1st e-bike project and a couple of questions

P

pschmatz

10 mW
Joined
Jun 2, 2008
Messages
23
Location
Sammamish, WA
Hello,
I ran across this forum while looking for E-bike conversion kits, and it looks like you've done it all already :)

I'm planning to build a commuter bike for my trip to work (8 miles each way, mostly flat with slight inclines however with a steep 1/2 mile 9% incline at each end of the commute), and I'm looking at a full suspension MTB with disk brakes.
From what I read here I guess I would go for a Crystalyte 408 Rear with disk brake, and a 48V 10Ah or 48V 15Ah battery. (I would recharge the battery once at work, so is 10Ah enough?).

Regarding bikes: I've looked this bike Forge Sawback 7xx (http://www.forgebikes.com/saw7.asp) and while it is a department store bike it has pretty decent comments at mtbr.com.
This bike is 21-speed and has an aluminum frame, and I'm not sure if the swing arm is steel or aluminum.

My questions: Would the M408RD26 from ebikes.ca with a Shimano 7 speed freewheel just fit? I believe space between the dropouts on the bike is standard at 137mm. Would the disk fit onto the caliper, or would I need to be prepared for some adjustments (washers?).

Torque arm: Assuming the swing is aluminum I would want a torque arm, and I wonder if I could just use this one "Phoenix Torque Arm R2" (found here http://www.electricrider.com/parts/motors.htm). Is this likely to fit, or is there no space left anyway on the rear axle?

Thanks Peter
(Seattle Eastside)
 
Welcome to the forum.
a 408 on a 26 inch to 700C (29 inch) will get around 2 miles for every amp hour used at 48V and full power, very roughly. So if your batteries are SLA, you should still get 12 miles between charges at full speed. Much more if you slow down to normal pedal speeds.

you're safer using a 5 speed with a disk brake. 7 speed and a disk will fit in the dropouts, but may not clear the seat stays or chain braces. Mine fits my Kona, but not my Schwinn. As with anything custom, be prepared to have to use spacers to make it fit regardless of what gear set you pick.

As for the torque arms, prevailing wisdom is to use 2. one per side. They fit on the OUTside of the dropouts, between the dropout and the nut.
 
Also welcome. How refreshing to see a newbie that has a realistic commute for an ebike. Unlike those who have to be gently informed that 25 miles round trip without charging at 30 plus mph aint happening, you have an ideal ride for the tool. You should very easily have plenty of range for that ride using good ol cheap lead batteries, and even get pretty good life out of them too. Some of the lower priced department store bikes have steel frame on the rear swingarm. Take a magnet and go shopping. The weight won't bother an ebike. You may end up putting the bike in the tallest gear and leaving it there. Since most of your stops will be on flat ground, you might find front disk, rear v brake good enough. Untill you start overvoting, he hee. You are going to love it, You should see the grin on my face when I pass a big line of cars at the cheap gas station.
 
Say that does look like a nice bike for conversion. I really like the strong gusset on the seatpost tube. Regular racks don't work on rear suspension bikes so you will be hanging about 40 pounds off the seat tube most likely. It's one of the reasons I went to Lifepo4. My cheapo mongoose allready flexes there with 15 pounds on the seat post rack.
 
Thanks Drunkskunk & dogman

For batteries I'm looking at LiFePO4 from ebay (Yesa from missbattery 48V 10Ah, or the 48V 15Ah from ping). I expect to pedal, and contribute around 60-100 watts myself, and want to be able to hit 25mph+ on the flat, and climb the final hills at 10mph without being to sweaty. So with 2 miles per Ah, a 10Ah would suffice, since I plan to buy a charger for the office as well. I'd like to keep the setup as light as possible. (I'm 6' 0" 185lbs)

Regarding the 5 speed vs. 7 speed: Wouldn't a 5 speed need re-indexing of the shifters?

2 Torque arms then on both sides on the outside: Would the Phoenix Torque Arms work, one each side? Or are these designed for a front fork? These look like made from steel and I guess one can bend them into the desired shape. I found a picture mounted inside and outside on a front fork here (http://www.electricrider.com/docs/Crystalyte_Home_Assembly_Guide.pdf - page 5). Do I have enough thread left with the torque arm outside?

dogman: I'd like to keep the disk brake if at all possible, since I don't like the wet performance of my v-brake on my old MTB (and Seattle is known to see the occasional rain..).

Is there a full suspension MTB that is known to work with a rear 7 speed and disk brake? Something in the <$400 range ideally.

Forge also has a hard tail bike with even better components (Forge Sawback 5xx), but it has a 9 speed rear which I believe would not work.

Thanks Peter
 
dogman: Yeah - the rear rack is a bit of an issue, and I would have a LiFePo4 at ~18lbs + the controller 3lbs and bag total around 23lbs. Not much room left for a flat kit or rain gear...

This one supposed to carry 25lbs http://www.amazon.com/Delta-Haste-Quick-Release-Bicycle/dp/B000FGVJEA/ref=acc_glance_sg_ai_-2_3_tit

Maybe a hard tail is the better route?

Thanks Peter
 
For the rear derailer, yeah. you would need one ment for a 5 speed, and a shifter for it as well, OR if the gearset has the same spacing, then you could use the ori9ginal and just remember that either the top 2 or bottom 2 gears can't be used.

Those seat mounted racks that say they can handle 25 pounds, can't. Not long term anyway. The best idea is to double up on the rack, or build something custom. Ypedal and a few others have them, and I'm building one now.

Hard tail bikes have some advantages as far as fitting things, but what you have looks good. only way to know if the 7 speed will work is to try it.
 
Boy I do sometimes forget that for most folks, water does indeed come from the sky! Here we have to mine it like oil. I just meant that it could be worth changing which bike if you could find the steel rear swingarm. But that was before I looked at the bike pic. A good rack will have no problems with a lithium battery. You may want to get the 20ah battery if you buy from ping. The bigger the sise the less chance you have of the controller being too big for the battery and having the bms cut out. You'll love making longer rides pretty quick anyway.
 
Drunkskunk said:
For the rear derailer, yeah. you would need one ment for a 5 speed, and a shifter for it as well, OR if the gearset has the same spacing, then you could use the ori9ginal and just remember that either the top 2 or bottom 2 gears can't be used.
Click to expand...

Does anyone actually use any gears ? I goobered mine into the fastest gear and have never once moved it from there. OK, i take it back, i accidently shifted to the middle ring this morning. Once i figured that out, back to the big ring it went.

I suppose if you have a mechanical of some sort shifting might come into play. But, for me anyways, active shifting never ever applies.
 
5 and 7 speed index gears usually use the same spacing, indexing and chain size! U just have to decide which end of the shifter u want to use. Go to 8 speeds at ur peril! Welcome! It is fun and saves on gas!
otherDoc
 
I too am a newbie. I found this forum after I bought my WE 36V kit and SLA 7ah batteries.
(Thanks to this forum, over clocked to 48V)

When Bill Clinton was running for president, he had a sign on the wall to focus his people. "It's the economy stupid!"

With E-bikes "It's the batteries, stupid"

With "small" AH batteries you will have to pedal more or they will die. I have to start pedaling before I turn the throttle to "save" my power. This is where the low gear comes in. Also, I have to provide most of the power to go up one steep hill. I do it at 10 mph.

After 4 weeks, using great discipline, I can go 20 to 25 Mph on my 8 mile commute.

For a bike rack on a fully suspended MTB. I didn't think about the travel the the rear end would be doing. I just cobbled up 2 flat pieces of metal with 2 bolts on each end to squeeze the seat post. the rack is attached to one of the bolts. It really flexes. I ride on a short section of sidewalk and when the cars clear out I "jump" off the curb. I haven't had problems yet.

I bought a "Watts UP" after the first week. I highly recommend a way of knowing what your power requirements are. You use it to see how much power you use and then can limit your throttle.

I bought my Mongoose off of Craigslist for $50.

I go to work a 10pm.
I went to a safety store and bought a lime green wind breaker with reflector stripes for $22
my next purchase is to buy some POV lights to trick out the bike.

I already have Ideas I want to try on my next bike. (next year)

Tom
 
Dime?

:mrgreen:
 
Welcome to the forum, Peter and PedalingBiped!

Let me see if I can bring this thread back on topic...

Just as a point of reference - I have a 48V 12Ah NiMH pack with a 408 and I can easily ride my 16 mile commute. Although I've never done it....I would think my pack could take me 25 miles on a charge. My average speed is usually 20.x mph (23-26 mph on flats).

Peter, do you get to ride along the Sammamish River Trail for your commute?

pschmatz said:
I wonder if I could just use this one "Phoenix Torque Arm R2" ...
Click to expand...
I'm sure I asked the same question when I started. Unfortunately, these are for front hubs only. That is one of the challenges for folks with rear hub motors - there isn't a one-size fits all torque arm. If you search the forum for "torque arm" you'll see many different styles in use - most are fabricated in some way.

It looks like Seattle is in for a wet June. I recommend buying some full length bike fenders. They really help but today even I took the bus as it there was too much standing water on the roadways.
 
Thanks Jeff: So I would be ok with a 48V 10Ah pack, but might want to go with a 48V 12/15Ah pack also to get more Amps?

Sammamish River Trail: I live aboute 1/2 mile up the hill from Lake Sammamish, and my commute takes around the lake to the north through Marymore Park and up to the MS main campus.
I could use the Sammamish River Trail however it is gravel and you cannot go very fast. Most bike commuters stay on East Lake Sam Pkwy, I will do the same.
Apart from the gas and the exercise, my main added benefit of taking the bike is that I can bypass the daily 520 -> Redmond Way traffic mess by riding through the park. My average speed on my commute when taking the car is 15mph (!), so I guess I can do the same if not better on an e-bike.

Fenders: Yeah - we need those here in the Northwest :roll:

Torque arm: Seems like such an obvious mechanical requirement that I'm a bit puzzle that those don't come as a standard part, even if one doesn't fit all - the kit should simple have some assortment of torque arms which fit most bikes.

I ran across this page, and it looks like this fellow has assorted DIY solutions: http://www.users.bigpond.com/solarbbq/torquearmsandwashers.htm

Peter
 
enough already. :?
I've always like the saying "Seize the day" (Carpe diem)
I posted my thoughts after a 12 hour graveyard shift. mea culpa (I'm guilty) :roll:

If I could spell or do math I wouldn't be a truck driver.

I'll go back to lurking until I can get over my chagrin.
 
PedalingBiped said:
enough already. :?
I've always like the saying "Seize the day" (Carpe diem)
I posted my thoughts after a 12 hour graveyard shift. mea culpa (I'm guilty) :roll:

If I could spell or do math I wouldn't be a truck driver.

I'll go back to lurking until I can get over my chagrin.
Click to expand...

Juz jokin ya... I could care less how ya spmell...

We like most anybody who posts authentic experience and honest questions.
 
MyPC8MyBrain said:
Does anyone actually use any gears ?
Click to expand...
/me raises hand. I use the shortest 6 of my 7 gears all the time: Nexus 7 hub, 48t chainring, 16t cog. That'll let me pedal a 50 rpm cadence at ~8 mph and a 100 rpm cadence at ~35 mph if I so desired.

With regard to the case for a hardtail bike in the context of commuting around Seattle I'd recommend reading my thread. See "Seattle commuter bike" link in my signature. Fenders are absolutely necessary around here, imo. I run SKS Race Blades on my road bike and full fenders on my e-bike.

The last few pages of my thread also have bits on torque arms...

IMG_4589.jpg
 
PedalingBiped said:
enough already. :?
I've always like the saying "Seize the day" (Carpe diem)
I posted my thoughts after a 12 hour graveyard shift. mea culpa (I'm guilty) :roll:

If I could spell or do math I wouldn't be a truck driver.

I'll go back to lurking until I can get over my chagrin.
Click to expand...

Hi Tom,

I only mentioned it because it seemed to be in your signature. I'm not that fussy about typos.... :)
 
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