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Old 12-01-05, 12:20 AM   #1
Seggybop
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Can I lose the seatstay bridge?

Or whatever it's called. The thing that the rear brake normally attaches to. It's annoying me, preventing me from fitting some fat tires. Would it horribly compromise the structural integrity of the frame to kill it, or can I grind it out? Maybe grind off the sides and then epoxy it in closer to the intersection? I have no rear brake, so that's not a concern.
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Old 12-01-05, 12:57 AM   #2
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I regularly ride a frame with no chainstay bridge. That doesn't answer your question, of course. I would think the seatstay/brake bridge is more important to maintaining stiffness in the rear portion of the frame, but I'm not sure if it's necessary. Maybe a framebuilder will chime in.

What about using a smaller rim? Seems less permanent.
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Old 12-01-05, 01:03 AM   #3
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I could, but the tire and rim I'm trying to fit are each cost more than the whole frame, so I'm attacking the cheapest part x.x''
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Old 12-01-05, 01:03 AM   #4
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Quote:
Originally Posted by Seggybop
Or whatever it's called. The thing that the rear brake normally attaches to. It's annoying me, preventing me from fitting some fat tires. Would it horribly compromise the structural integrity of the frame to kill it, or can I grind it out? Maybe grind off the sides and then epoxy it in closer to the intersection? I have no rear brake, so that's not a concern.
Epoxy? That won't help you in the slightest. Either weld it or don't bother.
Why is it you feel you need "fat tires" Is this some sort of cyclocross conversion gone wrong? If that's the case pony up the cash for a frame intended for the purpose.
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Old 12-01-05, 01:17 AM   #5
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Originally Posted by Raiyn
Is this some sort of cyclocross conversion gone wrong?
Basically ~ I'd buy proper parts, but this horrific experiment has a total budget of $35.79 >_>'
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Old 12-01-05, 04:08 AM   #6
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Quit while you're ahead
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Old 12-01-05, 04:47 AM   #7
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If you really want to , go for it.....bzzzzzzzz, we need pioneers.

we'll all learn from your discoveries or traumatic failures.
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Old 12-01-05, 04:59 AM   #8
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I'd rather not read about someone snapping a seat stay. Thanks
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Old 12-01-05, 05:22 AM   #9
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Thinking about the stresses in the rear fork, seems to me the seat stay bridge does not lend much strength or stiffness to the rear triangle, as long as the attachment to the seat tube is robust, which it is anyway or the frame wouldn't work at all. That bridge is probably only for attaching brakes and fenders. It forms a parallelogram with the rear axle and seat stays, so can't be strong in that direction.
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Old 12-01-05, 05:31 AM   #10
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When I was a wee lad (16 or so) I had an old cruiser frame that came with 24 inch wheels. I had laced up some 26 inch wheels and they wouldn't fit, so I bent the heck out of the seat stay brace to squeeze in the wheel... Never had a problem with it.

Of course, I didn't cut it out, but I don't suspect the piece adds much rigidity.

The answer to one question MAY answer the base question. Do track bikes have this brace? I suspect that a track bike would only have it if it added strength, sionce otherwise it is just added weight for them.
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Old 12-01-05, 08:38 AM   #11
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You could cut out the brake bridge with a hacksaw or Dremel tool. I don't think the seatstays are open to the air with the bridge removed since it is likely just a mitered butt-joint. Just cut the bridge off close to the stays and smooth the cut ends. I'll assume a frame as cheap as your using is both heavy and pretty durable so it won't miss the brake bridge.

However, be sure there isn't a similar bridge in the chainstays just behind the bottom bracket shell. Four of my five bikes have this bridge and it may also interfere with the larger wheel.
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Old 12-01-05, 09:36 AM   #12
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The bridge doesn't do anything. It helps a little when the wheel isn't in, but the skewer is the thing that maintains the integrity.
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Old 12-01-05, 09:54 AM   #13
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Track bikes do have a bridge, just not usually drilled. I believe Don Walker said that when he first started building frames, he decided to build one without the bridge to see what all the fuss was about. Turned out the damn thing was floppier than a wet noodle.
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Old 12-01-05, 10:07 AM   #14
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When the seatstay/seat tube junction fails on a normal frame, the bridge makes the end result much less catastrophic.

Imagine the bridge isn't there, and that junction fails. Where's the seat stay going to go?
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Old 12-01-05, 10:12 AM   #15
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Quote:
Originally Posted by lyledriver
When the seatstay/seat tube junction fails on a normal frame, the bridge makes the end result much less catastrophic.

Imagine the bridge isn't there, and that junction fails. Where's the seat stay going to go?
I can tell you exactly where it's gonna go..
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Old 12-01-05, 11:09 AM   #16
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Also, apart from potential noodliness, removing the brake bridge might change the spacing of the rear dropouts, or, worse, offset the spacing (so it's swung to one side or the other, i.e. not even with the axis of the bike).
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Old 12-01-05, 12:58 PM   #17
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I think in general compromising your frame is a bad idea. However there are lots of valid points about removing it that could beat me in a debate since I am not an engineer or a frame builder, but if track bikes have them that gives you something to think about. Latly, no one seems to have mentioned this, What size frame do you have? If it is smaller i would imagine that it is stiffer and will miss the bridge less. If you ride a big frame then it probably will make more of a difference.
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Old 12-02-05, 01:20 AM   #18
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Reporting back on what I did, I ended up invoking the hacksaw upon both the seatstay and chainstay bridges. This, along with compressing sections of the chainstays with a clamp, has finally allowed me to fit my 700x38 wheel ><

I have no idea how it will hold up now, or how any kind of flexiness will affect the ride. Based on how much I've abused the rear triangle in the past day and how seemingly unaffected it's been by most of it, I don't expect any sudden catastrophic failure, which is probably good enough.

The frame wasn't that bad and I wouldn't normally subject one like it to such hate (80's lugged Schwinn Prelude) but it was already really beat up and sort of bent, so I figured I couldn't make it much worse.
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Old 12-02-05, 06:05 AM   #19
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Just make sure you keep posting on a regular basis so we know you're still alive...
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Old 12-02-05, 07:34 AM   #20
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I did this to a cheap frame in order to fit a 27" wheelset to a road bike. The bridge was deeply notched for clearance, but not eliminated.

I had no problems related to frame failure or lack of rigidity with this particular mod and this particular bike. Every case may be different, with certain frames being built with the bridge as a structural member, others where it is superfluous.

I've seen pictures of very old bicycle frames that didn't use the bridge. They make me curious as to its real purpose.
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Old 12-02-05, 11:09 AM   #21
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If you remove it, I'd clamp on some other support structure further up. When you surpass 40mph going down a hill, you will wish you had gone the extra step. I suspect a bridge will help mitigate failure of the seatstay (which was possibly compromised by removal of the original bridge)

Also sign the organ donor line on your driver's license. And let us know how it works out.
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