[Closed] Small bump sensitivity...

What tyres and tyre pressure are you running?

Nobby Nic 2.35 front tyre and Rocket Ron 2.35 in the back... both tubeless and at 24 psi. I am currently running DT Swiss XM481 rims. Internal Diameter is 30 mm.

My weight is 85 kilos, so I am not exactly a racing snake.

I had a 100 mm Reba (2004 ?) - never was happy with it (not enough progression).

The only RockShox fork I bike right now is a RockShox Sektor 130mm. And what you describe sound very similar how I would describe the Sektor. Progression is o.k. now and small bump sensitivity is bad.

When the fork starts feeling like "wood" I do the small service. New oil in the lowers, bit of PM600 into the seals. Friction is fine then - but "small bump sensitivity" is not improving... (run also around 25% sag)

Comparison to other bikes: my other bikes have low cost Fox forks (34 Rhythm). Huge difference. Appears like Fox uses better technology also in the "cheaper" fork versions?

Hmmm... Does not sound promising.

The fork had a complete overhaul less than 20 riding hours ago.

Anybody think that a little stanchion deodorant might help?

I think that the small bump stuff is what you tend to get when you pay more for a fork, tbh.

I'd try fitting a bigger tyre run at lower pressure.

do yo have compression damping adjustment?  If so back it off?
its always a problem with tele forks as you get flex and stiction in the stanchions and bushes

wwaswas

I think that the small bump stuff is what you tend to get when you pay more for a fork, tbh.

Hmm, not sure on that, I thought they ran the same bushings and seals up through the range. Might be wrong though.

Certainly my bargain basement Sektors are a lot more supple than the Revolutions they replaced.

I think to some extent it is the luck of the draw with how tight the bushings are. I think there is an adjustment which can be done. LoCo or somebody can probably advise.

When you say 'serviced' do you mean the lowers only, or a full service?

The reason I ask is that my 2014(?) Sektor has a similar issue which is caused by a small nick on the inside of the stanchion in the air spring. This was probably caused by a washer thingy that had broken and was floating around in there (as far as I can remember when the guy at TF explained it). Reassembling with a bit of fork grease to fill the nick was a good temporary fix.

Personally I've always thought small bump compliance was up there with vertically compliant laterally stiff...but my tuppence for what it's worth

Either

Set your fork up for where you want it to perform at its best in the conditions you choose, and be prepared to compromise in other situations

Or

Buy a fork that has properly adjustable settings and play with it until happy. Usually this is 'negative air chamber' to help a fork overcome initial resistance.

It was a full service, at a RockShox certified service centre. There is no room for larger tyres, but I suppose I could go slightly lower regarding air pressure.

I always set up the compression as close to the "rabbit" as possible on RockShox. Would it make sense to go towards "turtle" instead? 🙂

I might also get away with lowering fork pressure a bit, but I would hate to have to worry about bottoming out on hard landings.

do yo have compression damping adjustment?  If so back it off?
its always a problem with tele forks as you get flex and stiction in the stanchions and bushes

It is an issue, but it varies widely dependent on the fork. I'd not necessarily simply back off compression, as it won't affect the stiction, but when that force is overcome the fork will move too easily making it feel wallowy.  I have a lot of experience with stiction in forks 🙂 and I prefer more compression damping on a sticky fork.

Your stanchions might be slightly bent, causing more friction in the bushings.

There is a massive difference between a bad fork e.g. my old Marzocchis (that particular model was apparently pot luck if you got a sticky one) and a good one like my current Foxes.  A fork should not have much stiction.

stanchion deodorant

Friend of mine uses the stuff. On an RST fork.

Yes - the stuff helps. But for one ride only - and then you have to use it again...

And: use little amounts only. Too much of that stuff will help dirt and crap getting into the fork.

For me: too much hassle.

My strategy: waiting for a Fox sale.

Its unlikely either your 30s or Andrea's older sektors have a negative spring, meaning that you have to generate the force to overcome the airspring before they start moving, add to this the effect of stiction etc. and as you say small bump sensitivity will go out the window. That is the nature of the beast. The only thing you can really do is run them softer and also run the rebound more open (it probably will be effecting the compression too).

Personally I’ve always thought small bump compliance was up there with vertically compliant laterally stiff

I think you may well be right here. I've got 2018 Pike forks, which should be better in this regard. But having come from a fatbike (which really does smooth out the chatter) I'd say that small bump sensitivity is still pretty much non-existant. A fast descent at the weekend on a track littered with small rocks and really I might as well have been on a rigid bike. Given them a big hit though and they are great 🙂

….doesn't really matter.

Just completing the title for you OP 🙂

That is the nature of the beast.

@benpinnick:

yes. Sounds like that. Good explanation!

"Softer", "rebound more open": that's what I do. And correct - that helps (a bit).

The only thing you can really do is decrease the rebound damping (i.e. set it faster) in order to avoid it packing down on repeated hits. I never really thought about this until someone suggested it on a demo ride and it did help on that bike, don't know who had set it up prior to me.

FWIW I can't find anything that spoils me for small bump sensitivity as well as my 2005 MX comps (air sprung) and 2001 z1 BAMs (er, not air sprung). The more modern (air sprung) forks I have seem to be more controlled on the compression stroke, but lose out on small bump sensitivity as a result. Or it could be the more sophisticated damping instead of the open bath that at least the Z1's have - not sure about MX comps as they've never needed a service so I haven't checked (but they were basic even for then so I can't imagine they have anything particularly sophisticated in the damping).

If they've just been serviced, as long as there's a bit of lube on the seals it will be as good as it's going to get.

Personally I’ve always thought small bump compliance was up there with vertically compliant laterally stiff

I've recently come to the conclusion that "small bump compliance with mid-stroke support" is the equivalent. Neither of the forks I mentioned above have great mid stroke support. But I still like them!

So, basically... Live with it?

As I said, no major investments right now, I am saving up for a fully.

Thanks for all your help!

So, basically… Live with it?

Sounds like it.

O.k. - the fork does it's Job on the "rough stuff". That's good. The performance of the bike is not suffering.

But the "feel" of the fork ... I know what you mean!

New bike, new fork: yes.

I have the impression that Fox tries to get into the market of bikes "around 1.5 k" - and this with really good technology. In the "long run" all fork manufacturers might be able to supply us with "budget forks" which are also great with "small bump sensitivity"....

Having ridden some Fox 36 factory (2018) forks on a demo bike and compared them to my 2018 Revelation RC's - I'd say it's all down to what you pay - the level of plushness on the fox forks is just awesome.

I'm hoping I can get the revelations a bit better with the new debonair damper, and possibly a charger 2 upgrade at some point.

So many replies and nobody has suggested simply letting some air out of the fork? 25% sag is a fair-enough starting point, but 30% is fine, even 35% if you like. Depends how the fork ramps-up on bigger hits.

Let some air out, see how it rides. If you don't like it, put some air back in.

Surely less sag is better for small bumps? An air spring is naturally progressive so having a fork deeper into it's travel, the spring will ramp up faster. Whereas a fork only 20% into it's travel is still in the sensitive initial travel area.

Also remember that when the wheel hits a bump, the force pushing the wheel (and fork) upwards has to have an opposite force - if you've got no weight over the front end the bump will just force the wheel, fork and rest of the bike upwards as there's nothing to resist in the opposite direction, unless you have the most sensitive forks in the world... Putting some weight over the front allows the fork to do it's job and absorb the bumps as there's an opposite force resisting the handlebars from moving up.

It's why e-bike suspension feels so much better, all that weight in the frame acts as the opposite force. In an extreme example, motorbike suspension is super plush, because the suspension has all the weight of the bike to push against.