Does this bike have rack support?

[Moto-roto-electrico]

https://i.imgur.com/VSNqDIj.png

I plan to convert this bike into an Ebike with a hub motor and silverfish battery. I intend to put the battery on a rack in the back of the bike. The bike is a Viribus 26" Carbon Steel Folding Mountain Bike with Dual Disc Brakes.


I was looking into seat post bike racks but noticed that this bike seemingly has rack support. I found this rather odd because I have read on Reddit that you shouldn't put a rack on a full suspension bike. However, after looking at the structure of the frame, it looks like with where the rack attachment points are, that the rack will move with the tail of the frame during bumps instead of the tire potentially smashing against the rack.



That said, I plan to make this bike a hybrid road bike. So I will be using it for my daily 10-15min commutes. I do not intend to take it on trails and only plan to load the rack with the 8lb battery/controller and a pannier. I often get some groceries or do laundry but it's just for myself so the max that I'll be carrying is probably around 15lbs maybe 20lbs most and for about 7min otw home.


I mostly bought it because I thought it looked beautiful, the suspension will help stop my seat from wrecking my crotch, and has a carbon steel frame and it'll end up being 10lbs lighter than my previous bike.

 

[amberwolf]

There are a lot of kinds of racks, each with different kinds of mounts. Whether that frame's holes are made for that or not, i can't tell. If they're not threaded, then they're not the type I've got on any of the bikes I've had made for racks / accessories, but it doesn't mean you couldn't use them for a rack--you'd just have to use nut-and-bolt-with-lockwashers to ensure the rack stays in place.

Some racks come with clamp-on hardware for areas of bikes that don't have threaded hardpoints.

Note that any rack mounted to the swingarm is unsprung weight along with everything you carry on it, so the more you put on it the harder the suspension has to work and the worse your ride will be.

A seatpost rack fixes this, but adds significant un-designed-for stress to your seatpost and frame, both up and down as well as sideways, with repeated stresses that can eventually damage the frame under the wrong conditions. Also, not all seatpost racks have well-designed or made mounts, and they can break at the mount itself (base of clamp, usually), under repeated loading.


If you ride on smooth roads or paths with no bumps or rough surfaces at all, neither of those is likely to be a problem.

If you are on bumpy roads or paths, keep in mind the actual weight on the rack and stress on the mounting points is multiplied by the force of going in and out of each bump or hole, and for a cantilevered load like on a seatpost rack, also multiplied by the distance of the load from the cantilever / mount point. This can be several times the force, meaning a 20lb load can become 100-200lbs momentarily, which probably wont' break anything the first time, but over time can overstress the mounting/etc.


Keep your loads as close to the mount point as possible on a seatpost rack and it helps this.

On a regular rack, get one that is "triangulated' or gusseted against side-loading at the rack-side-brackets, and one that does not have "adjustable" vertical mounting tabs for the frame mount (these weaken that mounting point and make it more likely to break there).


In general, Topeak racks are nice, and they have a range of accessories for them including side pannier bags that fold up into the top rack bag when not in use.

 

[docw009]

While it wasn't a mountain bike, I've mounted a rack on a folding bike with similar rear suspension and similar mounting points, and put a battery on the rack. As a pavement pounder, it works fine, although one common fault on many racks that use the tubular front struts is that they work loose til you torque the heck out of the nuts.

The trouble with the silverfish battery is its high overhead in both weight and length. You have the two end pieces which do no good on a rack, and add 3 inches of wasted length. Unless it's a 48 Volter packed with cells, there's about inch of space inside the metal. In fact, on this 36V pack, there's 50 cells in the shrink wrap, but still about 60mm of unused space. On the other hand, the silverfish does have that metal casing. A very solid battery. We use shrink wrapped packs in a battery bag.

 

[99t4]

Those seat stays have attachment points that could serve to mount a rear rack (with appropriate H/W, as AW stated above). Nice feature.

Since you are planning to use the rack for carrying groceries, why not hang the battery from the top tube? On those folders there's a great amount of space there (big open space there under the top tube), as you aren't constrained by the confining interior of a triangle, as in a common diamond frame.

That would help reduce the unsprung weight on the rear suspension, and balance out the weight distribution F/R for better overall handling. Also reducing the weight stress on the rack.

 

[Moto-roto-electrico]

Thank you all for the replies so far. I've learned a lot from this thread.

Since you are planning to use the rack for carrying groceries, why not hang the battery from the top tube? On those folders there's a great amount of space there (big open space there under the top tube), as you aren't constrained by the confining interior of a triangle, as in a common diamond frame.

Haven't received the bike yet but by the dimensions on the site, the distance between the handlebars and seatpost is 21inches and I expect the main top tube to be possibly less than 1/3rd of that. My battery measures out to around 15inches so I think that while I could mount it there I'd potentially lose foldability or would have to hang it at an awkward angle. Will try when I get it though.