ricardo kuhn

A friend of mine give me this Titanium Bar/stem combo to see what i think of them and I install them on my tandem since is pretty much the only "None Hard Core" Mountain bike I have..


They are somehow inspire on Jeff Jones fantastic work, weightless but also extremely rigid if you consider the material and the wall thickness they are made off..


So far I only have about 20 miles on them (install them yesterday, ride them today)





They Fit my Funky dual brake set up and everything, so I have nothing to complain about.




A more in deep review when I have a few more miles on them.

Peak Team

Looks good - especially with the dual brake set up !

What is in the blackboard behind the photos ?

mrfish

Neat! That triple stem looks like a welding work of art, and no doubt took a lot of time to build.

But why are you keeping the old stem? Surely not just as a spacer?

ricardo kuhn

I Borrow that Trick from Chris Timm bag of tricks (This guy is amazing, super heplful, None Dogmatic, and No Ego), so i can have a "Piggy Bag" mount to install my Headlight, Handlebar bag, etc.

Here is my CatEye "Stadium light" install.


On the Purple bike I have a really l short and low stem, but I can install A much longer one in seconds to clear all the cables if I want to carry my handlebag bag.

I be changing the forks for something a lot less agresive if I was going "Touring" anyway (I have four forks for this thing, two 20mm axle two QR's,)

ricardo kuhn

I'm really happy with the Dual brake setup, the Ergonomics are Perfect (On the normal flat bars and on this ones too) very easy to activate, modulate, etc and obviously very powerful also.

Oh Nothing,
Reason why I try to crop the Photos as much as Possible..

ricardo kuhn

Today I took a little mini ride in the dirt with a clumsy heavy guy friend (220 or so), the handlebar ergonomics are great for street type riding in fact very comfortable and upright. wrist is in perfect correlation to the grips and controls.

But they don't offer as good leverage as the normal flat bars for more than obvious reasons, I'm going to keep them on the tandem for sometime and take them into different type of environment until i really get use to the new shape..

Maybe some day I will mount them on a single speed or something a little less massive than a tandem were I think leverage and dinamics will be a little less critical

So far the damping provided by the titanium is a welcome side effect, plus they are so pretty and trick I just like to look at them.

Brian

Can I puleeeze get a pair of those bars for our titanium tandem? They look like they would resolve some wrist pain issues.

ricardo kuhn

Brian this bars are a prototype from a local frame builder (Berkeley California/ El camino fabrications) so I have no idea if is going to make more, but at the same time maybe he can even make you a custom set.

let me ask and see..

your other option is a guy call Jeff Jones that makes the coolest freaking bikes and bars I have ever seeing.

Here are some examples of his amazing work from his own website.






Here are the details Of the H-bars

The ones I have are even more "Evolve" being a single piece unit, for sure I will hate to know how much they will cost, plus being a single piece limit the angle (Upwards, downwards) of adjustment, but then again if you get them custum made maybe is not a issue..

Ps: Being the dummy that I'm I did not measure how much they weight, but I'm sure they are under 300 grams, if anything about 250grams but also super rigid (no notifiable flex even with mark in the back) but still great damping ability..

psII: Can I see pictures of your Titanium tandem..??
I'm intrigue how you can make a tandem rigid enough out of such material

Brian

Ricardo, I'm sure you've seen this before. It's not very rigid, as it's more of an XC for two than anything else. But good teamwork is rewarded with a very smooth ride. This is a very old photo, we've since switched to steel brakes (from titanium) and replaced the dual crown with a Marzocchi DJ.

ricardo kuhn

Actually I did not, I don't spend so much time around here..


So you used to have Titanium rotors on the monster..??

I don't think they will work to well, do they..?

Maybe you need something like this Hope's ,Aluminum carrier and a semi floating, very narrow and light steel rotor.



even for the rear.


About your forks sounds to me like your bike will be perfect if you got Jeff to make you one of his "Moving Partless" Suspension forks with the correct length so your bottom brackets were not a mile high..

They are for sure rigid and strong.


but they also provide sufficient comfort do to the way the arches flex on the wheel path axis.

Personally I don't believe in telescopic front ends on tandems, specially hard tail tandems (even if I'm a motorcycle parts manufacture and I ride all kind of them) the poor little fork just have the whole mass of the captain at a really high leverage ratio, do to the location of the rear pivot point a.k.a. rear wheel axle, so they need to be to sprung to hold the mass with out providing ultimate performance

I think something like a JP Morgan suspension stem is a better option.

mrfish

I thought the argument was that the lower the unsprung mass the better; ergo better to have a suspension fork than a stem.

Also I thought spring rate versus need to support a certain mass are different things. A spring rated at 1kg per cm could hold 10kg, it would just compress somewhat; this is what preload is for I thought.

I'm no expert in suspension though - my knowledge only comes from the theory rather than practice.

Brian

The stem is not going to help keep the wheel planted. And while the bike does look tall in the photo, once I get my fat ass on there, it settles in a bit.

ricardo kuhn

Your arguments are also right, suspension systems are a matter of compromise, specially telescopic forks on a bike with such a long wheel base as a tandem and more important with so much mass so close to the fork (the captain's body)

Remenber the pivot point of the suspension travel is the axle of the rear wheel, unless we are taking a full suspension tandem were the frame moves downwards all togheter (well somehow)

Here are some examples of really early suspension fork designs a little better suited for tandem duty since the have "Leading Link" properties that lets be ore reactive to bumps and terrain with out needeing to be ultra preload.

Jp Morgen front end circa 1986


The contact patch with the Object is far forward on the wheel as oppose to right under the wheel.


This forks are base on motorcycle sidecar technology, that still in use to this days, maybe because a sidecar can not be lift (willie) at will like a normal motorcycle can..


Joe lawwill's (son of Mert lawwill) bike and one of the cro-molly prototypes made by Kosman in san francisco.


The one in the middle is the vintage model the one on the left the CNC production model.

This Mert Lawwill forks made by control tech are a excellent example of a commercial fork

ricardo kuhn

Some world cup motocross sidecars examples just for reference.








My friend Scott 700pound, 150Hp Paris dakar sidecar racer


Yeap they are mandatory on heavy road warriors too.

ricardo kuhn

Again Compromise..

You are right the wheel does not trace the path of travel as well as a suspension fork, but then again the bike is not bouncing and diving all over the place and the pedals touching rocks and walls.

For about two years I race pro class using one of the softride stems with excellent results when the only other choices available were the Manitou I or a Mag21 rockshocks.

Personally until the day I build my own full suspension tandem with a G-boxx on it.



I don't think I'm going to install a suspension fork on my hardtail tandem and believe me I have plenty, but again to each his own.

Actually my next tandem project is to convince my friend JP to make me on of his funky fork/front ends for my Ibis.

A "Linkage" system somehow like this.


But with a "Dual triple clamp" fork like this for added rigidity.

the Forks never got painted

This is a extremely rigid design, that provides excellent control even if the tyre is not as prone to follow the terrain and get stuck on rutts and things from time to time.


Again a personal choice.

cat0020

Hello Ricardo,
ADVRider unite in Bikes Forums.. this is a first for me.
That G-Box, is it similar concept as the GT I-Drive downhill bike? having an internal geared hub as part of the mid-drive to eliminate rear derailleur?

ricardo kuhn

Hola senor i was wondering if you were you..

Yes the GT's are a good example, but the company at the fore front of this development is Nicolai from Germany.

This company makes frames like the "Nucleon's" that are at the top of the food chain

Here are the Frames they make


Just take a look at the construction, is supperbe.


well they are for sure not cheap at 6200 euro's just for the frame..


Actually I'm being in Contact with Karl Nicolai for sometime about the G-boxx concept, here is the main G-Boxx site, very interesting for sure, specially the "History" page..

In fact about 18 months ago Nicolai release a "Universal G-boxx" in cooperation with suntour that manufactures can purchase to make G-boxx bikes, is even a standard for the mounting bolts and everything..

very interesting future we have..

Sadly they don't make tandems that way, mostly because the market is to small, the prices much to high and maybe the bikes will be much to heavy.

This is the only Nicolai G-Boxx tandem I have ever seeing, but is the old style using the rooloff hub and not the new gear box at the bottom bracket.




In contrast here are so more of my cheesy concept drawings from a few years back (2003 or so) trying so see what the best options are.


Is for sure a Challenge, but still far easier than developing motorcycle frames for sure.




This "X" shape frame, gives you excellent ground clearance, but is much less rigid, plus the top tube is missing from the drawing.


So what kind of tandem do you ride mister Cat...!?!?

cat0020

I'm faily familiar with Nicolai's bikes, seen a few of them in person, always wondered is they weight as much more as them look susbtantial.. want to get one every once in a while, but I don't do as much DH or freeride style riding as I used to, so the need for a super strong/rigit frame with efficient suspension that doesn't soak up pedaling effort.

Our tandem does not have fancy suspension and drivetrain arrangement:





So far it's been popular with the neighbors, our longest ride on it was approx. 45 miles on mostly flat, paved railbed trail. Climbing steep hills can be interesting, the frame is not nearly as stiff as I like it to me, bottom bracket tend to sway side to side as I sit and grind up the hills.
We've gotten it up to approx. 45 mph when going down some nice long hills, the brakes worked well, but more braking power would be nice to keep things cool temperature wise.
It's a far cry from a high performance tandem, but nice enough to scoot around at decent speed and effciency.
I like the fact that I could switch riding position with stoker if need to and not have to turn my head around to communicate with stoker.

ricardo kuhn

My Nicolai M-pire is about 43 pounds, in downhil terms that is actually light, the Nicolai frames like mine are warranty for 5 years for 10meter drops to a 45degge landing and from 3 meter to a flat landing.

the new Nucleon "race version" Not exactly downhill are about 36 pounds and they can do pretty much anything, exept build up they are about $15.000 and that for me is a little to much..

Then again I'm a Old fart already and I don't have the Ba^^s I use to ride a bike like this like is soppose too.

Ps: I race the Mammoth lakes Kamikase world cup downhill in 1994 on a full on rigid Klein attitude and I reach 48,6mph, last year I try the same course on my Nicolai M-pire (pure breed Downhill race bike, build up to perfection) and I did not pass over 45mph.

man I suck this days, maybe that is why I like tandes so much this days..

Oh man I'm being in love with that design since the days of the Opus III

Great machines but i can totally see the shortcomings.

cat0020

Dude, I weight approx. 150 lb. with full DH gear and helmet, I've probably never did a 5 meter drop, unless I'm on my motorcycle.. I take far less risk as my 32lb. MTB could handle these days:



The semi-recumbent tandem is a hoot to ride, captn or stoker.

What do you think could improve the frame stiffness to the semi-recumbent tandem frame? besides the obvious of beefier chain/seatstays.

I try to position the crankarms insync so the power stroke start at roughly the same time for both the captn and stocker... that seem to have improve the B/B flex a little.. but still pretty scary when you have both riders cranking up a steep hill.

Brian

Do you know Kye Sharpe?

ricardo kuhn

Nope I came to the Mamooth to race my country's team, a year later I end up moving to california.

I did not know anybody, well unless you count the magazine rockstars but they have no idea who i was.

cat0020

I think for my next bicycle, I will try and put together a cargo sidecar bike:

ricardo kuhn

Can you say Midlife crises

some guys but Red FERRARI's I purchase a $10,000 german P66us Extension..

I have a bunch of less aggressive suspension bikes, that are far more pragmatic than this monster.BB flex....

Front BB, or the rear one...!?!?

I always wonder why they never use a parallel set of tubes coming from the sides of the headstock (actually a small trellis will be optimal and not so heavy) probably do to manufacturing simplicity but even more to the fact that a round telescopic junction can be spin around if seize but a pair of tubes will be impossible to persuade.

let me think about this, maybe i can find a siple fix for it.

ricardo kuhn

If you ever need one of the X-cycle whatever extensions, I do some work with Paul and Nate the guys that distribute them...


I have seeing a few of this "Leaner" bicycle sidecars and i really like the concept, are they hand made, or is a commercial source for them...!?!?