Credo di aver trovato la risposta ai miei dubbi sull'angolo sterzo della Jet direttamente sul sito niner. Riporto il testo:
"Although the Jet 9 is designed around the same handling characteristics as our hardtail frames, many things change on a full suspension bike that make this a lot more difficult than plugging the numbers in from our rigid bikes. BB height difference and chainstay length change to accommodate rear wheel travel and the head tube angle has to take into account sag of the rear suspension.
>> You can see by the geometry chart above that our head tube is still a steep 72 degrees. Once again, this is to account for the larger trail number (see trail chart) of the 29” wheel. Thetrail chart is showing the difference in trail between a 29” and 26” wheel at 71 degrees and a 29” and 26” wheel at 72 degrees. In order to maintain the tight, fast handling of our hardtails, the Jet 9 continues with a steep 72 degrees. Through our testing, we realized that the larger size of the 29” wheel offers so much increased stability that a shorter trail measurement did not adversely affect the handling of the bike at high speeds but made for faster slow speed handling. This was an ideal situation for the Jet 9, giving it the ability to fly down high speed descents while still having amazing steering characteristics around even the tightest hairpin corners. In addition, the steeper head tube angle on the Jet 9 keeps the wheelbase short and tight and works brilliantly with either an 80mm or 100mm fork."
"Although the Jet 9 is designed around the same handling characteristics as our hardtail frames, many things change on a full suspension bike that make this a lot more difficult than plugging the numbers in from our rigid bikes. BB height difference and chainstay length change to accommodate rear wheel travel and the head tube angle has to take into account sag of the rear suspension.
>> You can see by the geometry chart above that our head tube is still a steep 72 degrees. Once again, this is to account for the larger trail number (see trail chart) of the 29” wheel. Thetrail chart is showing the difference in trail between a 29” and 26” wheel at 71 degrees and a 29” and 26” wheel at 72 degrees. In order to maintain the tight, fast handling of our hardtails, the Jet 9 continues with a steep 72 degrees. Through our testing, we realized that the larger size of the 29” wheel offers so much increased stability that a shorter trail measurement did not adversely affect the handling of the bike at high speeds but made for faster slow speed handling. This was an ideal situation for the Jet 9, giving it the ability to fly down high speed descents while still having amazing steering characteristics around even the tightest hairpin corners. In addition, the steeper head tube angle on the Jet 9 keeps the wheelbase short and tight and works brilliantly with either an 80mm or 100mm fork."