Fat bike with QS205

ebike11

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Hi guys...i was thinking on doing another bike build with another qs205 and doing a simple setup.
Do you think a steel fat bike frame with sufficient torque arms to handle the motor power be possible? If so..the rear dropouts would be too wide for the 155mm qs205 so since its a steel frame, could i perhaps use a threaded rod and nuts to tighten and reduce the width slightly in order to fit the motot?
Thanks!!
 
You can order that motor with custom dropout width, if you don’t mind waiting. You could also order the motorcycle version of this motor, that has a wider standard width, thus easier to adapt with simple custom dropout plates design.

If this choice of motor is for speed, you need to know that steel fatbike frames are sh*t. All of them that I have seen at least. I don’t know if a manufacturer somewhere, does make a good one. Generally, fatbikes are not made for speed, not their stiffness, nor their geometry. Yet some very stiff fatbike frames are available. All of them that I have seen are alloy and expansive. If you need suspension, best is to make a custom swing arm to fit a DH bike frame. Same for forks, fatbike forks are not stiff for speeding, and it is much better to use some DH fork that is wide enough to clear 4 inch tires.
 
MadRhino said:
You can order that motor with custom dropout width, if you don’t mind waiting. You could also order the motorcycle version of this motor, that has a wider standard width, thus easier to adapt with simple custom dropout plates design.

If this choice of motor is for speed, you need to know that steel fatbike frames are sh*t. All of them that I have seen at least. I don’t know if a manufacturer somewhere, does make a good one. Generally, fatbikes are not made for speed, not their stiffness, nor their geometry. Yet some very stiff fatbike frames are available. All of them that I have seen are alloy and expansive. If you need suspension, best is to make a custom swing arm to fit a DH bike frame. Same for forks, fatbike forks are not stiff for speeding, and it is much better to use some DH fork that is wide enough to clear 4 inch tires.

Thx for the info as always!
I was thinking on just taking off the front forks and installing DH ones. Id just need the main frame itself since its steel and not aluminum. The rear wheel would be a 17 or 21inch rim with motorcycle tire. I would not be using the fat tires or rims.
I already have another qs205 so custom axle is not gonna work.
Would just the frame of the fat bike be posible to use?
I checked the standard mtb but the width is too narrow on the dropouts for a 155mm motor. Thats why i thought of a steel fat bike
 
What about a longtail for cargo for "no speed no fun" just low gearing slow utility?

Has anyone ever done a "swing arm" design for that?

I guess the rear rack foundation would need to be levered out through the seat post, floating completely independent of all elements to the rear of that point?

 
Im not looking to customize or fabricate coz i have only access to normal hand tools.
Just want a strong frame for the qs205 since it will pit oit a lot of power. Something i can bolt together.
 
The biggest question, what sort of riding, what sort of surfaces, speeds, slopes etc?

80-100lbs of bike likely too, is that OK?
 
john61ct said:
The biggest question, what sort of riding, what sort of surfaces, speeds, slopes etc?

80-100lbs of bike likely too, is that OK?

Ah only street riding and highway..no offroading. Purely for speed on fairly smooth streets
 
MadRhino said:
You can order that motor with custom dropout width, if you don’t mind waiting. You could also order the motorcycle version of this motor, that has a wider standard width, thus easier to adapt with simple custom dropout plates design.

If this choice of motor is for speed, you need to know that steel fatbike frames are sh*t. All of them that I have seen at least. I don’t know if a manufacturer somewhere, does make a good one. Generally, fatbikes are not made for speed, not their stiffness, nor their geometry. Yet some very stiff fatbike frames are available. All of them that I have seen are alloy and expansive. If you need suspension, best is to make a custom swing arm to fit a DH bike frame. Same for forks, fatbike forks are not stiff for speeding, and it is much better to use some DH fork that is wide enough to clear 4 inch tires.

What if i used DNM 8 forks with a standard 2.5inch front tire and installed it only in a steel frame fat bike? I would also have to beef up the dropouts
 
I was looking at the dropouts of a steel fat bike. Its about 200mm.
Qs205 is a 155mm wide motor. If i used 2 steel torque at 1cm on each on the insides that would be 25mm left of space. Do you think I could cold set the frame with a threaded rod and nuts and tighten/squeeze it inward?
Thx
 
ebike11 said:
I was looking at the dropouts of a steel fat bike. Its about 200mm.
Qs205 is a 155mm wide motor. If i used 2 steel torque at 1cm on each on the insides that would be 25mm left of space. Do you think I could cold set the frame with a threaded rod and nuts and tighten/squeeze it inward?
Thx
If you're going to be pedaling, I'd check the chain line before bending anything, to make sure it's going to work out in the end.
 
E-HP said:
ebike11 said:
I was looking at the dropouts of a steel fat bike. Its about 200mm.
Qs205 is a 155mm wide motor. If i used 2 steel torque at 1cm on each on the insides that would be 25mm left of space. Do you think I could cold set the frame with a threaded rod and nuts and tighten/squeeze it inward?
Thx
If you're going to be pedaling, I'd check the chain line before bending anything, to make sure it's going to work out in the end.

Ok thx
Dont think ill be pedaling too much. It will be used as an extra bike to have
 
ebike11 said:
Ok thx
Dont think ill be pedaling too much. It will be used as an extra bike to have

Then you have a lot more leeway. If you are planning on having rear brakes, then if you go with spacers or torque arms on the insides of the dropouts, you'll need to account for that space for aligning your disc calipers, if you need brakes.
 
E-HP said:
ebike11 said:
Ok thx
Dont think ill be pedaling too much. It will be used as an extra bike to have

Then you have a lot more leeway. If you are planning on having rear brakes, then if you go with spacers or torque arms on the insides of the dropouts, you'll need to account for that space for aligning your disc calipers, if you need brakes.

Oh right thx
 
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