Rear rack mounting conundrum with a quick release hub?

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tsujinago

New Member
Dec 5, 2011
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Ann Arbor, Michigan
I'm building a rack mounted bike for my second build, heavily inspired by this lifan rack mount build. I've already mounted the top section to the seat post all fine and aligned, so that's not a problem - neither is acquiring tools, as I'm using my school's auto shop to do this one. However, upon taking off the rear wheel for inspection, I came across a problem - I don't exactly know how I can mount the supporting beams onto the rear axle.



Here is my rear wheel, a standard mountain bike quick release wheel. I've marked the two potential mounting points with red and blue here.

The red part is the part of the wheel held in only by the skewer. It would be easy to mount the beams here, but I'm not exactly sure the thin mountain-bike skewers are up to the job of holding up a 25 pound engine and rack. Sure, they may not have a problem holding my 135 pounds up, but I don't know if mounting there would be smart.

The blue part, on the other hand, is a heavier part of the axle made out of 10mm threaded bit covered by a nut. What I could do there is just use a couple of washers on the inside of the right side to take up space and mount a support beam there and then just take the nut off on the left side and use a couple washers there to mount the left support beam(s) - provided the nuts come off. This would be the more complicated option and I'd worry a bit about the support beams being in the way of both chains, left and right.

What should I do? Red or blue? Will a simple quick-release skewer hold 25 pounds of engine (I mean, it already supports my weight) or will I have to do something a bit more complex? If there is no decisive answer, I guess I'll choose red for simplicity, but I just need to make sure of the strength of that small rod.
 

dtj6ppc

New Member
Feb 23, 2011
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redondo
I'm building a rack mounted bike for my second build, heavily inspired by this lifan rack mount build. I've already mounted the top section to the seat post all fine and aligned, so that's not a problem - neither is acquiring tools, as I'm using my school's auto shop to do this one. However, upon taking off the rear wheel for inspection, I came across a problem - I don't exactly know how I can mount the supporting beams onto the rear axle.



Here is my rear wheel, a standard mountain bike quick release wheel. I've marked the two potential mounting points with red and blue here.

The red part is the part of the wheel held in only by the skewer. It would be easy to mount the beams here, but I'm not exactly sure the thin mountain-bike skewers are up to the job of holding up a 25 pound engine and rack. Sure, they may not have a problem holding my 135 pounds up, but I don't know if mounting there would be smart.

The blue part, on the other hand, is a heavier part of the axle made out of 10mm threaded bit covered by a nut. What I could do there is just use a couple of washers on the inside of the right side to take up space and mount a support beam there and then just take the nut off on the left side and use a couple washers there to mount the left support beam(s) - provided the nuts come off. This would be the more complicated option and I'd worry a bit about the support beams being in the way of both chains, left and right.

What should I do? Red or blue? Will a simple quick-release skewer hold 25 pounds of engine (I mean, it already supports my weight) or will I have to do something a bit more complex? If there is no decisive answer, I guess I'll choose red for simplicity, but I just need to make sure of the strength of that small rod.
When properly tensioned the quick release skewers transfer the support forces to the frame, the skewers then no longer are a supporting force component................Don
 

tsujinago

New Member
Dec 5, 2011
14
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Ann Arbor, Michigan
When properly tensioned the quick release skewers transfer the support forces to the frame, the skewers then no longer are a supporting force component................Don
Cool, thanks for the answer! I guess I'll try fitting the rack and maybe buy a little longer skewer if necessary.
 

lowracer

New Member
Oct 17, 2008
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Charleston, SC
tsujinago,
Glad you like my simple stem/hub mounting system. I'm actually going to be using it to hitch mount a new pusher trailer design I'm working on.
I didn't see pics of your bike from a side view but I'm guessing its a full suspension bike?You can replace the whole quick release assembly/axle with a longer, solid, nutted, 3/8" axle. This gives more strength & the 2 necessary axle mounting points. Personally I wouldn't trust the quick release skewer method only. If mechanically challenged for the job, I'm sure a local bike shop would do it for you at a reasonable price since they wont have a motorized bike being rolled in, just bring the wheel down there...lol
-Lowracer-
 

tsujinago

New Member
Dec 5, 2011
14
0
0
Ann Arbor, Michigan
tsujinago,
Glad you like my simple stem/hub mounting system. I'm actually going to be using it to hitch mount a new pusher trailer design I'm working on.
I didn't see pics of your bike from a side view but I'm guessing its a full suspension bike?You can replace the whole quick release assembly/axle with a longer, solid, nutted, 3/8" axle. This gives more strength & the 2 necessary axle mounting points. Personally I wouldn't trust the quick release skewer method only. If mechanically challenged for the job, I'm sure a local bike shop would do it for you at a reasonable price since they wont have a motorized bike being rolled in, just bring the wheel down there...lol
-Lowracer-
Ah, it's a hardtail bike so I've been roughly using your lifan setup as a general guide in terms of materials for setting up the bike so far (although the drivetrain is going to be set up a bit differently). As for having a 3/8" axle, that sounds like a smart idea for durability and safety - I'll remember to get to that once I'm finished mounting everything up rackside, thanks!

Love your designs, by the way. A godsend for my lack of welding knowledge.
 

lowracer

New Member
Oct 17, 2008
1,319
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0
Charleston, SC
Tsujinago,
Since its a hardtail, you could avoid mounting to the rear axle altogether. Again, no pic but does your frame has a seatstay crossbrace? This area connecting the seatstays is a strong point for a mount (Road bike caliper or BMX sidepull brake attach using one thru-bolt). Could cut a small piece of 1 X 1 X 3/16" angle steel or 1 X 1 X 1/4" angle aluminum a similar width as your top rack and connect from the rear of the top rack to this perch creating a nice strong triangle. Less metal, less weight & rear wheel remains unchanged?
-Lowracer-
 

tsujinago

New Member
Dec 5, 2011
14
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0
Ann Arbor, Michigan
Seatstay crossbrace? It's a single seatstay so here's how I've set it up so far.



I reckoned that if it could hold 120-150 pounds of person on it fine, then it shouldn't have too much troubles with the engine. Ferried my friend around a bit.


There are the disc brake mounts, but I don't know how to use those effectively. I do know, however, that I'll probably never be installing a rear disc brake (although I may install a front in the future)
 
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lowracer

New Member
Oct 17, 2008
1,319
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0
Charleston, SC
Yeah, The small bridge across the seatstays is too far down to use as a mounting point.
Replacing the axle with a solid 3/8" nutted would work best...
Thanks
-Lowracer-