K2 / Proflex Riders Group
General => Tech Forum => Topic started by: w2zero on October 23, 2014, 08:31:25 pm
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I see the occasional posting in reference to the fork legs being longer on a Way Big frame versus the rest of the frames. I find that assumption troubling to me coming from a manufacturing background.
Having worked a number of years in bike shops wrenching and selling I have a little experience with various frame/fork fitments. Anything from itty bitty to 27" frame size as long as they are all the same wheel size all take the same size fork. The only difference being the length of the steer tube on the fork needing to be a compatible length to mount the headset bearings etc on the head tube of the frame.
Proflex being a little strange, in a good way, has only two head tube lengths on the frames. Way big, and everything else. So, reading the parts list, the only different pieces for a way big frame are the steer tube on the fork and the ULM (Upper Link Mount). It is my opinion that the Way Big fork ULM has a bigger drop to locate the upper link and upper end of the shock absorber than the ULM of the rest of the frames.
I have one 855 and 4 856 frames, 2 of them are 16" and two 17" and one itty bitty. All the frame head tubes are 4-3/4".
I have two carbon X-Link forks and both of them are the same length from the upper link pivot hole to the center of the axle dropout @ 20-3/4". Both of the ULM's for these forks measure the same drop with the shock pivot hole centered even with the bottom of the ULM where it contacts the spacers or head set bearing top. The top link pivot is 3/4" below the bottom of the ULM where it contacts the spacers or head set bearing top.
Now we just need for someone with an X-Link fork on a Way Big to chime in with some dimensions on the fork legs and ULM.
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Well..... ;) I don't have a way big fork but I can definitely confirm that they are longer than the other fork used for S M & L, but only on '57 and after. On anything '56 and earlier the frame head tube is the same length from small through to way big but on '57 and after the head tube on the way big was an inch or so longer. The top of the fork legs between the bottom link and the top link had to grow by the same amount to keep the links parallel.
So beneath the bottom link they are the same length as S,M & L but above the bottom link they are longer. So over all the '57> way big fork is longer.
Chris
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All you have to change to accommodate the extra head tube length is to make the ULM a deeper reach and add a longer steer tube just like they did for the 55-56 models. To have separate tooling for a very limited production variation on a limited production fork seems a stretch. There would also have to be a longer shock absorber were the fork leg pivots farther apart.
In any case if anyone sees a Way Big fork, measure from the topmost bolt hole in the fork to the center of the axle dropout and let us know if that dimension is greater than 20.75 inches.
Since these old bikes are being modified through the years through upgrades or replacing broken parts we should keep updating any data that might be unique to the year or model such as changes that evolved that weren't necessarily listed on the sales brochures.
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I understand what your saying but Yes that's exactly what they did. The shock on a way big is longer on the bottom section. All parts are interchangable apart from the legs and the shock. Maybe it was cheaper to manufacture different legs than a different ulm. Although I've never owned a '57 way big I've seen many and this is the way they did it. One of the UK guys who is on here and on the Retrobike forum has a 857 way big so maybe he can take some measurements.
Oh, Carbon Angus has a way big with Crosslinks so he's the best bet.
Chris
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There's a picture of Carbon Angus's bike in my gallery so you can see for your self.
Chris
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i have some carbon x links from a 957 on the 756 which is a way big,although at that time they still called them 20's,i will have a measure,was "harvs" 957 was his a way big? Does anyone know?
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I have a Way Big and it measures 23 inches from center of axle to center of top tube pivot.
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By the way, it is a Way Big Proflex 4000.
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i have some carbon x links from a 957 on the 756 which is a way big,although at that time they still called them 20's,i will have a measure,was "harvs" 957 was his a way big? Does anyone know?
Paul yours will be the same as S,M & L size as the way big frame on the 756 had the short head tube.
Jcshincle's will be longer than yours as '57 & 4000 way bigs had the longer head tube.
My way big 955 and 856 both use S,M,L size fork in fact is just remembered I have your original vectors off your 756 on my large 856. And very nice they are too! :) :)
Chris
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Finally found the picture. Thanks for the measurement.
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22"and 24" is what me gots
(http://i112.photobucket.com/albums/n196/carbon_angus/1IMG_3630_zps92f8b7d2.jpg)
It probably doesn't make any diff with the way big fork but it's an EVO frame and a strut rear.
FWIW It is supposedly one of nine built for Beat Wabel 1998 Proflex k2 race team.
When I had a 5500 frame I would have liked to see if the strut would have interchanged with the cantilever style swing arm, but getting the 5500 swing arm back on is a bit^ch. Same car, same driveway, too ~8 years apart...LOL
(http://i112.photobucket.com/albums/n196/carbon_angus/_IGP4893.jpg)
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I'm definately sure Way Big forks (Which were called "Long") had longer legs, after all they had different part numbers............ 15203-1 and -3 for std and 15203-2 or -4 for long, I believe? (and for Carbons; 15367-1 std, -2 for Long)
15203-1-RB 1 Leg, Left Expert Std (red black)
15203-1-SB 1 Leg, Left Expert Std (silver black)
15203-1-YB 1 Leg, Left Expert Std (yellow black)
15203-2-RB 1 Leg, Left Expert Long (red black)
15203-2-SB 1 Leg, Left Expert Long (silver black)
15203-2-YB 1 Leg, Left Expert Long (yellow black)
15203-3-AO 1 Leg, Left Elite Std (anthracite orange)
15203-3-AY 1 Leg, Left Elite Std (anthracite yellow)
15203-4-AO 1 Leg, Left Elite Long (anthracite orange)
15203-4-AY 1 Leg, Left Elite Long (anthracite yellow)
15367-1- CAR 1 Leg, Left Carbon Std (carbon yellow)
15367-2-CAR 1 Leg, Left Carbon Long (carbon yellow)
and don't forget that OEM and AM ULM's existed!
15074 1 Upper Link Mount, OE
15378 1 Upper Link Mount, AM
http://idriders.com/proflex/files/crosslinkinstall.2.jpeg (http://idriders.com/proflex/files/crosslinkinstall.2.jpeg)
But this was to cope with other manufacturers frames with bigger headtubes.
Just back from holiday in Madagascar, no PRO~FLEX's but plenty of old French mountain bikes (VTT's)!!! No bike riding for me and the Missus, but plenty of trekking and Lemur tracking! I think there' s massive scope out there for epic mountain bike tours, maybe that could be my retirement venture?
Col.
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i have some carbon x links from a 957 on the 756 which is a way big,although at that time they still called them 20's,i will have a measure,was "harvs" 957 was his a way big? Does anyone know?
Paul yours will be the same as S,M & L size as the way big frame on the 756 had the short head tube.
Jcshincle's will be longer than yours as '57 & 4000 way bigs had the longer head tube.
My way big 955 and 856 both use S,M,L size fork in fact is just remembered I have your original vectors off your 756 on my large 856. And very nice they are too! :) :)
Chris
yes i thought as i typed i was prolly showing my forgetfulness bout things proflex..i am glad you are finding the AL2 to your liking!
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I must say Carbon Angus that your bike looks ace. It's a lovely looking ride. The proportions are perfect and I love the way the lines flow from the top tube straight down to the end of the swing arm. It just looks right!
I've always liked the look of these team bikes, with their mix of 5000 frame with 957 rear end. The stiffer 5000 frame with a shorter travel and some say stiffer 957/857 rear end, a true xc racer. I'd love to build one to see how it rides compared to the two bikes it is built off.
Chris
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Thanks Chris,
It's sweet but only a few know about it. Build one.
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Hmm .. Anyone got a spare '57 carbon swing arm?
Chris
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22"and 24" is what me gots
([url]http://i112.photobucket.com/albums/n196/carbon_angus/1IMG_3630_zps92f8b7d2.jpg[/url])
What's the black circle around the top fixing point of the top link, on the fork leg? On the yellow painted section. Mine are all yellow and screw directly into to link. Are yours bushed?
Chris
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To maintain geometry of the fork, the difference in lenght of the fork should be the difference in lenght of the shock, as they are different according to the fork size.
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Yup, appears to be about two inches longer between the pivots and there is an extension on the bottom of the shock.
Wonder how much difference that makes in the action down at the axle? Does it increase the much dreaded J-path? Not that I give a rip.
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It won't make any difference to the travel or J path as the top and bottom links are still the same length. They're just physically longer to suit the taller frame.
Chris
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I have built linkages and changing any of the dimensions will make a difference. How much difference depends on how big a change and where.
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I think a "Long" fork might have a slightly different axle path to a "Standard" as the top and bottom link lengths are not the same, so placing them further apart (than the std 148mm at headtube and 155mm on fork) will probably create a difference. I've modelled the std pivot points previously on here, but didn't extend this to the axle path ..........
(http://idriders.com/proflex/smf/MGalleryItem.php?id=523]http://idriders.com/proflex/smf/MGalleryItem.php?id=523)
Although if the headtube and fork mount points of the links were kept in some sort of proportion maybe the axle path would remain the same.
I expect Bob allowed for this back in the day..............
Col.
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Hmm in my head I was thinking as long as the links are the same length and the fork legs are the same length below the bottom link then the j path would be the same. But thinking on it, I don't think the legs sit perfectly parallel to the head tube. The top of the fork leg does sit slightly further out so yes I guess it would make a difference as lengthening the fork legs would increase the angle at the top? Hmm interesting this!
Draw us another picture Col! Lol
Chris
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Used to design and fab remote damper links for ship's fan rooms so had to deal with straight, rising and falling rate linkages. Was pretty good at it too since the machinists didn't have a go-to guy at the time. Now it just gives me a headache and I go back to simple stuff like shift linkages for engine/transmission swaps.
Just spitballin but the longer length between the top pivots (if the links are the same as smaller X-link forks) would probably decrease the length and speed of the J-path.