Let's talk about brakes

[Patriot]

Not for regen. Regen is not practical on bicycle. This uses the motor as a generator through a resistor to slow the wheel. Regen would go to the battery. Whole different thread.

What makes you say that regen is not pratical on a bicycle that can travel at 40mph+ . Yes the motor is used as a generator with a load ( resistor ) placed on the end of it , why cant the load be a charging circuit. This thread is about brakes, and using motor braking combined with mechanical braking and I think it makes perfect sence. Maybe not in a primitive form i.e switch for brake on/off, but a proportional brake lever that varies the load on the motor could be a very good way to go.

This is exactly what I have done with my 48v/5303.

I have variable regen through my Kelly controller, using a 5v thumbie on the left handlebar. I use it long decents, and when slowing down from 40mph. I works perfectly. It doesn't stop the bike completely, but it does slow it down nicely to about 10mph where it disengages. I then use my regular brakes to stop.

Using variable regen is a great way to slow down for ebikes, especially when using high speed setups that may otherwise eat up, or burn up lightweight mechanical brakes.

 

[StevenR]

C'lyte 72V48A? Your controller will do regen. It kicks in when the ebrake line is energized if you put the regen pad to ground. I have to look for the exact pad name (it is out in a thread here somewhere) but I did it on a 48V40A controller - I put in a switch so I could turn it on and off. It kicked in real hard with no modulation. I wanted to try putting a resistor in the line to ground or something to try to modulate it but never did. I have a front 5303 and regen tore up my 1" stearer headset. Torque arms in BOTH directions are REQUIRED, particularly if you can't figure out how to modulate it. I plan on experimenting with this further over the winter when I build ebike v2 but am too busy riding v1.32.75.10 to work on it now...

 

[MitchJi]

Hi,

Oh at the same time i went with mechanical disc brake because i didn't want to bother with bleeding the brake line if i needed to do maintenance.

When I asked Steve Gravenites aka Gravy (see info below) if he recommended mechanical or hydraulic he recommended hydraulic for easier/less maintenance.

That is a sensible choice ngocthach1130. In my experience, hydraulic disk brakes do not have easier maintenance.

They do have much less frequent adjustments though.

Exactly!

 

[chet]

Not for regen. Regen is not practical on bicycle. This uses the motor as a generator through a resistor to slow the wheel. Regen would go to the battery. Whole different thread.

What makes you say that regen is not pratical on a bicycle that can travel at 40mph+ . Yes the motor is used as a generator with a load ( resistor ) placed on the end of it , why cant the load be a charging circuit. This thread is about brakes, and using motor braking combined with mechanical braking and I think it makes perfect sence. Maybe not in a primitive form i.e switch for brake on/off, but a proportional brake lever that varies the load on the motor could be a very good way to go.

This is exactly what I have done with my 48v/5303.

I have variable regen through my Kelly controller, using a 5v thumbie on the left handlebar. I use it long decents, and when slowing down from 40mph. I works perfectly. It doesn't stop the bike completely, but it does slow it down nicely to about 10mph where it disengages. I then use my regular brakes to stop.

Using variable regen is a great way to slow down for ebikes, especially when using high speed setups that may otherwise eat up, or burn up lightweight mechanical brakes.

I was talking about recharging the battery with regen on bicycle. not enough return to matter. regen is good for braking

 

[pwbset]

not enough return to matter. regen is good for braking

I've recaptured as much as .8ah (16% of my total commute's wh usage) using regen, but I descend 1,600ft to do it, which is not a common example I don't think. I agree that it's really not worth it except for very specialized situations (like crossing Canada for example where every wh counts heh, heh).

 

[John in CR]

Chet,

I can guarantee that regen braking will be a big plus with the way I ride...ie maximum acceleration (typically to 40mph or so) and maximum deceleration (often frequently) using brakes, not to mention the hills that I deal with regularly. Justin proved on his cross Canada ride that it's useful even for commute type riding (fewer stops and starts), and that it really shines with alot of stop and go.

For me, I don't even care if I get 0% back, it's the non-mechanical braking force that I'm after, and if some goes back into the battery that's just icing on the cake.

John

 

[urace4me2]

Disk brakes with cables instead of hydraulics work fine too. Any disk brake will be a huge improvement over any rim brake for high speeds and wet roads. But since e-bikes aren't usually riden in wet conditions rim brakes that are working properly with CLEAN pads, work ok.

 

[patrickza]

Just thought I'd update you guys on what I've done. Went to the LBS and got a new 180mm disc for under $20. They said I should try it first and then come back later for a decent hydraulic caliper if I'm still not happy. Nice of them not to try and take all my cash.

Anyway with the larger disc and a properly adjusted caliper the breaking is reasonable, I'm actually pretty happy with it now, but I think I'll go back for a new caliper when I wear the pads out. I'll be adding e-braking as soon as I've sorted my BMS issue out. I only have space in my brain for one electronic issue at a time!

BTW this was the first bike shop I've been to that just loved my ebike. They couldn't stop asking questions and making suggestions, I think I'll be going back to them more often in future.

 

[BIG BEAM]

I'm thinking about a new build over the winter and have a few questions,

24" wheels what's the good the bad and the ugly?

what about FS are they durable?

disc vs rim(all I have now is coaster but on a cruiser like I have now they work pretty good but I wonder how long they will last)?

does a pack set in the triangle balance well?

I'm sure I'll have more questions,but that's a start.

Maybe get a few junk bikes with good parts ,That way I can weld what I want and then sandbtast and paint?

 

[spinningmagnets]

Disc vs rim brake probably depends most on how fast you'll be going, and how long the downhills are on your commute.

Personally I really like front disc brake, even though I live where its pretty flat now. With a front quick-disconnect axle (no tools required) it very handy to be able to pop off the front wheel so easily. Also nice that if I decide to start going faster (with a motor/voltage upgrade) I already have the front disc.

 

[rebelpilot]

I ride fast and I ride every day (rain or shine). Disk brakes are necessary. The rim brakes on my FS bike are very powerful, but I wouldn't trust them in the rain in traffic.
If you build FS -I think the driveline geometry is important, or the suspension will compress upon the application of power and it would be necessary to stiffen the shcoks to the point where they would only function as a safety valve when you take a big hit form a pothole or curb. I would imagine a frock motor on the rear wheel of a FS bike would effect the available travel/compliance.
I just tested my bike with the battery in the frame and found it to handle better and feel safer than when on the rear carrier. The downside is I had to increase the stiffness of the front shock to its maximum setting. I think that will improve if I move the controller to the rear rack, and drop the battery lower and further back.

My experience with wheels is; the bigger the diameter - the smoother the ride. The roads here suck.

 

[BIG BEAM]

I didn't know that the front suspensions are adjustable.Are all of them adjustable ?Do they make them with different "spring" rates.How much do they normally travel and is that adjustable too ?
DON

 

[rebelpilot]

the spec for my front shock is:

SR Suntour SF11-XCT-V3-DS-26, 80mm, 1pc. alloy lower, 28mm Hi-Ten stanchions, coil/mcu spring w/ preload adj.

I believe I can replace the "mcu" (multi-cellular urethane IIRC) with a harder or softer unit. The preload adj. is at the top of the right side of the fork.
These appear to have 80mm travel, my FS bike has air adjustable shocks with 100mm travel. I remember seeing some shocks that were only adjustable by opening them and replacing the springs.
I think mcu shocks are probably stiff in the cold, this will be my first winter with a set.

 

[Ricky_nz]

Definitely go with disc if you can, preferably hydros.
I find V brakes always need adjustment due to faster wear from higher speeds and heaver bikes and aren't very compatible with large tires like the 2.5" hookworms.

disk brakes need much less maintenance, just swap the pads out when they are done.

Also one failure mode for rim brakes is rim failure which would not be fun at speed. This is more so with the modern alloy rims that wear down.
The reason for hydro is because pipe failure is less likely to be sudden unless you are racing through bush and snag it on something whereas cable failure on rim brakes can leave you hurtling into the middle of an intersection without warning!

 

[rebelpilot]

Definitely go with disc if you can, preferably hydros.

Good point. I find the mechanical disc brakes aren't quite powerful enough for ebike weight and speed either. i wish I had bigger rotors.

 

[Hillhater]

but bear in mind ..
..one failure mode for disc brakes is wheel collapse from overloaded & broken spokes due to all the braking load having to transmit through them !
.. ( note.. braking forces are much higher than acceleration forces ( for 99% of bikes)

 

[amberwolf]

So...use inverted discs like that motorcycle that has been posted a couple of times in the last few months. It bolts the disc to the rim on the outside edge, and the calipers run on the inside edge.

 

[Ricky_nz]

..one failure mode for disc brakes is wheel collapse from overloaded & broken spokes due to all the braking load having to transmit through them !

True although I would think you would have a little more warning of the situation as you can have several spokes broken and still ride a wheel but know its failing. since spokes are steel and stretch/get lose thats a warning whereas an alloy rim can begin unseen cracking where it is thinned by the brakes then have a sudden failure.
It would be impressive to see sudden failure of say 1/2 the spokes in a wheel although I would not want to be the person riding it.

Edit: I guess the spokes could on a disc wheel cause rim failure stress cracks etc but that spoke hole part or a rim is not a wear area that gets thin over time.

 

[LI-ghtcycle]

I ride in the rain all the time, I don't know where this idea that rim brakes fail in the rain comes from, I guess it depends on the quality of your rim brakes, and there are definitely better quality ones on what you typically find in a bike shop verses dept. store. I have seen a ton of used bikes, and never one had rims warn out from the brakes? I wonder how many of you have actually seen that happen? I'd be curious to see it, not saying it doesn't happen, but I have to say I am skeptical.

That being said, I agree that with the average electric bike that has hub motor tech IS going to suffer from greater weight and then requires more stopping power, however, if you keep the bike lighter, good quality rim brakes are just fine, and it's a better mechanical advantage grabbing the rim to stop instead of a much smaller disc that is attached to the hub.

I will have a better appreciation for good brakes when I have my bike up to full touring weight, but as it won't be much heavier than the average hub motored E-Bike, I doubt my rim brakes will fail me, I might have to take a little more care and consider the extra weight, but that is true of any vehicle, there are good and bad brakes, but I don't believe that rim brakes are junk just because now we have the option of disc, and I have used these rim brakes to slow me down at speeds in excess of 40MPH (going down hill) with 40lbs of weight on my back, so I don't think the extra weight is going to make a huge difference if you have good quality pads/brakes.

Just my $0.02 :wink:

 

[dogman dan]

For "normal" riding that is typically under 30 mph, good rim brakes are fine. Not cheap side pulls, but decent v brakes. Rain is an issue, but can be dealt with if it's just occasionally. rims stay dry enough in light rain, but heavy rain of course keeps em wet. After a rain, you can dry the brakes with a short pump after a big puddle.

Above 30 mph, it's different. On my race bike, 45 mph, the rim brakes are obviously inadequate. I need a better frame, with disk mounts, or at least I need to weld some on for the rear brake. ( front hub so I'm stuck with no disk on the motor in use at the moment)

 

[jdcburg]

While modern rim brakes may have slightly poorer wet performance, the idea of terrible wet brake performance probably comes from older folks (like me) who remember side pull brakes on chromed steel wheels. When they got wet they got so slippery they seemed to accelerate the bike. It was scary. I'm talking about normal bike speeds, 25mph and under. I don't have experience with high bike speeds but I would want a disk on the front if I could - jd

 

[Drunkskunk]

Disk are better only because they are more consistant. they don't care if it's wet, dry, dusty, muddy, hot, cold, ect. The work better than rim brakes above 30 as others have mentioned, but below that, a rim brake is fine.

FS bikes are great, if you buy a good one. a cheap FS is worse than no suspension. A quality one will last thousands of miles with propper maintance. parts will wear out but a good suspension is rebuildable.

Its hard to beat the durability of a non suspension frame, though. one of my bikes is built on a frame made sometime around 1910.

Battery in the frame balaneces best, but isn't always possable

 

[rebelpilot]

It has been a while since I rode my bike with vbrakes in the rain. IIRC the brakes have awesome stopping power, but need to be dragged before they will stop when wet. This is fine if you can anticipate the stop and dry the rims by dragging the brakes, but in a panic stop..... (btw I ride fast)
In this area rims can get fried in a single wet season (offroad in the mud). Sometimes when the brakes are applied it sounds as if pads are made of 120 grit sandpaper (then they work instantly even when wet!).
The advantages of vbrakes are less weight and better modulation control.

 

[amberwolf]

How well rim brakes work in the rain also depends on the pad type. There are some with just a single flat surface across them, some with multiple surfaces with grooves perpendicular to the rim, some with V-grooves perpendicular to the rim, pointed along the travel path (which will deflect water off the rim as it passes the leading edge of the pad) and I used to have a set that had interesting repeating-chevron grooves parallel to the rim that worked really well in the rain, even with the oily puddles we have. It was like having tire tread, almost, from the look of it. I don't know what brand they were, though, and never found another set like them.

Also, some pads are long and narrow, some are short and wide, so that they each have roughly the same surface area in contact with the rim but in different ways. The longer they are, the more time there is for the front of the pad to push water off to give the back half more friction. But the longer they are, the more flex there may be in the ends and thus the less pressure they may be putting on the rim in the first place, compared to the center of the pad.

I have also seen some rims that have grooves in the braking surface, presumably intended to channel water away from the braking surface itself. The 9C's rim I have has one thin groove like that; I don't know how effective it might be (only had a couple rainy days that I tested it in, and mostly used the regen braking to slow down).

Speaking of that, if you have regen braking, then using that for the highest-speed stops may help too, in that it won't be affected by the rain. However, in most controllers it appears to not be modulatable, and is just full on or full off. That might be a problem in the rain, so having a separate regen brake switch on your levers might be a good idea for those that ride fast in the rain a lot. That way you can pulse them as needed to slow down, or just use your mechanical brakes modulated as necessary.

 

[BIG BEAM]

So let's see if I have this straight.
If I'm gunna ride in the rain,mud.snow or tornado disc brakes,but they put more stress on the spokes
If I'm gunna pleasure ride then rim brakes are ok
Full suspension is good but only the better bikes(rebuildable)

What are some of the better bikes that won't send me to the poor house?

I like the idea of air adjustable like on the back of the old El Cameno(for you old guys).