In the 2020 Electric Bike Review of the Radrunner, the reviewer said he'd let air out of the tires for a more comfortable ride. He claimed it also made the bike more stable. The president said he was running 18 psi, as I recall, and he was riding two up with a combined weight of 330 pounds, as I recall.

The review led me to believe I was buying a bike that offered the advantages of high or low pressure as I chose. 

The manual said it's critically important to keep the tires at the pressure on the sidewall. "The RadRunner employs 20'' x 3.3'' rubber tires with inner tubes. The tires are designed for durability and safety for regular cycling activities and the tires need to be checked before each use for proper inflation and condition. Proper inflation, care, and timely replacement will help ensure the bike's operational characteristics will be maintained, and unsafe conditions avoided. Recommended tire pressure is written on the tire sidewall."

"It is critically important that proper air pressure is always maintained in pneumatic tires. Do not underinflate or overinflate your tires. Low pressure may result in loss of control, and overinflated tires may burst. Failure to always maintain the air pressure rating indicated on pneumatic tires may result in tire and/or wheel failure."

They specified a certain tire and said it was important to maintain a certain pressure, but they didn't say what that pressure is. Online, Radpower recommended 20-30 pounds for that tire. That's double-talk.

After more than a year, I found the pressure, under the reflective stripe on the sidewall: "Inflate to 30 PSI." The manual says failure to always maintain the pressure indicated on the sidewall may result in tire and wheel failure. I wonder if wear and tear from riding at lower pressure can make tires susceptible to punctures.

A video posted here showed that at 25 PSI, a Radrunner wouldn't steer on soft sand. I had similar experience on snow until I reduced the pressure to 10 psi, which flattened the footprint enough to resist sliding sideways up onto the snow. The rolling resistance is very high, and the manual warns that it could cause tire or wheel failure.

Tires with lower thread counts are stiffer, which means worse handling and more rolling resistance. Rode bikes typically use 120 TPI. BMX bikes may be ridden down stairways and jumped off objects several feet high. Mountain bikes may hit rocks at high speed. Tires for those bikes have 60 TPI, which allows the "threads" to be thicker and tougher. Riding at 35 PSI is okay for these 2" tires, but they're tough enough to handle BMX stunts at 100 PSI.

The thread count of the OEM Radrunner tire is only 30 TPI. Stiffness would explain why the manual warns not to run less than 30 PSI. If stiffness were a tradeoff for toughness, pressures well over 30 PSI would be okay. In terms of rolling resistance and toughness, would I do better with mountain bike tires? I don't know if they come as small as 20 inches.

Mountain bikers moved to fat tires for better control on deep gravel. I don't plan to ride on deep gravel. Maybe a BMX tire would be a better choice, and they do come in 20-inch sizes. Two standouts seem to be the Eastern Bikes Throttle  2.2 x 20 BMX tire and the Maxxis 2.0 x 20 Hookworm. Would a 2" tire be too narrow for the rim?

Quote from: Radding Along on February 03, 2022, 11:54:08 AM
Outside diameter of the Runner handlebar where the mirror should mount is 22mm.

Rad doesn't advise installing a mirror in the conventional manner on the handlebar. There isn't enough surface area to attach the mount before the bar begins it's downward turn to the stem. Look at your bike and you will see what I mean.

You might look into mirrors that install in the end of the handlebar. I think they call them bar end mirrors.

My first was a bar-end mirror. The description didn't say it was convex. The first day, it was overcast and around sundown when I heard a car behind me on a quiet street. I studied the mirror and the street looked empty. I didn't like being followed by a vehicle that was invisible to me. When it passed, I saw that it was a similar shade of gray to the pavement behind me. That mirror was more convex than some, but I wouldn't trust my life to any convex mirror.

I bought four more from Amazon. None was described as convex, but all were. Just to try them, I had to mount them under the bar because the stems weren't long enough to see past my arm.

Finally, I found an old-fashioned flat mirror at Amazon. https://amzn.to/3JYP28t

The sheet-metal clamp was for a rectangular bar. I screwed it tight around progressively bigger sockets until it would fit my handlbar.

The photos show a car 100 feet behind me against a contrasting background early on a sunny afternoon. A car isn't always so conspicuous, and I want to see several hundred feet behind me.

Quote from: jcvdd on January 30, 2022, 07:44:45 AM
Obviously, there is no such thing as no-flat tires, but what do you electric guys do in order to minimize flats.
As an old road cyclist, I have used the following-
Tire Slime sealant
Inner liner
high quality tubes
Puncture-resistant Tires and Tubes
increase tire pressure to maximum level & quality tire pressure gauge
avoid all areas subjected to construction debris such as nails & glass
high quality rim tape
always inspect tires before each ride
minimize riders weight, easier said than done
Convert to tubeless
Ride with your cellular and cash, just in case

Any other ideas    Joe Florida  Thanks

valve tools
photos of axle connections from each side
vulcanizing patches
pump

From age 7 to 18, I rode 26x 1-3/8" English bicycles. At 14 I bought an antique. I put a speedometer on it and found that I rode 2,000 miles a year. I had typically one flat a year, fixable in minutes. I don't recall finding what caused a puncture. Lately I've read that inner tubes get brittle as they age. Maybe that was the cause.

From 18 to 48, I owned only motorcycles. I changed a lot of worn-out tires but never had a puncture. i think the round cross section of a well inflated bicycle or motorcycle tire, particularly the front tire, tends to knock pointy ends aside instead of being punctured.

My brother became a bicycle racer. Flats were routine due to the light construction of the tires. That construction also complicated repairs. Riding hundreds of miles a day, he must have been able to fix these tires by the road, but I don't know how he managed it.

In a year, I've ridden my Radrunner less than 1500 miles because most roads around here would be dangerous on a bike. I often ride on surfaces with glass and presumably nails to avoid traffic. I've had no puncture, and the only tire damage happened within 100 feet of my garage. Overnight, the pressure in the back had dropped to 6 psi. I quickly felt that the pressure was low. When I stopped with my weight on the saddle, the tire didn't look flat, but it had flexed enough to crack the sidewall.

Going from 20 down to 6 overnight was erratic, and soapy water didn't bubble anywhere. I replaced the valve core. Two days later, it went completely flat overnight. I cleaned the valve seat with a 4-way tool, then twisted in a cotton swab with a little silicone grease. It came out streaked with brown like oxidized brass. The erratic pressure losses continued. I removed the tube to check patiently for even one bubble underwater. I had removed the back wheel to install a fender, but this time I had trouble getting the pieces properly back on the bike. With photos, patching the tube could have been a roadside job.

There was no visible tube damage and no bubble. I figured the valve core hadn't been seated. I used a keyed valve cap to tighten it , then used a 4-way tool to tighten it further. The closeness of the spokes made that tool awkward. That reduced the leakage but didn't stop the incidents. Valve cores used to be torqued to 2 inch-pounds, which one could apply with a keyed valve cap. I discovered that the spec is now 5 inch-pounds, probably because valve seals are harder. I bought a screwdriver-type valve tool and sawed the handle short enough for the tool to fit between the valve and the rear hub. I discovered that even with the 4-way tool, I hadn't seated the valve seal. Finally, the leakage stopped.

Radpower says to check tire pressure every two weeks. Butyl tubes aren't porous, so it seems valve problems are common. Valve tools, including perhaps cotton swabs and silicone grease, may be necessary to prevent damage from underinflation.

I didn't know the proper pressure for my Radrunner. Before I bought it, I believe Radpower advertising recommended 20-30 psi. The Electric Bike Reviews guy told the sales rep that he'd reduced the pressure because that was too bumpy. When the president of the company rode him as a passenger, which vastly overloaded the back wheel, he said he had 18 psi.

The Radrunner manual warns against underinflation but doesn't specify the pressure. Huh? It says to inflate tires to the pressure on the sidewall. That was hard to find because it's under the reflective stripe. Usually, the pressure on a sidewall is the maximum, but these tires say "inflate to 30 psi."

It runs better than ever at 30 psi, and it will probably deflect puncture hazards better than ever. I can see why Radpower beats about the bush. The seating position is so bad that even with a suspension post and a big sprung seat, it would be terribly uncomfortable at 30 psi. Mine rides comfortably, but at that pressure I went airborne on a speed bump.

Quote from: Altema on January 29, 2022, 06:47:59 PM

I have little choice in terms of rolling resistance because of using Tannus Armour, so if I want to maximize range, I'd need to remove them.

As a teen, I rode an English bike a couple of thousand miles a year. I may have had one flat a year. There was one exception. At the end of 11th grade, a classmate and i went camping. It entailed riding our loaded bikes 20 miles on gravel roads. I think I had three flats (like rifle shots) on that stretch. Each took only a few minutes to patch, but it was embarrassing. (I didn't know what caused those flats. Recently, I learned that inner tubes get brittle as they age. Mine had probably been in service more than 10 years.)

Then, for 30 years, I rode motorcycles up to 30,000 miles a year and never got a flat. I think a bicycle tire at 60 psi or a motorcycle tire at 32 tends to put a rounded cross section on the road, and that tends to push puncture hazards to the side.

On roads around here, the stock Radrunner seat was so rough that I reduced tire pressure to 15psi. I moved the seat back with a layback post. As with the original 1885 Rover, that put most of my weight on the pedals for maximum comfort. I was comfortable at 25 psi, but I worried about fragile cargo like eggs. I cut it to 20 psi. Now it's back at 25. If I buy eggs, I buy cereal and lay the box on its side as a cushion for the egg carton. Maybe I'll try 30 psi.

Quote from: JimL on January 28, 2022, 10:26:30 AM
In my earlier life, we had occasion to check various road surfaces.  We discovered that all of them (and especially pavement) had considerable rippling effect from heavy vehicles use.  At very high speeds we could actually see the surface fluctuations using an FFT spectrum analyzer with a magnetic G-pickup on our vehicle. 

Interestingly, the slight variation in rolling tire circumference could be seen as periodic variation of vibration intensity (often 7-9 second cycles at normal highway speed.)  Most vehicle owners thought they were feeling intermittent bad patches in the road, but it was really their own tires getting in and out of "vibration sync"!

You might want to try "coast down" tests at various air pressures, to get some comparative data.  You can find good instructions/methods on the internet.

For longer distances, we used Google Earth to read elevation points.  You can calculate distances using the "1 minute of arc = 1 nautical mile (about 6000 feet)" rule.  You can look for road sections that are easy to distance measure on the screen (exactly east-west, or north-south).

Longer test sections can really help balance useable results.  Repeatability is everything with this kind of testing.

The coast down test needs a long stretch of flat pavement. It includes aerodynamic resistance. For now, I'm interested in "mechanical" resistance only. if the speed is low and there's no wind, air resistance won't make much difference. A bicycle can't start to coast from a dead stop or coast to a dead stop, so accuracy would depend on how close your end speed was to your push-off speed.

Around my house, the side streets are badly rippled. I don't know whether to blame truck traffic, pavement expansion under the summer sun, or frost. The main roads are much smoother.

Quote from: JimInPT on January 28, 2022, 09:44:25 AM

Quote from: handlebar on January 26, 2022, 01:04:52 PMShould I buy a laser level?

If you do decide to get one, I can recommend this one; works very well especially for the price (snagged a Lightning Deal for $30) - I've so far used it to hang a kitchen ceiling pot-rack and a VR-headset overhead cable-pulley system.  My  touch of OCD insisted on square and centered, or the voices in my head would get annoyed.   

https://amzn.to/34zxgcY

It should be plenty visible during twilight; I haven't used it outdoors yet but it's very bright indoors.

Thanks. They say green can be seen farther outdoors in daylight. Here's one I've been considering.
https://amzn.to/3Lz8L08

Darn! How did they get such a long URL?
They say 85 feet outdoors at 100 lux. A slightly more expensive model is advertised for 165 feet outdoors, if you buy their receiver.  That gives me an idea.

A little headlamp will light up a reflective stop sign 1000 feet away. I get a board 2" wide and maybe 3 feet long and fasten it to a base so it will stand vertically on the street. I put white reflective tape on the face. Measuring from the pavement, I use a felt-tip marker to make a line across it every six inches.  Suppose the reflected laser light is visible from 100 feet in daylight. My tripod has a crank to raise and lower a camera. I crank it until the reflection dims on the lowest line, 6" off the pavement. At my end, I measure and find the laser beam is 30" of the pavement. So the pavement is 24" higher at the reflector, for a 2% grade. I'll bet I can get away with using a dab of yellow acrylic paint to mark the curb at increments of 1 foot rise.

It looks as if Class 2 laser levels aren't very hazardous. A Class 2 pinpoint laser could cause damage if you stared in to it without 23 feet, but a level spreads the light in a horizontal plane.

I prefer pedaling my Radrunner where possible. I wish I'd bought a model with narrower tires and a bigger rim diameter.

With equal tire sizes, rolling resistance depends partly on air pressure. There comes a diminishing return for more pressure. On a bumpy road, too much pressure can even increase resistance by letting the vehicle be thrown higher; that energy is lost. More pressure means more wear and tear on the machine. More pressure means a rounder cross section, reducing resistance to sliding sideways, up onto mud or snow like the prow of a toboggan.

Rubber hysteresis causes the rolling resistance. With less air pressure, treads bend more, and hysteresis is the tendency of rubber to absorb that energy and turn it into heat. If I knew how to choose low-hysteresis tires, I might enjoy low pressure and low rolling resistance together. For now, I'd like numbers to show my rolling resistance at various pressures.

If you coast down a slight decline and onto a flat or slight incline, your rolling resistance in pounds will be your gross weight times the difference in height divided by the distance along the pavement. On a lightly traveled street, I could use brightly colored duck tape to mark my start and stop points. Pacing the distance would be accurate enough. I'd just need to find the change in height.

Some fairly inexpensive levels with green lasers are supposed to be good for 100 feet outdoors. They produce a flat line to show what's level and a vertical line to show what's plumb. Turning off the vertical line would keep all the light close to the ground. I have a camera tripod that adjusts from 20 to 54" high. I could set up the tripod at my finish point, aim the level toward higher ground, measure the height,  and carry a white paper along the edge of the road. I'd stoop to check the intensity of the line and when it got faint, mark the spot. I'd measure the height of the line, then move my tripod to do it again.

I haven't heard of a law against using a builder's level along a deserted street. The light would probably be knee high or lower, and I'd be within 100 feet. Should I buy a laser level?

Quote from: Webfor65 on January 24, 2022, 02:21:06 PM
Where does one buy a SMART SWITCH?

I bought a 12-hour mechanical timer instead. (Simply to count down, the digital timers I saw looked like a hassle to use.)

As a rule of thumb, the battery charges at 2 volts per hour. Suppose I'm at 47.6 volts and I want to charge to 80%. According to DickB's chart, that's 51.6 volts, so I set the timer for 2 hours.

It's possible that not topping off could be harmful. I've been keeping track of voltages and watt-hour inputs for several months. Generally, partial recharging requires about 1.16 x average voltage x voltage change. (in the paragraph above, it would be 1.16 x 49.6 x 4.0, or 230 watt-hours.

However, charging all the way usually takes a lot extra, and that extra amount varies so much that charging from 42 volts could take more energy than charging from 40. I think that extra energy goes into equalizing, and the need may be different every time. I think letting the cells get way out of balance could ruin a battery pack much faster than charging all the way.

Rad Power recommends disconnecting the charger as soon as the green light comes on. I may not be awake to do that. I may use the timer to avoid leaving the charger on for hours extra. To start, my estimate would be an hour for every two volts I need, plus at least an hour for topping off. I'll probably change that according to observations.

An hour after seeing a green light, I have reconnected the charger and had it continue charging with two red lights. That could mean that after the battery settled down, the controller found that some cells still needed equalizing. If the timer shuts off after a reasonable charge time while I'm sleeping, the battery can settle down before I turn the charger back on in the morning to check. Allowing that rest may help the controller equalize cells.

Quote from: DickB on January 20, 2022, 06:10:39 AM
Pretty simple. Cut the DC cord, strip the wires. Identify + and - leads with a voltmeter. Charge end to DC IN, battery end to LOAD.

I didn't know they made such a device. I'll try to think of where I could use one. It was fairly recently that I learned that there are clamp-on meters that will measure DC amps. I don't know how mine works, but it's mighty handy. Without it, I wouldn't know that my 13 hp mower needs more starting current than my car. (The mower is cranked at a much higher speed, and the automatic compression release is apparently not working.)

Quote from: DickB on January 20, 2022, 06:01:45 AM
I did run an empirical test on my Standard Rad battery and Rover 5. I ran full throttle on level roads, stopping every two miles to measure battery voltage after 30 seconds. I went 20 miles before the battery was basically exhausted, so for the most part every mile is 5% of capacity. I based my meter chart on these results.

I like your chart. Your knee at 44 volts(20%) agrees with other curves I've seen. For several months, I amassed empirical data by logging voltage and mileage readings each morning before riding. I've noticed that knee, so now I recharge at that point. From my data, I've noticed another knee: above 50 volts or so, I tend to get a lot more "miles per volt."

Internal resistance may be the problem. You were apparently able to maintain an efficient speed. Around here, I often have to slow to a walk. Perhaps below 50 volts (65% on your curve), battery resistance limits the current the controller can deliver. Acceleration would be slower and I'd spend more time climbing at inefficient speeds.

In particular, a 300-yard grade at 6% leads to my house. The whole block is 600 yards. Historically, the limit was 35, and that was quite safe. There are four small houses on that block, and apparently at least one household with political pull wanted it treated as a private road. About 1990, the town posted it at 16 mph and ordered the town cop to issue tickets. It was expensive for a town of 200  households to have its own cop, but how else could they enforce a law like that? There was a rapid turnover because it was as abusive to cops as to those ticketed.

I used to observe the hill with a stopwatch. In spite of all the tickets, about half the vehicles continued to drive at 35. That meant the cops were profiling. My mother was on the council. I told her the limit was a ridiculous burden to anyone who obeyed it. She ignored me until the day she got a warning. I think the cop was politely making her aware that he'd been told to enforce a ridiculous limit. When she brought it up at the next meeting, councilmen scoffed at her and fired the cop.

A mayor was elected who loved to do favors and inconvenience people. He got only 12% of the vote, but nobody else wanted the job. He had a speed bump put in at the bottom of the grade and another 200 yards from the bottom. Vehicles including his would come to a complete stop for each bump. He didn't mind the inconvenience as long as he was inconveniencing others.

After I installed a layback seat post, my Radrunner was the only vehicle in town that crossed those bumps without slowing. Hitting them at 25 wasn't uncomfortable because my riding position put most of my weight on the pedals. I changed my mind when I got home from the grocery store with cracked eggs. That wasn't so bad, but I was afraid I might arrive with broken spokes the next time. Now I slow to a virtual stop, like everyone else, and climbing  that hill is a drag. I should have gotten a mid-drive bike with gears.

Quote from: DickB on May 14, 2021, 08:00:36 AM
Although my smart switch works, I have a much simpler solution to partial charging with the Rad charger.

Standard silicone diodes have a forward voltage drop of about 0.8 – 1.0 volts at 1-5 amps. Simply placing two diodes in series in the circuit between the Rad charger and the Rad battery will drop the float voltage to provide less than a full charge. I've tested one cycle with two diodes and achieved an 80% charge level. Other than the reduced float voltage, the charger behaves just like before, charging at a constant 2.03 amps, then tapering off.  The Charge Indicator starts red and then turns green at charge completion as usual.

I've verified the charge level both by measuring rest voltage of the battery after charging and using the Rad Battery Charge Indicator.

The float voltage after the diodes was 52.7 volts, and the rest voltage after my dual diode charge was 52.0 volts.  This correlates to the following table from Benzo Energy, a Li-Ion battery manufacturer (I added the Rad battery column):

  Voltage
Rad    Cell    Charge
54.6   4.20   100.00%
52.8   4.06   90.00%
51.7   3.98   80.00%
51.0   3.92   70.00%
50.3   3.87   60.00%
49.7   3.82   50.00%
49.3   3.79   40.00%
49.0   3.77   30.00%
48.6   3.74   20.00%
47.8   3.68   10.00%
44.9   3.45   5.00%
39.0   3.00   0.00%

I made a similar chart last April, based on data from someone who had used a computer to record voltage each second as he discharged a Samsung 18650 at a constant current. I don't remember if it was a 35E. As I recall, each reading listed time, voltage, and culombs drained so far. There were thousands of entries. I took the culombs at the bottom and multiplied by .1, .2, .3... etc, to find the points on the list showing voltage at 90%, 80%, etc. Like you, I then multiplied by 13.

My chart varies from  yours.

54.7  100%
51.7    90%
51.0    80%
50.2    70%
49.3    60%
47.9    50%
46.3    40%
44.5    30%
41.7    20%
39.0    10%

At the time, I thought I'd validate this empirically, but that would entail routinely running the battery down until the controller kept shutting off the motor. Besides, my energy use per mile seems to vary from day to day, depending on things like hills on my route, pedal assist gear, throttle use, and speed. (I think a hub motor may use more energy per mile at lower speeds than at higher speeds.)

I've ordered a mechanical countdown timer switch, up to 12 hours in 15-minute increments. With the data I've logged in the past year, I should have a good idea how long to set the timer if I want to charge the battery from one voltage to another.

Oh yes... the display on my Bolton aftermarket controller reads 0.5 volt low, like yours.

Quote from: DickB on May 15, 2021, 08:47:04 PM
Probably just meter accuracy. My meter is specified as +_1.2% accuracy, so that's +- 0.5V.  Probably just a variation in meters.  I have two DVMs that do read within 0.1V on the Rad battery, but I have one that I got for free at Harbor Freight and it's different by almost 1 V.

Next time I order parts I'm going to get a Maxxim MAX6350 voltage reference IC and check it out against my DVMs.

In 2015, I paid $11 for this item:
https://amzn.to/3GQ6p9e

All I had to do was solder on leads for two 9 volt battery connectors. Since then, I have once sprayed the selector switch with contact cleaner. It was calibrated and came with a paper showing each of the four voltages to the nearest 0.01 millivolt.

It's advertised as an AD548. In fact, it's an AD584. The item I bought is out of stock, but searching for AD584 brought up quite an assortment.

I'm amazed at how accurate some cheap meters are these days.

Quote from: JimInPT on January 16, 2022, 08:47:32 AM

Quote from: Kmac66 on January 15, 2022, 04:03:50 PM
I need to use an extension cord with my battery charger.
What gauge / amp power cord should I use?

The standard Rad charger supplies 2A at a little over 50 volts, so that's about 100 watts, or about the same as a lamp with an incandescent bulb.  In the USA, 100 watts from the wall at 120VAC is less than 1 amp.  I think you can see where I'm going with this; the charger draws very little power compared to what every outlet in the house is capable of delivering, so any extension cord at all will work.

If you're charging in the garage or another location where you'll be walking in the vicinity of the cord and charger, I'd use an outdoor-rated power tool extension cord simply for their physical ruggedness, but you can easily get away with the smaller gauges.

As for being able to determine your battery-charge level and shut it off short of 100%, check out this thread:  https://www.radowners.com/index.php?topic=1001.msg7768#msg7768

peanutbutterpope is in the process of creating his first batch of charger regulators; I'm on the list now and I believe he is still accepting inquiries for potential future production runs.

To be exact, I read 1.35 amp. I believe it was using 109 watts from 122 volts, which would seem to be 0.89 amp. The difference is power factor, in this case 0.66. I find a plug-in watt meter the best way to see what's happening with many appliances, such as battery chargers. I've used one a lot for ten years. Sometimes I wanted to monitor two things at once, so I bought another one the other day. It's another brand because Amazon had a price spike in Kill-a-Watt.

I think the difference between outdoor and indoor cord is insulation. For example, GPT is interior automotive wire. Outdoors, the insulation doesn't last long.

I bought my newest cords because they are strong with thick insulation and a ground conductor. The indoor rating warns me that they won't stand up to the elements as well as outdoor cords. That's okay: I don't leave my outdoor cords out in the weather, either.

Quote from: Kmac66 on January 15, 2022, 08:49:19 PM
Thanks!

Come to think of it, I just got a 12-foot 16-gauge extension cord for charging. It's partly for the convenience of reach and partly to have room to plug in my Kill-o-Watt meter. It tells me three things: how long the battery has been charging, how many watt hours the charger has used, and the wattage at the moment.

I keep a record of voltage, miles, and watt hours. Knowing the voltage when I put the battery on the charger and the watt hours added so far, I can estimate how much longer. Not always charging fully is supposed to extend the life of the battery. I can avoid fully charging by unplugging the charger when I see the wattage taper.

Quote from: Kmac66 on January 15, 2022, 04:03:50 PM
I need to use an extension cord with my battery charger.
What gauge / amp power cord should I use?
Is 16 gauge too small?

Thanks.

My charger uses under 2 amps. Sixteen gauge is plenty big enough.