Full suspension custom fat ebike

Hello everybody!

This topic will end with a complete fat ebike, but first things first.
After going back and forward chasing different parts and components, I realized it all starts with the frame. I've been reading all sorts of topics for almost a month now, and I have tons of ideas but I have to slow down a little...

So I'm looking for a steel frame, for durability and safety. Although I wanted a rear hub motor, I had to change the design because I want a internally geared hub, so I'll put a BBSHD on it.

Although initially I didn't want a rear suspension, now I've changed my mind again, for personal reasons. But, now I have to find a frame that has a decent size triangle in the middle so I can fit the biggest battery available. I might build one myself, but I digress...

So, those kind of frames are VERY rare at this point in time. I only found 4 frames and can't decide which has the biggest "hole". I'm not familiar with those types of suspensions either, so please point out flows that are obvious to you.









After deciding, I'll contact sellers from Ali/China to confirm PayPal option, chromoly (those in the picture are sold as aluminum alloy), post mounts for different parts (disk brakes etc.), split frame (yeah, you know why), and other upgrades and dimensions. I'm sick of chains and derailleurs, so don't judge me too hard.

So, which frame do you think is best? Do you have other suggestions based on what I want from the frame?

It doesn't look like any of those frames are for a fat bike...... Can you fit an 80mm or 100mm rim in any of them, 'cause if you can't the final product won't be fat....... Minimum 4" tire to be fat, I'm running 5.8" now front and rear....

Given the way the downtube meets the BB at the front of the tube on these frames, your BBSHD will hang at the 6:00 position and may be low enough to be a clearance issue

It appears that the second (orange) bike already has 26x4.0 fat tires on it, which would make it a great possible candidate for an easy conversion. Am I seeing that correctly?
If so, can you post the link?
Hope this is doesn't derail you too much. :^)

Thanks,
Leelorr

leelorr said:

It appears that the second (orange) bike already has 26x4.0 fat tires on it, which would make it a great possible candidate for an easy conversion. Am I seeing that correctly?
If so, can you post the link?

Click to expand...

Looks like the Salsa Bucksaw.

Here's the Chinese copy.

http://www.aliexpress.com/item/21-Speeds-36V-X12-A-350W-Lithium-Battery-Electric-Snow-Bike-Mountain-Bike-26-Fat-Bicycle/32505300109.html?spm=2114.30010308.3.18.1VD5Ud&ws_ab_test=searchweb201556_0,searchweb201602_1_10017_405_301_507_406_9978,searchweb201603_1&btsid=c346ff62-6936-43ac-ad44-40363296a4f4

Reading a f/s review recently with comfort in mind, I was surprised to hear the reviewer wishing the bike had bigger tyres to offer more comfort.

Fat bikes are generally ridden with very low tyre pressure, so movement in the suspension won't be very immediate. Not unless very soft suspension anyway. You may even find yourself on the rims before rear suspension deflection occurs if the rear is set up for pedaling and the tyre typically flat.


Are you sure you want an f/s fatty?

The bikes are from aliexpress, and one is from alibaba I think... A simple "full suspension bike" gives you lots of bikes, and than you can sort some of them by different criteria. Don't try to search the perfect bike because you'll go insane, like I almost did. When I discovered that the bike I want may reach or exceed 2000 euro, I decided to buy as much as I can from China, and the rest from Europe manufacturers.

@WoodlandHills
After I pick a good frame, I'll ask the seller to confirm that he can provide the correct space between dropouts, chain-stay length etc.
I'm very interested about what you said. So, you had 4" and you weren't satisfied? What is your opinion on the 5.8" ? The thought crossed my mind , but 4" owners seemed happy with them, and 4" is almost a standard.

@Leelorr
Yeah, english is not my native language Sorry. Thank you for stopping by, and welcome to my thread.

@cjh
Yes, that's the one.

@friendly1uk
To be honest I'm not 100% sure, but I can't make a decision based on one review. I've read a lot, and for me, a soon to be old guy that wants an all terrain bike, this seems like the right decision.

I happen to know a Chinese manufacturer who could do you just one bike at the moment, as it is the current production run. Normally you would have to buy 20. Only front suspension but they do have the 750w mid drives in stock to assemble something similar to your request. I imagine 1000 euro's would be ample to fly just one to you. I could ask them, as it is my order they are completing. I won't trade here though, you would go direct.

Something like this, that you could add real forks to if you wanted or have made with some zoom or something.


Note the lower crank to accommodate the big wheels. Using a spread mtb frame will give a very high crank, leading to a high seating position, and a high top tube to drop your nuts onto :S

My 2 cents. find a FS bike that can take a 3" tire. That's plenty fat to float nice in sand, but on rocks, or street, the 3" tire can be pumped up more than a fattie.

If you want a true fat bike, then just a good quality front shock is quite enough.

At first I didn't want rear suspension, because of the complicated design, price, maintenance and so on. But I've talked with guys that had hard tail, and than upgraded to full suspension, and said until you have them both you can't appreciate full suspension, specially when you're 40+ years old. It took some time to decide, and now it seems that I'm right back where I started.

It would be a lot simpler and cheaper to make a hard tail. You guys are killing me...

Yes I'm in the FS camp (whenever possible).
I haven't done a whole lot of reading or riding on fatbikes, but they always struck me as 'fad'.

Now I think I realize their benefits/selling points/etc, and don't immediately dismiss. However, I think the main benefits/design kinda lean towards a true pedal bike, or lightly powered.

When adding an real cargo/rider/equipment weight, when adding any real power, and/or when doing any real speed, it seems to me the main selling points of a fatbike become liabilities. Ie unsprung and expensive-ish fast wearing bike tires.

Yes, a midbuild on one would still be awesome, and moreso with FS, but Imo once you cross lines of combinations of weight/power/speed, the best choice becomes a great frame and suspension, and more common/cheap/heavy duty moto tires. They will last so much longer at a similar price, be safer (can actually be road legal), and any weight penalties get washed away pretty quick depending on your ride demands.

If not moto tyres, I still am not sold on the wide frames and bike tyres beating a solid FS frame and ~3" DH tyres for the majority of use criterium.

OP, I don't think many FS bikes can run over 3" tyres, so if you're definite on 4", definitely start with that criteria, then try for FS and cromoly. Otherwise make frame shape the first criteria, then material and price.
The second one of those does fit closest with what you request, so if no others turn up perhaps get/ride it for a while before lacing an IGH, because you may also want try moto or DH rims and tyres on the bike. Just my 2c, I don't know your level of experience among the bikes!
It comes down to what you want. A powered fatbike would be more for legal speeds and power imo, and even then 3" DH tyres and rims have many more benefits unless you're in some soft sand or something.

No legal limits on my country... yet. No real bike dealer in my area. The closest one is 200 miles away. I'd love to make test drives on different bikes, but I can't...
My previous experience with bikes starts 20 years ago (I'm 40 now), on a cheap bike. I upgraded after a few years to a bit better bike (still no suspension) that I rode until 6 years ago when I gave up because of the stiffness of the bike, shit saddle, maintenance of the chain and rim brakes. Looking back I can't believe I rode that thing for so long.

A month ago I found the Sondors ebike on Youtube and I was stunned. I want to get back in the game. Researching even further I found that all those things that bothered me in the past are just that, the past. The bike technology came a very long way, and I want to have fun again. I want the best, to make up for all those years that I struggled with a shitty bike. Yeap, I'm just a little kid, and I want to have fun The "fat bike" part comes also from the esthetic point of view. I will try to get the best rubbers to compensate the downsides that you mentioned (fast wearing). With the BBSHD 1000W and the biggest battery that I can fit in the frame, all downsides except the price, disappear. I don't want to go fast, I want to go everywhere. I don't want to compete, just ride comfortably for hours.

dvdrwsor said:

I don't want to go fast, I want to go everywhere. I don't want to compete, just ride comfortably for hours.

Click to expand...

Normally I would advocate a mid fatty (like 2.5 tires) but a true fat bike sounds perfect for your criteria.

If you want FS fatbike foe cheap, buy one that is fat already. Mods to a normal FS frame to accomodate 4.0 or 5.0 tires can be expansive in both time and money. It is worth the trouble and expanses though, if you mod a better FS frame than FS fatbikes available. Yet this is for those who want to ride faster and harder, that fatbikes are made for.

I have a couple of fat ebikes, one with 4.00/4.25 tires that is quicker and more nimble and another FS one with the 5.8's that is more of a monster truck. The big guy is off-road only, but by swapping tires, the other is more of a dual sport.


I am not a fast rider off-road: I'm geared to top out at 20mph to be Class 1 legal in California, and I always ride at bicycle speeds, so comfort and the ability to roll over anything in my path is important to me. If I was riding all singletrack at near race speeds then even 4" tires would be too much, but that's not what I use them for. I really want to get deep into the mountains, so range is paramount and keeping the speeds down really helps. If you want to build an electric MXer, then you will probably need cycle tires, but so far I haven't had much tire wear to speak of on my bicycle tires. I buy only the 120tpi versions to get the benefit of going tubeless, but the 35 or 60 tpi tires are a lot cheaper and the stiffer sidewall may be no problem if run with tubes.

Full suspension Fat bikes are simply amazing. However, for going slowly, in any terrain, They aren't always needed or even preferred. At low speeds, a non suspension fat bike is more maneuverable, more responsive, and lighter than a full suspension Fatty. Non suspension bikes allow greater precision on wheel placement when trying to crawl a bike over a difficult obstacle. And a 4" tire is it's own air suspension, so the ride is pretty smooth

Of course, if you want to go fast, or you just want to have a full suspension Fat bike for... reasons... Go for it. You'll likely have to build your own frame, or modify an existing one extensively, but it's worth the effort. Luckily there are fat bike forks on the market now, so that end is easy.

I built my own. It does go anywhere.

Thank you all that visit my thread and give their 2 cents. I'll only reply if I have something clever to say, but rest assured that your comments are appreciated.

@Drunkskunk
Very nice bike you have there. Thanks for the input! Yeah, I met your design and it does make more sense, but I had to let go of it because I want it to look as a bicycle as much as possible. Stealth? Ninja? What's the word?

@WoodlandHills
That monster is be-a-u-ti-ful. Yes, the plan was to go tubeless too.

I think I just found my frame. It is the second bike in my first post, but just discovered something that I overlooked. On the Luna Cycles YouTube channel there's a video of a BBSHD installation:
https://www.youtube.com/watch?v=SmMtUVO5XZA
The last post is mine Watching the video I realized that the seat-stay has a nut and bolt system that allows replacement of the rear suspension shock and could also be used to mount a belt. You can see it clearly on the 1:05-1:07 mark. So that further pushes me to the rear suspension camp, as nutspecial said

Next step, contacting sellers of this bike to confirm PayPal/Escrow, price, chromoly, accessorys, different measurements and futures , etc.

Well, searching for the perfect commercial frame I realized it does not exist (at this moment). There are some that almost fit my needs, but they're too expensive for me to accept their little imperfections.

So, I decided to build my own frame. 15 years ago the government made me take a welding class (long story short, I have a diploma), and I have access to a TIG welding machine (although I'm thinking of buying one for myself).

I plan to build the bike Killer Tomato style. I've already contacted Drunkenskunk and he's willing to help. He confirmed that 4130 is still his preferred frame material, but I've run into a little problem. In Europe there are different standards of steel alloy. There is S235, which is a softer type, and also S275 and S355 which are a harder type. Here they're making roll cages from those steel alloy, so I'm thinking of building the frame with the S275 or the S355.

What do you guys think?