K2 / Proflex Riders Group
General => Tech Forum => Topic started by: Ionit on January 13, 2006, 12:51:44 pm
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It is my project for the next year but hopefully for much less. All of the geometry I plan on keeping. that means chainstay and both tube angles match the 4500. As you may conjure the rear travel will be a tad less. I am guessing total travel will be around three inches in back to match the crosslinks that I insist at keeping. Finding the magic spot for the rear shock eye was the most difficult process. I have to say, the linkage system demo was heaven sent. Before it I had intentions to do thing by trial and error. Thanks goes to whom ever found the program. Sorry please dive yourself credit. I will find that post ventually.
When using the program I modified a single pivot bike by changing the rear linkage points to simulate the x57 type linkage. then I tested different shock positions with the intent to up travel for a comparable frame. I think I can get a little over 3 inches without detracting from performance.
I was informed by Frankd3000 that this design benefit having a platform shock. Do others agree even if you have never tested one tell me your opinion.
Tell me what you think. I can always switch back to the simple swingarm. So you don't have be courteous. Let the criticism fly.
(http://www.alexlori.ca/4500Geo98Mod.jpg)
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Bravo Ionit! I think, at the very least, it'll be an interesting project.
Questions galore;
Have you checked that the s/arm pivot's are the same width yet? I never checked Frank and compared with the 5000 frame I have.
You're obviously going to be using the s/arm that we got with the group purchase - what about a strut??? Judging by your pic it looks like you'll be using an early style?
I'll go out and get the Champagne bottle and put it on ice 'till you're done. [smiley=laughing.gif]
Oh, you have (e) mail.
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Well Ionit I think I'm the one who posted the
linkage simulator demo though I can also link you to
a full programme (earlier version)if you wish,its what
I used on my project,
good to see new ideas BUT I don't know if your aware that design is exactly the same (I mean identicale) to the first Proflex carbon prototype bike (Oz style main frame 955 rear end),
there was a pic of the full bike built at a show on the old 855 heads site,hopefully Callum can dig out a pic for you,
anyway full marks if you pull it off as it will still be unique and IMHO stiffen up the rear end laterally very nicely indeed,should give a very fast ride [smiley=nod.gif].
Simon.
PS The s/arm and frame widths are the same (Terry checked his for the pivot mods we've done) so no worries there.
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Just checked,
you should get with a 1.5" stroke shock
69mm/2' 11/16" travel
with a 1.75" stroke shock
81mm/3' 3/16" travel
well thats what I make it.
Simon.
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Yes. I'm using the S-arm from e-bay. The pivots thickness is the same. That is the first thing I tested when I got it.
The strut is the only component I worry about fitting. I was going to tackle that problem once I have the strut. The most important fitting to me is the dropout pivot on the far back of the swingarm. It needs to couple perfectly because it will be hard modifying either fitting for proper fit. I can handle the lengthening or shortening of the strut and by the looks of it with Andrew’s help the cone adapter is covered.
Hopefully those areas will be addressed without to much trouble.
If you can foresee any other problems please make me aware.
While I was changing pivot locations I determined having the shock's top picot about 2cm higher then the existing pivot will provide best results.
Oh Simon thank you very much for the demo link before. It was very helpful. Can you post the non demo link. It would be nice to save and export data.
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Look what I found
(http://idriders.com/proflex/galleries/Simon/carbonframe.jpg)
(http://idriders.com/proflex/galleries/Simon/carbon1.jpg)
more info here
http://www.proflex.demon.co.uk/855headfeatures/bike97/
link to download simulator is here
you will need to translate and register,all straight forward before you can download the simulator.
http://www.mtbcomprador.com/
Simon.
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Awsome. Thanks Simon.
I did see that design before in one of the magzines back when. I guess my idea isn't so unique anymore is it. I long but forgot about that concept at the shows cica 97.
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I guess my idea isn't so unique anymore is it.
Oh yes it is,
yours will be built tested and used and there wont
be another one,thats unique enough for me :P,
Simon
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Here is the first update.
The clamp thickness on the swingarm is thicker by about .5mm but it still assembled beautifully.
(http://www.alexlori.ca/06_4500linkmod1web.jpg )
If anyone has a strut that accomodates this style arm for purchase give me a shout. looking for the x57 typs brace that reaches from frame to dropout. It will be around 19.5 inches but the length I can modify so any x57 type will do.
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Excellent, excellent, excellent! What a great idea.
I think the first thing you will notice when completed is a considerable reduction in swingarm flex. The strut in my opinion really stabilizes the rear wheel from twist and flex. And I am harboring the belief that the x57 swingarms are more stout.
And the 4500 has that lowered pivot for a more active suspension. You could definately benefit from a platform shock if you can adapt one.
You can shorten your strut pretty easily. The joints are bonded. To disassemble from the shock mount, just heat gently over the kitchen stove untill the glue melts. But make sure the air pressure does not build up too much inside that it launches the strut when the glue melts. Trim and rebond with whatever(JB Weld works).
Lengthening could be done by bonding a sleeve below the upper joint. The upper mount slides into the tube about 1/2 to 5/8 inch. So cutting the the tube maybe 1 inch below the upper joint and and bonding an oversize sleeve would work. Be carfull, the tubes are only about .5mm wall.
Or better yet, dissemble and reassemble with carbon tubes. [smiley=nod.gif]
It's going to look great. Again, what a great idea.
Terry
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Well look at that - it's on! Coooooool!
Okay, another Q - since you'll be changing where the shock mounts to the frame plate, what are you going to do about the location and mounting?? I'm sure you've noticed already that the shock's stock location is where it is because it's buried in the "V" of the seat/top tube's junction, right? If you're going to move it up then you'll have carbon (frame) in the way.
Input?
Also, this means you can run a ball bearing conversion on that, right? (still gotta look at Frank to see if I can do it or not)
Originality - well, I can speak from personal experience with this one. I was all set and ready to "do something special" when I joined up here. Heck, look at my username! Then I saw Simon's project and fell apart when I saw he did exactly what I had in mind. (damn, it's gorgeous!) Anyways, wether ProFlex made one or not, I certainly think the cudos goes to you for building one of your own. You're really taking the best of everything and rolling into one FINE package. Also, you're DOING it, not just hacking something up or being a big company and calling it a prototype. :o I say it's a proud piece to build. ;) Not many people build prototype's. :)
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great idea...the shock can mount to custom pltes fixed to the frame,dont do anything to the strut itself until you get the shock,cos you will prolly have to massage the length of the shock anyway via an adapter from shock to 957 strut.I am sure that fabing a stut from scratch wouldnt be hard for guys of your calibre....
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Ha. thanks Kiwi. But sometime my enthusiasm surpasses my actual skill in practice. My comfort dismantling it kind of scares me. The tip you gave me is a good one. I shall wait until I have the hole strut and shock assembly before I start chopping things. I still have the CF side plates and can move them around slightly for correct positioning.
I followed Dominic's instructions to take those off with the rest of the cable system bits. I think I will leave them off for good and redistribute them.
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Thought................
........comparing my 857 beside my 5500, the shapes of the swing arms are different......
Because of the lower mounting point on the 5500, the swing arm comes up higher before going horizontal, I think this is to clear the chainrings...........
.......with the lower pivot and a "low rise" swing-arm, you might foul the chain-ring..............
...........or on the other hand, you might not! :)
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Good thoughts colin. I will check this.
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I tested if the swingarm will in any way impede with the drive train and so far I would say it won't cause any problems. Thanks to Colin for bringing that to my attention.
During my test I attached everything to the frame that would possibly interfere and shifted from large gear to small without any problems. But I realize this is just a mock up and does not have any conclusive evidence the new swing arm will not cause problems.
I found that the drive side bushing sticks out closer to the tallest ring. If this causes problems during prototype testing I can either used a smaller ring or find a way to reduce the bushing length and permanently eliminate any problem.
I will post a picture when I have it.
Oh Simon do you still have the link to the second linkage simulator. I accidentaly deleted it during instalation of the first linkage sim and lost some newer files. I looked all over and could not find it.
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Oh Simon do you still have the link to the second linkage simulator. I accidentaly deleted it during instalation of the first linkage sim and lost some newer files. I looked all over and could not find it.
Does this help
http://www.bikechecker.com/
http://fs-kinematics.igorion.com/index.jsp
Simon.
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small chainring large cassette...... [smiley=coolfrown.gif]
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Last night I checked the geometries of my Oz and 957. Although the fitup seems perfect, there is a leverage difference.
Both my bikes are large size. The distance between the upper shock mount and swingarm pivot is approximately 1 inch shorter on the Oz.
My conclusion is that there will be a big increase in rear wheel travel by putting the x57 swingarm and strut on the Evo frame.
Given the increase in leverage also, there is quite an increase in tensile load on the bonded joints, as well as compressive load on the strut and shock. But given the strudiness of the strut and swingarm, my belief is that they can handle it.
Terry
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I make it the other
My conclusion is that there will be a big increase in rear wheel travel by putting the x57 swingarm and strut on the Evo frame.
Terry
Are you sure Terry ??? I make it the other way round
due to the strut located at the rear of the s/arm,
now if this was brought forward then the travel will be increased.
the simulator gives Ionits setup at 69mm travel with a 1.5
stroke shock,this gives a ratio of about 1.8 : 1
the Evo is about 2.7 : 1
I could be wrong but thats how I see it.
Simon.
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Simon,
You are right in regard to the ratios. But he is putting the strut on the Evo. The distance between the upper front pivot and lower front pivot is narrower on the Evo thereby increasing the amount of travel when the shock is compressed. This increase in travel also increases the leverage on the shock.
As I recall, the distance is 11 inches on the x57 as opposed to 10 inches on the Oz. Since the strut is somewhat more horizontal and the wheel is still traveling in a vertical direction, leverage has no choice to increase. But that will yield more travel.
Don't get me wrong, I like what I see, and am fascinated by what mayl emerge from this project. Stiffer rear end, and nice travel is what I am hoping for(and light as hell). And the old strut bikes were rock solid. This may be the best of both worlds, rock solid rear end on a carbon triangle.
One thing that does come into play is that the evo front pivots are lower not only between each other, but closer to the BB. However the rear axle remains the same. This is one more reason that I feel the way I do.
All this could become mute if the upper plates are modified to some extent.
Terry
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(http://idriders.com/proflex/galleries/I_2_ionit/ProjXChaindistance.jpg)
Ok so the picture doesn' help much but you can make out enough that the space for the chain is ok. I cycled the chain form the tallest ring to the smallest and kept the chain on the 11 tooth cog and nothing came in contact.
By the Linkage symulation I can modify it from 4" to 3" and get a fairly good ramp up.
Simon is right for the ratio. I would like to squeeze out a little more then 1.5" to 3" but I guess at base it would sufice. It would probably be more comprehensive if you see it in the symulator. Here is the file I am using for the demo Linkage modifier http://www.alexlori.ca/Proflex999.LTX that Simon posted a link to (http://www.bikechecker.com/ )
I am not processing anything in my head that is beyond my thought capabilities like leverage ratio's. I can imagine the differences one pivot point has over another. What I cannot imagine its relative itineration or proportion of force applied to the frame. After all I don't want to shear bolts and pivots.
And I hope I don't make a mute feeling as Shovelon expressed. He is right though, as you bring the pivots closer together theoretically I would need to use a exponentially stronger spring. Maybe I can tune it by changing the pivot location. I've already done that in the simulation with good results I believe.
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Very impressive,
I think you need to use a 1.75" stroke shock, this will yield around 81mm (3 3/16")travel more than
enough for a fast XC bike,
with the shock ratio at 1.8 : 1 you can use a softer spring if you leave the mounting points in there current position, this would give better small bump compliance
without running much sag,basically higher the travel to shock ratio
stiffer the spring needs to be (think I got that the right way round,anyway I know what I mean [smiley=laughing.gif]),
I can see this turning into a very light weight, fast,stiff,
XC trailblazer,maybe Proflex should of stuck to the prototype design.
Simon.
PS your simulation looks just like the one I did [smiley=laughing.gif]
though you have the shock stroke set at 42mm I have it set at 39mm.
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finally read this thread....fascinating!!!!
:-[
I can check some stuff on my Team Bike for anyone interested....won't be till Sunday though....
[smiley=beer.gif]
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First congratulations on the new frame Carbon Angus. That offer is as good as it gets. It is not often you are able to purchase a brand new Proflex in this day.
Even though your new frame (being size XXL) I presume that all pivot bolts are in the exact same position and configuration in relation to one another as other strut bar Proflex's.
Do you know what I mean? The designer of this bike used a 3000, 4000, 5000 frame because it provided a base to accommodate tall people without changing the proven mechanics of the production smaller frames. The distance between the pivots are all in the same place proportionally.
I would be happy to check it on the linkage checker. All I need is an orthographic photo of the bike. But a side view is probably the best that will come. Note taking side shots for dimensional trueness is best when standing away from the bike several meters leaving allot of border around the bike. This ensures that the camera is receiving more parallel light from its focused object. If your to close objects tend to distort.
But again that is a great bike. If it was only available in a small size. You are the envy of every one on the forum.
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check my other post about the bike...I can get a better straight~on photo for you in a few days..send me a PM if you want and I can measure it for you anyway you want.
[smiley=beer.gif]
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The one you have in your gallery is good. Don't worry about the new photo.
Re measuring: sure why don't you measure it. I wonder how diffrent it is from the others types built at the time.
Thanks.
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My Christmas present to myself was a Fox DHX Air 8˝" i2i / 2˝" stroke (gives 6 -6˝" travel).
However, the main air charge shrader valve and its locating body material, means that a slot has to be cut into the frame pivot plate on the chainring side and a lump cut out of the frame's central rib!!!
I was going to risk milling the carbon thermoplastic to suit, as it does seem very strong in this area (with the plates and all).
I see from your photo that you have removed these plates, excellent, as I thought they may be bonded and riveted onto the frame. Anyone - comments and where would it be possible to buy the correct rivets and carbon / Ti plate to make new but modified plate with slightly moved (backwards) shock pivot holes?
regards Oz-SUB
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Ionit, from the photo of your frame, were the frame pivot plates bonded on as well as rivited?
What size drill did you use and what rivets do you intend to put back in?
Anyone know where similiar thickness plates could be purchased in the UK?
I'm asking, because I'm taking the brave step of trying to mod my Oz frame to take a Fox DHX Air shock.
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Hey Sub,
I see what you mean with clearance. Just a thought, but if you want to keep the carbon, can you use the existing plates? Could you redrill a hole somewhat away from your existing hole to gain the clearance on the frame backbone? Could you then cut a slot into the old mounting hole?
Otherwise, aluminum plates would work too. 7075 alloy plate is the bomb for strength and lightness. It has mechanical properties close to steel, and is 1/3 the weight. And is stupid easy to fab, using woodworking tools. Looks good polished.
As far as rivets, as long as you are destroying the old ones, you could drill them out, ream, and install steel rivnuts. That way you could remove the plates when desired.
I am interested how your endevors turn out. Very fun.
Terry
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Oz Sub
Dominic made his own carbon Oz copy,he also made
new shock mounting plates and a carbon disc mount,
maybe he could help you out,
haven't heard from him for a while but I can give you his last email address if that will help.
Simon.
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Simon
Thanks I've sent you a message.
Oz-SUB
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Ionit, from the photo of your frame, were the frame pivot plates bonded on as well as rivited?
What size drill did you use and what rivets do you intend to put back in?
Anyone know where similiar thickness plates could be purchased in the UK?
I'm asking, because I'm taking the brave step of trying to mod my Oz frame to take a Fox DHX Air shock.
Hi Oz-Sub
Sorry I've been away so long. I did not check this thread until earlier today.
The actual hole in the carbon itself is 3.09mm. You can use a 3 mm or 7/64" drill.
At my attempt I used a 20mm drill to rip off the head but was careful not to cause excess heat friction. The bottom of the rivet in turn fell into the frame and still resides inside. I will not attempt to take them out. I will instead trap them with spray foam so they do not rattle latter on.
If you use the 3mm drill you may be able to eat more of the rivet material away so less material falls into the frame. But ultimately it is inevitable to take them off without making your frame sound like a maraca.
Your new plate is a good clean mod to adapt the new shock. Will you include different positions for the top shock so that you can change the sus rate without making a new adaptor.
As for the aluminium plates I do not know where to get any material. Dom hasn't been around for a while hopefully he will turn up. He probably would be pleasantly surprised in his mention several years after he posted his project.