Buy list: opinions are welcome

[Arbol]

I feel I am prepared to go ahead with my first e-bike project. After thinking about it, I will modify my current bike, a Rockrider 8.1, a bike I feel bonded with from the first time I used it.

Why do I want an e-bike?

1. Use it as an urban vehicle in Barcelona. I want to use the fact that in Barcelona we can ride e-bikes with a motor of up to 1kW if max speed is 25km/h. Stealthiness is key, due to the high number of bike burglars
2. Sometimes, use the e-bike also for fun. But as said, I like my bike a lot the way it is now, so I would like to be able to go back to the current configuration in an easy way

What I have decided (but not 100% sure yet, I want to read your contributions, if you have the time):

1. Bafang CST. This is quite easy, since I want to use the gears of my bike, and the CST is believed to be a good motor in general terms, and xofo does not sell retail anymore
2. Controller: this is when things become interesting. I believe I will go for the S12P (with the kit: http://www.bmsbattery.com/controller/649-s06-250w-imitation-torque-square-wave-controller.html). The S12S is supposedly softer and "better" due to the sine wave vs the square wave of the S12P. But I guess this is only relevant for PAS, which I will not have (see next point). So I prefer to enjoy the 29A of the S12P (vs 22A of the S12S).
3. The key design decision I will make is I will not install either PAS or e-brakes. I would like to have them (especially when riding for fun). But installing the PAS is cumbersome, and e-switches for hydraulic brakes are too new to be fully tested. Also, the number of wires multiplies exponentially, and stealthiness suffers. With only a throttle (thumb or half?), there will be only one long cable. The others (controller-battery / motor connections, and possibly the speed sensor, if the S12P requires it, as the S12S requires) will be contained at the rear rack (http://www.aliexpress.com/snapshot/6040813877.html). Even, I believe I will put the LCD at the rear rack, since I will only use it as an on/off switch (I will not have PAS, so I will not be able to select anything from the LCD).
4. Battery: a 36V15Ah high C-rate of BMSbattery http://www.bmsbattery.com/battery-pack/664-36v-12ah-38140-lifepo4-battery-12-cells-ebike-battery-pack.html

I believe it makes sense to use 36V and not 48V, since max speed has to be 25km/h, and with the 270rpm of the CST, max speed will already be above that, so I will have to limit it through the LCD. Also, within the city average speeds will be lower than 25km/h, so efficiency is going to be better with a 36V battery, I believe.

From the controller kit, I will have a PAS spare, a set of e-brakes spare, and a waterproof cable spare. If in the future I decide not to use this bike in the city anymore, then possibly I will install the PAS, and I will buy an e-switch for hydraulic brakes (hopefully already tested by other forum members, here or at ES). Are the two slots of the waterproof cable ok for any possible e-switch for hydraulic brakes? Or is there the possibility that they do not match?

The advantage of this configuration is I can just change the wheel, take out the rack, put the original wheel, and in less than 1 minute, I have my current bike (plus a throttle, but this is not a problem).

I still need to see how I will hide the battery and the controller in the best possible way, and how I will secure the whole package. I am still thinking about it.

I will buy a few throttles (thumb or half?).

I will buy a rim (http://www.bikester.es/llanta-mavic-ex-325-disc-negro-296836.html), a disc and a cassette, and I will have to have the wheel built (this is what I need, right? a rim, spokes, the motor working as a hub, a disc and a cassette, anything else which I am missing?).

What else? Possibilities:

- Torque arms: are they necessary? As said, I would like to be able to return the bike to the original state, and having torque arms do not fully allow this. Is it necessary to put them? Are the BMSbattery ones http://www.bmsbattery.com/36v/450-a-pair-of-ebike-torque-arm.html good enough?
- Cassette remover tool http://www.bmsbattery.com/tools/659-cassette-remover-tool-.html

Any ideas are welcome.

 

[Deleted member 4366]

You definitely want a torque arm which you can fit tot he brake caliper mount.

You can get the CST ready built into a rim, which saves a lot of messing about, but you will have to dish it to get the rim central to your frame, so get their spoke key as well. I uilt one CST in a high quality rim with eyelets, but the 13g spokes were a bit too tight in the eyelets so didn't sit straight. If you do go for a separate rim, make sure it's suitable for 13g spokes.

http://www.bmsbattery.com/ebike-kits/589-q11-48v1kw-front-driving-hub-motor-e-bike-conversion-kit.html
http://www.bmsbattery.com/accessory/511-thumb-level-throttle.html

If you have a rear motor and a rear battery, the battery needs to be as low and far forward as possible. As you have a hard-tail, you can make your own rack like in my DIY rack thread

 

[Arbol]

Thanks d8veh.

Three questions:

- From the picture you post about the CST being already built into a BMSbattery wheel, I believe the rim is for V-brakes. Can you please confirm it is not a problem to install this rim / wheel into a bike which uses disc brakes?
- I do not fully understand your comment " you will have to dish it to get the rim central to your frame". Does that mean that I will have to tighten the spokes? Or I will have to "reposition" the spokes?
- Unfortunately, I cannot do a rack like yours. The only problem about the Rockrider 8.1 is that, despite the fact of being a hardtail, it has no eyelets for standard rear racks. The only possibility for a rear rack is a seat post rack (like http://www.aliexpress.com/snapshot/6040813877.html). This has been one of the reasons for doubting about using my Rockrider for this project, and I have considered buying a cheaper, second hand bike to electrify only for urban usage. Another possibility would have been to build a triangle box to be fit inside the frame. I still could do it with the configuration outlined in the first post.

 

[patpatbut]

Good to know you want to start the build

Consider this easy kit

http://www.bmsbattery.com/controller/649-s06-250w-imitation-torque-square-wave-controller.html

Hiding colourfully cables helps the stealthiness

The cst kit from Dave is good if you are not confident about wheel build

I know stealth is good but no ebrake is not safe. Considering you run it below 25km/h you might be OK

Do you be able to show the photo of your bike ? Personally I am against using seat post rack for battery but if you can re enforce it that should be OK

Pat

 

[Arbol]

Photos about my bike: it is exactly this model:

http://www.decathlon.es/bicicleta-de-montaa-mtb-rockrider-81-id_8168918.html

You say: "I know stealth is good but no ebrake is not safe". I assume that the risk is the throttle stops working when on, right? Otherwise, if there is no PAS, there is no risk from not having ebrakes, I believe.

It is funny you recommend this S12P kit, this is the one I have quoted in my first post! This probably means this kit is a sensible choice.

From the comments I am receiving, I might reconsider using my current bike, and maybe buying a second hand bike might be a good idea. There are some Rockrider 5.1 (I use Decathlon bikes just for the ease of comparison) for 80 euros, having the possibility of adding a rack, and 7 speed freewheel non-cassette, so a BPM no CST is possible to install (cheaper, it almost self-finances the purchase of the bike). Brakes are V-brakes, so the standard kit could be installed without bothering about hydraulic brakes (but of course, a V-brake is not that good ... I would have to buy the best pads in the market to have the best possible braking power).

This alternative bike would be as the following:

http://www.decathlon.es/bicicleta-de-montaa-mtb-rockrider-51-c1-id_8231773.html

Mmm I knew asking for opinions would complicate things!

 

[Arbol]

Irrespective which bike I am going to use, I believe I will use some box like this one, for example:

http://ca.ikea.com/es/es/catalog/products/00138432/#/00227923

Screw it to the rack (whatever it is, either seat post rack or standard rear rack), put the battery and controller below, and put a flat cover on top of it, screwing to the base. Optically, it would be really hard to find out there is a battery + controller down there.

 

[patpatbut]

Your response is quick lol

For ebrake, if you are using twist grip throttle you might accidentally trigger it when you try to grip the handle bar. Not a problem if you use thumb throttle
Also it seems using it would reduce the wear of the brake
Of course the main concern is sticky throttle might happen under heavy rain

Can I ask why you want to run the bike at 25km/h with
Powerfully setup? (270rpm motor and s12p)

Pat

 

[Arbol]

Your response is quick lol

For ebrake, if you are using twist grip throttle you might accidentally trigger it when you try to grip the handle bar. Not a problem if you use thumb throttle
Also it seems using it would reduce the wear of the brake
Of course the main concern is sticky throttle might happen under heavy rain

Can I ask why you want to run the bike at 25km/h with
Powerfully setup? (270rpm motor and s12p)

Pat

Because bike regulations in my city allow powerful setups (up to 1kW motors), but always if max speed is 25km/h.

Also, for urban usage I believe max speed is almost irrelevant (pedestrians cross bike lanes, etc so speeding is a recipe for disaster), but acceleration is key, since you have traffic lights all the time, so speeding up from 0 to 25km/h is essential to be fast.

In fact, if I go towards the "cheap bike" solution, I will probably choose a BPM @ 201rpm, such that max speed is 25km/h with a 36V battery by construction, without needing to limit the speed through LCD.

 

[patpatbut]

I see. This setup should do nicely in term of acceleration ( 29amp ).

For the choice of the bike, it would definitely easier with the bike (rockrider 5.1 in this case) that has bike rack mount

It means u would lose the disc brake and I do think this is quite important for your case(high torque and acceleration)

The most important is the front brake if you could fit a disc brake there that should be OK. You might need a new fork though

Of course you do not need to do this if you are willing to maintain and adjust the rim brake regularly

Pat

 

[Cyclezee]

I
- Torque arms: are they necessary? As said, I would like to be able to return the bike to the original state, and having torque arms do not fully allow this. Is it necessary to put them? Are the BMSbattery ones http://www.bmsbattery.com/36v/450-a-pair-of-ebike-torque-arm.html good enough?

Any ideas are welcome.

Hi Arbol,

Our Cyclezee V2 extra strength torque plates are now available here
http://www.ebay.co.uk/itm/261430656364?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1586.l2649

 

[patpatbut]

The cheap bike option you just added would lose that acceleration ability you planned at the beginning


The torque arm from John is essential for high torque setup. I got it from him and it is a very good quality stuff

Pat

 

[Arbol]

The cheap bike option you just added would lose that acceleration ability you planned at the beginning

Pat

Why is that? The "cheap bike" would continue having a S12P, a BPM and a strong 36V battery. I believe acceleration ability would be unaffected, or even increased (a 201rpm BPM is probably stronger in acceleration than a 270rpm BPM CST).

 

[patpatbut]

Yes you are right if you are using the same controller.

One thing to add bafang CST uses much better component than BPM so for long term it is better

Pat

 

[Arbol]

OK, then from what you say, possibly a Rockrider 5.3 makes more sense: it has mechanical disc brakes front and rear, and a 9spd cassette. It accepts standard rear rack and it has a decent suspension:

http://www.decathlon.es/bicicleta-de-montaa-mtb-rockrider-53-id_8206682.html

There are a few second hand ones in my city for a bit more than 100 euros. Adding a BPM CST and the S12P kit would be reasonable then, I believe.

 

[patpatbut]

Yes that looks good to me

Would you mind to give us a shopping list before you go ahead?

Pat

 

[D C]

Rockrider 8.1, a bike I feel bonded with from the first time I used it.

I felt the same about my bike before fitting a kit to it, after fitting it the bike felt and behaved completely differently, like a bike i'd never ridden before.
Although I got used to it I never felt at one with it as I had before.
You are considering getting a different bike to fit the kit to and that's what I did in the end, wish I'd done it sooner before the seat post rack cracked the frame, luckily not terminal.
Now I have the best of both worlds, a perfect (for me) powered bike and a light lively unpowered bike for when I'm feeling energetic and want a bit of fun, though at 67 my definition of energy and fun ain't quite what it used to be!

 

[Arbol]

I felt the same about my bike before fitting a kit to it, after fitting it the bike felt and behaved completely differently, like a bike i'd never ridden before.
Although I got used to it I never felt at one with it as I had before.
You are considering getting a different bike to fit the kit to and that's what I did in the end, wish I'd done it sooner before the seat post rack cracked the frame, luckily not terminal.
Now I have the best of both worlds, a perfect (for me) powered bike and a light lively unpowered bike for when I'm feeling energetic and want a bit of fun, though at 67 my definition of energy and fun ain't quite what it used to be!

A wise recommendation. As said, I believe I have to reconsider the bike to electrify. Irrespective of that, though, the questions posed in the first post of this thread about motor / controller / battery remain unchanged.

 

[Deleted member 4366]

Thanks d8veh.

Three questions:

- From the picture you post about the CST being already built into a BMSbattery wheel, I believe the rim is for V-brakes. Can you please confirm it is not a problem to install this rim / wheel into a bike which uses disc brakes?
- I do not fully understand your comment " you will have to dish it to get the rim central to your frame". Does that mean that I will have to tighten the spokes? Or I will have to "reposition" the spokes?
- Unfortunately, I cannot do a rack like yours. The only problem about the Rockrider 8.1 is that, despite the fact of being a hardtail, it has no eyelets for standard rear racks. The only possibility for a rear rack is a seat post rack (like http://www.aliexpress.com/snapshot/6040813877.html). This has been one of the reasons for doubting about using my Rockrider for this project, and I have considered buying a cheaper, second hand bike to electrify only for urban usage. Another possibility would have been to build a triangle box to be fit inside the frame. I still could do it with the configuration outlined in the first post.

This bike didn't have any fixings for the rack either. I made U-brackets to hold it at the front. See the photo below. You just need a strip of aluminium, a drill and a file. I've since discovered that the lower struts work best if they're about 2/3 of the way along the rack to stop it sagging in the middle.




All rims are disc compatible. to be rim-brake compatible, they need flat sides. The motor has the fixings for the disc, so no problem for you.

Dishing means that you have to loosen the spokes on one side and tighten them on the other (about 4 turns of the nipple) to pull the rim closer to one side than the other. You then need to do some final truing. Any bike shop should be able to do it, ut it's not difficult to do yourself. It's a good chance to learn basic bike maintenance skills.