Wave Tubing Xplained!
Sunday introduced the Wave downtube at Interbike in 2007. This unique feature quickly became a centerpiece in our goal of bringing riders a frame that’s both strong and light. Surprisingly, a lot of people didn’t notice the Wave when we initially showed it at Interbike, and to this day some riders STILL haven’t noticed it. There are also riders out there that are unaware of how well the tube design really works. However, with that said, I have heard countless stories from Sunday frame owners about what their Wave downtubes have been through. It’s understood that the tube won’t take “everything” thrown at it (after all, it’s still just made of 4130 chromoly), but it will take a lot of the abuse that ordinary round tubes won’t, and once the downtube of a frame has been damaged, it’s only a matter of time before a new frame will be needed. At this point it’s been over two years since we began testing the original prototypes, so I figured that it was time to show some photos of what a Wave downtube looks like on the inside.
So, why would someone need a downtube shaped like this? Well, most modern frames use double-butted tubes. What this means is that the wall thickness is thicker at the end of the tube and thinner in the middle. This allows the frame to use a lighter tube while still retaining the strength needed to get a good weld at the frame’s headtube and bottom bracket shell. Now, as I’m sure you’ve already figured out, the thinner walls of ultralight butted tubes are easier to dent, and in many cases they’re being used in one of the most vulnerable areas of the bike. When you dent the frame in an area like this, the tube becomes weakened structurally, making the frame much more susceptible to cracking, and then ultimately this cracking can lead to a failure if the frame is not replaced. It has always been of utmost importance for us to address this issue on frames, and our solution was to incorporate the double-butted Wave downtube shape.
A lot of people have asked me how the tube is made, and I always tell them that it’s a simple but very effective design. As you can see, there isn’t any excess material added to make the Waves, it’s just a simple change in the cross-sectional shape of the tube. Here are two photographs that show the interior of the Wave on the “top” and “bottom”. The shadows help to illustrate the tube’s shape. On the left, you can see the light variation caused by the wave, while on the right you can only see a smooth lighting surface because there are no waves present.
Although the design is simple, the benefits should be obvious. It’s much easier to dent a tube that has a large, round, non-reinforced diameter, than one that IS reinforced with smaller diameter waves or ridges. Applying the waves to the lower, most vulnerable area of the downtube not only keeps the Waves hidden, but it also makes the downtube much more durable than an ordinary round tube. So, while it’s still possible to dent a Wave tube, you will find that when dents occur that they will mostly be confined to the smaller Waves, rather than all the way across the tube as a whole, which is what tends to happen on a conventional frame.
When we introduced the Wave frame back in 2007, its downtube was larger in diameter than it is today. This photo illustrates the difference between the original Wave frame’s downtube size and the slimmer size that’s used on the 2nd Wave frame. This smaller size accompanies the tapered seat and chain stays and the smaller dropout, giving the 2nd Wave frame a slimmer look when compared to its predecessors. The new size also allowed us to lighten the frame, while still retaining the Sunday frame’s legendary reputation for strength and durability, as proven through long term lab and real world ride testing.
The Wave downtube is just one of the many unique features on a Sunday frame. Look for more insight on our other features soon!
Very VERY cool! It’s amazing how simple design changes can increase structural integrity so much.
Stephane DauryMakes complete sense, like shot peening. Pre-stressing the surface makes it less likely to stretch under force.
Like bending a piece of slat tin vs a corugated tin roof, more structurally sound.
Also like the FLIP decks, nice work!
I’ve always ben psyched on the amount of thought that goes into your parts Jim. You, Sam @ Tree, David at Fly, Darcy Sagucchi, and of course George are part of what keeps making bikes interesting.
Ewan ForrestHats tipped and hands shaken, haha.
[...] check it HERE [...]
Sunday Wave Tubing Explained « Edinburgh BMXit’s the same reason lacrosse sticks always shaped funny rather than being round. or hockey sticks. they are designed to be slammed into each other and not dent or fold. i have always thought this to be an awesome idea for a bmx bike frame!
tdc[...] Sunday have a bunch of info up about their Wave downtube along with some cross-section photos of what the inside of the downtube looks like. Sunday July 6th, 2009 Respond Close this box [...]
Sunday Wave Downtube Cross Section. / The Come Up / BMXsunday is not dent resistant. i seen someone dent the 2 wave. and sunday frames arnt even made in the USA.
robert anthonyit says there not completly dent resistant, and alot of bike parts are not made in the USA
EvanDent RESISTANT and dent PROOF are two different things. Sunday frames ARE dent resistant.
ryankeep it up jim
Rossi89its stuff like the that makes sundaybikes so good!
Robert anthony, you can keep riding your old gt if u like, but don’t talk shit about sunday, sunday is just the best!
Brunoit seems like you were about to explain how the wave downtube is made, specified that there isnt any extra material added and then went off on another tangent about its benefits again… but how is the wave actually produced? extruded that way? hydroformed? something else? and i was also under the impression that sunday frames are rustproofed inside and out with blackmajic. but in the pic illustrating how the wave was larger in diameter compared to the second wave the ouside of the tubes are painted as if they were actual frames cut open but the inside of the tubes are raw metal, no blackmajic rustproofing to be seen. and the first wave actually looks to be rusting… anyway i have had my sunday for about a month now and last weekend ended up doing a frame grind down a handrail (somehow making it all the way down the nine stair rail without bailing or even taking my feet off) i was scared to look at the downtube expecting a nice dent. but nothing! some paint was scratched off but that was it. it obviously works and just wanted to say thanks for producing good, quality parts jim, best frame ive ever had.
jdsI have the 2nd Wave in Karl Poynter’s colorway. There isn’t a single thing I would change about it. It is truly the best frame i have ever owned, or even rode for that matter.
I LOVE IT!!! THANKS JIM!!!
Jamesin response to jds -its not black magic coated on the inside because it was most likely a sample taken from the center of the tube therefore it is impossible to powdercoat the inside of it once the frame is welded. When sunday says it is rustproofed inside and out they mean that the inside of the head tube /BB/ seat tube is rustprofed. Rustproofing the entire inside of the frame would not be practical or needed. Back to the wave , I think it would be cool if the downtube and gusset were one hydroformed piece like an intense race frame , it would have the same profile but it would look a little cleaner.
Kevinyes , more to love about this frame
OZbmxHmmmm.. interesting! I was under the impression that the wave part was a welded piece of material that protected a full round down tube. Thus having double the material under the downtube. Of course that would be quite heavy so the way it is done here is kinda cool. Like jds asks how is that wave produced on the cromo? It would take quite the machine to fold cromo like that I would think.
Ryan B.cant wait for the next frame. sunday, you guys rock
Jordan Dyei cant find any triumph bars in post it yellow or forumph bar in post it yellow where do i look
devonDevon, hey check this link. http://www.danscomp.com/362335.php?cat=PARTS
jimcI want a waved downtube penis so I can grind it vigorously everyday and be resistant to being flaccid. Is there a place to do this in Thaiwan?
TastyPenisoh yeah thanks for the link right after i sent that i found them they where out of them in that color for a while i wish they had forumph bars in that color they whould be perfect. by the way sunday is the shit
devon“Like jds asks how is that wave produced on the cromo? It would take quite the machine to fold cromo like that I would think”
The steel is drawn through a die.
T,O,i hate people lyk tasty penis : /
nicoOi. Sunday. It seems like someone is bitching in BG about paint in their headtube. Tend to it.
booI have the second wave frame and it still hasn’t dented or cracked
And I have done a 11 foot drop!!
GO SUNDAY
All day on SUNDAY!(\_/)
(=’•’=)
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Any ferrous or non-ferrous material that is extruded (drawn through a die) will corrode or rust much sooner than raw stock. Absolute fact! Take a look at any aircraft tubular structure where weight and strength are the most important aspect- Extruding is only done on solid stock for a reason, never, never on any kind of tubing. Just a gimmick to sell frames, and is obviously working. Nice marketing job!
samI’ve just bought a firstwave 21″ in creamscile yellow. It is the frame for me!!!, a little beat up but it is probably the last frame i’ve ever bought. The greatness of sunday! is in the details!
Adam(romania)awesome concept. ive never owned a sunday but i really would like a wave2 frame. the headtube gusset thing, thick but hollow dropouts and wave downtube give me the confidence that this frame can take quite alot of abuse especially from a street rider. so till im proven wrong i rate this design is pretty bomb proof!
Killian Henricklong live sunday
hellz yeah,this design is the shit and deff can take a beat from what ive heard and read, i luv it it has the same geometry as my old frame but is made 10 times better
Bradbest frame i ever bought looks clean, rides clean, and it cleans me of words! lol keep it up Sunday!
cameronMam rame Sunday Funday i muszę przyznać, że te rurki to bardzo dobra rzecz!
BiałyI love them!
I have an 06 non wave frame and it’s still going strong… no cracks, dings or bent bits. Beaten up like hell but then what do you expect for a 4yr old frame?!
Also….. Biały…. mam trochę polski, i tak, myślę się ramek są najlepsze!! Cześć!
Alexyou guys should make a version 3 of the wave with removable brake mounts and a wave chainstay to make it better for grinding
Kevin