Several years ago, I bought a 21-speed "all-terrain" bike and after just a few short rides folded up two rear derailleurs. I am going to replace the derailleur with a higher quality unit, but if I need to replace the chain also, I'm a little lost. Is chain pitch the same for all bikes/chainwheels/cassettes/derailleur pulleys? What about getting the old one off and the new one on? I have looked all over the original chain and can't find a master link anywhere. Will I have to grind off a rivet to get it off, since the frame passes through the chain? And will the new chain come with a master link ready to go in? I've ridden for a large portion of my life, but never gotten into the bicycle itself like this, so this is all new to me. Any advice would be greatly appreciated. Thanks in advance - Chris

 

Hi, CMil-
The answers to your questions depend on how much upgrading you plan to do with the new derailleur. Everyone please check my logic, here, wouldn't be the first time I'm wrong.

Working on the assumption that you have a 7-spd cassette and 3 chainrings in front:

You may have a tough time finding a higher end 7 spd derailleur, and I don't think an 8- or 9-spd derailleur will be compatible with the 7-spd cassette. Can anyone comment on that? If you *can*, you may wind up replacing the chain, not because it's worn but because it won't be compatible with the derailleur.

You'll need to play the compatibility game: the cassette has to be compatible with both the derailleur and the chain, so if you change one you may wind up changing all three.

Let us know how it goes!

 

Bicycle chains are specific depending on the amount of cogs (gears) that you have, and if you are using index or friction shifters. Also there are chains that are Shiamno IG or HG specific. However most mass merchant rigs use 5 to 7 speed freewheels that are either Sun Race, or Falcon.
So in essence we need to know if you have friction or index shifters. Also a chain tool is the device you need to remove and replace chains. They are a inexpensive tool that can be had at your LBS (local bike shop).
Also most chains today, at least all that I sell come with a tool free chain connector. It is a "master link" of sorts but alot different.
On to your other subject derrailleurs. Depending on the way your der. fixes to the frame any 8 speed der. will work with your rig. Eight speed der. are still available, some LBS may have some older Shimano units laying around (I stock many) and SRAM still makes 7 and 8 speed compatible der. and shifters. Most LBS can procure anything your rig needs or suggest a suitable replacement.

 

Thanks, responders! Okay, let me fill in the blanks a little. The shifters are index-type (Grip-Shift brand), and the original derailleurs were Sun Race units (model 525, to be exact). The bike is a Barrington FS Elite, purchased from Sears. The rear derailleur is secured to the frame via a bracket held down by the right side hub nut/wheel nut(not sure of the nomenclature here). I would like to find out what derailleur will fit properly and improve durability, and how to replace the chain. The deal with the chain is that it got all bent up when the derailleur folded. Precision Pedal - if you could give me a website address, phone number, mailing address or whatever, I would be open to doing business with a knowledgeable person/business. I hate the idea of replacing the bike for want of a few affordable parts. Thanks in advance - Chris

 

Our web site is:
http://precisionpedal.homestead.com/home.html
Phone number is 915 648 3961
I am there Mon thru Fri from 11 to 6 CST and on Sun. from 12 to 5. I am glad to help in whatever way I can.

 

To remove the chain on the old bike, you'll need a chain tool. These usually run around $10-12 and you can get them at any bike shop and some department stores.

Here is a link to one from REI. If the link doesn't work, go to www.rei.com and search for this item #: 544208

http://www.rei.com/online/store/Prod...ory_rn=4500918

 

CMil,

We need to determine why your rear derailleurs are getting grunched. I have seen many bikes with this problem and jsut putting on a new part is not going to stop the problem unless you understand what is happening.

If the bike is involved in any kind of crash which results in the bike going down on the right side, the derailleur is probably going to be damaged to some degree - the same is true if the derail is bounced off a rock beside the trail. Up grading to a more expensive derailleur will not prevent this kind of damage. (Because of the way your derailleur attaches to the frame your choices are going to be limited to low or moderately priced derailleurs - expensive derailleurs do not come with the plate which slips under the right axle nut because expensive bikes have incorporated this plate into the frame. The good news is you are bending only your derailleur - on expensive bikes the frame tab can also be bent or broken, sometimes ruining the frame.)

The other major cause of bent rear derailleurs is getting them caught in the spokes when the chain overshifts the biggest rear sprocket. This can happen for one of two reasons: a) the low gear limit screw is not correctly adjusted, or b) the bike has fallen on the right side and the mounting plate gets bent slightly, throwing the adjustment off. If everything is properly aligned, the derailleur cage rides very close to the spokes in first gear, but cannot actually contact the spokes.

When the rear derailleur gets caught in the spokes it can ruin both the derailleur and the wheel (very expensive) and can lock the wheel and cause a crash. Don't let this happen to you. Any time you install a new rear derailleur or the bike goes down on the right side, you need to check the adjustment before you ride it. Do this by holding the rear wheel off the ground and, while slowly turning the pedals, try hard to shift into low gear; if the chain wants to go over the top of the big sprocket then the bike is not safe to ride until an adjustment is made or the derailleur is straightened. You can often make a quickie field adjustment after a minor crash by simply grabbing the derailleur body with your hand and pulling out until the cage that hold the pulleys is parallel to the plane of rear wheel. After straightening the derailleur you may need to adjust your cable tension to get the index shifting clicks to line up with the sprockets.

As for the low gear limit adjustment - you will see two small screws somewhere on the derailleur body - if you are lucky, they will be marked 'L' (low) and 'H' (high) - turn the L screw clockwise until the derailleur travel is limited to just allow the chain to climb up on the big rear sprocket, and no more (it's a good idea to have the chain on the innermost front sprocket as well). If the screws are not marked you can figure out which is the low gear screw by observing the ends of the screws while shifting the derailleur towards low gear - some part of the derailleur body will move towards the end of the low gear limit screw.

-GW

Oh yeah - I just re-read your post about the chain - another possibility is a frozen chain link - sometimes a stiff chain link will bind in the rear derailleur with enough force to bend it if pedaling hard. Sometimes a customer would put a 'master link' from a 1/8 inch wide coaster brake chain on a 3/32 inch gear bike chain with the same result. Also, if the chain is too short to allow it to go up on the big rear sprocket and the big front sprocket at the same time, trying to shift into this combination can bend the rear derailleur. These are much less common causes of trashed rear derailleurs than the first ones I mentioned, but ...

My bike shop experience ended in 1994 when I changed professions, but at that time it was common for cheap Tiawan made chains on brand new bikes to have stiff links - likewise new chains fresh out of the box, even some name brand stuff. Chain tools can also leave a stiff link on a new chain, but these can usually be worked out by flexing the link from side to side.