Bicycle Mechanics - changing the gear ratio and got question

hi folks.

I have a 2002 city bike which I want to chage the gear ratio of the bike. Now bike has 13-34 7 speed free wheel and 28-38-48 ront chain rings. I want to change to 11-34 7 speed free wheel and 22-32-42 front chain rings. The changing of freewheel has finished with any abnormal performance.

But after I change the front chainrings, by the way, the 28-38-48 ront chain rings is shimano, and the 22-32-42 front chain rings are also Shimano. After I changed the chain rings, I could not get the front deraileure work, namely, the original deraileure does not have the range to go towards the biggest chain ring. Also I relaxed all the way the low and high stoppint screws. But seems that the front deraileur does not have the range to go all the way, I compare the two chainrings and they seems have the same dimension from small chain ring to big chain ring. Also I checked that they go almost the same on the spindle of bottom bracket. What is the problem?

I am going to buy another set of chain rings of Shimano, Can anynoe of you tell me if that chain ring will work together with my front deraileur? Thanks.

by the way, the length of spindle of Botom Bracket is 125 mm, the description of Chainrings set is 110/113.

I attached the picture of bike and chain rings in the attached file


Lei Lin

sounds like you just need to re-adjust range and tension on the front derailluer for the new chainrings.

Are you saying the BB you are currently using is 125mm? If that is correc that is the incorrect BB, it shoudl be 110/113 and that is why it cant' get to the outside ring. If you changed the whole crankset, or did you just change the chainrings?

Going from a 48 to a 42 large ring, you should lower the front mech, so that it clears the large ring by about 1-2mm.
This will give you a bit better performance on the small->med change.
28/38/48 is a good combo for city riding. Ive used it in hilly areas with a 13-28 cogset.
22-32-42 with an 11-34 is for loaded touring on steep trails and very steep roads.
Before you go buying lots of spare rings, maybe you should find a good bike shop who can advise you.

Kev is right.......you need a shorter BB spindle with your new triple.
Now that you've got a nice low to mid range gearing, what about your top end???....looks like you've lost it with this setup...

Ah...the joys of working on a bike for that first major job!

The only real change here is a 2 tooth difference at the rear. I think Michaels suggestion should work, but you could also check that the chain is long enough to cope with the change.