This is the second-generation Orange ST4 with a new square chainstay and dropout, which apparently increases rear-end stiffness, but compared to the Marin and other bikes we’ve ridden it’s still flexy. The main frame is solid enough with the top and seat tube from the Orange Five but you can really feel both ends flexing around the links and see them if you just put a foot on a pedal and press down. Nice frame touches include full seatpost adjustment, a useable bottle mount and external cable routing. On the office scales the Orange ST4 SE with CrossMarks and pedals weighs 26.23lb.
Orange is king of the single pivots so what’s the deal with the linkage? The Rockr link allows Orange to play around with a 2:1 leverage ratio, which magnifies the sensitivity and response of the compression and rebound damping on the rear shock. The shock moves faster and further for the given wheel travel but the shock performs as if it has a longer stroke and feels more controlled, you’re not bottoming the travel nor is it kicking up to full extension. The Fox RP23 on the ST4 has a 200mm shock with a 50mm stroke; there’s a slight discrepancy with the links as the travel works out at 106mm.
You also notice that Orange has placed the main pivot slightly lower and further back than on the Five. There isn’t an engineering reason, Orange just made some bikes and tested them and performance-wise preferred this position. In truth the lower pivot does cause the ST4 to bob more when climbing, and sprinting out of the saddle does amplify the flex in the rear end. We spent most ascents seated with the ProPedal switched on and still had to concede ground to the Marin. The only time we could match the Marin was when the climb was loose because the ST4 does have good grip.
Where the ST4 does shine is on the descents — the rear shock and swingarm are low down, lowering the centre of gravity, plus the bike has a 13 1/8in bottom bracket height and 44in wheelbase, encouraging you to get in a feet level, head down hammering position. You have to work and pump the bike through technical sections because you can clip a pedal, and you also have to accommodate the rear-end flex in rough sections but this bike will pay you back. It’s a confidence bike — getting the wheels off the ground is insanely easy; the ST4 cleared most of those mashed table-tops on the Spooky Wood descent. Now the bad news. We had the worst chainsuck ever on the ST4. It was so bad in fact that we had to split the chain on two separate occasions.
Overall we really liked (sorry, make that loved) riding the ST4. For a bike with a 106mm of travel it was an absolute missile but we can’t rate it higher because it doesn’t feel like the finished article. If Orange can increase rear end stiffness without adding weight it’s looking at another 10.
Mbr rating: 9