Ask Pinkbike: Bike Development Project, Fox X2 Bottom Out Point, Quiet Chain Stay Protectors

Dec 30, 2019 at 4:38
by Dan Roberts  

Here at Pinkbike, we get inundated with all kinds of questions, ranging from the basic "Can I have stickers" to more in-depth, soul-searching types of queries like if you should pop the question or what to name your first child. Ask Pinkbike is an occasional column where we'll be hand-picking and answering questions that have been keeping readers up at night, although we'll likely steer clear of those last two and keep it more tech oriented.




University Project - Developing a Bike

Question: A good friend is currently at university and has chosen to develop a bike frame as his final year thesis. He recently asked: Where do you find out information on the fundamentals of bike design and engineering? How do you go about figuring out the process for the first time?


bigquotes This one is close to home, as I chose a similar endeavor for my university thesis. While it might seem like there is a complete lack of information, there are some bits and pieces out there. Bike engineering as a profession isn’t as established and recognized compared to the likes of aerospace and motorsport engineering.

There’s interesting and relevant literature on websites like Linkage and i-track. It’s applied to bikes and explains the fundamentals really well. Lots can be found from Google with manufacturer's two cents and other academic documents from individuals who have done the exact same thing and set about designing their own bike.

Pinkbike has also recently provided some information on suspension with the Behind the Numbers series, and we plan to offer more explainers and information in the future.

Lots of literature is available from the automotive world looking at motorcycle suspension and chassis design. For example, Tony Foale’s book, Motorcycle Handling and Chassis Design. Many of the fundamentals and concepts are the same for bikes, but they do need to be translated due to the lack of internal combustion engine and also the lack of consistently smooth tarmac.

There is, though, much less information about the process of bike development floating around. Most brands keep the exact process under wraps, and like most development cycles, it needs a couple of times around the Ferris wheel to understand and learn by actually do the necessary steps.

However, here’s a really condensed version from concept to going about making something physical.

Identifying the Concept – A bike doesn’t suffice. It needs a purpose, a potential rider, and potential riding terrain. The concept needs to be defined, no matter how obvious, and damn clear otherwise the coming steps will continue the haziness. Decisions always relate back to this concept and questions use it as guidance for an answer.

Defining Ideal Geometry and Specs – You can define the geometry you would ideally want. It will change as you go further into development, but you need a starting point. Also defining all the parts you want to fit and be available to work with your bike.

2D of Geometry and Kinematic – Converting the numbers on a table into a 2D line drawing. Geometry is the first drawing, and you can add in as many knowns as you can to see how clearances and parts standards come into play. Adding in the kinematic is next, with a lot of time behind the scenes in deciding which layout, which characteristics and iterations of 2D design to put the pivots where you want them, and also in a place that works in the real world.

2D to 3D – Bit by bit you start to add in 3D volumes of parts and no-go areas of the bike. Important things like clearances and spec parts go in here and effectively narrow down the envelope that you have to work in. Rough volumes of your frame parts can go in here to. They help make the model look more like a frame, helping you see improvements or issues, and generally adding stoke as you can see a form you recognize as a bike.

3D Modelling – You can then start to model the parts of the frame properly taking into consideration your chosen material or production method. Tube by tube, forging by forging, bolt by bolt you’ll build up a full model of the bike.

Iterations, Development and Refinement – Rarely does the first shot at modelling result in the final part. It takes time and many iterations to balance all the clearances, suspension layout, shapes, volumes, parts (I could go on forever here). These iterations can go back all the way to the geometry and kinematic as you tweak and dial things in. The more experience you have here results in fewer iterations between the first model and the final model. But this is usually the longest segment in development for the engineer, barring industrialization. Other factors like FEA or CFD can come in here and influence the development time and number of cycles round you go.

Deadlines – Unfortunately, we can’t just develop for ever and a day. At some point we need to have a deadline and call it time to move onto the next stage in development. For my friend that will be when he has to write up the thesis. For brands it’s often moving onto industrialization or prototyping or handing the project across to a different department.

As mentioned, this is a very condensed version. I honestly could write a book on the development process with all its factors and intricacies. And while the condensed version may put the process across as easy, it is anything but. However, the challenge and the final product are two of the most satisfying things ever. This question hit close to home and got me stoked to see someone wanting to develop a bike and perhaps pursue a career in the industry. Let’s get more smart people in the bicycle brain trust!

Kavenz


Final 3D Modell
Images from 77designz's We Develop a Bike Frame series show them moving from a simple definition of concept to a complete 3D model.





Fox X2 Bottom Out Point

Question: @sihotaman asks in the Bikes, Parts and Gear Forum: Trying to figure out if my X2 is bottoming out. Should it go right to end of the shaft/stanchion, or is it a few mm before, or does it vary between stroke lengths?


bigquotesRockShox have a patent on printing shock information on the shaft, which means other shock manufacturers can’t make it that easy. But most bike companies give you the specs for your bike including the shock length and stroke. Taking that and measuring your shock would give you your bottom out point on your X2.

Another way would be to measure the eye to eye of your shock, and go check the Fox website to see what stroke is available for that shock length. Then you can do a quick measure on your shock to see where the max stroke is.

On a lot of the imperial length shocks, the end of travel was easier to line up as the end of the shaft. But with metric shocks it’s not always as clear, since some shock lengths have multiple strokes. You can also let the air out of the shock (record your air pressure first), then compress the shock to see exactly where the bottom is. On the X2, there's a generous bottom out bumper that saves those last few millimeters of travel for really big hits.

Always trying to get the O-ring to the end of the shaft might result in you compromising your setup for a bigger chunk of your riding, and getting full travel every ride shouldn't be a priority.

The Fox website is really helpful for the information you’re after. And grabbing a measuring tape too will help implement that knowledge for your specific bike.

FOX Float X2 shock review
The amount of shock shaft you have isn't necessarily the amount of available stroke. Finding out the actual stroke figure and measuring your shock is the best way to figure out when your O-ring is at the end of travel.





Quiet Chain Stay Protectors

Question: @rangerdanger2001 asks in the Mechanic's Lounge Forum: Anybody have a really quiet chain stay protector setup they recommend?

bigquotesFor a long time, brands would include a chain stay protector with the frame. But some were more an afterthought with naff-all coverage and hard plastic adding to the potential bucket of bolts sound of your bike. Recently, more and more brands are doing a wicked job of covering up the chain stay and seat stay in good soft rubber, molded to the shape of the frame and including a ribbed design to deaden the chain slap. So now there’s less reason to buy Velcro or rubber tape to custom make your own.

That being said, and looking at World Cup DH race bikes, we see a lot of custom setups still being used.

Time and time again, soft Velcro and 3M tape seem to be the choice setups. Doubling up layers also helps add extra cushion for the chain.

I’ve been a long-time fan of Velcro, and one of the best I can find, Tesa, comes with a 2m roll of the soft side and hooky side. Not one to waste the hooky side I often use it as the middle layer in the 3-part sandwich. First, I lay down a thin strip of soft on top of the chain stay. Then I cut the exact same piece of the hooky side and lay it on the first soft piece, hooks down. The final layer is the soft side and uses the full width of the strip to cover over the previous 2 layers and have good purchase on the chain stay. You can extend this as far back and as far forwards as you need and use a real sharp blade to trim that final layer into all the shapes you usually find at the yoke and drop out, and around the tire and heel clearance areas.

3M Rubber Mastic 2228 tape is also a really good option and a favourite on the World Cup circuit. It can be trimmed to all shapes and sizes and even molded to itself with a bit of warmth and thumb action. It can be a pain in the arse to remove off paintwork, so sometimes it’s good to lay down a layer of decent electrical tape before you add the 3M tape. That makes it easier to remove further down the line for sale or for re-applying a new protection setup. The 3M tape also enables you to get wild with your protector design with ridges and bumps galore.

In any case, it’s best to stick your stuff to a clean and degreased surface. If it’s warm, that also helps the adhesion between the glue and your frame. Other solutions have popped up, with the likes of the STFU offering their take on chain slap silencing which appears to receive praise.

Otherwise, channel your inner Neko Mulally or Aaron Gwin and do away with the chain all together.


Velcro and rubber tape are two of the most common protector solutions. After that you can go wild to get the coverage and silence you're after.





123 Comments

  • 82 3
 "RockShox have a patent on printing shock information on the shaft"

what the heck
  • 12 5
 Yeah, what! C'mon Rockshox, that is pointless.
  • 45 15
 @matixsnow: The printing is useless? Or the patent is useless?

The printing definitely isn't useless, I get use out of it all the time by not needing a tape measure to check sag on my Pike.

And obviously the patent isn't useless since it's prevented anyone else from doing it, so it's a differentiator for RS products.
  • 148 1
 Sounds like I have to get my latest tattoo removed...
  • 21 2
 @just6979: it feels a bit strange to get a patent on "we just write the numbers on the stanchions". what is the invention?

just a clever patent engineer who is handy with words so he could reinvent a ruler, or is it really a new technical process (laseredging the writing into metal/surface treatment etc.)?

can somebody please elaborate?
  • 8 1
 Always wondered how these bike patents work.

RS with a patent application on writing things down where you need to know them.

Spec with the FSR patent(finally expired) on the suspension system used in almost every car for the last 40 years.

VPP and all the other patents on multi link suspension(invented something like 100 years ago.

A lot of these are just "we patent a pivot location in space on a very common type of suspension".

I always joked about patenting even tooth chainrings as it seems like it would work in the cycling world.
  • 2 1
 @iamamodel: tried this for my last Enduro start times... worked
  • 2 0
 Velcro is a registered trademark of Velcro BVBA.
  • 7 8
 Not much to write about, RS did very little service to themselves by patenting it. This bullet point on the list of features will gain them 2 more OEM clients per year. It definitely makes them into c@nts for everyone else who heard about it. Yes they did it first and they did it well, at the time they developed it Fox was printing KC logo under their BS bling.
  • 5 3
 I actually prefer not to have sag markings printed on, specially in forks. With RS when you put an airshaft outside the 2 printed travels you end up with two useless rulers on the side of your fork. And, IMHO, adjusting fork pressure by sag is pretty pointless, particularly in modern geo bikes
  • 2 0
 Park Tool has a patent on blue tools at least in North America it seems. I got some blue tire levers along with the Schwalbe ProCore bundle as the color of Schwalbe is blue too. But as a tire lever is a tool it actually has to state that blue belongs to Park Tool. Not sure whether Schwalbe actually had to pay Park to include these tire levers. Same with Unior tools. Blue is their color too but I think for the North American market they use a different color.
  • 6 8
 @vinay: in the latest news: Trek patents Press releases containing information about riders joining new teams
  • 2 0
 Came here to post this. That's the reason noone else has the sag markings, I've always wondered.
  • 2 0
 Can someone help me find the actual patent number? It could be an interesting read.
  • 2 0
 My guess is they don't have a patent on "putting numbers on the stanchions", but rather on the technique to do so, and no other manufacturer has figured out another, non-violating way to get this done. Pretty sure you can't patent putting numbers on a fork, not really how patents work. You need to patent a specific method of doing so.
  • 1 0
 @Lanebobane: Plus of course there aren't many fork manufacturers who actually produce their own stanchions.
  • 1 0
 @Lanebobane:
I don't know. Santa Cruz went after Yeti over violating their patent on an axle path, even though it was done totally different with the switch infinity rear end. Bike patents seem to be the silliest patents out there.
  • 2 1
 @Chris97a: they are not the silliest but just like many other ones they are stopping the development of the whole pack. It’s safe to say that Quite a few bikes out there got better after the Horst link patent expired and they could use it. What is ironic is that VPP patent expired too and this amazing, unique design allowing full control over kinematics - nobody wants to use it!
  • 2 0
 @WAKIdesigns: The horst link patent was only in North America. Loads of European brands were using it through the years. German brands like Cube and YT in particular. It is just that now that it has been lifted in North America, these brands are starting to sell there too. But the YT Tues for instance has been a great bike right from the start (well before it was being sold in the US).

I think VPP may be a bit more difficult to work with as it requires bearings that take higher loads, higher speeds and they need to have less play than what horst link allows.
  • 2 5
 Patents are bullshit. They might have seemed a good idea at the time, but now are just inhibiting progress - the exact opposite of what they were intended to do. Patents were meant to make sure that inventors laid open their methods, getting protection of the use of their ideas in exchange. The way it is now, patents are used to protect ideas that are completely obvious and trivial, like in this case, or the patent applications are not formulated in a way that leaves anybody reading them any wiser concerning the actual invention, but are just intended to hinder the progress of the competition in the field. Therefore they have become useless, and imho the entire idea of patents has become obsolete. If someone invented the wheel today, someone else would immediately patent two, three, and four wheeled vehicles leaving us all with five wheeled contraptions to ride in the mountains...
  • 6 2
 @FuzzyL: Yeah patents are BS...
Just wait until you come up with a concept you want to develop and then a big player with big development, prototyping and manufacturing capabilities releases it to the market in 2 seconds for half the price you could ever do.
I'm sure the concept of intellectual property would still be BS by then...
  • 2 0
 @WAKIdesigns:
The reason I say that patents like FSR are silly is because it was a patent on McPherson strut suspension, the most common suspension layout for vehicles. In my head it is a very short hop from being able to patent the most common type of vehicle suspension system to being able to patent things like even number of teeth on a chainring and whole number sizes of Allen wrench bolts.

There are other silly patents like split pivot where it is just a simple swingarm with a linkage driven shock, but with a patent on moving the pivot for the linkage an inch away from where it typically goes.
  • 2 0
 @Arierep:
The problem isn't when someone patents something which is innovative or pushes the boundaries somehow. It is when someone takes a completely common design which has been proved to be a good idea, works well and is adaptable to many different layouts and situations. They then add "but on a bike" and somehow are granted a patent on it. Those are the silly patents, it is not new processes in manufacturing or actual inovations that shouldn't be granted patents.

Another great example is the Shimano derailleur clutch patent. They somehow patented being able to have the ability to turn off or service the clutch. Then SRAM somehow got a patent on being able to have a little poppet that keeps the derailleur fully extended. These are all just silly, not a big innovation, just the bike companies poking each other in the eye.
  • 1 1
 @Arierep: Won’t matter, by the time I’m ready to got to market, the big player will have a patent portfolio that will hinder any use of my invention anyway.
  • 1 0
 @Chris97a: my issue with the original statement from @FuzzyL is the absolutism of saying the entire concept of patents is obsolete.
I agree that some patent offices could be more competent and use better criteria, but the patent system, even if subject to potential improvement, is fundamental for the market and for entrepreneurship.

Also, is very easy to say from the couch that "they are patenting trivial applications of existing concepts" but in real life the line is not that easy to draw. Don't forget a good number of innovations are in fact improvements on existing designs or the use of concepts from a different area. But someone had to have the idea to do that nonetheless. Patents exist to protect innovation and intellectual property.
Using some aerospace technology in passenger cars is generally considered an innovation, why can't be using automotive suspension designs in a bicycle innovative as well? Lots of shades of grey here
  • 1 0
 @Arierep:
I see the point you are talking about but just totally disagree. Taking an established design and just applying it in an obvious way is not an innovation. Helmets in many Motorsport are designed to limit buffeting at high speed, should I be able to patent this for cycling because it is an established design but not specifically for bicycles? If someone started making cored composite structures for bicycle parts should they be allowed to patent this very established form of manufacturing because it is for bikes?

In my opinion, no, they should not be allowed to do that. These things are not unique, they are not innovative, they would take almost no effort to patent or research, because it is a completely mature technology and would just be an effort to stop other people from using a very obvious technology.
  • 1 0
 @Chris97a: I see were you come from, but I think we'll have to agree to disagree.
Being obvious or not is not the criteria used to warrant a patent, nor it is to consider something an innovation or not. Someone still had to come with the idea of applying the concept to the different product or field. On the other hand, being the first to do so meet the general accepted criteria.
  • 1 0
 @Arierep:
I understand that those are not a criteria for patents, but should be, which is where FuzzyL is coming from. To just be able to make vague patents on established designs or on something like an axle path no matter how you get there is a broken system. Shimano patenting being able to maintain a part of your bike??? Come on, that is ridiculous.
  • 1 0
 @Arierep: Then of course when would you call something a "different field". So bicycles are a different field than aerospace apparently, yet they are still vehicles. Where to draw the line. Are motorcycles different enough from cars? Are unassisted bicycles different enough from motorcycles. Are mountainbikes different enough from road cycles. Is downcountry different enough from XC? Not sure which company claimed to be the first to make a "smartwatch", which was apparently a watch that could communicate with a cellphone. The first watch I recall to communicate with a cellphone was the Polar S625X from 2004 or so, would that qualify as a smartwatch? And maybe someone else was even earlier. Obviously the people at Casio always loved to stuff their watches with gadgets (calculators, thermometer, barometer etc). I wouldn't be too surprised to see them link their watches to phones too. To me being the first in a certain field is already so vague it is just best to just stick to "first, full stop".
  • 1 0
 Yeah, kind of ridiculous. I wonder if they patented the markings as imperial %sag. So, if someone comes up with a metric % sag, that patent does not apply. This is as stupid as Amazon trying to patent the letter "A" some years back.
  • 3 2
 In this thread: people who don't understand IP.

Straight out of the US Constitution, Article I, Section 8, clause 8:
“The Congress shall have Power To…promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries….”

And also, 35 USC 101
"Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions and requirements of this title."

RS has a fabulous patent and they are differentiated in the market as a result. They have secured a limited monopoly as a reward for bringing innovation to the marketplace.
  • 2 0
 @Stanthebiker: patft.uspto.gov/netahtml/PTO/search-bool.html. Searching Full Text Patents (Since 1976) --> Quick search -->Term 1: Rockshox --> in Field 1: Assignee name. I don't see the one being discussed here in twenty-three results, so best of luck.
  • 2 0
 @Chris97a:I agree with you, I just meant thaT I am pretty sure there are much dumber patents Smile
  • 32 0
 @sihotaman one trick I've done in the past is use the back of a business card and make markings along the edge with a pen at various intervals, then laminate it and carry it. You can put it up next to the shock and see where your usage is easily without calipers or measuring tools, it's also lighter and more convenient to carry around and won't mar stanchions.

For instance, with a 50mm stroke shock, I'd mark 12mm, 13mm, 14mm, 15mm, 16mm, 17mm (for checking sag), 25mm (50% usage), 37mm (75% usage), 48mm/49mm/50mm (for the last few mm of stroke)
  • 5 1
 This is almost exactly what I've done! Have cut out a 60mm strip of thick paper and marked 18mm for my 60mm stroke shock and 32mm for my 160mm Fox 36 on the basis that I should probably be aiming for 30% and 20%, respectively. Just need to get it laminated now and maybe add a few more markings.
  • 3 0
 @sihotaman: this is what I did. Simple yet so very useful....

www.pinkbike.com/u/JBW450/album/Handy-tool
  • 2 0
 Eyeing out the sag here... seems fine wtf
  • 22 0
 Let's please refrain from recommending STFU until those of us who ordered the trail version 6 months ago end up with a viable product. They never shipped and the last email said they were going to have to test other materials before they felt comfortable bringing them to market.
  • 7 0
 I appreciate you posting that. I was this || close to ordering one.
  • 1 0
 Hahaha, brutal. Yeah, I never got mine. But at the same time, they have big shoes to fill. I guess as a consumer I shouldn't have to put myself in their shoes, but when I do, I'm also fuckered. I just wouldn't put myself in the position though.
  • 23 3
 So the guy is choosing to develop a bike and is wondering about the fundamentals of bike design?

I heard Sick are looking for new recruits
  • 7 0
 It's not exactly unreasonable to go looking for literature on design principles when you're at school and doing it as a learning exercise not a commercial product. Nobody would try to build a car without first trying to work out how other people have done it and what the basic principles are.
  • 1 1
 @Socket: Seemed to work out ok for Pole and "Nobody would try to build a car without first trying to work out how other people have done it and what the basic principles are." Eton Musk Wink
  • 3 0
 @gnarterrorist: who's Eton Musk
  • 1 0
 youtu.be/6o6kcVsjMs8

This is a German bike company explaining the whole process of the frame development in a very transparent way. BUT, it’s in German.
  • 3 1
 @Socket: there’s a difference between developing a car and a bloody bike. Building a bike is no different from installing heating in a house. When I hear about some grandiose “engineering” Or “aerospace Standards” when in relation to bicycle design, especially when it comes from people who claim to be engineers I fear for the future of the world. No not every company works like UNNO. It is the Selling of the bikes that is biggest the challenge. Only Fools who can’t ride believe one degree there or there makes any bigger difference, what makes difference is whether your excell sheet works out each year.
  • 1 0
 @WAKIdesigns: what are you on about? I said it makes sense to work out how and why people have already done something before starting. Same thing as Youtubing how to install heating in your house - dunno about you but I wouldn't go trying to do it for the first time without seeing how it's usually done. Your rant had zero to do with that.
  • 18 1
 Am I the only one that would take my old tire and cut a length out and zip tie it to the stay?
  • 67 0
 How do you keep the sealant in?
  • 2 0
 No But Why not put the chain in a box, makes it stay clean too!
  • 15 1
 The best anti chain slapper: old school tube wraped around the chainstay!!!
  • 13 0
 Maybe its the Canadian in me but I always wrapped my chainstay in a bunch of hockey stick tape.
  • 5 0
 Road bike bar tape is pretty legit. And cheap. And weighs nothing.
  • 3 0
 @nskerb: what kind do you use? I'd imagine regular cork tape would get torn up super quick.
  • 4 0
 also the ugliest! win-lose!!!
  • 1 0
 @nskerb: I agree, but it's super fragile, especially in rocky terrains. I keep on using that solution... but with an extra layer of tube to keep it longer.
@bbqmike: it can be classy when it's well done with patience and precision ;-)
  • 1 0
 @dthomp325: I have no idea lol. Seems like cork. I just grabbed a pack for 13 bucks, enough to do the chain and seat stay pretty heavy at least twice. The first (and current) has lasted several seasons. Lots of riding and 8-12 days of pretty rocky bike park riding included.
  • 2 0
 @GravityCandy: Yes, that is the Canadian in you.
  • 3 0
 @panchocampbell it's 2020, where am i going to find a used innertube?
  • 1 0
 @dthomp325: Deda Elementi Mistral white. Where's that Smash review
  • 2 0
 @scottzg: On the chainstay of @panchocampbell 's bike.
  • 1 0
 @dthomp325: I also recommend Newbaum's cotton cloth bar tape. Not as cushy as the foam stuff but you don't have to throw away plastic when it wears out. And it comes in lots of fun colors.
  • 1 0
 @GravityCandy: I used some kind of cloth tape that I think was for tennis racket handles years ago, it's probably the same type of stuff. Worked like a champ!
  • 11 0
 take the air out of the shock to find the bottom out point. Why did Pinkbike need to answer that question with multiple paragraphs?
  • 6 0
 Getting a personal license for Linkage is a great place to start. You can learn a lot if you have a decent understanding of statics and how forces will be transferred through a system.

MTBR frame building forum is also a wealth of knowledge. I know I just read a report jdyer8989 (over on MTBR) just wrote for one of his engineering classes that has some good information in it. Plenty of threads with good info if you search.
  • 1 0
 +1 for the Bike Checker Linkage and MTBR Frame Building forum combo. Lots to learn from there.
  • 1 0
 I’m on a Mac. Any ideas how I can get to use Linkage?
  • 2 0
 @whatshubdoc: dual boot into Windows with Bootcamp
  • 1 0
 @davemays: only have a work issued computer that does not allow additional OS install. The remote windows server I have access to doesn’t allow software install either. SOL?
  • 2 0
 @whatshubdoc: VMWare, Parallels, VirtualBox
  • 1 0
 @whatshubdoc: talk to your IT department, they might be able to help.

BTW you may find 3D graphics on a remote Windows server to be to slow to use.
  • 1 0
 @whatshubdoc: I'm a software developer and work entirely on remote Windows VMs, if you can get a cloud Windows desktop and remote into there then you'd be set. My coworker works on her Mac using Citrix receiver to remote into her VMs.
  • 6 1
 Holy shit, that is a lot of extra bullshit for the shock travel question.

The simplest answer is "it varies". Fox and RockShox both sometimes use the same size damper body/shaft for a few different strokes per e2e length, adding internal spacers to limit travel. So some shocks might not go right to the end, but others will be much closer.

My own DPX2 210x50 is the same as the 210x52.5 and 210x55, just by removing 1 or both internal travel limiters. I'll be having one taken one out during next service, since I bought a Stumpy 29 shock for my Stumpy 27, and the 27 frame has room for the extra 2.5mm of stroke at 52.5mm (allegedly it'll fit the 55, but it looks too close for comfort to me).

Even the uneeded answers are overly complex. To find what the stroke length should be you either enter the 4 digit code on Fox's website (I think there is a place to lookup by the serial number also), or you check the bike's manufacturer's site (and hope their archives of past models are easy to navigate). Compare that measurement to what you see, give or take a few mm for tolerances and bottom-out bumper, and boom done.

(As a last resort to get the actual stroke measurement you remove the bottom out bumper and measure how far the shaft actually goes in and out.)
  • 1 0
 There is plenty of clearance to run the 55mm shock on a 27.5 SJ. I have a 55mm Super Deluxe on my Evo 29, a buddy has a 55mm dpx2 on his evo 27 and they both work great.
  • 1 0
 I just put a 210x55mm DB Coil on my 29 stumpy and have tire clearance to spare.
  • 8 0
 Thats a whole lot of bullshit to respond to some bullshit
  • 5 0
 Your answers are needlessly complex, too.

Take the air out of the shock/fork and push it down. Voila, bottom out point.
  • 1 0
 @Dethphist @bigwavejames1

The original question isn't about finding the bottom out point. It was if the bottom out point not being right up to the end of the shaft/leg is expected. OP was not seeing the o-ring get to the "end", and wanted to know if that's normal: "Should bottom out always use the entire visible shaft?". Thus the simple answer of "It varies." Then I gave a little explanation, still pretty simple.
  • 4 0
 My tip on the shock thing would be, if you’re bottoming out you would probably know from the sound. And if you’re not bottoming out but you have the feel you want from the back end, don’t worry about not bottoming out. It does say this in the article. I think bottoming out too much is more of a problem on the back end. In my experience it’s the opposite for forks. I very rarely get full travel out of a fork if it’s set up to feel how I like.

Most shocks and bikes are made such that if you set the recommended sag, you will achieve full travel at least some of the time.
  • 3 0
 3M VHB (carpet tape) with a strip of clean butyl from a cut up inner tube makes a thick, quiet, and (if you're precise) clean looking chainstay protector. This also works for extending or adding to a stock chainstay protector that's too short (looking at you Trek!!).
  • 2 0
 The latest revisions of the Float X2 include a foam bottom out bumper that could reduce travel slightly in it's fully compressed state. If you are within 2-3mm of the stated stroke it is probably correct.
  • 4 0
 on the fox website you get all information for your shock via the serial number on your shock. then just measure...
  • 1 0
 To me, sag doesn't measurements don't make much sense. The are very dependent of rider position and seat height, both of which change during a ride. I built a "huck-to-flat" jump in my back yard. I fly at least as high off of it as I ever do on the trail. I set my air pressure so that this landing uses > 95% of the travel. For me (a Clydesdale), this corresponds to about 20% sag.

Also, have most Clydesdales concluded that our mass sufficiently dampens the shock? I have these knobs set to zero damping. I don't notice a huge difference when I go to maximum damping.
  • 3 0
 Did everyone forget the easiest way to figure out the stroke of your Fox shock? Just look up the four character code on their website & it tells you.
  • 3 1
 Is this an undergrad final year thesis or a masters thesis? If a masters thesis, then someone needs to figure it out through primary sources rather than secondary.
  • 4 0
 Put marshmallows on chainstay.
  • 2 0
 Riding chainless can also be a solution :-)
  • 1 0
 @softsteel: Works for scooter kids!
  • 1 0
 @aljoburr: yeah... actually working on it with Aaron Gwin Jr. Wink
  • 3 0
 Not fussed about asking just guna wish you all a happy new year guys stay safe
  • 3 0
 Rocky Mountain has the quietest chainstay protector. It actually allows your chain to pass through the chainstay.
  • 1 1
 Regarding bike development, where can someone simply find a list of all current bike standards??

(For example, lets say I want to machine a head tube. Where can you find what the internal dimensions need to be?)
  • 1 1
 I think that would be going about it backwards. First you would choose the overall geometry, then the fork and headset you want to use, then just machine what fits that. Also, I think you can purchase a pre-made head tube, but you would still start with what your final goal is in mind.
  • 1 0
 There's a long way to go before you get to that stage - and in your example - you buy a head tube of the right size and post welding resize it.
  • 1 0
 If you have to ask about bike standards, Measure bearings or bearing cups etc?
  • 3 0
 That’s not how the bike industry works, the student needs to invent a new standard to render all spare parts useless...
  • 1 0
 @korev: Or may be need to study something that can google the answers too, or at least ask some one that has a clue, shame on Pinkbike for including this question!
  • 1 0
 @mtb-sf: @nouseforaname haha yes obviously you wouldn't go out and machine a headtube before designing a bike, but I'm honestly asking that if you really have a design laid out geometry wise, where honestly do you find the "standards?" They're obviously recorded somewhere so they can be standard, is there like an ANSI or ASTM spec or some bike industry database for the standards?

Headtube was an example, but things like current bottom bracket widths / diameters, axle spacings, correct threads for thru axle dropouts, standard seatclamp diameters etc?
  • 2 0
 @davemays: That was maybe channelling a little too much hot sauce - this has no snark intended:
Each manufacturer has their own version of the 'standard'. Usually published somewhere obscure on their website. What's the point of worrying about .25mm when your first bikes won't be within 3mm? For those purposes, measure what you have and use that info. For things like BBs dropouts, headtubes etc - you'd just be buying those off the shelf, not making them, so it's not really an issue. What's the bearing seat dia of a PF92 BB shell? Who cares, you're buying it ready made and using a standardized reamer - that someone has made up from the specifications - to ream it post weld.
Read Peter Verdone's blog (yes him) for more info. Most useful compilation of information on bike design and the process of design and manufacturing. He is (IME) willing to share information when asked from the perspective of trying to learn something, not debate with him about whether he's right or wrong (he's right BTW). He actually digs down into the 'how' of the standard and is able to articulate on why it might be flawed - disc mount 'standards' for example.
I'd start here: www.peterverdone.com/actually-youre-not-a-bike-expert
  • 1 0
 @nouseforaname: Thanks!! That's super interesting.
  • 2 2
 I'm so glad I went all fox this time around. Shady patenting a label on the shocks. I was wondering g why there was a label on my old monarch but not my dpx2. Another reason for me to dislike the SRAM/Rock shox axis
  • 6 0
 Why is a patent "shady"? By the very nature of patents, the idea is now transparent and in the public. They just get an exclusive license for a period in exchange for sharing the innovation.

And this is coming from someone who just upgraded from an RS to a Fox because the DPX2 is so much better than a Deluxe (I'm assuming the damping on a Super Deluxe would be closer, but the DPX2 3pos-adj damper is hard to beat. And looking at parts I think the air spring on the 2 RSes is quite similar, and the Fox spring is just so much better.) The sag and full travel indicators still aren't even close to enough to make up for the performance difference.
  • 1 2
 @just6979: err I think you misunderstood. Patents GOOOOD. Patents on labels preventing you from killing yourself or at minimum destroying your components BAAAD. They patented a label telling you proper psi by weight.

That's not innovation
  • 1 0
 @jofn00: Pretty sure the patent is around putting sag gradients directly on the damper shaft/fork leg. The "recommended PSI" sticker is just a convenience, the same information is in the manual for any shock/fork. If that sticker is the only thing between killing yourself, you've got way more problems than can be solved here. Maybe someone should remove all your fancy stickers and see what happens.
  • 3 0
 Happy New year! May 2020 bring you all miles and miles of hero dirt!
  • 2 1
 Was hoping would not have to wait till May, but you are most likely right?
But you derailleur in a box makes it real quiet!
  • 1 0
 I use the cheapest roady bar tape I can find on my chain stays. Keeps it quiet. If done properly looks smart and it’s cheap to replace
  • 2 0
 Pinkbike isn't going to kiss fox's ass so we can get information on the fox 38?
  • 1 0
 It's most likely just going to be a beefed-up single crown enduro race fork. I'm still holding onto the possibility of it being a "light-duty" dual crown for riders who don't need all the stiffness of the 40, or just want a "short travel" (180-190mm) dual crown for super-enduro bikes, while keeping weight a bit lower than the 40
  • 2 0
 The Santa Cruz chainstay protector looks like the toothed belts that's used in engines. Hmmmm.... Maybe maybe
  • 3 0
 Ha! That’s what I use - cut up some old alternator/fan belts from the car, they’re the perfect width and durable. Noticeably quieter than Velcro or flat rubber such as old inner tubes. I can’t take credit for the idea tho, a friend suggested it when we were replacing the alternator on my old Toyota.
  • 2 0
 PinkBike poll: STFU is the best brand name
  • 1 0
 lizard skin neoprene with velcro, plus electicians tape over it. no chain slappy slappy.
  • 1 0
 Simple answer to the shock travel question... remove spring or empty air and compress the suspension.
  • 1 0
 Chainslap? Go singlespeed! Ha, ha, just kidding.
  • 2 5
 so SRAM holds a patent on something like sag marks in the stanchions, but then they're the philantropists that develop a universal hanger to make everyones life easier, just like that, without any hidden interest. Yeah, right.
  • 1 0
 Link to Velcro tape? Would like to give that a try.
  • 1 0
 Who else uses there rear mech for single speed chain tensioner
  • 1 0
 You wrap your chain stay in velcro? M'kay.
  • 1 0
 Chain tamer. Similar to stfu but not as ugly. My bike is silent.
  • 2 4
 Stfu guide. Nuff said

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