Girder front suspensions are pretty much as old as motorcycles and you see them on custom bikes all the time but not very often on sportbikes. This Yamaha R1 streetfighter from R1 Engineering is being fitted with a girder setup and it looks pretty neat.
There’s no reason this shouldn’t work great and it will be interesting to see the finished bike.
Thanks for the tip, Doug!
Link: R1 Engineering
Adam says
A poor mans Wraith? Yes please. I don’t really go for the stripped street fighter look. They usually look really cheesy, but this is done well. I hope to see more customs like this. There are a million soul-less sportbikes out there with cracked plastics, rotting in garages that could be had for a song, and reborn as something far more interesting.
motoxyogi says
Should be interesting to see how the hossack front end affects the balance of the bike. It looks to have a steeper steering angle than standard but that could just be the sawn off rear end affecting my judgment. Look forward to seeing more bout it.
Brian says
This is not a Hossack. It’s just a double-wishbone girder, similar to the Wraith. Also, the steering angle is dictated by the steering stem on the chassis, not the angle of the girder forks. So if they did it right, this set up should have the same rake and trail as the stock R1. Poor man’s Wraith, you say? Interesting idea…
Brian says
By the way, this bike is pretty sweet. Nice job.
Ride says
Any advantage to this or just for looks?
pghcyclist says
In theory a parallelogram suspension is far superior to a telescopic fork. Because: the path that the front axle takes can be more that a straight line. By changing the lengths of the horizontal members you can cause the wheel to move in a j path. this allows for more subtle bump activation and at the same time critical relationships like the rake, trail and steering angles can be maintained thought out travel.
Motoxyogi. The steering angle is still the same don’t let the steep angle of the vertical members fool you. Look at the relationship of the steerer tube to front axle. i think you will find that it is still the same as your average R1.
my only question is why aren’t there more of
these.
Skizick says
Doesn’t look like it does much for the unsprung weight department
todd says
have you ever held a conventional front fork in your arms? It’s amazing that bikes can do wheelies! This is either a big hunk of machined aluminum or better, thin wall oval tubing.
The only draw back is the additional slop brought about by all the links.
Do people actually like the look of those type of wheels?
-todd
chappy says
Very cool, but then I love the look of girder forks. What is the word on how the legs are constructed, is it a hollow extrusion with extra bracing made into the mounting points or milled from sold stock (which would be quite heavy, right?) or I suppose it could have also been extruded solid? I didn’t see any pictures on the sight that showed how they were done.
Second question, is he planning on producing them for sale? I am thinking about starting another streetfighter project soon and would love to get a get a set assuming I could afford them.
Sean says
The problem with girder forks, a problem that Britten found out once he made the decision to use them (based on shocking the world, not on their technological merits) is that they’re extremely difficult to set up right. The Britten had a problem with shaking and shuddering about under braking, which was thought to be a simple fix but proved more than elusive. The problem was fixed, for about five minutes, but no-one can remember how they managed to do it. However, for that five minutes, the rider commented that he knew he was riding the fastest bike in the world.
They look cool, and they’re adjustable for rake/trail, and that looks like it’s going to be one seriously kickass ‘fighter. Pity they don’t make anything that bolts into a VT250.
B. Case says
That’s aero-tube, hollow extruded aluminum. Shouldn’t be too heavy. But you do have to watch the steered mass flopping around. I suggest a Ti coil, they’re twice as costly but what a difference over steel.
And “pghcyclist”, we found that the multi-link worked best actually when the wheel trajectory was not a “j” or “s” line as in traditional girders, but more closely matched a straight line. This is possible through a virtual pivot and provides a familiar feedback to the rider.
Lttlcheeze says
Is this the same thing that MotoCzysz (www.motoczysz.com) is doing with their front end? I have never seen an uncovered pic of their bike.
B. Case says
No.
Lttlcheeze says
Could you be a little more vague?
Jason from R1E says
Thanks for posting Paul. A poor man’s Wraith indeed – with 50 more horsepower. The “steeper” angle you see is not just an illusion. During mock-up we found that this girder set-up couldn’t achieve proper trail numbers with the 24 degree neck of a stock R1. Machining arc’d legs and re-raking the neck are a couple ways to fix this. But we decided to go with machining a set of offset bearing races for the neck in order to give it the proper angle to achieve 4-6″ of rake. This will also help lessen the “steep” appearance. This girder is built by RMD Billet out of Jasper MN. Uses a Penske shock and all billet aluminum. Many, many machine hours and is a real piece of art. Check them out at http://www.rmdbillet.com. Will have finished pics soon.
B. Case says
Actually, no, I couldn’t. The Czysz design is completely different.
The more I look at this R1 though, I would say they either need to drop the rear suspension a bit or lengthen the front tubes on the RMD front end. In my opinion the steer tube looks too steep for an R1. Lower the rear and you’ll get more trail.
Jason from R1E says
The legs are solid extruded aluminum. If you check out “The Girder” on the r1engineering site you can see many more detailed pics.
hoyt says
The look of this Leo front-end is spot-on !
Teles (even the beefy ones of 43mm +) look like skinny, wimpy legs compared to this setup. The weight should be competitive.
Looks are part of the moto experience, but, what I understand about suspension systems like this, the function will rival a very expensive tele front-end.
Good job Jason – you are helping break through the tele mystique. Not an easy thing to do, but worth every ounce of energy.
Tim says
I love those wheels.
fork is cool too. Like the Britten, yes?
By the way, I was at a race meeting at the weekend, and there were five (count ’em) Brittens on display in the paddock, and one doing parade laps at lunchtime.
Even now, its QUICK!
Tim says
Just to segue back to these forks, what are they like when the linkages and bearings are side loaded (like when the bike is at 55 degree lean angle hammering through some corner)? Better or worse than the original forks? All those little bearings and linkages might bind up a bit or something?
B. Case says
Tim, what about stiction in conventional tele’s leaned over at 55º? Tele’s are just two long tubes sliding together, you think they don’t flex?
Also, it appears I was mistaken. I assumed this RMD front end used light weight hollow extruded tubing, and apparently they are solid. Certainly, lighter unsprung weight will perform better.
Jason, Penske does have a Ti coil that will fit that body.
Sean says
Tim, were you out at Ruapuna on Sunday? I know I saw number 1 bike on a paddockstand on Saturday, but didn’t get the chance to go on Sunday.
As far as looks go, this thing is the business. Muscular and raw, and the contrast between the (beautiful) black of the bike with the silver of the forks works wonderfully. I love those wheels too, and the super-cut-back tailpiece. I saw an R1 fighter at a race meet, and that was similarly cut back in the tail. You don’t get to see just how big and intimidating those engines are until you see them naked.
hoyt says
…at the same time, the overall bike looks tiny from the picture of (I assume) Jason standing next to the bike while its on the stand.
The bike looks great here: http://www.r1engineering.com/100_0589.JPG
Not to get off topic, but 5 Brittens in one place is not fair, damnit. Are you writing from NZ?
christopher says
jason, anything to add on the subject of vibration/stability under braking?
Alex says
Somehow this appears much more logical to me than standard forks… What about the cost?
chris says
Are they cheaper to replace than telescopics? Are they lighter? If they’re lighter, you created one hell of a hooligan bike. I love to see how this configuration would handle.
pghcyclist says
Thanks B.Case
I love hearing from builders.
Its one of the many things that sets this board above the rest.
Jason from R1E says
Girder designer Leo Diorio and RMD owner Shannon Rodman should be stopping by soon to chime in.
Tim says
Yep, i was out at Ruapuna on Sunday. It was the 25th anniversary meeting of the “Sound of Thunder”: Bears racing (British European American Racing Society) was invented in Christchurch in New Zealand and their first meeting was in 1983. John Britten was one of the original people involved IIRC, and the the Estate had a display there to celebrate that. Every time I went to get a photo of the five bikes there were too many people round to get it clearly. There was a ducati powered first attempt and the Denco powered second attempt, and three slightly different versions of the V1000….. sorry for the hijack, and I will try and get a photo, because I would like one myself.
Oh, and I did think about telescopic fork stiction while leaned over, and my thought was because the tubes and sliders were round, that the forces would be similar no matter what angle the load was applied from. But to misquote Dr Leonard McCoy “Dammit Jim, I’m a lawyer, not an engineer” so I have no clue really. If you can explain it to a layman, I’d be interested. I’d buy one just cos its so damn cool though, no matter how it worked.
Adam says
No, I’m serious. Who do I give my money to?
And, I don’t even have an R1. Yet.
Redmarque says
Jason – Quick question are the bearings plain or tapered needle rollers in the wishbones?
I guess the forces on them would be simular to wheel bearings?
Jason from R1E says
chappy – yes, RMD Billet is producing them for sale. Retails around $3500. Check out their site for more info.
Bcase – as far as the steer tube looking to steep…this pic was taken at a stopping point after discovering we had a trail issue. the ride height and tube lengths are initial mock-ups and are being adjusted.
tim – although hard to determine the amount of side load and therefore “binding” of parts in the the real world, the modeled version performs extremely well. the contact areas where binding could take place are very minimal and the wishbones are connected to the trees using bearings (two in the wishbone one in the leg) and shoulder bolts.
sean – thanks for the comments. raw, muscular and minimalist were all visions for this bike. and it continues to be a work in progress. if the race you were speaking of was last summer’s GP race in Laguna Seca this may have been the bike you’re speaking of.
hoyt – yes, this bike does look very small (almost ridiculously so sometimes) next to a 6′ person. and it doesn’t help if you’re in the 220lb range. 🙂
christopher – i don’t personally have experience with stability/vibration conditions with this particular front end. it was used on Roger Goldhammer’s Bonneville bike last year and performed well.
adam – make me an offer. 🙂
redmarque – bearings are plain. 2 in the wishbone and one in the fork at each (total of 4) mounting location.
taxman says
if you go to RMD’s website they have the girder front end for sale for $3500. currently only for aftermarket frames though. a set of forks alone on ebay range from $1-6k. so if you wanted something different this would be fairly similarly priced. at least it seems so from the little looking i did. to me the front end on the wraith looks to much. this looks a lot nicer. i think it’s the more compact look of the forks on this one that make me like it more. i’d love to put this on the front of my bike.
hoyt says
“Taxman, yeeaaah, I’m the taxman…”
I agree.
As much as I like the look of the R1 with this front-end, and as much as I like the look of the beefy Ohlins front-end on Curt Winter’s black Big Twin bike, I’d like to see the BTR with this front-end too.
Leo says
I had never herd of knee slider until I was informed that you guys were hashing over the good and the bad of the girder that I have a Mfg agreement with RMD, I will for sure come back to this site its a very good platform. Here is a couple of things that will clear things up abit first, I have been following the work that Jason and RMD have been doing on the R1 and although we came out and our first customer was rodger Goldammer for salt flats Tv this project is by far the most exciting I hope to conqure many fitments that I feel have merit also the first ones were built out of thin wall chrome moly tubing with solid bulkheads at the at the atachment points this was only a pound or two lighter but very labor intensive and the fallout was more then I could stand, now it is extruded 6061 piece and we are working on a Iso grid pattern that will be lighter then the thinwall and stronger ,also the upper and lower control arm feature adj for trail tuning and controling some of the dive features some of you have asked about and I appricate any imput I get from this most people who have considered them have been for over built barges that will never really put these things to work and I too belive that Jasons bike fall in a new and growing market hyper street fighter
tom says
Here’s another take on girder forks; versions of these have been in production for about ten years now:
http://www.2-wheel.com/moulton/d_pylon/d_pylon_slv_comp.jpg
Tom
B. Case says
Uh, Tom…that’s a bicycle.