What could be wrong with my bike?

Question

I had been riding a new bike for a week and notices that ocassionally while pedaling, it feels like my chain gets loose and skips for a second. This doesn't happen too often, only about 3-4 ocassions on a 24-mile ride. I know it is not actually coming loose because I continue pedaling and is able to keep going. I want to know if this is not something to be concerned about or does it need to be checked? I hope you get the idea of what I am trying to explain about my bike situation, I do not know how to explain it any better.

Answer 1

Several possibilities. All mean you must get the bike adjusted again at shop. It is normal for new bikes to need adjustments in first few months.
1) Your rear derailer must be adjusted. The adjustment screws at the rear are set incorrectly. Take it back to the shop to check.
2) The chain is too short.
3) The chain rings (front sprockets) are bent. You might have to argue with the shop to get them replaced under warranty.
4) The rear wheel is badly out of true (not round) or misaligned. Have someone hold up the rear of the bike while you spin the wheel, looking from back. Check for any side to side movement, especially where the brake pads are close to the wheel rim. There shouldn't be any lateral movement if it is a quality bike.

Good luck!

Answer 2

Once per hundred miles is acceptable for non-matched components.

For a new and factory-condition bike, this is never acceptable behavior. It indicates future foul behavior when the parts do get worn.

You might check your chain to see if it has "Shimano" or "Sram" written in tiny print. Most Shimano will also say "HG" as in Hyperglide. If you have any of these marks, it is good news.

However, if you have a "Z" or "KMC" or some weird off-brand, I'd suspect that as the culprit of the behavior.

Your chain could be an inch too long. That does not cause a skip, but it can irritate a system that already has a problem.

Your chainrings may not be completely straight. Check by taping (Painter's Tape!!) a wooden ruler to the bike frame straight out so that it touches the chainring. Turn the cranks. Well, look and see if the chain ring is straight and if it isn't get it close to straight with a 10" adjustable wrench. Remove the ruler.

The rear derailleur has FIVE alignments:
1) Cable length
2) Low limit ("H")
3) High limit ("L")
4) The "B" screw (clearance from biggest cog--prevents "bumpity")
5) Angle (There's no screw or dial)

You might take it to the bike store and have them unscrew the derailleur to check the (#5 above) angle of the derailleur hanger. This can help avoid "mystery" problems in the future.

The rest of the alignments are all extremely easy, and a cyclist from the road club or mountain club could do it for you in 3 minutes. The bike store can also do the regular alignment.


In the case of the "Toy Department" bike, the rear derailleur could be of such foul quality that it is not even used in the country of its origin. Easy enough, just replace it with a Shimano Tourney TX50 or TX70 (about $18) rear derailleur. This is the derailleur that would be on that bike if that bike were intended to work right.
These are strong and reasonably precise. They are available in "clamp on" for very cheap bikes or in "bolt on" for reasonable quality bikes. You'll also need a reasonable quality gear cable, not the brake cable that attempts to control shifting on most "toy department" bikes. 1 derailleur and 1 gear cable. Go zoom.
However, if it is a toy grade bike that happens to be within the return period, just raise a fuss (if necessary) at the department store, return the bike and then go get an adult quality bike at the bike store.

If it is an SRAM rear derailleur, I do not have news except that they have a very good reputation; but, it looks like there's not as much "wrap" over the cassette--so they do appear to be more vulnerable to chain skip. This has not been reported.
Shimano Alivio 8 or Deore 9, rear derailleur plus right-hand shifter replacement part can convert the rear drive if you so desire (use whichever matches the current total number of rear gears). But, I've never heard of this problem associated with SRAM, only that the design makes it possible.
*These shifters also work on a road bike, although it is a stretch to get the little trigger shifter up on the handlebar to the top grip near the stem--once you've got it up there, it is quite a pleasure. --just a fun note.

Go to the bike shop. They'll fix it right up in a jiffy. I hope I've given you some good ideas where to look for the problem.

Answer 3

If it is skipping between gears (makes some noise and acts like it is shifting from one gear to another then back). It is cable stretch and is normal for a new bike. Most bike shops offer a free tune up to deal with the new bike break in.

If it feels like it is slipping as you pedal foreward it could be that the chain isn't seating up correctly on the teeth of either the front chainrings or on the rear cog. Since it is a new bike, it may be due to a stiff link in the chain. Usually a slip as you pedal is a sign of a worn chain, cog, or chainring - not something found a new bike.

Answer 4

I had that problem a while back! I thought first chain issue..so checked out chain and everything was fine. Then I though ohhhhh my clipless pedal shoes have gotten looser and aren't clipping as well and it's the drag..so I tightened the tension still a problem. I was about to go to a bike shop shoulders shrugging when I discovered one of my cranks from my pedals was coming loose. Took some tools and tightened it up,

Answer 5

An extension of bikelife's comments, the teeth of the chain rings(front) or cog(back) may be worn down. Intermittment skipping will occur as a result of this as well. If it happens only in certain gears, check the rings associated with that gear.

Answer 6

A damaged, stiff or frozen link. Check your chain I think you will find 2 links that are hard to move. No problem, just gently bend the chain at the problem spot until the links move freely. Lubricate and think about replacing the chain in the near future.

Answer 7

Sounds like the gear shift needs to be straightened...or maybe the back wheel is loose. flip it upside down and hand pedel it and see if the chain is straight. It should just need a minor adjustment.

Hope this helps

Answer 8

I agree with eveything bikelife had in his answer. He covered just about everything that could be wrong .In the interest of your safty I would suggest you take the time to have your bike checked...Good Luck and happy riding.

Answer 9

Sounds like some Cable stretch. Happens on new bikes and takes 30 secs to fix... take to bike store and they will do it for nothing at the store you got it at...

Answer 10

I agree with the other guys. It's probably a derailleur adjustment. Go by the local shop and they'll fix it in about thirty seconds.
Good luck.