fork upgrade

[alex]

i have a marin mount vision with 120mm either end

and want to upgrade front shocks

mate has some manitou shermans with 160mm travel and 20 mm axcel

will this screw up gemotry of frame or break it

[Andy]

It shouldn't do. I run 130mm forks on my Trance, which is designed for 100mm. I'll be getting a 150mm fork for it next, cos the extra fork length so far has made a really positive difference.

[sean cadthingy]

Yes 160 travel forks will screw up the geometry of your bike, the axel to crown length will be a,lot longer, it will,raise the bottom bracket and the bike will feel very odd.
Try again with something else!

[Tym Burman]

Alex, I would not do it to my bike for the following reasons:

Longer fork = extra leverage on head-tube. May damage frame, esp. twin-crown forks if they spin in a crash.

Slacker head-angle = slower steering, more 'wheel flop' & rider weight further back. Makes technical climbs more difficult, though may improve descending stability and lifting front wheel.

I think Shermans are for aggressive riding (= extra weight).

Will you have to buy a wheel with 20mm axle as well as fork?

My opinions are based on being a cross-country rider, they may not be true for you. However, most people have to pedal up hills at some point.

Ride on, Tym