First bike, first ride, chain off.

catkingdom

Hello
I bought a bike yesterday! First bike in years. It was a Gary Fisher Tarpon at about 300.00 Question for you: on my first ride the chain fell off. I believe it happened during shifting, on uneven terrain. is this a sign of poor bike quality, inexperienced shifting or unajusted bike? Is this fixable? how do I do it, or should I see a mechanic at the store?

Bike was bought at International Bicycle in Boston.

catkingdom

Another point to add: the gears got displaced by one on their own, while i was riding on a gravel road.
Now when the counter shows the seventh gear as the last gear.

alfeng

This is a very "fixable" problem ... it is more-than-likely the result of a poorly adjusted bike -- there may be a couple of extra links in the chain which could be removed, too.

Regardless, there are a couple of chainring-rear_cog combinations which invite trouble regardless of good the drivetrain, but more so if everything isn't optimized.

You don't want the chain to be on the largest cog in the rear AND the large chainring at the same time; AND, more so, you don't want the chain to be on the smallest cog in the rear and the inner-most chainring on a triple crankset (the "granny"/third ring) ... these combinations are ill advised because of lateral stress on the chain, but the small-small also combination means that you are also asking the rear derailleur's jockey cage to maintain adequate tension on the chain to prevent it from possibly boucing off a chainring if you are not maintaining constant tension on the chain.

Sometimes, when your chain is on one of the two largest cogs in the rear and you downshift the chain from the middle chainring to the granny, the chain can come off ...

Dropping a chain when downshifting from a larger chainring to the smallest in a crankset (double OR triple) can happen on the BEST bikes if an adjustment is just a little off with regard to the front derailleur's stops ... I was passed by a rider (we were going uphill, but he would have passed me regardless) whose bike appeard to have an 11-21 rear cassette & a Dura Ace (double) crankset ... he dropped his chain when he was about 100 yards ahead of me on relatively smooth asphalt.

The easiest solution is to add a $10+ gizmo which prevents the chain from dropping onto the bottom bracket -- there are at least TWO ... I can't recall what either is called.

But, you should bring the bike back to your shop & have it adjusted ...

THAT's the briefest of explanations ... others will elaborate (probably, more clearly).

catkingdom

Alfeng,
I took your advice, and visited the bike store.
Information you provided is appreciated. The gizmo u mentioned, is that a specific product?

What do you think of my bike choice, GF Tarpon?