Townie with discs

[Lunar Cappuccino]

I test rode one of Electra's Townie bikes the other day, specifically the 7D. I really like these bikes, they're very pretty and the whole "pedal-forward" idea that lets you put your feet down at lights while still getting full leg extension when pedalling is great. They're a bit heavy but if you've followed my other threads I'm planning on putting 2000+W through it. They don't cost that much either so the fact that electrifying it voids the warranty doesn't bother me. The only thing wrong with them is - cantilever brakes. I'm in Portland, OR and we have some insane hills here and rainy weather. In fact that's why I want all the power. The particular grade I need to climb with the thing is Marquam Hill which has a long steep rise of about 140m above the local terrain. Even if you can get up it you have another problem - getting down it, alive. I just don't fancy riding that thing without discs. Any ideas?

 

[nicobie]

I honestly don't think that a disc will be better than the V brakes that come with that bike. I own one and have used both. I only changed because I needed to run a 24" rim. With the best pads on the v brakes compared to an avid 7 with also great pads, neither will skid the rear tire.

I do like the BB7 better. Nicer feel. With a 203mm BB7 on the front I can clamp down hard and not go over the top

 

[nicobie]

*.*

 

[Lunar Cappuccino]

I honestly don't think that a disc will be better than the V brakes that come with that bike. I own one and have used both. I only changed because I needed to run a 24" rim. With the best pads on the v brakes compared to an avid 7 with also great pads, neither will skid the rear tire.

I do like the BB7 better. Nicer feel. With a 203mm BB7 on the front I can clamp down hard and not go over the top

My main concern isn't panic stops. I'm sure the cantilevers do fine for that. My concern is heat dissipation as I ride the brake all the way down that grade for the 8-10 minutes it takes to get back to the flatlands below. The Townie is heavy to begin with and mine will have a big motor, controller, and the biggest battery I can afford/carry. Add to that the fact that I'm always carrying a backpack with papers and a 15" Macbook. I'm not a small guy either (85kg). All of that puts the thing well out of spec for the brakes they put on it at the factory. I'm hoping to go with a regen system in the controller though I need to research that more. Still, it's really heat that worries me and also braking power loss in our notorious rain. They do tend to mitigate each other, though.

 

[chvidgov.bc.ca]

I hope you get this sorted. I've got a Townie 7D myself, with huge Fat Frank tires on it, and front Crystalyte 406 and 15lbs of Headways on it and I can tell you it is a super plush ride, and I'm pretty comfortable at only maybe 25mph with just the stock V-brakes on it. Totally enjoying it - the bike is actually lighter than you think with the aluminum frame. A fork replacement would get you into a front disc brake, but the steerer is really long on the 7d so it might be hard to find just the right replacement fork. Eight or nine inches anyway I think. I call it my Cadillac. The breaking performance is just "pretty good", but could be a problem in very wet hilly conditions as you indicate.

 

[Lunar Cappuccino]

I hope you get this sorted. I've got a Townie 7D myself, with huge Fat Frank tires on it, and front Crystalyte 406 and 15lbs of Headways on it and I can tell you it is a super plush ride, and I'm pretty comfortable at only maybe 25mph with just the stock V-brakes on it. Totally enjoying it - the bike is actually lighter than you think with the aluminum frame. A fork replacement would get you into a front disc brake, but the steerer is really long on the 7d so it might be hard to find just the right replacement fork. Eight or nine inches anyway I think. I call it my Cadillac. The breaking performance is just "pretty good", but could be a problem in very wet hilly conditions as you indicate.

The problem going down Marquam Hill isn't keeping your speed at 25mph, it's keeping it under 150mph . Did I mention the switchbacks? I thought of the replacement fork idea too but yeah that was my concern. It's kind of an unusual style of bike so I wasn't sure if I could find forks with discs for it. As for the weight - I'm just comparing it with my old super-light mountain bike (that got ripped off, hence my current obsession).

 

[-dg]

My main concern isn't panic stops. I'm sure the cantilevers do fine for that. My concern is heat dissipation as I ride the brake all the way down that grade for the 8-10 minutes it takes to get back to the flatlands below/

Rim brakes have more heat dissipation capacity than discs. The rim has more area, more mass, and is aluminum, a better heat conductor than the steel disk.

600 feet of descent for a single is not normally a problem anyway. I'm big (270) and rode down from the Aerial Tramway (which you said was similar to your comute) on a rental Breezer hybrid. On my cross country tour I descended from Trail Ridge (12,183) into Boulder (5,430) with road caliper brakes on a loaded bike and had no problems (although I was lighter then).

 

[Lunar Cappuccino]

My main concern isn't panic stops. I'm sure the cantilevers do fine for that. My concern is heat dissipation as I ride the brake all the way down that grade for the 8-10 minutes it takes to get back to the flatlands below/

Rim brakes have more heat dissipation capacity than discs. The rim has more area, more mass, and is aluminum, a better heat conductor than the steel disk.

600 feet of descent for a single is not normally a problem anyway. I'm big (270) and rode down from the Aerial Tramway (which you said was similar to your comute) on a rental Breezer hybrid. On my cross country tour I descended from Trail Ridge (12,183) into Boulder (5,430) with road caliper brakes on a loaded bike and had no problems (although I was lighter then).

Hmm.... You make a compelling point. In a way, the rim is a giant disc (admittedly without the vent holes). Perhaps even more reason to go with the stock Townie and certainly cheaper than replacing the fork. Good to see a fellow Portland person who knows the terrain too. Thanks!

Edit: My concerns are due partly to being from the East Coast. Outside the Appalachians we have nothing like the sustained steep grades of the west so I have no real idea of what will work and what will turn into a cloud of smoke. I'm not from around here, in other words.

 

[-dg]

Good to see a fellow Portland person who knows the terrain too. Thanks!

Edit: My concerns are due partly to being from the East Coast. Outside the Appalachians we have nothing like the sustained steep grades of the west so I have no real idea of what will work and what will turn into a cloud of smoke. I'm not from around here, in other words.

I'm actually an Oakland person who has ridden around Portland a little bit. I'd say the Bay Area is hillier in general. I've also ridden over the Sierras and the Rockies and lots of up and down in the East Bay hills. You will be fine. The mountain bike guys like discs because they don't get mud on them as much and because good ones can be more precise, which is nice on uncertain surfaces, but for road riding the advantages usually don't outweigh the disadvantages.

 

[dogman dan]

You could swap out the front forks, and get disk mounts on the new fork. That would get you front disk so you'd tend to get better stopping when it got really wet. And you might like disk better, once you have stepped up to the 40 mph club with that bike. For a hard stop, you need that front brake working well, but able to modulate fine so you don't lock it up. I don't think you will need disk so much with 2000w. My huge cargo bike goes 30 mph all the time, weighs 160 pounds, and stops just fine with rim v brakes. Half the reason I don't put front disk on that bike is simply that I don't have a good strong front wheel handy for the disk. My disk wheels are on off road bikes.

Regen braking would work, if you use a dd motor. But, if you have a direct drive motor, you tend to not need the brakes so much on long downhills. It works like this, even without regen enabled, a certain winding of motor has a small rolling resistance when it's not under power. As speed increases, this resistance called cogging increases. You will find it very hard to coast faster than 40 mph with a dd motor.

If you chose a slower winding motor to climb hills more effectively, you will find it hard to find a hill steep enough to coast faster than 30 mph or so.

Problem is not a problem after all, with a dd motor.

 

[Ykick]

Properly setup rim brakes can be very effective pinchers IMO. I'm fortunate to have hydro rim brakes on main bike - 'wouldn't trade them for anything else. They can be found used cheap enough on PinkBike and/or eBay.

Yes, I have another bike with BB7's but the Magura Hydro rim brakes just feel nice while extremely effective, by comparison.

That said, ANY brake will overheat over long descents and you should learn to alternate front/rear use to allow ample cooling. Yesterday, followed a couple Roadies down a steep hill I actually smelled their brake rubber burning up!

Another unusual advantage of rim brakes is that you get a little feedback if/when your rim/spokes need attention.

Another similar feet forward frame - Day 6. They have an interesting seat/chair design but dunno about disc brakes, etc?

Good luck but if you go Townie or similar and desire excellent rim brake performance I would suggest shop used Magura hydro rim brakes.

 

[wineboyrider]

Sounds like a great candidate for regen brakes! Regen will slow you down and save your brakes ...

 

[Ykick]

DD motor with regen is a very good possibility given the terrain and situation.

But, isn't the collective ES in agreement those motor installations practically require clamping TA's (torque arms)? At least for use with significant regen/braking levels?

 

[nicobie]

The Townies take a standard 8" uncut 1 1/8" dia. fork. If you must have discs, don't bother with the rear as it won't work any better than the v brakes, neither will skid the tire. I do like my Avid 203mm disc on the front.

 

[Lunar Cappuccino]

Thanks for all the advice guys. Looks like the setup should be something like

1. Townie with rim brakes as base platform
2. Rear DD motor with slow winding for hill climbing
3. Regen capable controller
4. Torque arms to hold motor in rear dropout

Any suggestions about specific motor/controller/battery combos (i.e. make/models)? Remember I'm looking for at least 2000W and also range so bigger battery is better.

 

[wineboyrider]

Lyens controllers have programmable regenerative braking capabilities. So for 2kw a 12 fetter seems in the works. My 9 fet is regen capable up to 18s!

 

[Lunar Cappuccino]

Lyens controllers have programmable regenerative braking capabilities. So for 2kw a 12 fetter seems in the works. My 9 fet is regen capable up to 18s!

Thanks, but I still don't know all the jargon. What is "fet" and 18s (seconds?)

 

[wineboyrider]

18s is 18 cells series lipo and fet is the number of gates that pump current into your motor.
Just make sure if you use regeneration you don't start with a full pack as you can overcharge your batteries. Otherwise regenerative braking is very useful.

Fet is short for mosfet.

 

[Lunar Cappuccino]

18s is 18 cells series lipo and fet is the number of gates that pump current into your motor.
Just make sure if you use regeneration you don't start with a full pack as you can overcharge your batteries. Otherwise regenerative braking is very useful.

Fet is short for mosfet.

OK, thanks. So, it's my understanding that each cell is about 3V so 18 in series makes about 54V. What if I had, say, 72V? Or would any controller that can be used with a 72V battery also be regen capable at that voltage?

 

[Eskimo]

One LiPo cell is 4,2V when charged full. 18S is 75,6V. Around 66V when "empty".

 

[dogman dan]

Two sources I know of for slow winding motors able to take 1500w reliably. These 9 continent type motors are rated for about 800w, but many have run them up to 3000w.

In the USA E-bikekit. It's not on the website per se, but they may have some slow rear motors. I have one right now waiting for me to review it. Mines a sensorless motor, so maybe best left stock 36v.

In China, EM3ev has similar design motors that have hall sensors. His rear direct drive motor, in the slowest rpm. To get any speed at all, get a higher voltage controller. 48v gets you about 20 mph max, and 72v gets you 30 mph.

It's a real nice setup with a 72v 40 amps controller. 3000w, but you will never pull 3000w except for the first 5 feet from a stop sign. You get a very snappy take off, and most very very steep hills will still only pull 2000w. So you don't tend to fry the motor unless you pound the thing super hard up 20 degree slopes.

More reliable with a 72v 20 amps controller. I use that one in summer to keep the motor heat down. But less snappy taking off from stop signs with the 20 amps. That's 1500w max.