Rear derailleur won't shift out

[nccycling09]

I just bought a brand new Trek 520 yesterday and rode it 18.5 miles home from the store without a problem. Today i just went out for an easy ride and going downhill after about 2.5 miles the chain got twisted and i couldn't pedal. I got to the bottom of the hill and fixed the chain and got back on the bike. I had to shift onto the large ring at the back to get started while on an uphill slope. Once i had got going i realized that i couldn't shift back down to the smaller rings in the back. I managed to ride home on the large ring.

I can manually pull the rear derailleur out to get onto the smaller rings when i am off the bike and then get back up to the larger ring without a problem.

Any input or suggestions as to how to fix this would be greatly appreciated.

The derailleur is a brand new Shimano Deore LX with less than 20 miles on it before this happened.

Thanks in advance for any input

 

[daveornee]

I just bought a brand new Trek 520 yesterday and rode it 18.5 miles home from the store without a problem. Today i just went out for an easy ride and going downhill after about 2.5 miles the chain got twisted and i couldn't pedal. I got to the bottom of the hill and fixed the chain and got back on the bike. I had to shift onto the large ring at the back to get started while on an uphill slope. Once i had got going i realized that i couldn't shift back down to the smaller rings in the back. I managed to ride home on the large ring.

I can manually pull the rear derailleur out to get onto the smaller rings when i am off the bike and then get back up to the larger ring without a problem.

Any input or suggestions as to how to fix this would be greatly appreciated.

The derailleur is a brand new Shimano Deore LX with less than 20 miles on it before this happened.

Thanks in advance for any input

Tough to guess without looking at it and getting a feel of the cable.
Sounds like the cable/housing might be involved.

 

[nccycling09]

When i try to shift down the cable goes slack and the derailleur doesn't pull on it at the other end.

 

[daveornee]

When i try to shift down the cable goes slack and the derailleur doesn't pull on it at the other end.

Cable housing pieces are out of whack some place. Follow the cable housing pieces and make sure they are properly seated and not otherwise messed up.
Also check where the cable goes under the bottom bracket grooves.

 

[Retro Grouch]

I just bought a brand new Trek 520 yesterday and rode it 18.5 miles home from the store without a problem. Today i just went out for an easy ride and going downhill after about 2.5 miles the chain got twisted and i couldn't pedal. I got to the bottom of the hill and fixed the chain and got back on the bike. I had to shift onto the large ring at the back to get started while on an uphill slope. Once i had got going i realized that i couldn't shift back down to the smaller rings in the back. I managed to ride home on the large ring.

I can manually pull the rear derailleur out to get onto the smaller rings when i am off the bike and then get back up to the larger ring without a problem.

Any input or suggestions as to how to fix this would be greatly appreciated.

The derailleur is a brand new Shimano Deore LX with less than 20 miles on it before this happened.

Thanks in advance for any input

So why don't you want to take your "brand new Trek 520" back to the store and let them sort it out? If you have a twisted chain link, for example, that should be on them.

 

[maxwellman1000]

It’s possible the cable is too tight on the front [font=&quot]derailleur[/font]….



What I would do is sent it back to the shop u brought it from and let them fix it


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