Mountain Biking - Changing forks 80mm to 100mm _Increasing A-C measurement

I have an older MTB that I refurbished last year and made into a fully rigid bike. I want to get a new suspension fork this year. The original fork was a 80mm Judy TT. I am considering replacing it with a 100 mm Manituo Match. This will result in a 20mm increase in the axle-to-crown measurement. I know this will slacken the head tube angle and relax the steering, but will this make the bike unrideable and/or cause any damage to the frame? The bike is a 2003 Gary Fisher Wahoo. It has the older pre- G2 geometry.

Thanks.

What are the fork rakes on both forks?

I made this change to a 2001 Specialized Hard Rock Sport and I asked this forum and the mechanics forum for input. One comment that was made is that the actual sag on the larger fork will probably be more than the sag on the 80mm fork. So the true difference between the forks may be less than 20mm. Most posters felt that this was too small a change to be a concern. But I think you should keep an eye on the headtube and watch for cracks after you make the change. If you see a crack, don't take that bike out again. As for handling, I went from a 80mm Suntour SR 6200 spring fork in fair condition to a 100mm Manitou Axle (with rebound control) in great condition. All I could tell is the bike seemed to handle better with the better fork. I gave this bike to my son who had previously been riding a Trek 820 and he really liked the Specialized. So I don't think the new fork will have a negative affect on your bike.
One last comment, we do not do big jumps on our bikes. most jumps are under one foot.

Jumping to 100mm won't hurt it.

. . . But I think you should keep an eye on the headtube and watch for cracks after you make the change. Being a bit alarmist aren't we?


One last comment, we do not do big jumps on our bikes. most jumps are under one foot.Why not?

Jumping to 100mm won't hurt it.

I'm considering upgrading my '90-92 Diamondback Axis to suspension but I'm unsure as to how much travel I'll need, 100mm seems to be the only thing I can afford w/ my current budget...I've found several used ones locally and I'm pretty knowledgable mechanically to decide if the forks are good...but how are these rebuildable? I'm guessing the springs can be swapped because I've seen some kits on ebay that are either firm or soft...I guess I'm trying to avoid hydraulic or air, as those could be more work to rebuild? Or am I completely wrong here..?

Thanks for the responses. I ride singletrack & xc..... too old for jumping anything big.

^^ So you are . . . 70? Good on you for still riding :thumb:.