Rim brakes for hub drive conversion?

[Balsa61]

I have an old road bike collecting dust in the shed - 27" wheels, 14 speed and rim brakes. Probably 30 years old.

Are the brakes adequate for a hub drive conversion?

Looking to put in a low cost / low power hub motor of say 350W. Planning to use for pedal assist and not throttle only.

Should I not even waste my money. Bike is too old to convert to disk brakes without a lot of customization.

 

[mclewis1]

What kind of rim brakes ... center pull or cantilevers? Are the rims alloy or chrome steel?

If you ride the converted bike like the original then yes your brakes with some new pads and perhaps brake cables or just some good TLC will be fine. What most ebike owners find however is that their avg speeds go up substantially, that combined with increased weight really starts to increase the stopping distances. The higher speeds also leads to more robust tires. So having the clearance for better rubber is usually something to consider when upgrading.

IMHO a bike with alloy rims, better tires, well maintained and adjusted cantilever brakes (or even better - upgraded to V brakes) with good brake pads will stop very well even from the higher speeds often seen with ebikes. But do a lot of off road riding, add a lot more weight, ride it like a scooter/moped and you're into the realm of really needing hydraulic disk brakes as your braking distances will really start to lengthen and your reliability will also suffer (for example - going through pads too quickly)

 

[indianajo]

Cantilever, side pull, blah blah blah. I'd like to point out, rim brakes lose 80% of their stopping power after a pass through a puddle in the rain. Does it rain where you live? I hit the side of a car that ran a 4 way stop, after I'd stopped restarted and was going maybe 1 mph. Damaged the bike, not me, fortunately.
Disk brakes are much better in the rain. Almost as good as the obsolete, reviled, coaster brake. I use cable pull 160 mm tektros, fine at 330 lb gross on 15% grades.

 

[harryS]

Conversion kits were designed for mountain bikes or bikes with upright bars. Drop bars don't work with kit levers or throttle. If you wish to keep electrical brake cutoffs. which I recommend, you could mount a magnetic switch on a road bike brake lever.

I don't ride much faster with power than I did without, so a good rim brake works for me. At the same time, nothing like the one-finger-pull of a good hydraulic brake.

 

[tomjasz]

rim brakes lose 80% of their stopping power

Buy better pads. I ride year round with blah blah blah. Kool stop has some great pads. Slow down.

 

[tomjasz]

good rim brake works for me.

26” disks.

 

[Balsa61]

Thanks for all the advice. In answer to some of the questions:
- this is an old, cheap bike. I'll be very surprised if it has alloy rims
- center pull brakes. I know, I was surprised myself.
- we only ride in fair weather. The hint of rain or cold and we wimp out.
- planning on changing the drop handlebars to something more urban friendly.

Background.
We live at the top of a hill. Until we bought a Lectric XP Lite for my wife, she walked the bike up the hill. Now she races ahead of me and waits at the top.
So I could either buy another Lectric XP Lite for myself for $799 + tax. Or build an ebike for that price.

Thanks to all your answers, I'm going to price out a 350W hub motor to see if it's going to be competitively priced. And buy new pads and handlebars.

Thank you all

 

[JES2020]

Thanks for all the advice. In answer to some of the questions:
- this is an old, cheap bike. I'll be very surprised if it has alloy rims
- center pull brakes. I know, I was surprised myself.
- we only ride in fair weather. The hint of rain or cold and we wimp out.
- planning on changing the drop handlebars to something more urban friendly.

Background.
We live at the top of a hill. Until we bought a Lectric XP Lite for my wife, she walked the bike up the hill. Now she races ahead of me and waits at the top.
So I could either buy another Lectric XP Lite for myself for $799 + tax. Or build an ebike for that price.

Thanks to all your answers, I'm going to price out a 350W hub motor to see if it's going to be competitively priced. And buy new pads and handlebars.

Thank you all

My vote is for rim brakes being just fine, as well. I don't ride in the rain which is a concern with those brakes. But if your tires skid to a stop , that's the best ANY brakes can do.
One update on brakes, word is someone is about to release anti-lock brakes for bikes !

 

[TrevorB]

Thanks for all the advice. In answer to some of the questions:
- this is an old, cheap bike. I'll be very surprised if it has alloy rims
- center pull brakes. I know, I was surprised myself.
- we only ride in fair weather. The hint of rain or cold and we wimp out.
- planning on changing the drop handlebars to something more urban friendly.

Background.
We live at the top of a hill. Until we bought a Lectric XP Lite for my wife, she walked the bike up the hill. Now she races ahead of me and waits at the top.
So I could either buy another Lectric XP Lite for myself for $799 + tax. Or build an ebike for that price.

Thanks to all your answers, I'm going to price out a 350W hub motor to see if it's going to be competitively priced. And buy new pads and handlebars.

Thank you all

For cost of replacing handle bars, seat, stem you could pickup 2nd hand MTB with disk brakes which can be cable operated. Whatever brakes you use will need motor cutoff switch. Cheaper to buy a wheel with motor in it that than rebuild wheel using old rim.
Do all costings before you start as maybe cheaper to buy Lectric same as your wife.

 

[AHicks]

Thanks for all the advice. In answer to some of the questions:
- this is an old, cheap bike. I'll be very surprised if it has alloy rims
- center pull brakes. I know, I was surprised myself.
- we only ride in fair weather. The hint of rain or cold and we wimp out.
- planning on changing the drop handlebars to something more urban friendly.

Background.
We live at the top of a hill. Until we bought a Lectric XP Lite for my wife, she walked the bike up the hill. Now she races ahead of me and waits at the top.
So I could either buy another Lectric XP Lite for myself for $799 + tax. Or build an ebike for that price.

Thanks to all your answers, I'm going to price out a 350W hub motor to see if it's going to be competitively priced. And buy new pads and handlebars.

Thank you all

I built our first 2 bikes, and they were reasonably successful. Since, I shop for a production bikes that come as close as possible to what I am looking for and modify them as necessary. Mods almost guaranteed necessary for riding position for instance. I don't believe you can save enough money doing a quality build as compared to what you can get a production bike for. Bonus: production bike will very likely have disc brakes, an important factor when living on top of a hill.

My vote, buy another Lectric. That bike will teach you a TON, putting you in a MUCH better position to buy or build something nicer later on....

 

[m@Robertson]

Just buy a hub motor kit, service your brake pads and go for it. But since you are doing hills, go for this: A front hub. Low-power, it'll be fine on the forks. And leaving the rear alone lets you keep your gears so you can add power yourself.

Last week on vacation I spent a full day riding around Amsterdam with a zillion other cyclists and I gained a new appreciation of what a PAS-only front hub motor can do on its own. The biggest drawback of a hub motor is it is single-speed and as such is at a big disadvantage on hills. A front hub motor is an aid to the rear, not a replacement for it. Your own pedal effort will keep any traction issues from occurring - which won't happen anyway unless you are on wet or unpaved ground.

Rim brakes are far from ideal but proper pads will deal with the rain issue. As much as is possible, at least (350w is not going to set the world on fire so no need to upgrade to discs even if they are preferable). On my road bike I have Modolo sinterized pads that are unaffected by rain... 1980's technology. Something has to be at least equivalent today.

 

[Balsa61]

Update:
After researching for the past couple of days, I'm not finding a reasonable priced rear hub motor kit. Also, the current trend seems to be 750W and up - definitely not where I want to go.

I had not thought of the front hub motor. That way, I can get assist only when I need it. I'll look into this.

But right now, I'll probably just buy another Lectric XP Lite and save myself time and frustration

 

[JES2020]

Update:
After researching for the past couple of days, I'm not finding a reasonable priced rear hub motor kit. Also, the current trend seems to be 750W and up - definitely not where I want to go.

I had not thought of the front hub motor. That way, I can get assist only when I need it. I'll look into this.

But right now, I'll probably just buy another Lectric XP Lite and save myself time and frustration

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Wouldn't suggest a front instalation as the front fork is not strong enough and is likly to snap at the worst possible time.

 

[Balsa61]

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Wouldn't suggest a front instalation as the front fork is not strong enough and is likly to snap at the worst possible time.

Okay - good to know. Not something I had thought about. I think my options are narrowing to just buying a pre-made ebike.

 

[m@Robertson]

Okay - good to know. Not something I had thought about. I think my options are narrowing to just buying a pre-made ebike.

Your front fork isn't going to snap for the kind of use you are describing. Ebike DIY discussion groups are littered with pictures of snapped forks and the cause is largely well known: The use of high powered motors coupled to suspension forks (they break without warning even when torque arms are used). Generally its accepted not to exceed a 500w motor on any suspension fork, and to be sure to use at least one torque arm on the thing (two is better). If you are doing a 350w motor, its likely going to be 25-35Nm and that is well under any limits - provided you install it smart (i.e. torque arms).

Front hub motors are pretty common on suspension forks in the EU (the ebike I rented just a few days ago in Amsterdam had one), but thats because they are limited by law to 250w ... at low power levels you have no issue - and they are PAS-only. No throttle. We here in the US would rather eat ground glass than use such a low power motor hence the universal shying away from them.

If on the other hand you are installing to a solid fork, you have nothing to worry about period at this power level although you always should use at least one torque arm. A solid, steel fork is by far the preferred solution. I've been using 80Nm, 750w fat motors on solid front forks for years and thousands of miles without issue, although they are part of a 2wd solution so the front fork is not pulling on its own. Even on a steel fork, I wouldn't put one on its own on a big, heavy fat bike. But for a low power bike, now having spent the day riding one and realizing its not the bugaboo (traction) its made out to be, a front motor is ideal for a basic city bike.

 

[harryS]

XP Lite is not a bad value at $799. You get their 5 level PAS. For me, the tradeoff is the one speed. Without a shifter to change, what am I gonna do with my right hand. For others, the tradeoff is the 20" wheel, a true 20" with the 2x2.0 tires, but there is a lot of good in a small bike where I can spin tight circles. I see they offer 20x2.8's now.
For one thing, you and your wife will be well matched in speeds, A converted 26" might not be able to ride as slow.

And any conversion is going to cost at least $799. My wife wheeled home a junker girls bike, against my objections, and to make it meet my standards for my grandaugher's occasional use will mean new tires, new seat, basket, grips, bell, etc, It has cost more than buying new, not that a kids 20" is expensive,

 

[indianajo]

The biggest drawback of a hub motor is it is single-speed and as such is at a big disadvantage on hills. A front hub motor is an aid to the rear, not a replacement for it.

You keep saying that. How on earth do I cross 80 hills, some up to 15% grade, with 60 lb groceries, with a front hub motor? Twice a week in the summer. Must be imaginary. The one gear would pull me up to 26 mph on flats with the 1300 watt ebikeling motor, faster than I want to go.
1000 w Mac12t was great, would drag 330 lb up the steepest hill at 8 mph even if I couldn't pedal (like this month, thank you US Army). It topped out at 23 mph on the flat. This used 500 w bafang 36v (48 v battery) requires a lot of pedaling in 2nd low speed (32:28) to help it up the grade at 1 mph. None of the front motors has done any damage to the steel fork on a 2017 yuba bodaboda or a 90's huffy savannah. I have one torque arm 4" long.
My conversion cost $840 originally but I got a 1300 w motor a 26 A controller & a 48 v 17.5 AH battery. Wore the gears out on that one in ~4500 miles. You can pedal them home with bad gears without drag. Controller lasted 3 1/2 years,$630 battery is still fine at 4 years.

 

[m@Robertson]

You keep saying that. How on earth do I cross 80 hills, some up to 15% grade, with 60 lb groceries, with a front hub motor? Twice a week in the summer. Must be imaginary.
1000 w Mac12t was great, would drag 330 lb up the steepest hill at 8 mph even if I couldn't pedal (like this month, thank you US Army). This used 500 w bafang 36v (48 v battery) requires a lot of pedaling in 2nd low speed (32:28) to help it up the grade at 1 mph. None of the front motors has done any damage to the steel fork on a 2017 yuba bodaboda or a 90's huffy savannah. I have one torque arm 4" long.

Its easy for anyone to understand on their own without having to believe two idiots arguing on the internet:

Hub motors power thru the axle. Therefore they are singlespeed. Anyone: Try and ride up a hill without downshifting. How much fun was that? It sucked, right? Its no more fun for the motor. A hub motor can fight its way thru often times (or not; YMMV) but its out of its element. A motor that can take advantage of the bike's gears gets the same advantage a normal rider gets when *they* shift gears. Even a moderately powered mid drive should be able to go up a hill like its not there (i.e. the motor will not strain itself). The only difference is you will go up slower because of the gear change. But you won't burn out the motor.

 

[AHicks]

Its easy for anyone to understand on their own without having to believe two idiots arguing on the internet:

Hub motors power thru the axle. Therefore they are singlespeed. Anyone: Try and ride up a hill without downshifting. How much fun was that? It sucked, right? Its no more fun for the motor. A hub motor can fight its way thru often times (or not; YMMV) but its out of its element. A motor that can take advantage of the bike's gears gets the same advantage a normal rider gets when *they* shift gears. Even a moderately powered mid drive should be able to go up a hill like its not there (i.e. the motor will not strain itself). The only difference is you will go up slower because of the gear change. But you won't burn out the motor.

This could be worded a little differently and a lot more people would understand the point I think?

First, and this is a really big one. Not all hub motors are alike. There are 2 different types and they offer vastly different performance potential, especially when accelerating from a stop. One has built a built in gear reduction, usually something like 5:1, and it's known as a geared hub. The other has no gears and is known as a direct drive. There's a lot more to each of these types, but suffice it to say the geared hub is far more popular due to it's much sportier performance.

Hub motors do not power "though the axle". Axles are fixed, and you're in trouble if they aren't. This isn't true of both type hubs either "Therefore they are singlespeed.". That's out of context.

Both hub types generally offer the ability to have a multi speed freewheel (6-8 speed most often I think, changed using a derailleur) attached to them to allow you to downshift when climbing a hills.

Mid drives, the 3rd type of drive, do have their place. Because they are able to capitalize on the fact the bike has from 6 to 10 or 12 gears on the rear wheel hub, and the motor drives the bike through whatever gear you are in, these things can really do a nice job in hilly areas. Downside is they are generally more expensive to buy, and they are not nearly as easy to ride as the brain dead simple, get on and go hub driven bikes. I have both types, love them and ride both frequently, but they do have different purposes.

 

[JES2020]

Your front fork isn't going to snap for the kind of use you are describing. Ebike DIY discussion groups are littered with pictures of snapped forks and the cause is largely well known: The use of high powered motors coupled to suspension forks (they break without warning even when torque arms are used). Generally its accepted not to exceed a 500w motor on any suspension fork, and to be sure to use at least one torque arm on the thing (two is better). If you are doing a 350w motor, its likely going to be 25-35Nm and that is well under any limits - provided you install it smart (i.e. torque arms).

Front hub motors are pretty common on suspension forks in the EU (the ebike I rented just a few days ago in Amsterdam had one), but thats because they are limited by law to 250w ... at low power levels you have no issue - and they are PAS-only. No throttle. We here in the US would rather eat ground glass than use such a low power motor hence the universal shying away from them.

If on the other hand you are installing to a solid fork, you have nothing to worry about period at this power level although you always should use at least one torque arm. A solid, steel fork is by far the preferred solution. I've been using 80Nm, 750w fat motors on solid front forks for years and thousands of miles without issue, although they are part of a 2wd solution so the front fork is not pulling on its own. Even on a steel fork, I wouldn't put one on its own on a big, heavy fat bike. But for a low power bike, now having spent the day riding one and realizing its not the bugaboo (traction) its made out to be, a front motor is ideal for a basic city bike.

The fact that there is a known history of front fork falure w/ motors,that should be enough to give a reasonable person concern for their safety.
I personally (being a reasonable person ) would not feel safe knowing this front fork weakness. BTW it's not just the fork that fails , it's the weakness of the drop outs, so that the front wheel departs the rider leaving them to figure out how to ride on only the rear wheel.