If you want to monitor progress on my DIY springless rear derailer project, a flickr album

[Bill Lindsay]

I'm working on a DIY desmodromic rear derailer project as one of my Winter projects.  I successfully got the spring extracted from my victim derailer, and so took that accomplishment as the impetus to start the photo record of the project.  If you want to see what's up, here's a link to the flickr album that I'll keep updating as progress is made. 

Desmo!

I think the latest activity will always be at the bottom. 

I need to work with my Brother in Law to generate three solid models for parts that I will have 3D printed.  The most complicated and most important one will be the shift lever.  The other two smaller and easier tasks will be setting up a secondary cable housing stop on the chainstay, and modifying a BB cable guide for the extra shift cable. 

[Anton Tutter]

Okay, but why?

[Bill Lindsay]

Anton, 

Can you be more specific?  Why what?  I'll take a guess at five possible things:

1.  Why would you want to try using a springless rear derailer?  Because they were popular during a very interesting period of cycling history, and disappeared basically by historical accident, and are now essentially forgotten.  I'm curious at what was lost.  

2.  Why would you bother destroying a perfectly good derailer?  Just a creative outlet.  I think about bikes a lot.  It's meditative and at the same time it is mental exercise.  

3.  Why don't you just ride instead of over-thinking things that are perfectly fine as they are?  If I had more free time in the daylight I probably would.  If I had less mentally idle time, commuting to and from work, maybe I'd come up with fewer ideas

4.  Why make a non-linear shifter to complement your non-linear derailer, making the pair linear?  Because in the lower end of my 9 speed cassette, I find the action on my downtube friction shifters very sensitive.  All my overshifts and ghost shifts happen in cogs 1 and 2.  Looking at the math, I found the geometry of my derailer demanded that sensitivity.  I'm thinking maybe I can smooth that out and get fewer missed shifts and ghost shifts in the low gears

5.  Why make DIY bike parts?  Why don't you just buy what is available?  Partially because I don't always find the industry at large is motivated by the things that motivate me.  Partially because I'm a design guy and I enjoy putting my own fingerprint on my builds.  Partially out of just a general curiosity and desire to explore ideas.  I'm inspired by current and historical builders.  One builder who particularly has inspired me is Charlie Cunningham.  That's a guy who feels absolutely zero obligation to conform to what anybody else thinks a bike should look like or should be.  

6.  Why do you think a springless rear derailer is vastly superior to a normal derailer with a return spring?  I don't, and never said I did.  I'm just curious and like exploring.  

7.  How much faster do you expect to ride with this?  Zero miles per hour faster

8.  What are you trying to get out of this project?  Grins

Maybe you meant none of the above.  Maybe you asked because you are pretty sure it's a stupid waste of time, which it might be.  Add it to the long list of ways in which humans have wasted time.  Maybe you meant something much different.  

On Monday, January 12, 2015 at 8:43:28 AM UTC-8, Anton Tutter wrote:

Okay, but why?

[Chris Chen]

Bravo. I love these these "stupid bike tricks" :)

--
You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bun...@googlegroups.com.
To post to this group, send email to rbw-owne...@googlegroups.com.
Visit this group at http://groups.google.com/group/rbw-owners-bunch.
For more options, visit https://groups.google.com/d/optout.

--

"I want the kind of six pack you can't drink." -- Micah

[BSWP]

Why? Well, if you're on your bicycle, then you're necessarily NOT on your Ducati. But that's no reason not to enjoy and employ an iconic aspect of Italian engineering design on the bicycle.

Tanti Auguri!

- Andrew, Berkeley

[Anton Tutter]

Fair enough. And you KNOW I would never ask about #5, as I embrace DIY and a hack culture in general.

I was just curious why you would do this unless there was something particularly nagging about your current derailleur setup. To do so out of historical curiosity alone earns bonus points.

Carry on. Interested to see the outcome.

Anton

[Eric Norris]

Jan Heine talks about making a similar custom derailleur for his Rene Herse in the latest issue of Bicycle Quarterly. He says that having a constant tension on the chain provides huge benefits in shifting and overall performance.

—Eric N
campyo...@me.com
www.campyonly.com
www.wheelsnorth.org
Blog: http://campyonlyguy.blogspot.com
Twitter: @campyonlyguy

[Joe Bunik]

Wasn't there a Shimano rd that tried this somewhat recently, perhaps
from a MTB line? And I am not talking about Positron, though that also
might be a good source for parts (twin-cable dt cable stops, for
example)...

=- Joe Bunik
Walnut Creek, CA

On 1/12/15, Eric Norris <campyo...@me.com> wrote:
> Jan Heine talks about making a similar custom derailleur for his Rene Herse
> in the latest issue of Bicycle Quarterly. He says that having a constant
> tension on the chain provides huge benefits in shifting and overall
> performance.
>

> --Eric N

>> <mailto:rbw-owners-bun...@googlegroups.com>.

>> To post to this group, send email to rbw-owne...@googlegroups.com

>> <mailto:rbw-owne...@googlegroups.com>.

>> Visit this group at http://groups.google.com/group/rbw-owners-bunch

>> <http://groups.google.com/group/rbw-owners-bunch>.

>> For more options, visit https://groups.google.com/d/optout

>> <https://groups.google.com/d/optout>.

[Deacon Patrick]

I've often wondered about this, especially if it helps with two way shifting in icy conditions.

With abandon,

Patrick

[Bill Lindsay]

I'm not doing anything in this project to attempt to achieve constant chain tension.  Jan has mentioned multiple times that constant chain tension is much better, but he has left out a LOT of details to that theory, I think.  Constant tension is better, but what value of tension?  What procedure did he go through to optimize his chain tension?  A "normal" derailer presumably has looser tension when you are in small-small and higher tension when you are in large-large.  What tension range does a normal derailer have?  Is it always too tight?  Always too loose?  Does it transition from too loose to too tight?  What gear has the optimum tension.  When it is too-loose, what performance are you losing?  When chain tension is too tight, what performance are you losing?  He hasn't developed that theory in any cohesive way, yet, that I've seen.  

Positron did not have dual cables.  Positron had a monowire cable that would PULL and PUSH.  There were special housing clips at either end and continuous housing all the way from the shifter to the derailer.  You would pull the shifter to pull that wire, moving the derailer to a bigger sprocket.  Then you'd push the derailer to push that same wire, which would push the derailer to a smaller sprocket.  Shimano learned a TON about SIS housing from Postitron cable housing.  

[Steve Palincsar]

On 01/12/2015 03:46 PM, Bill Lindsay wrote:
> I'm not doing anything in this project to attempt to achieve constant
> chain tension. Jan has mentioned multiple times that constant chain
> tension is much better, but he has left out a LOT of details to that
> theory, I think. Constant tension is better, but what value of
> tension? What procedure did he go through to optimize his chain tension?

What Jan did was fix up a Nivex. By design the Nivex has constant chain
tension.

[Eric Norris]

Jan mentioned chain slap in the small/small combos (when chain tension would be lowest) as a major problem solved by constant tension. That suggests that normal “low” tension is “too low,” so perhaps somewhere between that and normal “high” tension?

—Eric N
campyo...@me.com
www.campyonly.com
www.wheelsnorth.org
Blog: http://campyonlyguy.blogspot.com
Twitter: @campyonlyguy

[Joe Broach]

From what Jan's written, I'd go with Eric N. that "high enough to avoid chain slap" is the sweet spot for a constant tension setup. Wasn't a major trade-off with the Nivex setup the forward placement blocking the rear wheel from dropping out easily? Maybe that's not inherent to the design, though. Modern derailers are solving chain slap with clutches in rear derailers, some with special "I"m removing the rear whee nowl" modes. I'd like to try one, but I think they're all 10-speed and up, and I'm not quite there yet.

Best,

joe broach

pdx or

[Bill Lindsay]

Perhaps.  In his Vol 2 No 2 BQ article, Jan hinted at the benefits of the Nivex derailer system.  He said that the benefit was that every shift felt exaclty the same at the shiftlever, and he tried to attribute that to the chain tension being constant.  The implication then would be that on my "normal" bike I shift even easier when chain tension is looser, but I work harder when chain tension is tighter, but more importantly, I never shift precisely because every shift is different?  

To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsub...@googlegroups.com.

[Eric Norris]

With a three-speed hub, all the shifts feel the same, and the chain always has constant tension. 

--Eric N

www.CampyOnly.com

CampyOnlyGuy.blogspot.com

Twitter: @CampyOnlyGuy

[Bill Lindsay]

How about with a single speed?  All shifts feel the same and the chain tension is constant.  :-P

[James P]

Great project Bill - I recently picked up a copy of the "100 years of Bicycle Data Book", and it's really cool that you're giving it a go. Will be watching your photo thread with interest.

Now, just because Eric started... (and said with tongue firmly in cheek): With a Fixie, not shifting feels great (except on the unaccustomed knees), the chain also has constant tension, and you're in the "wrong gear" most of the time... ;-) 

[Eric Norris]

And that would make a fixed gear the best of all!

—Eric N
campyo...@me.com
www.campyonly.com
www.wheelsnorth.org
Blog: http://campyonlyguy.blogspot.com
Twitter: @campyonlyguy

[Steve Palincsar]

On 01/12/2015 04:50 PM, Eric Norris wrote:

With a three-speed hub, all the shifts feel the same, and the chain always has constant tension. 

The chain tension may be constant, but the internal friction losses vary wildly from gear to gear.

[Eric Norris]

I use the Sturmey-Archer S3X fixed gear hub with a freewheel; in the top gear the hub’s internals are basically just locked in place, so there’s no perceptible friction loss (it’s also quieter than a normal 3-speed hub, since there are no internal pawls). If I’m in the 2nd gear or 1st gear (lowest, which is very rare), there’s a little friction loss, but I’m going slow at that point anyway.

I ride my 3-speed bikes in the top gear 90-95% of the time, so friction loss isn’t a big deal for me.

—Eric N
campyo...@me.com
www.campyonly.com
www.wheelsnorth.org
Blog: http://campyonlyguy.blogspot.com
Twitter: @campyonlyguy

[princeofsherwood]

Hello,

great subject on tinkering.

I am curious to understand how the nivex achieves to maintain constant chain tension.

I have ridden on bike equipped with the cyclo and the smooth action of the lever is impressive since there is no spring on your way!

I have a NOS suntour S1 that I purchased in order to try something new but have't had the time to start this project and winter is soon over;)

 

[Patrick Moore]

Any photos of the Cyclo-fitted bike?

Long ago, Dick "call me Mr." Hallet, owner of the now closed World Champion Bicycles here in ABQ, showed me a NOS Cyclo rd, which I hefted in this my very hand -- 2 lb of pristine ironmongery. I wonder if that desdromic design could have been developed to outshine modern spring loaded r d's.

--

You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bun...@googlegroups.com.
To post to this group, send email to rbw-owne...@googlegroups.com.
Visit this group at http://groups.google.com/group/rbw-owners-bunch.
For more options, visit https://groups.google.com/d/optout.

--

Resumes, LinkedIn profiles, bios, and letters that get interviews.

By-the-hour resume and LinkedIn coaching.

Other professional writing services.

http://www.resumespecialties.com/

www.linkedin.com/in/patrickmooreresumespec/

Patrick Moore

Alburquerque, Nouvelle Mexique,  Vereinigte Staaten

*************************************

The point which is the pivot of the norm is the motionless center of a circumference on the rim of which all conditions, distinctions, and individualities revolve. Chuang Tzu

Kinei hos eromenon. It moves as the being-loved. Aristotle

The Love that moves the Sun and all the other stars. Dante