A perfect match for single speed and fixed gear bicyclists, the Genetic Track Chain Tensioners will keep your rear wheel from sliding forward. For chain tensioners, the Genetic Track are lightweight and made of high quality materials like forged alloy and stainless steel bolts and locknuts, making sure you get a lot of bang for your buck. Colors available are white, blue, gold, red, and black (not shown). Retail price is £12.99, and add £2.99 for white. Purchase at Geneticbikes.