Hey guys I want to know which chainring can fit on Shimano FC-6750 crank arms? Ive tried to find it in a app called carousell(a place where you sell products) and I can't find any. I had to go google search and is able to find one but can't ship to my country. Thanks
Look for 110 BCD (or PCD) chainrings for 5 arm spiders, for 10 speed. That's an Ultegra crank. They may not specify "Shimano", or "Ultegra" compatible. Then, look if chainrings' bolt area looks like as yours.
You may have more luck with AliExpress. It's not hard to find chainrings for Ultegra's. At AliExpress, there are plenty..
As previously stated, the 6750 is a compact crankset meaning the chainrings have a BCD (Bolt Circle Diameter) of 110 mm. Shimano had several gear combinations, all of which had 110 mm BCD's: 52/36, 50/34, and 46/36 for cyclocross racing. If replacing the large ring, for best shifting performance you'll want the same size chainring.
If you're replacing the large chainring, I have not tried other brands of 5-bolt chainrings on the Ultegra 10 speed cranksets, but for aesthetic reasons I don't think another brand will look good. The 105 chainrings will work just fine and are less expensive but they are anodized a slightly different color.
For the small chainring the different color won't show up and from a functional point you'll be fine with Ultegra or 105 10spd chainring.