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Peter Towle

FRICTION WHILE COASTING ?

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Hi I had a question,when i stop pedaling going downhill the SONDORSX 7speed seems to be reluctant to free wheel as if there is some friction somewhere,is this normal for an ebike or should it freewheel going downhill more like a nonmotorized bike? THANKS

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Hey Peter, Check your chain tension and make sure your rear wheel spins freely, backwards, with the tire off the ground. Look for resistance somewhere  in the componentry. Check your front wheel bearing adjustment. The Sondors Chinese factory has a bad habit of over tightening them. What tire pressure are you using? They operate at considerably higher pressure than a bagpipe.)) Most fat tire PSI recomendations are based on Snow and Sand Beach riding and too low for how most Sondors owners ride.  I like 30 psi with the stock tires (ignore the complaints, they are really rugged tires albeit, noisy) for street riding as that reduces the contact patch size and reduces rolling resistance. Presently using 22 psi with the thin sidewall 120tpi 26 X 4.7 Vee Tire New Mission Command rear tire but after 2200 miles, on them, I have the heaver 60tpi version of the same tire reddy )) to install and they have very low RR and are some of the fasting rolling fat tires available but will probably try slightly higher reassure in it...trial and error until finding a sweet spot. 

image.jpeg.429e4626c080852c57cfe3dd49e535d9.jpeg

image.jpeg.b8bec3ed6d409c68a55f5c983611290d.jpeg

Reddy

Edited by Reddy Kilowatt

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Thanks REDDY , in my case i'm going to go to a bikeshop and have them adjust the brakes and loosen the wheel bearings for me.Its a new bike and a proper tune up is a good idea before i wear it out unnecessarily.

1 hour ago, Reddy Kilowatt said:

Hey Peter, Check your chain tension and make sure your rear wheel spins freely, backwards, with the tire off the ground. Look for resistance somewhere  in the componentry. Check your front wheel bearing adjustment. The Sondors Chinese factory has a bad habit of over tightening them. What tire pressure are you using? They operate at considerably higher pressure than a bagpipe.)) I like 30 psi with the stock tires for street riding as that reduces the contact patch size and reduces rolling resistance. Presently using 22 psi with the thin sidewall 120tpi 26 X 4.7 Vee Tire New Mission Command but after 2200 miles I have the heaver 60tpi version of the same tire on order and they have very low RR and are some of the fasting rolling fat tires available but will probably try slightly higher reassure in it...trial and error until finding a sweet spot. 

image.jpeg.429e4626c080852c57cfe3dd49e535d9.jpeg

image.jpeg.b8bec3ed6d409c68a55f5c983611290d.jpeg

Reddy

 

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Hub motor will have drag when no power has supplied to it.  Some bikes would recapture some energy with regen, but they are of more costly designs.

Edited by Shocker

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Hello @Shocker. Our Geared hub motors freewheel when you coast, they are not capable of regenerative braking because of this. They have No Drag when coasting and the planetary gears are the only differences between Fixed Drive and Geared and that's why they are named such.  This site will better help you understand our Bafang Geared Hub Motors:  

https://www.ebikekit.com/blogs/news/electric-bike-motor-introduction

As a matter of function, non geared, direct drive hub motors are less expensive to manufacture because they don't include the planetary gear system and because direct drive motors turn into generators by a function of the controller. Because they produce less Torque for a given current at low speed, they are generally larger and heaver, to produce acceptable low speed performance and thus they can cost more, especially since motors like the Crystalyte/Crown, are at the top of the hub motor food chain, and in most cases driven by many times the voltage and wattage of our Bafangs.

"The geared motor also has an internal freewheel, so when you coast, or ride without the motor on, the motor does not have to spin unpowered. This improves coastingdistance, and the motor does not add resistance to pedaling with the motor power off.

image.thumb.gif.81b395a8778b85a9caa31c836e04d8db.gif

image.jpeg.b8bec3ed6d409c68a55f5c983611290d.jpeg

Reddy

 

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28 minutes ago, Reddy Kilowatt said:

"The geared motor also has an internal freewheel, so when you coast, or ride without the motor on, the motor does not have to spin unpowered. This improves coastingdistance, and the motor does not add resistance to pedaling with the motor power off.

 

Right.  That is one difference between direct and geared hub motors.

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56 minutes ago, Peter Towle said:

Thank you SHOCKER,if i get brakes lined up and loosen the bearings and increase my tire pressure i should be freewheeling downhill better than now.

How do the wheels feel when spinning them by hand off the ground?  I had to adjust my front brake on my fold X after assembly, as I can hear the pads rubbing.

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Ive been trying to get my brakes to stop rubbing, and have been running into trouble trying to balance brake lever resistence with freedom of the wheels spinning,my wheels spin nicely when i slacken the brake cable and if the pads would be aligned at proper distance from disc the wheels should still  spin freely when brake levers are not  squeezed....i really need to seek professional assistence at my local BIKE SHOP tomorrow because i have done best i can . P.s. i enjoy my 1/2 hour ride every day anyway and did an 18 mile rail trail last Saturday.

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Hopefully your mechanic will find the root cause and fix your problem.  That is awesome that you are enjoying your bike.  My daughter and I also did 18 miles last Sunday, with her on a Fold X.  Now I have to develop her confidence and ability, so she can go higher than 15 mph to keep up. ;)

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Brake adjustment on mechanical disks is something of a black art.  Its just not intuitive and when you get it right, the cables will stretch and then you get to do it over again.  With that said, once you get a feel for it you can fix the associated issues without difficulty... but it never becomes a welcome task and frequency is accelerated because of the higher speeds and increased weights that come with electric bikes.

Assuming you have not changed the rotor size and introduced issues with your spacing thataway, don't forget the inner pad adjustor that you have to reach thru the spokes to get at.  Try a few turns in each direction (remember the click count) and see what happens. Remember you can loosen your brake caliper in its mount so it is somewhat loose, then spin the wheel and apply the brakes.  Hold the lever down.  This is the natural resting place for the brake caliper.  Gently tighten each bolt alternately while holding the lever until its snug, then release the lever and again alternately and gently, tighten each bolt further.  Take care not to torque the bolt hard enough to shift the caliper in its new resting place.  Spin the wheel each time you gently tighten so you can see if you have screwed the process up and shifted it.

Warped rotors will increase your misery index.  Oddly for cheap brakes the Tektro rotors that come with Sondors are a)not available for sale and b) nice and thick.  Actually very nice rotors.  But if they warp, make your life easier and just buy replacements.  Using a crescent wrench or rotor tool to try and straighten them is not worth the effort.

In the end, a lot of us have gone to hydraulic brakes.  They self-center over the pads and there are no cables to stretch.  Stopping power on the basic models is no better but they should require zero maintenance after an initial fitting.

Edited by MattRobertson
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Thank You MattRobertson for the EXCELLENT description of the theory and practice of brake adjustment,i was stubborn and decided to keep trying to master the art of brake adjustment ,instead of going to a mechanic and i finally started to get the hang of it, now things are rolling freely AND braking well.

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Couple more things to add to doing brakes above:  the spin-it-while-a-little-loose tactic works great but instead of doing the tightening the way I describe, just baaarely snug up the bolts for the first go-round.  Then let go of the lever and get down and put your eyeballs as close as possible to the pads so you are looking thru the caliper front to back and are seeing daylight (hopefully) on both sides of the rotor.  Using your thumb and forefinger on just one of the caliper mounts, physically shift the already-barely-snug caliper so that, if its not perfectly in the middle of the available space, you make it so while looking at the situation directly (technically, there should be more slack on the outside side rather than the inside side, but lets try and just get the thing not to touch first off and that should be good enough... sidle it over a bit once you get the hang of this).  You may need a pair of reading glasses or similar (I sure do) to be able to see properly.  If the caliper is too close to the rotor to allow this hair of daylight on both sides, then backing that inner adjustor out a touch can make the difference you need, followed by re-centering it using one of the two above methods, or both of them.

Lastly, tightening cables:  You can buy all sorts of brake cable torture devices that purport to stretch the cable with one hand, while you clamp the cable bolt with the other.  These tools are awful, usually result in a ruined/crushed cable and should be avoided entirely.  To tighten a loose cable, just use your thumb and forefinger of one hand to slightly clamp the brake caliper (use the lever to see what moves, then do it with your hand on the caliper).  Then with the brake partially engaged like this, tighten the cable and let go.  In theory you are partially engaging the brakes which is bad.  If you do it right you are doing the same job as the cable puller tool, but without tearing at the cable.  Just don't over do how much you compress the caliper and its a 10-second low-impact easy-peasy way to cinch up a stretched cable.

 

Edited by MattRobertson
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If a picture is worth a thousand words.....well a video is worth....nuff said

This may help visualize mechanical disc brake adjustment and make it less complicated. Offered by Park Tool the leading manufacture of bicycle support components.

image.jpeg.b8bec3ed6d409c68a55f5c983611290d.jpeg

Reddy

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On 11/1/2017 at 10:18 PM, Shocker said:

Right.  That is one difference between direct and geared hub motors.

Actually, GMAC now has geared hub motors that can do regen.

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