I asked Charge in January last year:
I've been looking at the Duster but am curious about using forks longer than 100mm. I have U-Turn Pikes which although go up to 140mm I run at 120mm – in fact, normally wound right down to 100mm. 120mm would also slacken the head angle by one degree or so, something I'd prefer.
I also note that What Mountain Bike make the comment in the February edition that "… XC angles are arranged around a 100mm fork, but it'll take a longer-travel fork without getting lazy… a long throat gusset helps it handle forks over 100mm…"
What would your comment be on this – would you recommend against a longer fork?
And the reply:
Thanks for your email. The guys at What MTB are right. You can run up to a 125mm fork without a problem. The throat gusset gives it the extra strength to enable it however it is designed around a 100mm fork and that's the length which the frame handles at its best. Running your pikes at 120mm would be absolutely fine and certainly wouldn't hurt when the trail points down the hill. I hope this is useful.
Best Regards
Jim
Charge Bikes