should i take the bike back?

thebourke

I recently took a bike back after 6 weeks to get it checked up as i bought the bike new..however when i brought the bike home i noticed that the gears were not working properly....its a specialized sirrus bike..basically it has 24 gears..its only 2 gears that are not working properly..should i take the bike back...i did tell them at the time that there was one or 2 gears that there was problems with it...what do you think?

Bit confused - are you meaning 2 of the 24 combinations of gears are not working? While a bike has 24 gears you wouldn't be using all the combinations as this would damage the chain. Which 2 gears do you mean?

blue chuzzle

Dónal wrote: »

Bit confused - are you meaning 2 of the 24 combinations of gears are not working? While a bike has 24 gears you wouldn't be using all the combinations as this would damage the chain. Which 2 gears do you mean?

ah donal, he means that he cant get to some of the gears because the derailleur isnt adjusted correctly or has been given a whack. if its been in for a service you can bring it bac as it hasnt been serviced correclty or you could follow some of the online tutorials (very straightforward) this one is good

kincsem

I bought a Specialized Sirus in 2005. I had the same after the first spin. I did 70km. Just as I got home the chain jumped on the rear derailleur. The next time I took it out the chain was jumping a lot. I brought it back as I was a newbie then and didn't know how to adjust the gears. They adjusted it in a few minutes.

Its just the cable stretching a bit in the first few kilometers.

blorg

As Donal suggests if it is the big-big and small-small (chainring-sprocket) gears that aren't working, this is normal and these gears are not meant to be used (it is called "cross-chaining.")

thebourke

what do you mean by big big and small small..ive never heard of this cross chaining..if this is the case..why do they offer these gears on the bike if they dont work?

niceonetom

small small: small cog on front and small cog on back.

big big: figure it out from above ^.

thebourke wrote: »

what do you mean by big big and small small..ive never heard of this cross chaining..if this is the case..why do they offer these gears on the bike if they dont work?

There's no way not to.

kincsem

For efficiency you try to keep the chain straight. My bikes all have triple chainsets (three chainrings on front). On the flat or downhill you travel fast so you use the big chainring (furthest right / on the outside) and the smallest rings at the back.

So 52 sprockets on the front and 12 at the back gives 52/12 or 4.33 turns of the back wheel for each turn of the big chainrings / pedals.
The middle front chainring is used for flat / slightly uphill, so 39 on front and the 16 at back gives 39/16 = 2.44 turns per pedal turn.
Going up steep hills its 30 on the front and 27 on the back = 1.11. This is the inner front ring (near the frame and the inner ring on the back.

As you go from flat to uphill those gearchanges move the whole chain from right to left keeping it roughly parallel to the bike. 52 with 12,13,14: 39 with 15,16,17,19: 30 with 21,24,27.

What you should not do is use the 52 on the front with the 27 on the back as that is the furthest right on the front and the furthest left on the back. The chain is stretched and not in a straight line. Same with using 30 on front and 12 on the back - the chain is stretched left to right.

petethedrummer

http://www.youtube.com/watch?v=24vfX2PtSMM