Journal Comments - Crosswinds - CycleBlaze

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From Crosswinds by Paul Krieg

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Paul Krieg replied to a comment by Bob Crosser on Comments on e-assist.


I have just one Shift Sensor on my bike, which is for the rear derailleur. Not shifting on the front so often, I found I could get away with shifting on the front without. Just speed up a little and shift while the bike is "coasting". However, I could see the front derailleur and the chain rings while doing so. Would not hurt to have two shift sensors on a tandem. One for the front and one for the back. That falls under the category of Personal Preference.


4 months ago
Bob Crosser replied to a comment by Paul Krieg on Comments on e-assist.

Thanks again, Paul. I'm going to take some time deciding which motor to go with but I'm leaning toward there BBSHD, which can be programmed as a 750w by Luna (I also read a forum comment that the sticker on the motor days 750w). I'm not sure if I'll need that much power, but it opens up options. More importantly, it is supposed to be a heavier duty motor, which is particularly appealing to me. I'm a big fan of durability. Loctite blue, duly noted. 😉

BTW, I gather the shift sensor monitors one shift cabl. for a 3x9, or any 2x/3x X, wouldn't you need two sensors? If so, any idea if this is possible?


4 months ago
Paul Krieg commented on Comments on e-assist.


As to the charger, a 2 Amp is sufficient. I use a couple of Bafang 2 amp chargers, even on my main batteries. When the big batteries are all the way flat (read 40 volts), it takes about 7 hours to bring them back to maximum charge. During the last few days of my tour, I typically had both main batteries run all the way down, and having the two 2 amp chargers with me allowed me to put them both on the charge at the same time so I did not have to try to get up in the middle of the night to switch the charger from one to the other. I also carried a 15 foot extension cord with me that had a triple outlet on the end. It always seems like motel rooms never have enough wall plug-ins and if they do have an extra, it is always in the place farthest from where you can conveniently park the bike. My extension cord was heavy duty, but I already had that at home, so I used it. No more power than the chargers pull, I would have used a light duty cord if I had had one.

The main concern with Lithium Ion batteries is to NOT charge them TOO fast! You do not want to charge an 11.6 Ah battery at 5 amps. With a 30 Ah battery, that is no problem. You charge a small battery too fast and bad things start happening. With Lithium Ion batteries, slow charging is preferable, because it is better for the batteries and is much safer. Why I suggested to read the publication about DIY Lithium Ion batteries.

Regarding the hills on the Blue Ridge Parkway, I have not been there, but I have heard they are steep. That said, the question remains: Are these hills something you could climb on a bike with a low enough gearing? I guess 5 mph may be about as slow as you want to pedal on a tandem. Typically, an e-assist motor removes the need for the small chain ring. In the case of hills, the small chain ring comes in to play. The faster the e-assist motor spins, the more efficient it is. Lugging an e-assist motor is not recommended. My rule of thumb is: Ride an e-assisted bike the same way you would ride without and you will do fine.

On my tour, I came across a couple of steep hills. One was the detour thru Klondike park, which was a short climb of about 100 yards at about 10 % grade. I started up in bottom gear and ended up having to shift UP a couple of gears (and durn near fell over because the bike almost came to a complete stop, and lugged the motor a bit getting going again in the process). Did 5 mph all rest of the way up. The other was in Jefferson City in a residential area. This hill was every bit as steep and about three times as long. I rode all the way up, but I was huffing and puffing when I got there. It was steep enough I was hesitant to shift to a higher gear, so I left it where it was when I started. The motor stayed with me the entire way up in both cases.
(Having said that, I did see some streets on hills in Hermann, MO that were so steep I was scared to ride down them, much less attempt to ride up.)

My point being taking hills on a bike equipped with e-assist will take some practice so you will know about where you want to be for any particular hill. And having a motor with an extra 250 watts would make it easier, for sure. I have always associated 1000 watt e-assist motors with mountain bikes........but that is just me.

When I first got to the rollers in eastern Kansas, it took me most of the first day to figure out what gearing to use in tackling them. After that, it was no problem. I found I had an easier time shifting to a lower gear under load than to a higher gear. I would ease off pedaling about the same time I did the shift and the Gear Sensor would interrupt the motor and I got a smooth transition.

The aluminum spider you see in the images on my bike I made out of a RH crank. I cut the actual arm off and then machined the "arm" portion to match the rest. On the Bafang motor, the main spindle goes all the way thru the motor and it has the square taper on each end for mounting the crank arms. The actual chain ring is attached to an outer shaft that is driven by the motor once the movement of the cranks registers on the sensor. (Near as I can tell, the Bafang unit is activated by a movement sensor rather than a torque sensor.)

Because I mounted the motor under the seat, the mount was constructed such that the motor was as far to the left as possible to maintain a straighter overall chain line. With that set up, I did not need to install crank arms at all, just the RH crank arm spider. All that remained was to make those stainless chain ring "nuts" to position the outer chain ring closer to the inner.

One last item: Always use blue thread locker on the fasteners associated with a motor installation. When I first set up the motor on my bike, I was expecting I would have to take it back off at some point before my tour, but that never happened and I forgot I had not applied thread locker to the two bolts holding the clamp-on BB shell in place, nor did I apply any to the locking ring. After 3,000 miles, those items worked loose and I started having problems on a Sunday in far western Missouri and eastern Kansas.......and I did not have an English (1/4") allen wrench. The only two English bolts on the entire bike and I did not have a wrench! There were auto parts stores in two of the towns I went thru (where I could have purchased an English allen wrench set), but, being Sunday, they were not open. I had planned for every thing else but that, and Senor Murphy picked THAT day to put in an appearance.


4 months ago
Bob Crosser replied to a comment by Paul Krieg on Comments on e-assist.

Wow, thanks so much. That is incredibly helpful, Paul. Definitely not too much info. I was glad to see that the Bafang system works well and is reliable.

You've answered a lot of questions I had and some I didn't know enough to ask, 😁. I had noticed in your you were using a non-standard spider, and I think I've read a bit of the DIY battery guide (that was a while ago, so I wasn't sure we're I'd found that). I'm going to reconsider there 750w system as well, though we're at least 100 lbs heavier, and might ride in a hillier area (we did a very little bit of riding on the Blue Ridge Parkway last summer and we ran into more than a few hills that we couldn't handle).

BTW, what charger do you use? Some of the Bafang vendors offer a 3a quick-charger, and I read somewhere in there battery literature that they can be charged at up to 5a (though I haven't seen anything higher than 3a, and I know with other battery technologies, faster charging leads to shorter battery life).

Thanks, again.

4 months ago
Paul Krieg replied to a comment by Bob Crosser on Comments on e-assist.

Bob: this may be a bit more information than you want, so, take what you want and ignore the rest.

Mounting a Bafang e-assist motor on a steel frame tandem is doable. The Bafang motor assembly will install directly onto/into the bottom bracket as a self contained unit, which is held in place by a "D" shaped plate bolted to the motor housing in two places and doubly secured by a lock ring that threads on to the "off" side of the housing that fits thru the BB. You will have to adjust the spacer on the front loop idler to conform to the new chain line, but that is not really an issue.

When set up with a few of the aftermarket components available, you can make it a very slick set up. Mounting the motor on the front BB is how you would want to do this, with the motor mounted "under" the main tube. As to the 1000 watt motor, I think that would be overkill. I have seen a couple of RANS Screamer tandems set up with 750 watt Bafang motor kits that seemed to work fine. Also, on my tour using the 750 watt motor, I seldom had the assist setting higher than level two.........and that was with a full combined load of rider + gear + water of 380 pounds. Keep in mind the 750 watt motor is street legal, but the 1000, maybe not. Check up on that rule where you live.

You will need some after market components to make a nice set up.
Very nice battery mounts are available from T-Cycle (Terra Cycle) in Portland, OR. Also, you will need to provide some kind of mount for a torque bar on the front end, and a T-cycle 2" diameter idler mount clamp will work very nicely. A torque bar need be nothing fancier than a piece of 1/8" x 1/2" flat stock from a hardware store cut to length with the correct diameter hole drilled in each end, with one end bolted to the clamp around the main tube on the bike frame and the other bolted onto the motor housing. The battery mounts I have seen on the Screamers were under the stoker seat. On a Seavo, that might not be doable, because of the brake and rear derailleur cables being in the way. That being said, T-Cycle may have a battery mount for that particular bike. Also, the chain rings available for Bafang motors that I have seen are either 44, 48 or 52 teeth. That may play hobb with your timing chain. The IPS set ups I have seen usually had a 38 or a 39 T chain ring on both ends. However, there are aftermarket spiders available at EMBev:

You can select the spider for the motor you eventually select from their "California E-Bike" selection, which are available with both 4 bolt and 5 bolt installs. I have a "California E Bike" 5 bolt 110BCD on my bike now. After about 3,000 miles, the stamped steel, 48 tooth metal Bafang chain ring that I was using originally started showing some wear. With one of the aftermarket spiders, all you have to do is replace the worn chain ring itself. The California E-Bike spiders are very precisely machined, to the point you will more than likely will have to remove material from the inside diameter of whatever chain ring you select just to get them to fit on the spider. I used an oscillating drum sander to perform that task for my bike.

You will also want a Gear Sensor for use on the rear derailleur cable. This unit mounts between the shift unit on the handle bar just down from the shifter and is connected to the main controller with a "Y" connector. The Gear Sensor cuts power to the motor while you are shifting so you do not do any power-on shifts.

The Screamers I have seen had narrow handle bars, and a separate "T" accessory mount was attached to the riser for the display unit. Also, keep in mind the Bafang display unit is not very tolerant of rain, so, you will want some provision to protect it from rain.

Another item you may need is a control cable extension about 18" long. If you do the install in the winter, wait and see if you actually need that extension before ordering. Those are available on line. Lastly, there is a braided "cable wrap" that is available that can be used to make all the wires and such more "presentable". Look on line for "braided nylon cable sleeve".

Once the motor is installed, you have to program the thing, but, there are videos on line that tell you how to do that and what all can be done. I just did a default set up.

Regarding what size battery to purchase with the motor kit, it all depends on what you want to do. An 11.6 Amp hour battery on a tandem will probably be good on a tandem for about 40 miles if you are conservative. If you are looking at loaded touring, then perhaps a 17.5 Amp hour battery (with maybe and extra packed away somewhere) will fit the bill. The bigger the battery, the greater the weight, but remember: the battery and motor carry themselves. An e-assist motor is like having 1, 2 or 3 extra friends along on the ride. All they do is help pedal, they never grumble or complain about the hills or the headwinds, are never thirsty, and all you have to feed them is electrons at the end of the day. My set up was good for about 130 loaded miles. My battery set up had power left at the end of the single 98 mile day I rode. As for me, I was exhausted and ready to stop at the 90 mile mark, and I had been on the road for three weeks at that point.

As to where to purchase the motor, you have several options. Getting the kit from China costs about the same as making a purchase from some stateside dealer, you just have the extra time in transit and maybe a bit more in shipping costs. The two places I have done business in the US had different connectors for battery charging, to make it difficult to use a charger sold by "the other guy".

One last item to consider is a golf cart volt meter. One example is:®-Digital-Battery/dp/B008LO3FAO/ref=sr_1_14?keywords=48+volt+golf+cart+battery+meter&qid=1574622285&sr=8-14
This is similar to what I got for my bike. The controller on the Bafang unit is set up to shut off at 40 volts. These golf cart meters typically will register from 0 to 60 volts DC. With a full charge, the Bafang battery pack will generally register 53.2 to 54.6V, just depending on the age of the pack. The volt meter is a better indicator of the battery level that the read out provided in the Bafang display unit. Just know, the battery will start getting anemic around 42 volts, and at 40 volts, the controller will shut the system down. These meters can be mounted anywhere out of the way and do not necessarily have to be on the handle bar. On a tandem, there is no reason not to mount it where it can be read by the stoker.

A volt meter is also handy for monitoring the state of the charge on the battery as well. When new, Lithium Ion battery packs have to be charged up to 100% (54.6V) the first half dozen times you use them to balance all the individual cells in the pack. Provides for better battery life. After the first half dozen charges, you can do lesser charges, say 80 to 90 %, if you are not gonna be riding every day. While on tour, my two main batteries got a 100% charge and the "reserve" smaller battery only 90% every night, because I was for sure going to be using both the main batteries the very next day.

Lithium Ion batteries do not like extremes of heat......not too hot and not too cold. Seems like the temperature range in which they do best is 40 to 120 degrees F, which means bring the battery pack in the house in the winter. Speaking of winter, when not being used on a regular basis, the battery pack is best stored at about 80% charge. So, with a Bafang charger, if you want an 80 % charge, just unplug the battery from the charger at 48 volts.

For more information on Lithium Ion batteries, see: DIY Lithium Batteries, by Micah Toll. Even if you are not planning to construct your own battery packs, this publication is full of information about the do's and don'ts of Lithium batteries. The information provided in this publication helps clarify the importance of correct charging and general battery care. Knowledge of the charging phase is most important.


Hope the above answered some of your questions.

4 months ago
Bob Crosser commented on Comments on e-assist.

I stumbled across your blog from a link on the Rans blog, and I really enjoyed it. Your addition of the Bafang e-assist really got my attention because I've been mulling one for our bike (the 1000w unit, since we're a tandem...and, I'm, not light).

Last March, I bought a well cared for used Seavo that my wife and I have fallen in love with. I haven't seen a Bafang unit in person so I'm not sure exactly how it mounts, but I've thought it probably would be possible to mount it to the front crankset and leave everything behind that alone (our Seavo has the Sync/timing chain on the same side as the primary chain, FWIW).

Based on your experience, do you foresee any problems doing this? Any tips, advice, and suggestions you might offer would be appreciated.


4 months ago
Jeanna & Kerry Smith commented on Post Script

Hey Paul,
Congratulations on your trip - I really enjoyed your journal as it brought back a lot of memories. We have ridden the KATY twice - a round trip a few years back on our singles and then a one way E-to-W in 2018 on our Seavo.

On another topic, I'm ordering a Phoenix for a trip from FL to WA and would like to pick your brain about some options. I neglected to get your email address last year, so if you wouldn't mind, would you send me an email so I can write to you about it?

Kerry (and Jeanna) Smith

5 months ago
Steve Miller/Grampies commented on a photo in Day 22 Almost Century Day

Yup, we can remember 1969, on our first long road trip, when we shuddered at gas prices greater than 35 cents a gallon.

5 months ago
Kathleen Jones commented on Day 23

Nice adventure. Thanks for taking us along.

5 months ago
Bill Shaneyfelt commented on a photo in Day 22 Almost Century Day

I remember DX stations from when I was a kid!

5 months ago
Bill Shaneyfelt commented on a photo in Day 20 Leaving the river

Nice shot! Looks like a black rat snake.

6 months ago
Paul Krieg replied to a comment by Bill Shaneyfelt on a photo in Day 19 Shuttle day

I saw the bug fly up just as I was about to click the shutter. I actually got him in the first image, but this was the better of the two.

6 months ago
Bill Shaneyfelt commented on a photo in Day 19 Shuttle day

Oh, I like this shot! Photos with critters on flowers are wonderful!

Flower is some species of fleabane. Can't tell about the bee.

6 months ago
Holly Willeng commented on a photo in Day 14 Rest Day

This brick work is spectacular. I wish people would take this kind of time and effort now, we have better tools and less skill.

6 months ago
Bill Shaneyfelt replied to a comment by Paul Krieg on a photo in Day 12

Interesting about birch. Had not heard that. Hope I can find that in my old brain when/if I need it!

Here is an interesting poison ivy info. link I ran across. Not sure how much is useful info. but interesting anyway.

6 months ago