Donor bike for new build\rear hub wheel recommendation.

[tpaktop]

Hi, I'm new and need advice on my new build.
I commute to work around 7 miles each way and 90% of the time it's a pleasant ride on my Trek 7.3
There is one hill I need to attack, but it's nothing big. That is 90% of the time.
Now, on the windy day it can be little bit more work than I want, plus the summer is coming and the things will get worse.
Originally I was thinking of buying ebike, but could not find anything good below $3K.
Rebuilding my existing bike: I'm concerned about the wheels -want something stronger, because there are few rough patches during my commute.
Also, it was my trusted friend during last 5 years - why break something that works?

What I want is commuter friendly bike with some off-road capabilities (if it will come out right maybe I will try some low level mountain biking).
Ability to mount rear fender and Topeak MTX rack is a must. Hate those seatpost attached ones - I want a real rack.
The other important thing is - I want to be able to use it without power.
That is why I had to abandon the idea of using DD motors and mid-drive's - really concerned about the drag.
I lot of people claiming that without the battery their electric bike rides just like regular bike, but I'm yet to hear somebody say - I rode 10 miles today with my motor off.
So far I come up with this set:
Donor bike: Trek 820 http://www.trekbikes.com/us/en_US/bikes/mountain-bikes/sport-mountain-bikes/820/820/p/1008600-2016
Motor: Lynacycle hub http://lunacycle.com/motors/geared-hub-motor-kit-1000w-front-rear/
Battery: Lynacycle bottle 48V http://lunacycle.com/batteries/packs/48v/48v-panasonic-11-5ah-or-13-5ah-bottle-battery/
The thinking is - steel frame is solid enough to handle additional weight of battery and motor, have mounting holes for fenders and rear rack, no drag, battery should give me enough range.
Concerns:
Don't know if the wheel from Lunacycles will be exact fit for Trek 820. Can I just take out the freewheel from original wheel and transfer it to ewheel ?
WIll bottle battery fit on the frame? It looks like there is enough space, but I have no info on minimal required distance between lower bottle mounting screw and bottom bracket.
The wheels will be different, in ideal world I would like to have the matching wheels. Theoretically ,I can take ewheel and original wheel to bike shop and ask them to lace it, so rims will match.
The other way would be to by two nice double walled rims, so bike shop can build 2 nice wheels for me. Not sure how expensive that might be.
Ebrakes: I don't plan on using sensors, just the throttle, but there is still danger of trigger malfuncion - would be nice to be able to cut the power with the brake.
The ebrakes that come with the kit looks cheap and ugly comparing to nice integrated brakes\gear switches.
I hope to use something like that: http://www.greenbikekit.com/hidden-wire-brake-sensor.html

Following guidelines on sticky - here is the filed questionary:
Desired max speed on level ground: 20 mph
Desired max range at what cruising speed: 20 ml
Preferred bike wheel size, or wheel size of bike you want to convert: 26
Brake type of motor wheel: not disk
Rider weight: 210
Terrain:some short hills under 20% grade
Budget: $1500
Location: USA\ VA

 

[Kevin Crawford]

Hello!

I don't understand why your existing bike would be unsuitable, or why you think you'd be breaking it. It's aluminum, right? Should be plenty strong for the performance you're after. A lot of people seem to be obsessed with these high power capabilities... you might be surprised to find, as I did, that even 350W is a lot of assist. My speed requirement was similar to yours, and I used an eZee front motor on an aluminum fork (with torque arm) for many thousands of miles. I learned that there was no reason to use anything more than 350W (7A). More than that saved no time, and only taxed the expensive battery pack more than necessary. You might find that even 250W is plenty, especially since you're already riding without assist. I think you would be just fine this way, especially with just one hill to worry about.

Here's an idea: get a kit with a new front hub motor wheel, which should also be strong enough to placate your concerns about existing wheel strength (at least for that wheel). Then, when you want to use the bike without any assist, just remove the battery and swap the original wheel back in. That will remove the overwhelming majority of the weight added by doing the conversion - I'm thinking roughly 90% for a typical setup off the top of my head. You may have to spend a bit of time adjusting the brake for the different wheel, but you might be able to avoid that if your rims are well-trued and the same size. I would do exactly this if my commute was as short as yours, but since mine is about 16 miles each way and somewhat hilly, I like using my carbon road bike for unassisted rides.

To minimize the amount of time (and times) you spend changing the wheel, you could do something like this, assuming you work Mon-Fri:

Mon: Ride unassisted. Switch to assisted when you get home.
Tue: Ride assisted. Take as much needed stuff as you can with you, to make your unassisted rides lighter and faster (= more fun).
Wed: Ride assisted. Take as much needed stuff as you can with you, to make your unassisted rides lighter and faster (= more fun).
Thu: Ride assisted. Take as much needed stuff as you can with you, to make your unassisted rides lighter and faster (= more fun). Switch to unassisted when you get home.
Fri: Ride unassisted.

This way you still get some good exercise with 2-3 days rest and recovery between unassisted riding, and will only be changing your bike back and forth once. And if you want to do some weekend exercise riding, your bike is ready to go.

Also, keep in mind that if you want your shop to use an existing rim, it must have the same # of spoke holes as the motor. This is easy to overlook. Also, the spoke thickness must be compatible. Another good reason to use a lower-powered setup is that it's more likely to work with a more typical rim (at least without modification), assuming the # of holes is compatible.

 

[tpaktop]

Hey Kevin,
You're absolutely right - 250w will be enough to make my commute more enjoyable. Front hub is easy to install and can be used with smaller battery.
But I really want to keep my existing bike as a regular bike. Once in a blue moon my wifey will ride with me and we always have to cut the ride short, because she is getting tired. I can ride my existing bike and she can ride electric. 26" wheels - I should be able to drop the seat low enough for her to be comfortable.
So, I want to build ebike from scratch and do it right. Make it a project. 1000w motor should be able to add some adrenaline into my blood.
Reasoning aside, what would you buy if starting from scratch? I want it to be commuter + light mountain bike. Probably will be bad in both roles, but I'm not into speed and jumps from the cliffs. Maybe there is a way to find a middle ground?

 

[Kevin Crawford]

I understand. I've only used the eZee so far, and it exceeded my expectations. I think you'd be very happy with it. For me, it did all I expected of it and quite a bit more. I've learned it was more than I needed, and am planning on going with a mini geared motor next. I think going over 500W (10A) is going to be overkill for your commute, and will wear our your battery pack faster. But if you do plan on doing a lot of severe climbing with it for mountain biking, you may want the extra current capability. Still, 10A is typically more than enough, even for climbing. Keep in mind these opinions were formed solely on my experience with eZee, a geared motor. A direct drive motor may perform differently, but the added bulk makes those unappealing to me.

 

[dogman dan]

Well, you won't be getting everything you want on your list. But you are on the right track. I often say that if you like the pedaling that much, don't ruin your favorite bike with a motor.

The trek 820, or similar bikes from giant, specialized, etc are not bad bikes for a commuter. But no reason you could not run an aluminum version with a bit better components on it either, except for price.

The main thing you are fretting about too much is riding with the motor off. That's what you saved the other bike for. On the commute, just use your motor. you can ride a 1000w setup at 200w when you feel frisky. At least 100w will be needed to just eliminate the effect of the weight. A geared hub motor will be lighter, and coast better on the downhills than a DD. But you are wrong that a mid drive will create drag. That's what the freewheel on the back wheel is for.

Freewheel, just buy the kit with one on it. But if you wish, you can remove the one from the 820 and screw it to a geared motor.

matching the wheels. Stop worrying about it. They won't match perfect. So what? But you might want to look at getting a kit with a quality built wheel. It will cost more, but on the extreme low end of kit prices, (even lower than luna I mean) the wheels truly are shit.

 

[tpaktop]

Hi Dan,
I guess the answer to my troubles is between the lines:
Pushing electric bike without the motor is too much - in this case I can just run it low power most of the time and add some more in case of the hill or wind.
If legs doing most of the work battery can last longer (30-40 miles?)
Now, I don't see it's possible with just a trigger - that is the perfect case for pedal assist.
That takes me back to mid-drives - no worries about wheels, tires, e.t.c ...
BBSHD should be the easy install. No drag on downhill, low power mode for 90% of the time.
Capable of doing some mountain climbing if I'll ever get brave enough for it.

How does pedal assist work on the mid-drive?
If it's on the lowest settings, i'm riding 5 mph or let say 1 RPS and its adding 10% of the combined power.
The second I will start pushing harder with my legs - will it just add 10% more to what I push right now or it just have the target speed of 5 mps, so if I'm pedaling faster than that it will do nothing?
If I will push half of what I was pushing before - it will try to keep 5 mph speed?
Not sure what is the logic.

 

[dogman dan]

I'm no expert on PAS, I'm a throttle man for sure. But most PAS just senses rotation, and essentially throttles up if your cadence increases. There usually will also be assist level choices, so level one will not add much power even at high cadence, level 2 adds a little more, and so on. Using the power level button, you can shift the power level much like shifting a gear. Lots of the throttle only kits also have power level choices too. So either type can be put in turbo mode, or hypermile mode. The lower levels are ideal for a ride that has similar effort to a naked bike, but you then get to pull out turbo mode for that hill, or 30 mph headwind.

This sensitivity to cadence is my basic problem with PAS. To me the beauty of throttle is you can set a gear and a cadence (a cruise speed), which your body loves. Then with practice, you vary the throttle instantly to keep your effort and cadence exactly the same all through the ride. I can't sprint anymore, so this is a perfect thing for me. Same effort, same cadence, regardless of the speed I'm going, up or down hills.

I'm sure if I was still young and healthy, I'd enjoy variations of effort like I used to. At one point, I rode sprint and coast from stop light to stop light. But now, I just want to cruise without a sprint making me sick. Steady effort, but not slow with the motor helping.