My wife has an older Trek that I just replaced the 8 speed cassette on. She has a double chainring set I need to replace but I'm having trouble finding them. They are 39T-53T type B 130 bcd. Can I use 9 or 10 speed chain rings with the 8 speed cassette? If I can what chain do I need to buy?

tooth thickness is easy to test.. if the chain settles easily over the teeth it should work

you stick with the chain you need for the rear 8 "speed"

9 or 10 speed rings will work. You may find that they are not spaced quite as far apart as the 8 speed ones, but it shouldn't be an issue. I found that a 9 speed chain worked better than the 8 speed chain on my mixed drivetrains with 8 speed cassettes and 10 speed chainrings.

Somebody directed me to this source a while ago. These are 3/32" thickness, so appropriate for 8-speed chain.

https://www.universalcycles.com/shop...s.php?id=23785

There is also this source for Stronglight rings for even cheaper. No 39 here, but they do have a 38.

Stronglight Dural 130mm Shimano 8/9/10 Chainring - Chainrings - Ribble Cycles

If the front shifter is friction, you can probably get away with throwing any two rings of the previous tooth-counts together. My rando bike used to feature a "9-speed" Shimano 50T and "6/7/8-speed" Sugino 38T on a 6-speed crank to good results. Now it's a pair of 9- or 10-speed Sugino (XD700?) rings on a different 6-speed era crank. An 8-speed chain ties it all together.

Watch Nashbar ads. They've sold Raceface 130mm bcd 53T-39T chainring sets for $7.49 several times this year. These are index chainrings with pins and ramps. Regular price is about $20 a set. These are nice because they include the chainring bolts and nuts. Most all other companies sell the bolts and nuts separately.

Even if you end up paying full price because you can't wait for a sale, they are not a bad value. Shimano gets more than $20 for a single chainring.

When they go on sale, someone usually posts a message to make other people aware of the sale.

Thank you all for the advice.