Guillermo

I'm wondering how much, if at all, upgrading a rigid fork to a suspension fork would affect the intended geometry of a frame. Several mtb's, particularly some single speeds are sold with rigid forks. If you swap that out for a suspension fork, will you be affecting the handling, etc at all?

Dax

PeterG1185

no, a suspension fork does nothing at all to the handling of a bike when compared to a rigid fork

dirtbikedude

Untrue. If you put too long of a fork it will change the geometry and cause the bike to turn slower but make it more stable at speed. Also, the right suspension fork will keep the tire on the ground over the rough stuff causing it to track better through turns. It will also make your rides smoother and less fatigue on the hands.
Negitive aspects, it will be heavier and cause you to use more energy when climbing unless you get one with lock out.

Slainte

PeterG1185

ummmmmm ya. nice going. i was being sarcastic

Maelstrom 

Peter. Your response is uncalled for but also next time you try to be sarcastic try using a smilie of some kind otherwise you come accross looking like an ass.

PeterG1185

ok, just felt like posting a pic

bikerider

Well, it would have been more appropriate to post it in the 'Introductions' forum.

bikerider

I suspect that most current SS bikes have rigid forks which are 'suspension corrected'. That is, the axle to crown height is about equivalent to a 3-4" travel fork (440 mm give or take). A non-suspension corrected rigid fork would measure about 400 mm axle to crown.

If you are changing the geometry by changing forks then yes, it will have an effect. A longer fork slackens the head angle and increases 'trail' or 'caster', effectively slowing down the handling of the bike. It will also affect your weight distribution on the bike and perhaps make it more difficult to keep the front wheel down on steep climbs.

WoodyUpstate

Easy to check this. Look at how much clearance there is from the top of the tire to the crown of the fork. Now, imagine the tire moving 3" - 4" up. Would it ram the bottom of the fork crown?

If yes, then adding an 80mm fork would slow your handling down, and make steep climbing difficult. If you ride bike paths and dirt roads and you aren't particularly aggressive, it might be okay. If you like tight singletrack and climbing, forget it.

Rich

I upgraded my 1991 Trek 8500 from rigid to suspension and had to use an 80mm travel fork.

This didn't upset the ride quality too much, and I got used to it over a few weeks.

How old is your bike and what make? Bike's after 1995 should be ok for forks upto 100mm as previously stated for being "suspension corrected".

Good luck

Rich

Guillermo

don't have a specific frame in mind yet. Some of the more affordable singlespeed setups currently available are spec'd with rigid forks. Kona's Unit, Redline's Monocog, one of the Bianchis, Gunnar also makes one.

Guillermo

would someone mind measuring for me the distance from crown to axle/dropout on their 80 travel fork?

TIA,

Dax