Is this bike scoocum enough for 48V 1000W RWDD motor? y/n

General Discussion about electric vehicles.
Post Reply
danielkr
100 µW
100 µW
Posts: 8
Joined: Aug 31, 2017 3:11 pm

Is this bike scoocum enough for 48V 1000W RWDD motor? y/n

Post by danielkr » Sep 06, 2017 11:09 pm

I read the "before you post" post and i know this isn't steel but i do plan to use double torque arms. Would this be safe at 30 MPH with a 170 lb rider and 48 Lithium cells? Would you feel safe pushing it to 40 MPH? I didn't test ride it yet the tires seemed out of air at the shop but it felt comfy - again, low air though so not sure.

I tried to upload the photos and it failed me sorry. This is the google album of photos I took of this bike called Specialized Enduro. I didn't get a full picture of the bike because I was trying to get pics of details like welds and stuff for a guy I know that has over 10 years as a bike mechanic for opinions on sturdiness and general opinion before I decided to ask the forum.

https://photos.app.goo.gl/w3otkeSDOhd8Ltrj2

Thanks,

Daniel

markz
10 GW
10 GW
Posts: 4755
Joined: Jan 09, 2014 11:38 pm
Location: Alberta Canada

Re: Is this bike scoocum enough for 48V 1000W RWDD motor? y/

Post by markz » Sep 06, 2017 11:32 pm

The frame itself doesnt look good for triangle availability, which is good for battery placement.
Specialized is a great company and you are on the right track buying a used bicycle of higher quality then a Bicycle Shaped Object from any department store.

Have you already purchased your motor and controller?

edit - It looks to be a 2005'ish Specialized Enduro Comp
http://1mg.me/image2.aspx?filename=2005 ... g&f=Photos

I'd stay well away from that bicycle, as I mentioned, the triangle above the crank, need space for proper weight distribution of the battery. Plus a traditional spot for a water bottle cage.

danielkr
100 µW
100 µW
Posts: 8
Joined: Aug 31, 2017 3:11 pm

Re: Is this bike scoocum enough for 48V 1000W RWDD motor? y/

Post by danielkr » Sep 07, 2017 10:51 am

I have purchased the motor already, it arrives by Saturday evening. I haven't bought the bike yet, though. The bottle mount points are under the frame (you can see the studs in the photo you linked), is that what you meant by "traditional"? I only ever go about 5 miles at a time, and my superhuman physique allows me to cycle for 15 to 20 minutes at a time without liquid intake, even when pedaling!

How would this work for battery placement -

Image

Not sure it if is clear from the image but it attaches to the seat post and I have had it for about a year, frequently occasionally carrying 12 packs and gallons of milk. I have also lugged 30+ lbs in panniers that are designed to hang from the sides of this rack when grocery shopping.

I have several bags similar to these salvaged from bicycles during a local police department bicycle refresh (only the best when the taxpayers are buying) and they secure atop the rack in the above image. I think they're branded Bontrager.

Image

If you think they're suitable, I would bleach or paint one white for the batteries and secure it to the rack that attaches to the seat post.

Would the weight distribution work on that frame with this rack and bag for batteries mounted to the seat post? Or should I still move on? I'm not meaning to argue I just want to make sure I'm not passing on something with good durability that I can afford if I can safely get past the triangle battery mounting problem. Just to clarify, it is 48 cells, not 48 lbs of battery.

Daniel

User avatar
amberwolf
100 GW
100 GW
Posts: 23954
Joined: Aug 17, 2009 6:43 am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: Is this bike scoocum enough for 48V 1000W RWDD motor? y/

Post by amberwolf » Sep 07, 2017 3:05 pm

I can't see any of the images (attaching them directly to the posts would allow anyone to do so; there is a thread Adding Pictures with various ways of doing this) but there have been a few failures of bikes with seatpost racks.

Sometimes it's the rack that fails. Sometimes it's the seatpost itself. Rarely it's the bike's seat tube (frame) that fails (depends on the frame design and loading).

For instance, Dogman Dan's failure was the seatpost itself, IIRC, leaving him with nowhere to sit for the ride home, while carrying the battery under one arm, riding one-handed. :/ He came up with a brace to fix that and hasn't had problems since, once the load was triangulated https://endless-sphere.com/forums/viewt ... A#p1060023



The problem with seatpost racks is that they are a long lever on a part not designed to take a leveraged load.

The heavier the load, and the farther back that load is (away from teh post), the higher the multiplication of damaging loads.

The problem is not usually with a continous high load, though this can still cause bending or cracking--it's usually the shock loads from curb hopping, potholes, etc. But even just the constant little vibration of a normal road surface is magnified greatly by a load on a lever like that.

Even a full suspension bike still places shock loads from that stuff on the rack.

So keep an eye on the bike itself as well as the rack.


FWIW, there's a lot of posts about racks, problems, and solutions, if you look around.



BTW, one problem you've probably already noted is that weight up high on the back wags the back end of hte bike around while pedalling, and makes it handle less well. So if you can move the weight down low around the axles instead, or up in the middle fo the bike, it rides better.

danielkr
100 µW
100 µW
Posts: 8
Joined: Aug 31, 2017 3:11 pm

Re: Is this bike scoocum enough for 48V 1000W RWDD motor? y/

Post by danielkr » Sep 07, 2017 3:55 pm

That confirms my fears - forcing this purpose-engineered component to serve an additional purpose not in the original design specification might give me problems later. Unless I can come up with some decent triangular support for this battery weight I'm going to need to move on.

Daniel

User avatar
wturber
1 kW
1 kW
Posts: 324
Joined: Aug 23, 2017 8:52 pm
Location: Fountain Hills,AZ
Contact:

Re: Is this bike scoocum enough for 48V 1000W RWDD motor? y/

Post by wturber » Sep 07, 2017 10:16 pm

danielkr wrote:I have purchased the motor already, it arrives by Saturday evening. I haven't bought the bike yet, though. The bottle mount points are under the frame (you can see the studs in the photo you linked), is that what you meant by "traditional"? I only ever go about 5 miles at a time, and my superhuman physique allows me to cycle for 15 to 20 minutes at a time without liquid intake, even when pedaling!

How would this work for battery placement -

Image
That looks like the rack I purchased for my batteries. I felt uncomfortable with the possibility of the rack shifting/spinning around the seatpost, so I triangulated the rack to the frame with a couple pieces of 1" x 0.25" aluminum bar. I figured that would add stability and a greater carrying capacity. The rack is rated for 25 lbs, and my bike has no rear suspension. With those mods, I feel pretty confident in the rack's ability hold my batteries long term.
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
7 x 36v 4.3ah 10s 2P battery packs - Wangdd22 1500W 30A DC Boost Converter delivers 54v and about 1175 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
https://endless-sphere.com/forums/viewt ... =2&t=90369

User avatar
wturber
1 kW
1 kW
Posts: 324
Joined: Aug 23, 2017 8:52 pm
Location: Fountain Hills,AZ
Contact:

Re: Is this bike scoocum enough for 48V 1000W RWDD motor? y/

Post by wturber » Sep 08, 2017 9:34 am

Here's the bracing on my rack. Maybe I should have made the braces longer and extended them further back along the rack's center beam? But either way, I'd think that these braces will shorten the beam cantilever and reduce bending loads on the seatpost substantially - as well as inhibit any tendency for the rack to pivot around the seatpost. I guess the safest thing would be to have a steel seatpost - if you could find such a thing in the right diameter. BTW, I was wrong about the stated rack capacity. It is only 20 lbs, not 25 lbs. Also, I intend to have soft packing around my batteries. That should reduce shock loads to the rack.

Oh - and please forgive the wire rat's nest. The bike is currently in its first phase of the build. I'll clean that stuff up as I finalize placements etc. But I'm pretty sure I'm keeping the controller where it is, so I may shorten those wires and tidy things up this weekend.
rack_braces2.jpg
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
7 x 36v 4.3ah 10s 2P battery packs - Wangdd22 1500W 30A DC Boost Converter delivers 54v and about 1175 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
https://endless-sphere.com/forums/viewt ... =2&t=90369

User avatar
amberwolf
100 GW
100 GW
Posts: 23954
Joined: Aug 17, 2009 6:43 am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: Is this bike scoocum enough for 48V 1000W RWDD motor? y/

Post by amberwolf » Sep 08, 2017 2:52 pm

Any bracing is better than none. ;) Most likely that will be sufficient.


If there's room for a wooden broomhandle or similar to fit very tightly into the seatpost, to fill the space starting above the rack's clamp going down to below where it is clamped inside the seattube, it should add significant stiffness to the seatpost.

User avatar
wturber
1 kW
1 kW
Posts: 324
Joined: Aug 23, 2017 8:52 pm
Location: Fountain Hills,AZ
Contact:

Re: Is this bike scoocum enough for 48V 1000W RWDD motor? y/

Post by wturber » Sep 08, 2017 6:24 pm

amberwolf wrote: If there's room for a wooden broomhandle or similar to fit very tightly into the seatpost, to fill the space starting above the rack's clamp going down to below where it is clamped inside the seattube, it should add significant stiffness to the seatpost.
I'll check to see if I have any dowels or other round wood hanging around that is the right size.

I was thinking (after reading about all the failures of seatpost based racks) that it might also make sense to check all the edges of rack's clamp to make sure that they are rounded and smooth such that they don't dig into the seatpost in any way. I can imagine that an edge scoring the tube could give rise to failure.
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
7 x 36v 4.3ah 10s 2P battery packs - Wangdd22 1500W 30A DC Boost Converter delivers 54v and about 1175 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
https://endless-sphere.com/forums/viewt ... =2&t=90369

markz
10 GW
10 GW
Posts: 4755
Joined: Jan 09, 2014 11:38 pm
Location: Alberta Canada

Re: Is this bike scoocum enough for 48V 1000W RWDD motor? y/

Post by markz » Sep 08, 2017 8:22 pm

OK Then if the bottle mounts are on the bottom of that tube thats fine.

Whats not fine is there is no space between the seat post tube and the headset, its taken up with tubes and shocks.
If you want to ride with a battery on the rear pannier bag, and the controller ontop, it will ride differently because the weight is high up hanging off the rack.

Buy a decent quality bicycle and if you want FS there are better mounting solutions. Look for something similar to this below.
http://www.wigglestatic.com/product-med ... h=1200&a=7

markz
10 GW
10 GW
Posts: 4755
Joined: Jan 09, 2014 11:38 pm
Location: Alberta Canada

Re: Is this bike scoocum enough for 48V 1000W RWDD motor? y/

Post by markz » Sep 09, 2017 3:17 pm


Post Reply