Nova5

Bike: Trek 700 Multitrack
I have to replace all three stock junk chainrings. the larger two are fairly well worn and beat up. the middle most heavily (there are torn spots in the ring..)

its a
L - 48-49
M- 38
S- 28.

My guess is at $14 this one is worse than the stocker..
https://www.bikepartsusa.com/cgi-bin/...ory=chainring#

Recommendations on what is good? street use only. i just rid in my subdivision right now, moderate hills (to me) about 3 miles of roads before repeating them. one of the pedal arms has Shimano C101 on it if that helps.

Al1943

Before you buy any chainrings you need to know what the BCD of the crankset is. With those rings it could be either 130mm or 110mm.
The big ring and middle ring should have teeth of various shapes to aid in shifting. Is it possible that's what you are looking at?

Al

Nova5

BCD? No, I had my brother look at it. long time mountian and road bike rider. I'd already determined at least the middle ring needed replacement. there are Tears in the metal near some teeth. the rear cassette is in good shape, its just the chainring that is shot. according to him the set should be replaced. he's been riding for the past 10+ years. ~20.5cm diameter on the largest one.

HillRider

If the crank is what I think it is, a Shimano Tourney, I'm pretty sure the chainrings are riveted on and aren't removable. You have to replace the entire crank. Are the rings steel or aluminum and are there clearly bolts and nuts holding them in place? If they are steel and the fasteners are rivets, the crank in not servicable.

BTW, are you sure the "tears" in the metal aren't intentional and are there as shift enhancers. A lot of current chainrings can look "damaged" because of the shaped teeth, ramps and other shift aids but they are designed in features, not bugs.

I'd be surprised if the chainrings are really shot, particularly if they are steel, but the cassette is still good. Usually chainrings outlast multiple cassettes.

Bill Kapaun

The chain ring in your link won't work either.
It's designed for the OLD style cranks with 1 ring.

Nova5

they arn't uniform cuts. its a torn look, and there are two of them, not equally spaced. its not the teeth that look that way, its the main body just below the teeth. I was thinking the chainrings and cassette needed replacing, he tells me the only thing needing replacement is the chainrings. that the cassette was in good shape. Chain needs a cleaning thou. Bill.. how can it be designed for one ring? its sold as a completed set. it reads like.

pics of the tears.

https://img.photobucket.com/albums/v2...chainrings.jpg
https://img.photobucket.com/albums/v2.../Temp/tear.jpg

Wordbiker

The rings are spotwelded together and not replaceable. The good news is they're steel and don't show any signifigant wear that I can see. Those "tears" are punched and engineered into the chainrings to help the chain shift up to the next ring. With alloy rings there would be pickup rivets in the same locations.

Nova5

I know i can't replace the individual ones on that rig. the full set would need replacement. There would only be two on the full ring that arn't uniform to each other nor evenly spaced? it seems illogical to me. I appreciate the help and info you folks have given me. Just from my experience in other areas (quite unrelated thou) engineering of things usually leads to some uniformity.

HillRider

This is a very low-line crank and replacement parts aren't available and wouldn't be worth paying for if they were.

First, your crank is probably still plenty usable. Other than appearance, are there any problems such as skipping or refusing to shift properly? How it looks is immaterial. How it performs is the important thing.

Second, if you are really having performance problems, you will have to replace the entire crank.

Nova5

are the pedal arms part of that due to how they attach to the chainring? I see alot of chainrings that have 4 or 5 mounting holes. I do have a snapping/popping problem but that is from a hesitant link. a good cleaning and lubing of the chain will fix that. Its mainly just that presence of what appear to be "tears" that concerned me, and him. he very likley has better chainrings that use a better method of assisting in gear changes. and like me may have seen those as damage rather than intentional.

Peter Jon White

The tears are from the manufacturing process. They are there by design. These chainrings start out as flat plates of steel, which are then broached to form the teeth. Some teeth have then been reshaped to help lift the chain from the smaller inner ring to the larger ring during shifting. You have nothing whatsoever to worry about. The rings appear to me to be as good as new, except cosmetically. Keep your chain clean and lubed and enjoy the ride.

HillRider

Everything will have to be replaced including the arms. There are a lot of cranks that have the rings bolted onto 4 or 5 "spider" arms and the rings are replaceable. Yours are permanently fastened to the arms and the crank must be replaced in its entirety. As I said, this is a very low-line crank and isn't worth agonizing over.

Again, the tears are intentional and part of the design.

Yes there are better cranks and more sophistcated chainrings available but do you have any compelling reason to spend significant money on a new crank and, probably a new bottom bracket to match it? Clean and lube the chain and repair the tight link then see if the bike performs to your satisfaction. I expect it will.

Nova5

With you folks help I think the current set is just fine. If i had to replace one ring i expected to replace all of them due to them being melded into one unit. The arms i didnt expect but am not surprised after looking around.

Thanks folks! I just wanted to be sure all was in good shape to start riding more. thou i only have a 3 miles to ride around in before i start repeating roads. Trying to get in better shape.