Head tube angle?

dflash

Hi guys, a friend of mine want's to buy a new fork for his MTB a 2012 specialized hardrock sport disc. So what's the ideal travel for his bike? He rides Trail. I suggested him to get a fork with max 120mm travel because more than that he gets out of geometry. The head tube angle is 70.25°. So can he get a fork with travel more than 120 mm ( like 150 mm)?

felix.london

who knows?

I'd say 100mm but I run a '06 Rockhopper with a 120mm and it's spot on. Specialized will probably tell him 100mm or he'll void any warranty.

150mm would be ridiculous though - the thing would probably ride like a pig. The bike was designed for 80-100mm I guess. What fork is on there now?

felix.london

...btw it's not only head angle that will change but the BB height too.

The measurement that's important is the axle-to-crown measurement. For instance I went from a 105mm to a 120mm but the a2c height only increased by 10mm - might've slackened the HA by 1° but that suited my type of riding and terrain anayway

benpinnick

In a word no. As felix says, it will likely ride like a dog, and more worryingly might rip your frame in half. 120 is as far as I would go on that frame.

nicklouse

felix.london wrote:

...btw it's not only head angle that will change but the BB height too.

The measurement that's important is the axle-to-crown measurement. For instance I went from a 105mm to a 120mm but the a2c height only increased by 10mm - might've slackened the HA by 1° but that suited my type of riding and terrain anayway

and seat tube angle and center of gravity.

felix.london

indeed. So basically the whole f.ing shooting match!