mijohnst

I bought and Giant FCR3 a few weeks ago and it's been a great bike...as far as I can tell. Well, during some of my rides my chain comes off. When I shift to the largest sprocket connected to the petal it seems to make a strange sound (sometimes) like it's rubbing against something and sometimes, not always, the chain will just drop off. I've taken it back to the shop where I bought it twice for adjustment but it still keeps doing it. Would you say this is an adjustment or that it's something possibly bad? It really starting to bug me. Or could it's be that I'm not properly shifting correctly. Thanks!

Sheik_Yerbouti

I hate it when shops don't do what you ask them to. If you're willing to sit down and read a bicycle repair book you will be able to make the adjustments yourself. But I would go into the shop in which you bought the bike and demand that they actually adjust the front derailleur. You say that it is rubbing against something, and I think that it is the derailleur, and if you are shifting properly that shouldn't be happening.

I'm assuming that you know that you're supposed to keep the chain straight between the pedals and the rear wheel. So don't use the smallest cog attached to the pedal, and the smallest cog attached to the wheel, because one will be more to the right, and the other is to the left creating a diagonal chain line.

Big_e

Sounds like the shop don't know how to adjust the rear derailleur, or it's not putting in the Tender Loving care to adjust it just right. Before I try to explain it here is a link to a fine Bicycle Repair website that can explain it better. It's easy and involves all of adjusting two screws which are on the side of the derailleur housing. One restricts the derailer's movement towards the easy gear and the other, the movement towards the hard gear.
Place the bike on a stand and screw both screws all the way in. Start moving the pedal as if you were pedaling and shift all the way to the lower or hard gear and start screwing the lower screw out until the chain shifts to the lower gear.
Now shift to the easy or high gear and screw the top screw out until the chain shifts to the high gear. With the bike still on the stand. Shift up and down several times until you are assured that the derailer works properly.
Make sure that your derailleur isn't bent. If you lay the bike on it's side instead of a kick stand, make sure that it's not resting on the side the derailleur is on.
Loosen the tightening nut to the cable which goes from the shifter to the derailleur and pull the slack out, then retighten. Most of my bike knowledge, I got from this website and has helped me greatly.
Ernest
PS: The front derailleur has two screws also. I just assumed it was the back derailleur 'cause I had a similar problem with it.

BarracksSi

The chain drop is an adjustment thing, and whoever's doing the work at the shop doesn't know what they're doing.

It's also probably a chain rub issue, which really isn't so much of a problem as it is something you'd just learn to live with. With your bike (and others like it), you'll have a span of around four rear cogs that you can use with each front chainring. Say that you're on the largest front ring -- you'll be able to use from the smallest rear cog to about the middle cog before encountering chain rub.

For now, though, I'll suspect that the limit screw on your front derailleur needs to be brought in just a tad. Check at https://parktool.com and https://bicycletutor.com/ for some good DIY advice on adjusting your shifters. As they say, it ain't rocket science.

AEO

https://www.youtube.com/watch?v=SkzvfCaIbyQ
https://www.youtube.com/watch?v=xkGBajG4TPc
https://www.youtube.com/watch?v=ngm6dr-1na0

for the people who like a video version.

charly17201

If that's all you get out of your gears I'd be looking for another bike design or something. I use ALL my gears on all three rings. No problem after I got it adjusted right.

ok_commuter

+1

I've got a double up front, not a triple, but I can go all the way across (small front to smallest back)... whoever said you want a straight chainline is correct and all, but you should be able to get to your gears if you need them, it just isn't ideal to put the chain in the extreme position(s) and not how you want to ride all the time.

mijohnst

Thanks for all the great information guys! I'm pretty upset with the shop I bought my bike because they didn't take the time to fit the bike to me at all... I think I'll just learn to do it myself and save some money. Thanks for the lesson here guys!