Broken rear derailleur

brenmurf

Hello all, I'm after some advice.
I got my first road bike, a Trek 1.2 with Sora groupset, a few months back and have done a few hundreds miles on it. I was out this morning and I've completely totalled the rear mech. I was on the middle ring of my triple, tried to change down on the back cog, heard a 'clicking noise, then a loud clunk. When I looked down, my rear derailleur was in two pieces, the mech hanger was at right angles and one of the links of my chain bent. With my limited cycling experience but my engineering knowledge, I would say the chain's slipped and caught somewhere in the rear mech, causing the derailleur to seize. I'd like to know is this common and if so, is it a manufacturing fault or a maintenance fault?

I bought the bike from Evans and they don't seem interested so I've decided to take it to my lbs. It's a Trek dealer, 30 miles closer and a lot easier to work with the sales focused 'customer service' team at Evans.

My next question is, and you'll have to pardon my ignorance, I would like to know if its worth the extra few quid to upgrade to Tiagra or 105 on the rear mech? I've always found the Sora quite clunky and plasticky, and never trusted it. I believe they're compatible with the 9 speed cassette.

Any contributions gratefully received, cheers

declan1

A Tiagra or 105 rear mech would probably improve shifting, but so would better indexing.

I've never heard of a derailleur exploding like that before. Maybe there was something drastically wrong with the setup?

brenmurf

It was Evans that did the initial, then follow-up set up and they seem keen to wash their hands off it pretty quickly so there's every chance. Pardon my ignorance but what do you mean by better indexing?

samg123

The only way I'd expect the mech to blow apart like that is from having the chain too short and it doesn't sound like that's the issue with yours considering you were in the middle ring and shifting down.
How very strange.

Indexing refers to how well lined up the dérailleur is with each sprocket.

random man

I had an incident earlier this year where my chain broke and totalled the Sora rear mech. Took it to my lbs and he replaced it with a 105 and I've had no problems.

Edit: also, if you do a lot of miles it'll be worth upgrading your brakeset as well. I've got through two Sora right shifters in two years!

brenmurf

Just off the phone to my lbs and he's quoted me £80 to replace the mech hanger, the chain and fit a tiagra derailleur with a full set up and service. Seems fair enough to me. He's also at a loss to why it happened but he's going to do a bit of an investigation. All this with a 24 hour turn around. I read time and time again on these forums about the difference in service between lbs's and chain stores such as Evans and I have to say in this case, it's totally correct.

I think in future I'll upgrade as something breaks until I can afford a better bike in a years time or so but I'll definitely keep an eye on the brakes and shifters. Thanks for your comments and advice gents, very much appreciated.

bails1310

viewtopic.php?f=40088&t=12870222&p=17784372#p17784372

Your not alone.
My failure resulted in new frame being needed!
Glad u got sorted, like me I will stop immediately if I hear it again

ugo.santalucia

The shifting "feel" is 99% down to the shifters and cables. Derailleurs as new all work the same, then some wear out quicker than others... but really, a parallelogram and a spring is what they all are.. Sora and Dura Ace too