My fixed Swift has held-up through 2 years of torture on the streets of downtown San Francisco. I've dumped so much stress into the frame barreling up and down hills in a 67" fixed gear that there were times I was sure the frame was going to give out on me. The bike has held up excellently.

For riding fixed, I highly recommend replacing the quick releases with ATB seat post binder bolts. I've found that this is the only way to get the rear section stiff enough for fixed riding. Otherwise, you will get all sorts of squeaking and grinding noises from the chain stay/sea stay areas when applying back pedal pressure.

The chain tension is not affected in the fold.