seatpost rack for battery

[raylo32]

I have an older Specialized Stumper dual susp converted to CYC X1 Pro ebike and want to try to carry the battery on a seatpost rack. I got one on Amazon with a 20 pound rating which should be fine. Battery weighs about 10 pounds and this will be ridden on the street so the forces should be manageable.

The issue is that the seatpost rack angle is wrong. It was clearly made for a more upright seatpost angle than my Stumpy's ~72 degrees (IIRC). Would work better on a commuter or whathever with a steeper seat angle. Unfortunately the rack listings do not specify that angle so it is impossible to know in advance how close they will be. Anyone here have a rack that works on a bike like this and is reasonably level?

 

[raylo32]

I found one that will work. Local Dick's had these in stock, so I drove by to see it IRL and buy it at retail (how 1990s!).

https://www.jensonusa.com/Blackburn-Central-Seatpost-Rack-Black?loc=usa&pt_source=googleads&pt_medium=cpc&pt_campaign=&pt_keyword=&gclid=CjwKCAjwu_mSBhAYEiwA5BBmf8V3oN-AOY4h-iYqAhHyR1sZtuMjGBdBFnJqdyTRUBreJQRfGr41XBoCBDgQAvD_BwE

 

[dogman dan]

Good strong looking rack. Make sure your post is up to it as well. I had one break right off once. After that, I started shoving a broomstick up the seatposts, to give them a bit of time if it cracked, before it breaks off. Do something if the post looks thin and weak. It might be thick and very strong.

I was packing 15 pounds though. 10 should be ok.

 

[raylo32]

Yup, rack is super solid... and the seatpost is a Ritchey so it should also be solid... but it has a lot of extension for my long legs. I dunno... I know this is cantilevered so adds to the stress but the post is probably rated for way more than my 190 pounds. We'll see... I did have a saddle mounting bolt snap off once whilst accelerating hard on a fast road bike ride and the results were not pretty. I just weighed the battery on my people scale which won't be that accurate in that low a range and it was 8 pounds. Standard EM3EV 52V ~13 amp hour Super Shark pack.

Yup, super strong rack.

Good strong looking rack. Make sure your post is up to it as well. I had one break right off once. After that, I started shoving a broomstick up the seatposts, to give them a bit of time if it cracked, before it breaks off. Do something if the post looks thin and weak. It might be thick and very strong.

I was packing 15 pounds though. 10 should be ok.

 

[99t4]

I just weighed the battery on my people scale which won't be that accurate in that low a range and it was 8 pounds.

Correct, common bathroom scales are more accurate in the middle of their range. Weigh yourself, then weigh yourself again while holding the battery. Subtract the first weight from the second and the result is the battery weight.

 

[Chalo]

Nothing good can come of using a seatpost rack for anything heavy or important.

 

[calab]

You got a lot of trust on that rack for the most expensive part of an ebike, the battery.

 

[raylo32]

I agree. Good thing I am not putting anything heavy on there.

Nothing good can come of using a seatpost rack for anything heavy or important.

 

[raylo32]

Unfortunately this bike does not have a good location to mount a battery. No room in the "triangle" for a cased battery or even for a battery bag. I had it mounted under the down tube and did a half dozen rides but ultimately I wasn't comfortable with a few rivnuts holding it. This rack should be fine for road riding. I have a backpack to carry the battery for off road rides.

You got a lot of trust on that rack for the most expensive part of an ebike, the battery.