How safe is Co-Motions "InterChange Dropout"? Switch between vert and horizontal
07-21-13, 10:22 PM
#1
Mmm hm!
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How safe is Co-Motions "InterChange Dropout"? Switch between vert and horizontal
I'm thinking about the Co-Motion Nor'Wester but I'm very concerned about the bikes ability to:
To me it doesn't look secure enough/safe with just two little screws holding the rear wheel under the tension of the QR. Does anyone have a Co-Motion w/ this design (all of their bikes use this now) or some other brand that does?
Maybe I'll just have them make me a frame w/ purely vertical dropouts. I don't need a single speed conversion.
"Co-Motion Design InterChange Dropout, converts from vertical to horizontal for single-speed conversion"
Website
Website
To me it doesn't look secure enough/safe with just two little screws holding the rear wheel under the tension of the QR. Does anyone have a Co-Motion w/ this design (all of their bikes use this now) or some other brand that does?
Maybe I'll just have them make me a frame w/ purely vertical dropouts. I don't need a single speed conversion.
07-21-13, 10:39 PM
#2
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A single M4 bolt in Aluminum can safely be torqued to 2 N*m with a maximum of 2.5 N*m. That's the tension on the screw at 2.0 N*m is equivalent to a 250 kg load. That's before you consider that the majority of the stress would be taken up by the frame flexing, not the screws.
If you manage to tear those out with a QR I'd absolutely astonished.
If you manage to tear those out with a QR I'd absolutely astonished.
07-22-13, 12:14 AM
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As a Klein rider since the mid 90's I'll tell you rear facing dropouts are a real pain and probably the only thing on would change.
07-22-13, 08:22 AM
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1) Co Motion has been making touring bikes and tandems (both subject to heavy loads and stresses) for a long time. I think they know what they're doing.
2) The frame is taking the load there. The bolts only have to keep the dropouts snug to the frame. With the hub's axle and QR, holding the dropouts in the proper place, and the dropouts resting against the frame, the bolts are under very little load.
3) Ask Co-Motion. I'd be willing to bet you they've never had a failure of that part, when properly installed and torqued.
2) The frame is taking the load there. The bolts only have to keep the dropouts snug to the frame. With the hub's axle and QR, holding the dropouts in the proper place, and the dropouts resting against the frame, the bolts are under very little load.
3) Ask Co-Motion. I'd be willing to bet you they've never had a failure of that part, when properly installed and torqued.
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07-22-13, 08:59 AM
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In a strength standpoint, how is it any different than most replaceable derailleur hangers?
07-22-13, 09:14 AM
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On oue CO-Motion Tandem, the derailleur hanger does bolt on to the drop out, and the QR goes through it. But there's dropout welded into the frame behind the derailleur hanger.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
