KomutePunk

Hello everyone, I am new to the forum and to commuting to work by bike. I recently bought a GT traffic 2.0 believing it would be the best bike for my needs and budget but I recently came across a serious issue.

The other night I was riding home around 11:50 pm and very suddenly, after about 4 miles of smooth riding, my rear brake suddenly engaged itself and locked my wheel up. Needless to say going at a decent speed I crashed and received some injuries that have left me unable to even lift a heavy book for a few weeks, let alone what I need to do at work everyday. After I inspected the bike, the rear brake was being fully applied, harder than I could ever squeeze the lever by hand, and the lever was not even squeezed in at all- in fact the wire was so tight it kept me from budging it even a centimeter. I called my wife to pick me up and after knocking it around trying to get it in my wifes car the brake had released, unfortunately I am not sure how. I did not run over any debri, i checked for debri as well while it was still locked, and only hit a few minor bumps since buying the bike about a month ago. I notice the chain had come off after the accident, but i was pedaling just fine and hadnt shifted in a while right before the accident, so that may be from the fall. I cannot imagine why this has happened and have not found any reports of anyone with the same problem. If anyone could shed some light on the incident and let me know what it might be I would greatly appreciate it. Thank you all

trailangel

That is not possible.

dabac

What you're describing just isn't possible for the bike alone.
Brakes are spring-loaded to disengage.
There is no stored energy available anywhere that can pull the brake tight.
And it has internal routing as well.
Meaning getting something to snag and pull on the cable gets very, very improbable.

Only thing I can thing of that doesn't seem entirely stupid is if you managed to pick up some debris that lodged itself between brake pad and rim.
That'd act as a lever, force the pad out and tighten the brake.
And turning the wheel a little rearwards would probably be enough to dislodge it. I've had similar things happen while inline skating. And once managed to lock up the rear wheel by getting a short and stubby pine cone jammed between tire and the fender bridge.
Give both brake thracks a thorough inspection. Such a powerful jam might/ought to have left a trace.

It's marginally thinkable that a brake pad choose that moment to snag the tire sidewall.
But that is usually predated by chafing, sidewall failure and tube blow-out.
Can't see a snag strong enough to lock the wheel up w/o doing serious damage to the sidewall.

SkyDog75

If the brake engaged, something squeezed it or pulled the cable. If something like that happened, whatever caused it should be apparent upon inspection. There are other possible causes for the wheel locking up, like the axle slipping and the tire rubbing the frame or a misadjusted derailleur dumping the chain over the big cog and into the spokes. And again, these problems should be apparent to someone inspecting the bike in person.

Andrew R Stewart 

A common cause of brakes self applying is that the cable gets snagged or pulled by some unknown force. Spinning the handle bars completely around, a bolted on cable hanger shifts, a lock or a rack load contacts the cable.

I guess it's even possible that one or both pads weren't fully tight within the brake arms and somehow have dislodged and jammed up. But without more details or a photo it's mere speculation we can offer. For your safety and peace of mind you should take this bike to a pro who can check things out. Andy.

Bill Kapaun

I'd think you would have had to pick up some debris that jammed things up.