The Serfas® STX Inertia Folding Road Tire features a smooth tread constructed using their high-performance Alchemy Compound for lower rolling resistance and world-class grip.
Comprehensive testing at Wheel Energy® of Finland, an independent tire laboratory, found Serfas® Inertia tires to perform 8.12% better at cornering than their competitor's most comparable best-selling road bike tire.
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The product weight specified is an approximate weight based on the manufacturer's specifications (if available) or our measurement of one or two examples. For most products, the weight will typically vary by 5% to 10%.
Tire Type: Clincher-Folding
Threads Per Inch: 120
Wheel Size: 700C/29" (ISO 622)
700 x 23mm - Black
Weight: 222 grams
Tire Width: 23mm (0.9in)
Mfg PartNum: STX-23
700 x 25mm - Black
Weight: 242 grams
Mfg PartNum: STX-25
Tire Width: 25mm (1.0in)
The 23mm size mounted on narrow 19mm outside width rims are accurately that wide at .9". The height is just under at .8" above the rim. The bike has 400mm chain stays, crank center to rear axle center, and these have .3" clearance to the seat tube. I figure that the 25mm size may have fit with a .2" clearance like the 25mm Gatorskins that came off, but returning to the original spec 23mm size is interestingly quick and smooth at 80psi carrying less than 160 pounds total bike and rider. Losing 190 grams of revolving weight compared to the Continental set was noticeable when accelerating up hillcrests.
New, they took a good bit of cleaning up. The release coat was generous and crusty. That's not such a bad thing after seeing the flat black buffed up with fine steel wool. They felt like ribbon when mounting. Repeatedly working the initial bead down into the rim bottom and around to the loose side helped the edge drop over by hand. The outline had minimal wobble and runout when inflated.
The long injection hairs are easy to pull and nick off. Logos wrap into the cornering tread. Big white SERFAS letters will act as chicken strips that scuff up in hard turns.
All in all, these are fun, underrated tires not having a big brand name. The technology seems to be there.
I've tried several tires from this brand and have had terrible luck the flat. The weather crack after a few months handle terribly and fall apart. They're actually dangerous. I don't recommend them at all. I've tried these in the 25 mm and they were somewhat easier to mount to the rim but these are not good tires.
I've put about 1,000 miles on it and while it's been a solid performer I would say it is prone to punctures. I've had several with very small metal wire that I would have assumed would not penetrate the rubber.
I order a set of tires about month ago. I have put in around 300 miles on them. Average PSI is about 100. Rear tire wire bead started to crack and the front tire has a tear on the side wall.
I have over 3500 miles of paved road riding, without a flat tire, and on the rear wheel. The tire surface is getting a little flat now, so plan to change the tire within the next 500 miles