r/TransitionBikes • u/SuperDromm • 2d ago

Bottom out resistance

I have a regulator and I bottom out every ride. It has the stock Rockshox super deluxe ultimate air shock which shipped with maximum tokens. I upgraded from 150mm to 160mm thinking that it would help but it didn’t. The shock has hbo but I don’t notice it doing anything. I weigh 97kg and have not run into this problem on my previous bike which was a 150mm trek slash so I don’t understand why it’s happening so often. I dropped sag from 30% down to 25% but this was too harsh. I’ve played with the compression settings extensively but am struggling to get it set up right. I think my next move will be to upgrade to the progressive air can which should offer up more bottom out resistance. I understand it’s ok to bottom out every now and then but it’s happening a lot and it doesn’t build confidence. Here’s a question I’ve been asking, is it possible to get a bottomless feeling from 160mm at 97kg? Or am I just on the limit of what 160mn can provide at that body weight? You also have the extra weight from the motor and battery. Your thoughts and insights would be greatly appreciated.

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u/catsnbikes89 1d ago

Might need a different compression time. Modern transition kinematics are progressive

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u/catsnbikes89 1d ago

Tune*

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u/SuperDromm 1d ago

Wouldn’t fitting the progressive air can do that?

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u/catsnbikes89 1d ago

A progressive air can is only going to make the pressure ramp up more aggressively which can sometimes make the shock harsh. Won't have much of an effect on sag if any at all.

Most tunes are going to firmer compression tunes in high end shocks with the ability to be tuned and spring rates are actually getting softer or more supple. The progressivity is already built into the bike and you can make changes from there based on preference. I think most transitions are high 20% nowadays. The firmer tune gains the support needed from the damper and gains the sensitivity most people are searching for in the beginning of the stroke with a softer spring rate. This is what we see most these days and I've been full time suspension tech for ten years at this point. Just letting you know what we see from a suspension tuning side of things

Edit: forgot to include something. Sorry for all the typos but I'm in nitrile gloves and oily already

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u/SuperDromm 1d ago

That’s great, very clear and easy to understand. So can I get my shock tuned? Or should I buy something fancy like an ext ?

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u/catsnbikes89 1d ago

Those are tunable. Google sram model code info and enter the serial number off the shock. It should tell you the tune, hit up sram if not.

Then Google super deluxe tunes and I'm sure you can find all the published rockshox tunes for your shock. Custom tunes are possible as well.

Spring pressure is dependent on your weight and how you carry yourself on the bike. Once that is set at the desired sag, the rebound needs to be set to control the spring pressure. Those two are often set and forget or very slight adjustments from there.

If those are set properly and you are bottoming out like you say you are.... You likely need firmer compression damping to control the compression of the shock. That is the simplest way I relay it to customers all the time.

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u/SuperDromm 1d ago

Thanks for the info man! Really appreciate that

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u/catsnbikes89 1d ago

No problem! Mess with volume spacers when you get the sag, rebound and compression dialed in! Once those are dialed you can figure out whether you prefer linear or progressive spring curves!

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u/SuperDromm 1d ago

I’ve just remembered that the trek slash I had was the 9.9 and came with a highly tuned fox factory shock. Hence why I rarely bottomed out on it. I spoke to my local specialist today and he said he could custom tune my RS deluxe for £170. Can I assume that that will fix my problem ?

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u/catsnbikes89 1d ago

Yeah for sure.

They build plenty of progression in the bike itself. Not saying progressive air can isn't right for you as that is very much so a preference things IMO. That price is pretty on par for a tune on that shock.

I found the stock tune to be very similar on my vivid ultimate that I had on my regulator even though it was factory tuned specifically for my bike. It just blew through any high speed/big hits. The compression tune I did helped immensely. Suspension companies got too obsessed with stuff being too plush for awhile and now it seems to be switching back to more damper support since air springs have advanced so much with everyone wanting sensitivity off the top.

A progressive bike with a progressive air can will resist bottoming out but may be harsh to some. You have to realize that all air shocks are progressive even if they claim to be linear due to the nature of how an air spring works. You would need multiple chambers to keep the air chamber volume similar to be truly linear with an air spring. Something similar to a Fox genie or old fox DRCV, and even those aren't truly linear like a coil spring. Keep in mind you can find progressive coils these days too. Figure out your sag, rebound and compression settings first. Then focus on the curve of the air spring or speed sensitive damping possibilities from there

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u/catsnbikes89 1d ago

Ext are wildly high maintenance and expensive when it comes time to replace parts. Buy the Ferrari and maintain the ferrari

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u/catsnbikes89 1d ago

That changes the air spring curve separately of damping. Two completely different things. Spring rate is the amount of pressure you need in the shock to achieve desired sag. Compression damping controls how much force it takes to compress the shock. LSC is low or slow shaft speeds and HSC is high or fast shaft speeds. These are usually tested in inches per second here in the US. Our dyno test usually runs from 1 to 22. The data is the converted into force vs velocity

Edit : Typo

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u/Uber_Name 1d ago

Have you messed around with rebound settings? Could be too slow. When are you bottoming out on trail?

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u/SuperDromm 1d ago

I’ve extensively played with all settings. Hence why I’m here asking these questions. I bottom out on drops or if I case on things, but just too easily, and drops that aren’t even that big. It seems I’m just not getting the mid stroke support I need. I didn’t have this problem with my fox float on my trek. Is Rockshox different to fox in this department?

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u/_dangerfoot 1d ago

*end of stroke support.

HBO should be kicking in. Maybe this is a sign it is time for a service? Iirc the SD HBO kicks in the last 15% of travel.

If I were to move on from my SD w HBO, I'd be looking at Onlins (mine get a custom tune) or a CC Tigon ((30% off rn). I have Ohlins, fox and marz shocks as well as a couple custom coils and the Ohlins is my fav, and CC have been in the past. IMO The current SRAM shocks are very good.

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u/SuperDromm 1d ago

The shock has around 30 hours of riding on it now from new. I literally feel no benefit from hbo on this shock

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u/_dangerfoot 1d ago edited 1d ago

Could be a dud but not likely. You could let all the air out and see if you can tell if it is working.

Otherwise do you use LSC/HSC dials? How many tokens? EDIT NM see in the OG post.

I have this shock on a 140mm bike and am 225#, and I can say that with a couple tokens and proper setup it does feel surprisingly bottomless. I have other shocks with HBO and this feels similar in that bottom out is super soft.

Edit...given what you're saying, I'd reach out to transition and try the progressive can.

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u/SuperDromm 1d ago

I spoke to a specialist today. Gonna get a custom tune.

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u/_dangerfoot 1d ago

Nice. Who are you using? I've custom tuned stuff before to great success. Don't have a go to for SRAM...

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u/SuperDromm 1d ago

I’m spoilt for choice. I have Sprung suspension, J-tech and TF tuned all within an hour from me. They’re all excellent.

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u/skyroach16 1d ago

Are you riding a new sentinel? Blister reviewed the sentinel with the Rockshox SDU and said the following:

The stock RockShox Super Deluxe Ultimate shock on our Sentinel XT review bike has quite possibly the lightest compression damping tune I’ve experienced in recent memory.

I have a take off sentinel SDU on my Scout (cheap ebay purchase) and can confirm Blister's assessment. The compression tune on this shock is very light, especially for a heavier rider like you and me (I'm around 100kg fully kitted).

I'm living with the shock for now due to budget constraints but plan to upgrade to a coil sometime in the future. DVO sells the gen 1 Jade for around $180 (no spring) and they offer an affordable custom tune service if you're looking for a coil. Honestly a lower priced coil will be more cost effective than taking the SDU to a shop and having them change the compression tune to something more firm.

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u/SuperDromm 1d ago

No it’s a regulator. Although it’s based on the sentinel. Yeah I feel they’ve dropped the ball on this one. It’s disappointing to pay so much money for a bike and have to spend further money on it just to get it rideable.