RS Reba 100mm to 120mm

Oskik330i

Hello. Service for my fork coming soon so I'm thinking to upgrade travel to 120mm.
Now I'm running 25 % sag but with 120mm my idea is to run like 35 % and keep same geometry after upgrade.
Will my fork feel better ?

I have xc bike riding xc / light trail style running 89psi my weight is 92kg bike 13.2 kg

steve_sordy

If you ask the manufacturer of your bike they will say don't do it. A longer fork puts more leverage forces on your headtube and could damage the bike. Yeah,yeah,yeah, safety briefing over; 20mm will not make a substantial difference with your riding style. I would be concerned if you were heavier and did jumps, but even then many riders have done exactly what you have done and got away with it,.

Your 100mm travel fork will have 75mm stanchion showing at 25% sag. To maintain that with a 120mm travel fork will require a 37.5% sag. At that level of sag, your bike will ride like a pig wallowing in the mud. It will dive over every rock and you will be hitting your bump stop on every drop.

If you like riding at 25% sag, then I would continue with that as a starting point. You will continue to like the firm feel, but you will have some extra travel in reserve.

I say "start" at 25%. The thing to do is to experiment to ensure that you get the best from your increased travel. In theory, if you stay with 25% sag, you will notice an improved control when descending, a marginal increase in the potential of the front wheel to wander when climbing something really steep. There might be a slight reduction in your ability to turn very tight corners - I'm thinking weaving between trees. All of these are driven by a small reduction in your head angle. Whether you notice these or not, they are real.

I recommend that you take your shock pump with you on your next ride and reduce or add some psi to your fork just to see what happens. Pick a short section of trail that you believe will test you and the bike and keep testing. Don't forget that your rebound damping will also have an effect, but don't change both at the same time.

I love experimenting with new kit! Have fun!

JBA

Why?
25% sag at 100mm gives you 75mm of available travel.
35% sag at 120mm gives you 78mm of available travel.

Either stay as you are or if you up the travel to 120mm then also go for 25% sag. If you aren't regularly bottoming out the forks then the extra 20mm of travel isn't likely to make any difference but will cost you money to implement.

Oskik330i

steve_sordy said:

If you ask the manufacturer of your bike they will say don't do it. A longer fork puts more leverage forces on your headtube and could damage the bike. Yeah,yeah,yeah, safety briefing over; 20mm will not make a substantial difference with your riding style. I would be concerned if you were heavier and did jumps, but even then many riders have done exactly what you have done and got away with it,.

Your 100mm travel fork will have 75mm stanchion showing at 25% sag. To maintain that with a 120mm travel fork will require a 37.5% sag. At that level of sag, your bike will ride like a pig wallowing in the mud. It will dive over every rock and you will be hitting your bump stop on every drop.

If you like riding at 25% sag, then I would continue with that as a starting point. You will continue to like the firm feel, but you will have some extra travel in reserve.

I say "start" at 25%. The thing to do is to experiment to ensure that you get the best from your increased travel. In theory, if you stay with 25% sag, you will notice an improved control when descending, a marginal increase in the potential of the front wheel to wander when climbing something really steep. There might be a slight reduction in your ability to turn very tight corners - I'm thinking weaving between trees. All of these are driven by a small reduction in your head angle. Whether you notice these or not, they are real.

I recommend that you take your shock pump with you on your next ride and reduce or add some psi to your fork just to see what happens. Pick a short section of trail that you believe will test you and the bike and keep testing. Don't forget that your rebound damping will also have an effect, but don't change both at the same time.

I love experimenting with new kit! Have fun!

Thanks for explaining ))