What do you think about this ladies bike for conversion?

[lindalaw]

Hello,

I want to add a motor to my older Trek aluminum frame cruise . Frame size is 16.5", which Trek classifies as small. 35mm bracket diameter, and 73mm width. I have no experience building e bike, so wondering if you all can eyeball this frame and say whether it looks doable. Would probably mount battery on rear rack. I can get help with the install and am pretty good at learning from youtube, etc. It is not a $$ issue, would just like to keep this bike relevant. Linda

[ncmired]

Hi, and welcome to the forum. I've got a few questions for you that may help us help you better:

1. You list your location(s) as "Florida beach ; North Carolina mountains", which are somewhat contradictory with regards to the bike's overall gearing - is the one or the other location you'd generally more like the bike's gearing tuned to?
2. This is a roughly 10-12 year old bike, is this correct? You may need new tires, brake pads and the like.
3. You wrote, "It is not a $$ issue", but I'm guessing you have a rough figure you'd like not to, or doesn't make sense to exceed - $500, $1000?
4. Have you read anything yet about the most common add-on e-bike motor types, "mid" versus "hub" (or wheel) motors - if so, have you a preference? Generally, hub motors are better on flat terrain, for steep terrains mid-drive is usually considered more preferable.
5. How far / fast do you want to go, hauling how much weight (yup, had to ask)?
6. Do you want the bike to do all the work, or do you just want it to help you on hills or after a long ride?
7. You mentioned "help", do they have any bicycle specific tools - as in, a pair of pliers won't cut it.
8. Adding your own motor means, for the most part, you're on your own when it comes to maintenance and "warranty" repairs. I quote warranty, because it's been a problem to get some of the vendors to stand behind the product.

Almost all standard layout / standard dimension bikes (such as yours) can be electrified, but on your bike in particular here's some negatives:

1. e-bikes can go pretty fast - faster than car drivers expect and because of this we generally prefer the bike to have disk brakes. This negative can be mitigated by riding slower and or cautiously.
2. Your bike's frame down near the pedals (the bottom bracket or "BB" area) may interfere with installing certain mid motor brands (such as the Bafang "BBS" series), which gets back to the terrain you'd mostly be riding in and/or how much you want to spend.

The more info we have, the better we can advise.

[lindalaw]

Ncmired,

Thanks for the itemized reply. The bike will be used for level riding in Florida, casual cruiser mostly paved trails. Although the bike is old, it has little use and has been recently serviced for brakes and gears, tires are good. I would probably limit the budget around $1000, and would abandon project if frame needed serious modification. There are two welded cable attachment fixtures below the bracket that may need to be cut off. I would be willing to do that and relocate cables if the mid drive motor worked otherwise.

I have read about the front, rear and mid drive motors. I have a Trek Townie elec ladies bike with the bosch mid drive motor. I prefer the mid drive for this bike, but would consider the others if mid drive will not work. I would like this bike to preform similarly to the Trek Townie Electra that I already ride. I have a friend who is an experienced bike mechanic and I am willing to buy any special tools that are needed. I am a retired lawyer and avoid relying on warranties as much as possible. as I assess the risk vs. $$ involved before proceeding. This is a project that I consider as a challenge for me, and look forward to completing. I know there can be issues with various bike frames, so that is why I concentrated my question in that area. Really appreciate you spelling out the items to be considering. Linda

[ncmired]

Great! So you've delved into some of the nitty-gritty, like those cable guides. And, you like the Bosch motor - maybe the torque sensing Tongsheng motor would do the trick (a 36 volt motor and battery kit may slide under $1k). The Tongsheng might slot under that BB just dandy-like.

Also, how would you feel about mounting the battery (via the bottle mount screws) on the "top" tube, as opposed to on a rear rack. Yes it would intrude into some of the step-thru space, but the battery weight would be better there.

[lindalaw]

Will look into the Tongsheng. I would prefer the battery on the top tube, I just assumed the curve would create problems I can't solve, and I have not seen photos of that done successfully. Thanks for the encouragement, I will forge ahead, Linda

[ncmired]

On mounting the battery onto the top tube, fortunately that little section of tubing appears straight. If it turns out the battery / bottle mount screws don't place the battery high enough, you can install a Wolf Tooth Components B-RAD Mounting Base under the battery and slide it up some (like I had to do on this bike).

[73Eldo]

I would think a BBS would fit. It will hang down more than some installs but for a pavement bike ground clearance should not be a big issue. Kickstand could get in the way but a rear kickstand should be a way around that issue.

$1000 could be on the thin side but that would depend on what sort of range and quality of battery you are after. There are $300 12ah batteries and $600 12ah batteries.

I have not done a Tongshing but it seems like there are fewer options for those and less of a support community so maybe not the best option for a first build? BBS's seem to be more successful for first builds but don't have a torque sensing option.

Are you building a second bike because they will be in different locations?

[lindalaw]

I am building a second bike for so two people can ride together. I want the battery to have at least a 30 mile range. The $1000 is +/-. Just read up on the Tongshing/bafang lawsuit, seems like they Tongshing might eventually go away when current stock depleted?

[lindalaw]

So, one youtube video shows this exact cable holder being modified and reused, and another youtube video shows a somewhat hard to understand gentleman deciding the bafang motor wont work on a frame that looks alot like mine and he says it is because the chain wont line up correctly?

[73Eldo]

Ok this all makes more sense now. Kinda why I have 4 bikes. On road and off road primarily for me then 2 other bikes in the hopes that I don't have to ride alone so much.

Adding the +/- to the budget is good. $500-700 for the basic kit. $300 for a sketchy no name battery to $600 for something like a Luna Wolf. Probably figure in another $200 or so for some upgrades and tools. Things like brake cutouts, gear sensor, chain ring, and maybe a better display.

Since you have a 73mm BB and are not trying to get the ultimate performance a bbs02 may be worth looking at and Luna happens to have them in stock as I type this. Its just a little smaller, lighter, and cheaper than the BBSHD.

30 miles can be a little much for the smaller batteries. I don't know about store bought bikes but with the middle power level mid drives I like to use 2 miles per amp hour as my rough guide. So a 12ah battery I would feel comfortable planning on a 24 mile ride. That should leave you some margin but does assume fairly flat ground and some pedaling. There are people that barely get 1 mile per hour and others that can get into the 3. 12ah is a common battery. There are usually options in the 14ah range that are just higher quality cells so maybe look for that if you don't want to make the size and cost jump to the 17-21 ah packs.

[Dshue]

This battery, 48v 20ah 200-1500w rear rack battery is $474. The one caveat is that for this brand you must make sure it is sold by UPP OFFICIAL

https://www.amazon.com/UPP-Electric-...p;keywords=uni t%2Bpack%2Bpower%2B48v%2B15ah%2Brack%2Bbattery&amp ;qid=1648700151&sprefix=unit%2Bpack%2Bpower%2B 48v%2B15ah%2Brack%2Bbattery%2B%2Caps%2C122&sr= 8-9&th=1&psc=1

And a BBSO2 with 68-74mm bb and a 500c display and 44t chainring with no battery is $539

https://www.amazon.com/BAFANG-BBS02B...8-3&th=1&psc=1

Grand total is $1,013.
And 30 miles range would be a breeze, you could likely get it with throttle only. I'm sure you could get 30 miles from a 15ah battery in lower pedal assist levels. I love my UPP battery. And the above motor kit is the same seller I bought from. I had a display fail after a month and after showing them the problem they sent me a replacement under warranty.

As far as fitting that frame I think it's doable. Chances are the rear derailleur cable can stay under the bb. But its not a big deal to reroute, just install a new cable with a full outer sheath and route it over the bb.
There are things that can be done to allow the gear reduction housing to clear the rear chainstay. On mine I filed the back of the case to allow me to get the motor against the bb without any spacers. And there are chain rings that can help improve chainline significantly if spacers are required. The Lekkie 42t and the Lekkie 40t chain rings improve chainline over the stock ring by 9mm and 11mm respectively. They come at a price ~$70 and $125 respectively, but they are high quality and offer narrow wide teeth that aid chain retention dramatically.

[Retrorockit]

No disc brakes would be a deal breaker for me. The frame fork and wheels would need to be replaced to get them. Maybe you could get a Fork/Brake/Wheel combo from a Trek MTB to get one on the front. Avid BB7 in 180mm size would be my choice. Short travel forks of offroad quality are hard to find anymore. Ask a bike mechanic how to find one that will fit and not mess up the steering geometry. Many of the short travel XC forks were pre disc brake era. 50-60mm travel disc brake forks kind of came and went in the early 2000's. I consider the comfort bike stuff to be sub standard unless you're talking Gary Fisher or Cannondale. Look for at leat 28mm fork stanchions. The 25mm stuff is weak for E bike speeds. A better suspension seat pot would be part of the recipe also.
I always look at brakes, suspension, and tires first before adding power to a bike. I do these things even if I don't add a motor.

[73Eldo]

Looking at your BB photo I think you will have to re route the cable and remove that cable guide but that isn't a big deal. Looks pretty typical for a bike that age and style for overall design and spacing. I don't think it will be a problem. I don't know that for sure but it looks typical. A BBSHD would likely need some spacers, 02 maybe would fit without due to its slightly smaller gear case? Stock ring is likely a 48 there so you should not have any issues getting the new ring in the same plane as the stock was which should mean no major chain line issues.

I don't own any UPP packs and don't plan to. They have been around for a while and seem to have a pretty even split of reviews that seem to be extreme in both directions either the greatest thing ever or complete garbage that literally blew up. Maybe the note above about getting them from a specific vendor explains some of that? The literally blown up ones especially concern me. Price wise for stated capacity they are on the lower end of things which makes a person wonder where are they cutting those costs? If its just capacity or charge cycles and the buyer doesn't really need either of those to be that high they could be a good value. Or is it build materials and quality?

Don't forget to pay attention to the type of connectors on the motor and battery ends. There isn't really a standard so especially if you are getting things for different vendors or non ebike specialty vendors you may need to get some sort of an adapter cable to connect them.

[73Eldo]

Maybe try to find someone that has a cadence sensor ebike and see if the torque vs cadence is worth worrying about? I don't think it is but I have not spent much time on torque bikes. It may also make a difference which bike is going to be the loaner bike vs the one that the experienced rider rides. The torque sensor is more intuitive because most people can figure out that pushing harder = faster. Not all people can immediately wrap their brains around with how the cadence sensors respond. That's less of an issue on a lower powered bike because they don't tend to be powerful enough to really get away from you. 500-750w BBS02, that could get away from you if you had it up to full assist.

[Retrorockit]

I did a fairly simple TSDZ2 heatsink mod. at Endless Shpere. At 750W it's pretty much mandatory.
https://endless-sphere.com/forums/vi...79661#p1579661
https://endless-sphere.com/forums/do....php?id=293756

There are dozens of other ones here. Some overly technical ,and others oversimplified.
https://endless-sphere.com/forums/vi...?f=28&t=102046
The TSDZ2 is popular in Europe, but many places there have 250-350W power limits.
If you order one without a throttle you can't just add one later. A complete controller swap and rewiring is needed.
The TSDZ2 thread is full of broken parts, and Open Source Firmware modding. Things you won't see much of here in the BBSxx threads