities, if you need it as transportation and not just exercise vehicle.
Now, I am not telling you how to build your ride, but my perspective on it (I hope you don't mind, even though we might disagree here) is that if you took all the money you spent on chasing efficiency and put that into a bigger battery, you wouldn't need to care about such minuscule differences at all, and would retain speed, stability, safety, comfort and range at the same time, for about the same amount of money (and likely less work). Efficiency is just such a complex, holistic goal to meet that it will necessarily compromise all of the other factors if pursued aggressively. I understand your goals might be different, though.
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Quick recap:
- I have been lubricant ignorant and just used below average stuff until today.
- I am using the wrong lubricant for my dry and dusty environment and my chain is always dirty even with regular lubrications.
- My bike has 3 chains, 2 of which spin 25% faster.
- Because my bike has 3x the drivetrain parts, and the bike is intended to be a long distance tourer, using a very efficient lubricant could save me a lot of money and extend my range substantially.
- I want the bike to still be pedal-able with the motor off, therefore, efficiency of the bike is paramount.
- 7w is what you save on a bike with 1 chain at 250w, but given that i'll run ~1250w on a mid drive ( + 250w of pedal power ) , i expect the friction to be at least 2x what it is at.
- 50w is a very conservative estimate of the friction i could save.
Sorry, you can't convince me to stick with my current subpar lubrication setup
The optimization will continue until morale improves.
- I have been lubricant ignorant and just used below average stuff until today.
- I am using the wrong lubricant for my dry and dusty environment and my chain is always dirty even with regular lubrications.
- My bike has 3 chains, 2 of which spin 25% faster.
- Because my bike has 3x the drivetrain parts, and the bike is intended to be a long distance tourer, using a very efficient lubricant could save me a lot of money and extend my range substantially.
- I want the bike to still be pedal-able with the motor off, therefore, efficiency of the bike is paramount.
- 7w is what you save on a bike with 1 chain at 250w, but given that i'll run ~1250w on a mid drive ( + 250w of pedal power ) , i expect the friction to be at least 2x what it is at.
- 50w is a very conservative estimate of the friction i could save.
Sorry, you can't convince me to stick with my current subpar lubrication setup
The optimization will continue until morale improves.
