Fork Setup Query

DaveyDave

I have a 140mm Marzocchi Bomber Z2 tuned to the recommended pressure and rebound.

I've only been mountain biking for around 3 months so taking it fairly handy on red Coilte trails. Using around 100mm of travel which seems in line for the riding I'm doing.

I find my hands absolutely shattered on rockier stuff like Expressway at Ballinastoe, what should I do to help this?

My tyres are 2.6" tubes, the front is at 26psi which looks to be fairly soft. I'm 110kg so don't want to go too low. Some people say you should adjust your suspension pressure so you're using full travel for the trails you're riding but a lot of people disagree with this and 140mm travel on XC trails would probably handle like crap anyway and I don't want it to iron out all the bumps either.

I'm at 2 clicks of rebound but slightly over their plush sag guide due to my weight geared up. I'm wondering if there's any harm to let maybe 5-10psi out of the fork? Or maybe slow the rebound further to 1 click?

There's no volume spacers in the fork at the moment. If the fork wasn't cycled properly when adding air would this cause problems? I didn't cycle the fork when adding air as I didn't need to add much when the bike was new.

Wailin

What's your sag at? I'd recommend 20% sag so you should be looking at 28mm to the o ring from dust seal. Also, too little rebound could be a cause too. The fork just packing up and not rebounding quick enough from hits. But the first place to start is your sag, you may need to drop some psi. It might be a good idea to release all the air and start from scratch, compressing the fork through its travel every 30-40 psi to prevent air getting trapped in upper stanchion.

Screenshot_20230608_204736_Google.jpg

DaveyDave

https://www.boards.ie/discussion/comment/120692233#Comment_120692233

Sag is a little over their plush recommendation (28mm/20%) at 31mm. No mention of compressing the fork in the manual but I was thinking it might be worth a try, I didn't need much air in the fork when new so maybe it was just filled up without compressing in between.

Wailin

I wouldn't be leaving any more air out to be honest. You'll then mainly be sitting in mid travel which is not ideal. Maybe add more air to get your sag back to 20%? I like to keep mine at 18% on my 140mm fork and it feels nice and plush. The most sensitive part of the travel for small bumps is the first 20% of travel but if you've too much sag your in the less sensitive mid travel of the fork.

Of course, it may not be fork set up at all. It could be "grip of death" causing the arm pump. Very common with beginner riders. They tend to be too tense and grip way to tight on the bars. On any longish descent (3 min + like expressway) your arms will be in bits! Focus on relaxing your arms and shoulders next time on expressway and see if it helps.

Lemming

One other thing to mention when checking your sag; do it whilst wearing/carrying what you would for a typical ride. That includes any camelbaks filled with water, and/or bottles on the bike, etc.

prunudo

It might go against the grain here but if you're consistently only using 100/140 of travel and the o ring is never getting close to max I would let some air out. If you decide to start hitting trails with more drops or jumps then readjust.

But equally, I found playing around with settings helpful, buy a shock pump and stick it in your back pack in the trails. Add 10psi, hit a trail or two. Reduce buy 20 psi, see and feel the difference in real time.

MBSnr

https://www.boards.ie/discussion/comment/120692506#Comment_120692506

You could try as prunudo says.

I was the same - setting the fork to 20% sag and then wondering why my hands suffered. The shock had too much air in it and was never compressing more than 3/4 on the stuff I was riding. I let some air out, not that much, increasing the sag a little and now get decent travel on most of the stuff I ride. I tend now to worry less about the sag (it's hard to measure accurately and correctly anyhow at the best of times) and focus more on the travel I'm getting depending on what I'm riding.

mad turnip

I'm with Prunudo here aswell. If you aren't using 30% of your forks travel its probably setup too hard. For newer riders I'd probably recommend sag closer to 25-30%. Newer riders are going to suffer in there hands just also just a bit part of the sport in the beginning.

Due to how volume vs pressure works the last 30% of the forks travel is much harder to use than the first 30% so you've likely got it quite a bit too hard for the riding your doing.

Depending on the grip I can find my hand gets quite sore. Since your 110kg I'm guessing your quite tall with long fingers? Might want to consider some thicker grips.

Ceepo

You could also look at where you brake lever are both in terms of angle and bite point. When you're sitting on the bike you're forearm and wrist are at a different angle then when you're coming down a trail, some people ride with their brake lever tilted down a bit, this takes pressure of the forearm. Also if you have the bite point out a good bit on the lever this can cause arm pump too. This may not be the cause in your case, but it's something that I was told early on when I started mountain biking, and certainly help a lot when I made small adjustments

DaveyDave

https://www.boards.ie/discussion/comment/120709390#Comment_120709390

Yeah I've been meaning to recheck the levers, they're angled down a fair bit already as I sit fairly tall on the bike but I'll check my standing position. I think the brake levers need to come in a bit also.

The grips don't feel too small but I haven't used larger grips to compare so I might pick up a cheap set to see how that feels.

DaveyDave

Just to revisit this. I haven't managed to get my fork pump back but I used a key to let some air out for the craic, it ended up letting probably 20-30psi out which was more than intended but it wasn't a genuine test. As expected it was horrible, lots of brake dive so I was trying to keep myself upright over terrain. I can see why even letting 5-10psi out is the wrong direction for tweaking things.

I put the fork up to 120psi, slightly higher than before. I haven't hit Expressway since and my tyres are about 5psi higher now so nothing scientific but it felt solid, the tyre pressure made it bouncier over rocks but the suspension still felt solid. I do think there's an element of death grip for Expressway due to the speed and repeated rocks. I think I'll save Expressway until I'm more comfortable staying off the brakes and carrying more speed!

prunudo

Without asking an awkward question, but 120psi sounds high for the fork.

DaveyDave

https://www.boards.ie/discussion/comment/120832481#Comment_120832481

That's because I'm a fat arse :) The highest range on their tuning guide is 109-113kg at 114psi and the max for the fork is 120psi so I'm at the max. 114psi has me just outside the sag range geared up.

munsterleinster

https://www.boards.ie/discussion/comment/120832612#Comment_120832612

About the same weight as you.

The above comment about the grip of death is probably the most likely the main issue. Hard to overcome gripping too much without confidence so a few things to try.

Drop the pressure in the front tyre a wee bit more. Maybe 2-3 psi. This will take away some of the buzzing in the hands but the downside is risk of pinch puncture and less precise handling.

Drop the pressure in the forks in 5psi increments. Who cares if you go through all the travel. You want to get experience and need to be conformable to get this.

If you find it comfortable at slightly lower pressures but are blowing through the travel, you can add some volume spacers. They're little plastic spacers you insert into the top of the fork to increase the "progressiveness" of the fork.

If you are running high fork pressures, you need more rebound damping to balance this out. Don't forget to drop this if you reduce pressure as too damping will prevent the fork extending before it hits the next bump. Follow the number of clicks on the manual (or sticker).

Gerry

I'd agree with dropping 5 psi at a time. I was away recently in morzine and was still not using all the travel, dropped a few psi and got a bit more comfort.

You should really get your tyres setup tubeless, at the same pressure it will be more compliant. any decent bike shop can do it if you dont feel comfortable with attempting it.

iwillhtfu

Sounds like you have a classic case of death grip OP. You'll need to learn to loosen your grip a bit, which can take a conscious effort. Are you feeling some arm pump in the forearms also?

The fork likely isn't set up properly either which wont help. I wouldn't be compensating for rider weight with the rebound. Set the air pressure and suggested and set up the sag. After that go for a spin with your shock pump and add/remove air as you feel.

If the tyres/wheels are tubeless no reason not to set them up it isn't difficult to do a few youtube videos and you'll do it yourself. It'll allow lower pressures but at 110kg around 26psi is about right, I'd say maybe a little more in the rear and a little less in the front depending on the trails.