[Steve M]

UDI...

Dynos do not lie and when Dynod a BOS shock is head and shoulders better performing than anything else. Makes a Vivid look like a toy!

Mike, I'll thank you not to speak for my dyno testing, especially when you haven't seen the results yourself. The BOS has exceptionally fine and linear adjustments, but it also has a very limited adjustment range, and such high levels of HSC that it's no surprise that it's excessively harsh on a lot of frames and for a lot of riders. It certainly isn't what I'd call "head and shoulders better performing than anything else". It's great in many regards, but it isn't perfect, and more notably, it isn't well suited to all frames (even with the "correct" tune).

You should also be aware that Udi is both a BOS owner (in fact, it was his shock I dyno'd!) as well as being one of very few people who's ever seen actual dyno testing results of a Stoy. I think you may be wasting your time trying to tell him how good his shock is.

 

[sundaydoug]

Mike, I'll thank you not to speak for my dyno testing, especially when you haven't seen the results yourself.

Did you forget what website you're on? Opinions on the quality and function of mountain bike products with no real knowledge of them while basing everthing entirely on hearsay is what ridemonkey is all about.

 

[Udi]

Vikingboy -
My rider weight is fairly average at about 80kg with gear.

You don't "work with BOS" - you just get a preset tune for your frame (1 of 5 tunes back then) and they recommend settings and a spring to go with that - neither of which were correct in my experience. They do not take into consideration rider weight or style, only the frame's leverage ratio.

If you think about it, combining that principle with a very narrow range of adjustment is flawed logic. But when it doesn't work for someone of average weight, it's just poor valving. Interestingly enough the problem would only surface hitting square edges at quite high speeds (along straights for example) and in these situations the Fox RC4 shock was significantly better.

You have to understand that at the end of the day, all these products are just pushing oil through a shimmed piston to provide damping - and thus the primary area of concern is the valving itself. If the damping rate at the wheel is not suitable for the frame and rider, you've dropped the ball. To answer your suggestion specifically, BOS in France were rude had no interest in changing the valving, however my (excellent) local distributor was kind enough to offer me a refund and looked after me. I will revalve it myself in the future, however that defies the point of the investment.

For what it's worth, I also found the RC4's rebound curves to feel smoother and more linear, where the Stoy would tend to feel a little peaky / kicky where it shouldn't be. The BOS also lacks a hydraulic topout system (for those that know shock internals, the teardrop shaped cutout on the rebound port) - thus tends to topout a little harshly compared to other offerings.

I do think they have a good chassis - it is very sensitive and this appears to be a combination of the shaft and bushings used in the shock as well as the needle bearing eyelets, but apart from that I don't think they are doing anything that is night-and-day over CURRENT offerings from manufacturers like Fox, which I doubt many people throwing these crazy claims around have actually tried.

This year I have had the Stoy and a Kashima RC4 at my disposal, my preference has been the latter for a myriad of reasons (some are frame specific and thus I have not mentioned them here). However, to each their own - if you're happy then that's all that matters.

You should also be aware that Udi is both a BOS owner (in fact, it was his shock I dyno'd!) as well as being one of very few people who's ever seen actual dyno testing results of a Stoy. I think you may be wasting your time trying to tell him how good his shock is.

Thanks Steve, I didn't realise that djtrazer's dubious dyno claims were in fact about my personal shock - that he hasn't even seen charts for.

 

[Steve M]

Hey Udi, thanks for your follow-up post clarifying your concerns. From my personal perspective of riding Bos suspension recently I found the compression to be absolutely spot-on but this does depend on working with Bos to get the right settings for your frame and rider weight. Yes, if the basic shim settings are off you will not be able to compensate via comp & rebound settings as they do offer a narrower range than say a Fox shock. This is intentional I believe as the shim/spring should put it in the right ball park. Although this means the shock is less versatile than say a CCDB its not a big deal to have it re-shimmed if needed.

From your three points it sounds like your shock was wrong for your weight, you tried to compensate by maxing shock C&R settings and were frustrated it didnt have the range to compensate fully for the base setting being out of whack for your bike & weight. I'd encourage you if you have it still to return it to Bos to be tuned correctly before you make your final judgement.

For me the quality of Bos damping is a easily noticeable step above above both Fox & Rockshox offerings offering better control, traction and using its travel more efficiently.

In my opinion this is pretty much bang on, and a good illustration of the pros and cons of fine external adjustment ranges. The BOS has the potential to work SUPERBLY on the right bike, for the right weight rider, but given the small range of adjustment available for any of the five or so factory tunes, vs the variation in leverage rate and rider weight in combination with relatively extremist tunes (they're x-treme because they make you do backflip barspins on your DH bike mid-run ), it seems reasonably common that you find rider/bike/tune combinations that simply don't work that well. If you're going to revalve it to suit then fair enough - but once custom tuning is introduced into the equation, there isn't actually all that much difference between any of the shocks on the market in terms of the performance you can get out of them. With valving changes and other minor alterations, I could quite seriously make an RC4 feel so similar to your BOS that in a blind test you'd be unable to tell the difference.

Udi makes a pretty valid point - if you're going to pay THE absolute premium price for "the best you can get" - it's reasonable to expect it to be like that without requiring further modification.

Did you forget what website you're on? Opinions on the quality and function of mountain bike products with no real knowledge of them while basing everthing entirely on hearsay is what ridemonkey is all about.

hahah fortunately there's a good core group of members on this site who post up a LOT of useful information, including a lot of really helpful industry guys (DW, PUSHIND, John P., to name just a few). As amusing as internet misinformation can be, I'd rather not be responsible for it myself!

 

[StabprimoMonkee]

Boxxer Race + VanR + Push >>>>> Everything else.

The only downsides are that it is extremely cheap and won't get you any kind of brotherly attention.

 

[jonnymbx5]

Simple is better, happy BOS rider.

 

[RedOne]

A friend wanted to have his BOS Stoy coming off a Banshee Legend reshimmed for his new V10. The german distro told him that the old tune is ok for the V10 (seriously? 8" vs. 9.5" travel!?). R53Engineering in UK gave him a totally different setup and he is all happy with it.
You can imagine how the performance with the wrong tune would have been.

The most annoying problem with BOS Idylle forks are the springs beeing too short or getting too short and having play/making noise on the spring seats.

 

[richgardiner]

I bought some brand new Idylle Rares in april this year, the last set of 2010 ones from R53. They were flawless performance wise and maintenance wise in whistler for 3 months, absolutely loved how they felt! However, the high speed compression adjuster fell off, which I wasn't overly pleased about - When R53 eventually got back to me, apparently it was my fault and I must have been using the wrong tool (I used a 14mm socket as instructed) to adjust the HSC, which caused the grub screw and consequently the adjuster to fall off. This was only after 2 weeks of use, and I followed everything in the maintenance section of the manual religiously - perhaps they should mention to check the grub screws that hold the adjusters in!
I think the lowers have also twisted slightly, which is also annoying. Although it could be my eyesight, maybe I'll send them off and see what they think.

I have a stoy on my 2010 demo, although it needs a revalve, apparently it was tuned for a demo by the previous owner (the shock was originally a ST01, the demo needs ST04). Currently running it on the slowest rebound setting, I found it too fast at first but now im used to it, but still next time i get it serviced I shall get it revalved so my current setting becomes a medium setting, so I can actually have a workable range of rebound adjustment.

All in all, performance = great, but dealing with distributors can be frustrating...

 

[djtrazer]

Hi All,

This is an internet forum right? Somewhere people can express personal opinions right?
So I would like to enforce that all my posts are an opinion based on riding BOS for a few years and are exactly that. And BTW I run an RC4 on my Summum now which I am very impressed with too as its just done a full season in Whistler without any dramas and feels like it did at day 1. So not just a BOS bigot!

Steve with regards to your Dyno testing, I dont know your results and wouldnt understand them if you showed me. There is no reference in my post to you or anyone for the matter so not sure why you decided to write that I was referring to your testing?

Merry XMAS kids, hope you all got some BOS stuff under your XMAS tree this morning!

 

[richgardiner]

djtrazer, did you have a silver summum with black idylles, worked in the rental shop with the glorys, shockers, lapierres etc by anychance?

 

[Steve M]

Hi All,

This is an internet forum right? Somewhere people can express personal opinions right?
So I would like to enforce that all my posts are an opinion based on riding BOS for a few years and are exactly that. And BTW I run an RC4 on my Summum now which I am very impressed with too as its just done a full season in Whistler without any dramas and feels like it did at day 1. So not just a BOS bigot!

Steve with regards to your Dyno testing, I dont know your results and wouldnt understand them if you showed me. There is no reference in my post to you or anyone for the matter so not sure why you decided to write that I was referring to your testing?

Merry XMAS kids, hope you all got some BOS stuff under your XMAS tree this morning!

The testing you talked to Ken about was testing that Ken and I conducted. I think you may have read a little bit much into his comments regarding the BOS. The build quality and precision of adjustment that the BOS has is excellent, but there's more to a shock than that I know you've had an excellent run with your BOS stuff too, the service intervals alone are pretty impressive.

And merry christmas to all!

 

[djtrazer]

But people do.[/QUOTE]

Bit hostile? Are you calling me liar?

 

[djtrazer]

Service intervals are probably the one most amazing thing BOS has going for them, their tech feels and rides great but I really cant tell the difference in my bike between an RC4 and Stoy.
Not to say they are flawless, I have actually blown 2 Stoys in a over the years as they had a problem on a batch with the main shaft seals blowing and even though RC4's seemed to have issues for a bit I never had any of mine. Luck of the draw?
In my opinion and not based on anything to do with you guys testing BOS performs as good as anything else out there, what really stands it head and shoulders above the rest is the service and reliability. Thats the message I want to get across, well that and the fact that all RS stuff is crap!!! (come on some one bite!)

Now Im going to go ride my bike....Laters

 

[djtrazer]

Oh and Steve, stop saving money and come ride your bike at Buller

 

[Udi]

Service intervals are probably the one most amazing thing BOS has going for them, their tech feels and rides great but I really cant tell the difference in my bike between an RC4 and Stoy.
...
I have actually blown 2 Stoys in a over the years

Haha, service intervals are great but you blew two of them?
I blew one of mine too. Yes they updated it, yes it's fine now.

In short - BOS aren't perfect, neither is anyone else - they're not head and shoulders above anything, they just make some cool gear with a few imperfections just like everything else on the market. Fix the little bugs and they're great, but the same could be said for any other good suspension product.

I have nothing against you personally, it's just the part where you signed up to a forum and raved on about something you clearly understand very little about - in particular dyno results you haven't seen, of someone else's (my) shock.

If you love your gear, just go ride your bike - and I'll do the same.

 

[Deano]

Udi, you are working with/for a BOS service center since your taking it apart ?

Im just wondering cos of how you would pressurize it again once done, and how many PSI ? and air or Co2 to do so .. etc.

Im not a tech but i like to fiddle with my own stuff still, coming from a background in paintball mechanics, so im used to pneumatics, so i figure hydraulics like this is similar.

 

[IH8Rice]

It also has a complete secondary compression stack in the piggyback, that's why there are three sets of shims.

so the shims are for the rebound and 2 compression stacks? what is the reasoning behind having two of them?

 

[Jm_]

so the shims are for the rebound and 2 compression stacks? what is the reasoning behind having two of them?

Most high end shocks have a setup similar to this. Remember that the CCDB has a shim-stack on the main piston, and then the spring-controlled poppet valves at the reservior, those provide the "user-controlled" compression damping, as you'd have to have a wacky concentric rod going through the shock shaft to reach the main shim-stack to "preload" it or whatever. The avalanche and push shocks have a similar setup with a spring-controlled valve (there are also a couple shimz in there, but I don't think those are for damping based on the diagram), I've seen the RC4 internals and same thing, and so on. It depends on the complexity of the shock, but you are controlling low/high speed damping depending on the valving that is there. The main-piston is most likely "high speed" and the 2nd stack in the reservior is most likely "low speed" on simpler shocks, but there's usually going to be some interaction between them unless it has a more complex setup.

 

[RedOne]

Because moar shimz are moar good is the only good answer.

 

[Steve M]

so the shims are for the rebound and 2 compression stacks? what is the reasoning behind having two of them?

The reason you have two compression stacks (one in the reservoir bridge and one on the main piston) is to build up pressure between the main piston and the reservoir bridge via damping forces (oil flow through each compression circuit) rather than relying on the gas charge pressure to force the oil through the main piston. If you only had the gas charge pressure itself (say you had 200psi in the reservoir), once the pressure drop over the main piston became larger than the gas charge pressure, the pressure behind the piston (between piston and seal head) drops to zero ie a vacuum, causing extremely severe cavitation.

Having a 2nd compression circuit between main piston and the IFP means that you can run lower gas charge pressures/higher damping forces without cavitation. Ideally, in terms of cavitation/consistency, the pressure drop over the main piston should be no larger than the pressure drop over the reservoir bridge circuit, however this is not always the case because as a general rule, the larger the amount of damping coming from the reservoir bridge circuit, the wider your range of external adjustment - which can be a good thing or a bad thing depending on how specific the manufacturer wants to make the initial tune. In the case of the BOS, the factory tunes are very specific and the adjustment range is narrow, whereas at the other end of the scale you have the RC4 and the CCDB which have very wide ranges of adjustment.

Having a 2nd compression circuit also provides an easily accessible point on the damper for external adjustments - since you typically have your rebound adjuster in the shaft of the shock, it'd be extremely difficult to get any compression adjusters working on the main piston.

 

[Udi]

So as I said the Stoy is a nice chassis but there were a few problems with the stock shock that seemed to be replicated on the dyno, so I made a few small changes.

First issue was the rebound being too fast unless the adjuster was fully closed (which was also affecting compression damping), so valving the rebound stack firmer fixed that, allowing the adjuster to be run further out. Tested this separately before moving on.

The second and more significant problem was compression spiking at high shaft speeds. Usually taking a few shims out would be sufficient, but the stock HSC port area on the BOS piston was quite small (3x 3.4mm holes) so I decided to enlarge them to a generous 3x 4.5mm. Problem then was I needed a larger face shim, which was going to cover up the rebound entry ports, so some extended side entries were made.

After some beefing up of the dual-stage compression stack to deal with the extra flow area, all seems to be working well. Excited to get some proper testing in on the new setup.

Changes to the piston:

Larger comp face shim, side access to rebound ports:

Rest of the updated dual-stage comp stack:

Just before reinstallation:

 

[vikingboy]

Awesome...my kind of tinkering
Could you share dyno plots before and after please Udi along with your subjective review?

thanks in adv

 

[Sandwich]

just about the only person i would trust to crack open and toy with/drill a $950 shock...

 

[richgardiner]

Wow, some serious modding right there! Fully agree with you about the rebound being too fast. Mine's fully closed at the moment, doesnt leave me with any scope for adjustment!

 

[stiksandstones]

So...anyone want to give me a quick education on the BOS forks, out of curiosity, can you still buy the BOS fork? can you buy them in the USA? Europe? Do they sell parts? service centers?

I had the fork and shock 2 years ago and liked it, just wondering where they are at with it all.

 

[worship_mud]

they updated their range for 2012 and a friend of mine bought a Deville 140 blabla (insert three letter acronym), thought about getting a 2012 Idylle myself, but found noone to buy my 2011 model (hint, spam!)
they seem to be operating...

 

[RedOne]

So...anyone want to give me a quick education on the BOS forks, out of curiosity, can you still buy the BOS fork? can you buy them in the USA? Europe? Do they sell parts? service centers?

I had the fork and shock 2 years ago and liked it, just wondering where they are at with it all.

They are easily available in Europe. The 2012 forks got lighter. There are some service centers in Europe, the best being r53engineering in UK. Price for a 2012 Idylle Rare is on par with a FOX 40, in Germany at least.
Don't know how the situation is in the US.

 

[Deano]

very much alive in europe, better and lighter then ever..

tried one.. want one, but cant afford one right now..

 

[stiksandstones]

What is euro MSRP on fork and shock? the DH model?

 

[UiUiUiUi]

What is euro MSRP on fork and shock? the DH model?

according to bosmtb.com

MSRP for the regular Idylle 1570 Euro
RaRe 1990 Euro

can't find the msrp of a fox 40 but bike mail order is selling the 2012 Fox 40 for 1829 Euro and BOS at msrp pricing...

all prices include 19% sales tax

PS: Stoy 570 Euro,
Stoy RaRe 670 Euro

 

[-C-]

very much alive in europe, better and lighter then ever..

tried one.. want one, but cant afford one right now..

Hmm, sadly I wouldn't be so sure.

There are all sort of rumours floating around about BOS Motorsport being in serious financial trouble.

 

[vikingboy]

Would be interested to know if anyone in motorsport is ever not in financial difficulties!
I've not heard anything and I'm in motorsport too, not saying it isn't true but I would personally hate to see an internet rumour cause damage to a small company that has brought real performance gains to our sport.

 

[sethimus]

according to bosmtb.com

MSRP for the regular Idylle 1570 Euro
RaRe 1990 Euro

can't find the msrp of a fox 40 but bike mail order is selling the 2012 Fox 40 for 1829 Euro and BOS at msrp pricing...

all prices include 19% sales tax

PS: Stoy 570 Euro,
Stoy RaRe 670 Euro

there is always someone at the mtb-news.de bikemarkt section who sells a new idylle around the 1000eur mark...

 

[fizz]

Hi Udi,
I'm impressed with the way you modify and know science about shocks.
Do you work for a suspension company?
If so i would like your advise to make a good decision about my Bos Stoy either to sell and get a RC4 or CCDB or have my Stoy modified.

 

[Udi]

No company, just for my own interest - but I'll reply to your other message here too so it's all in one place.

Hi Udi,
I have a Stoy mounted on a Banshee Legend witch i like but found some disadvantages (top out) with the shock and apparently i don't run the correct valving (i have the ST-01 instead of the ST-02 according to Bos). I need your advise because you are the only one i know who seems to know this shock in North America.

The Legend has no progression in its leverage curve near the end of stroke (it actually becomes regressive), so I'd say the RC4 is the best shock for that frame, as it caters well for this characteristic with its position-sensitive compression damping (while regular shocks like the CCDB and Stoy do not). This will let you run an optimal spring rate without trying to compensate for bottoming out, and thus allow for better bump absorption. If you go this route, make sure you get the 2011 or later model RC4 as there are some important updates.

I am not sure of the exact differences between the Stoy ST01 and ST02 tunes (mine was an ST04 originally), however I believe the performance of the HS valving in the Stoys (at least the two I have owned) is less than spectacular, and while I am fairly happy with mine (actually spent last weekend testing it in a new frame), it is not really a BOS shock anymore as the piston and valving are both heavily modified.

The reason for the top out can be one of two things. I think on earlier versions of the shock there were a few failed top out bumpers (haven't had any problems with this personally) - but all of them will have a slight top out as there is no hydraulic top out implemented on the rebound port on the shock shaft. Most mainstream shocks (DHX, RC4, Vivid, etc) have a teardrop shaped port that increases rebound damping heavily immediately before top out. If it is just a light thud at top out then it is normal (there is a rubber bumper internally). If it's a loud clunk then there may be a problem.

 

[tacubaya]

UDI

Did you discover the lack of oil flow through the HSC ports during a dyno run or after removing HSC shims and finding out that doing such didn't cut it?

 

[richiedelf]

Hi all. So, how did any of you that have ridden the Idylle feel about it not having hi and low speed settings on the compression? I feel that it's a very big part of the way the fork rides, and really like to get mine tuned in to how I like it. I have to assume that it works well, but can't get how.. and after all... Assumption is the mother of all **** ups!

 

[curtmuss]

it annoys the hell outta me not having HI-speed comp as i like to run my Idylle pretty soft but cant get the progession i want .... Dam grippy fork though

 

[Juddos]

Does anyone have a spare lower crown for an Idylle that they could sell...?

Or know of a shop that would have one? Cracked mine last weekend.

Judd

 

[MrPlow]

Does anyone have a spare lower crown for an Idylle that they could sell...?

Or know of a shop that would have one? Cracked mine last weekend.

Judd

That sucks. I would say you will be hard pressed finding one hey. Talk to this months distributor in your area?? But don't be suprised if they can't help.