Bicycle Mechanics - Rear Ultegra Derailleur Problem?

Today during my ride I hit a bump on the trail and heard an unusually loud "crack" sound from the rear of my Kestrel Talon. It was alarming enough to make me wonder if I had cracked the frame somewhere, but after stopping and a quick inspection I found no frame problems. I took a closer look at home and the frame is intact, however when I bounce the rear wheel on the ground it seems like the chain is looser than normal and is striking the lower chain stay which appears to be what's causing the "cracking" sound.

I've never torn apart my Ultegra rear derailleur so I'm unfamiliar with its internal components. Is it possible a spring of some sort gave out? The bike shifts OK up and down the gears.

Thanks in advance for any advice.

i'd be surprised if there was something wrong with the RD if it was just a big bump with no other contact. It could have been a bunch of stuff, from the chain hitting the frame to the frame cracking.

Is the RD aligned properly? You could check the RD mount and just make sure it's still seated correctly and all that, although you've probably already done that.

I'd definitely be concerned about the frame/fork/seatpost. I can't find a link right now but i believe that the best way to diagnose a crack in CF is to do a tap/sound test all over the bike after a visual. It's possible that it did crack and it's just below the surface.

Without knowing the size of the bump etc it's hard to say, but i'd definitely start there. If you're confident that that's not the problem just ignore my rambling ;)

i'd be surprised if there was something wrong with the RD if it was just a big bump with no other contact. It could have been a bunch of stuff, from the chain hitting the frame to the frame cracking.

Is the RD aligned properly? You could check the RD mount and just make sure it's still seated correctly and all that, although you've probably already done that.

I'd definitely be concerned about the frame/fork/seatpost. I can't find a link right now but i believe that the best way to diagnose a crack in CF is to do a tap/sound test all over the bike after a visual. It's possible that it did crack and it's just below the surface.

Without knowing the size of the bump etc it's hard to say, but i'd definitely start there. If you're confident that that's not the problem just ignore my rambling ;)

Thank you for your reply. The RD is aligned and appears to be working properly. I'm still spooked that I may have cracked the frame somewhere where I can't see it so I may just take it to the shop and have it checked out by more experienced eyes.

there is a die that can be sprayed on the frame and then wiped off that will show the minor cracks
that is used by metal people to detect minor hair line cracks
you might check with your local metal shop and see where to get a cal but it did sound like a weld
that snapped
good luck

there is a die that can be sprayed on the frame and then wiped off that will show the minor cracks
that is used by metal people to detect minor hair line cracks
you might check with your local metal shop and see where to get a cal but it did sound like a weld
that snapped
good luckKestrel Talon is carbon fiber.

sorry I new I still don't know all the bikes

sorry I new I still don't know all the bikesNo problem. This is how you learn. I didn't mean it any other way. Just wanted you to know what he was dealing with. And so you know, the chain slapping the chainstay sounds just like the frame is cracking. It took me a while to get used to it. I run a compact crankset on mine so when I am in the small ring the chain is closer to the stay so it has a tendancy to hit the stay more often on rough roads.

No problem. This is how you learn. I didn't mean it any other way. Just wanted you to know what he was dealing with. And so you know, the chain slapping the chainstay sounds just like the frame is cracking. It took me a while to get used to it. I run a compact crankset on mine so when I am in the small ring the chain is closer to the stay so it has a tendancy to hit the stay more often on rough roads.

Right you are, sir! I wrapped a cloth around the lower chainstay and bounced the rear wheel off the ground with no sound. Without the cloth, the chain hits the frame with an unusually loud "crack" sound. I've been riding the bike for two years and never before have heard it as loud as I did the other day which is what alarmed me.

Anyway, fortunately I don't have to go frame shopping. :)

Springs can just break. Very unusual for the RD. It most likely would be a defect. How old is it. It could be covered by a warranty. Do you have a spare to try or another bike you can compare the tension of the cage?

that's great news ilmooz! i assume you have some sort of protector on there - my bike has a plastic-like sticker that pseudo protects that part of the frame from the chain in those situations. If it does that a lot you may want to get something a little more robust but it sounds like you're all set

I wrap bar tape around the righthand chain stay. You get to match your bars that way! Plus, you always have extra.

Tire kicked up a pebble and hit something? Happens.