Modifying the reach on the Silvio

[VeloLEV]

Greetings my friends!

I've been brewing this idea for some time, and the more I ride the Silvio the more I want to try it. On my Rans Rocket I modified the steering using Volae bars and the Terra Cycle stem and riser. This enabled the "Superman" recumbent position. Other than aerodynamics there are several comfort improvements with this design. On the original Rocket bars, the "Praying Hamster" position is employed, elbows bent with the controls in your face. My primary dislike stemmed from working out with my elbows bent and arm pits closed since I sweat alot in these areas. The modified position allowed me to open both my elbows and arm pits to the wind, immediately solving the sweat issue.

Its back now with the Silvio, at least for taller riders like myself. My solution involves replacing a single part on the Silvio with a new one, moving the bars to a position in FRONT of my knees instead of behind them. While sprinting or climbing hills I have discovered that lifting my back off the seat puts more weight on the driving wheel and seems to generate more power from resting muscle groups. However my arms are already bent and just end up bent further in this position. I feel more power would be available if I had to reach for the drops. This would allow use of the hoods as the primary position, some use of the curves outside the flats and the drops would actually require me to pull myself off the seat back to use them. Also I could use standard bars (instead of the WTB Mountain/Road bar I currently have or the On One Midge bar) opening up additional possibilities.

I have slashed together an ugly Photoshop rendition to give you an idea of my plan. The replaced part is yellow in the picture. What do you think?

 

[JonB]

Try it on. For better pulling power i would suggest placing the handle bars such that they are on a straight line from the bottom bracket to your shoulders, but i am not sure that gives you sufficient ventilations in your arm pit.

 

[Doug Burton]

Hi Lev,

The increased TFT angle will probably interfere with your front derailleur operation.

An alternative is to put a stem on the TFT and move the bars forward that way. The TFT-stem is a 30mm tube, which is not too common. One approach it to use a piece of 1 1/8' stiff aluminum tube (28.6mm) (7005 or 6061 T6), or 2014 (expensive) and use seatpost shims to match the lower tft and pivot clamp to it's diameter. Then you could use a lightweight long-reach stem (maybe a CF road stem at 45 degrees, mounted upside down) to get some additional reach.

Long-reach road bars may help, too...

Best,

Doug

 

[trapdoor2]

One big problem with your proposal would be that you're eliminating the strong triangle and creating a weak polygon. Pedalling forces are severe and the add-in you propose would need to be very, very strong (compared to the rest of the system). Even if you made it strong enough, you're adding a lever arm into a system that isn't designed for it...it could cause other failures.

Doug's recommendation is far better. Keep the TFT triangle as it is and adapt an adjustable stem to the upper portion of the TFT. A 31.8mm stem would take a mere .9mm (0.035") shim...ought to work fine...if you can get one long enough.

http://www.nashbar.com/bikes/ProductDisplay?storeId=10053&langId=-1&catalogId=10052&productId=174784&cm_mmc=1204522-_-Bike%20Parts-_-Nashbar-_-NS-ADJS&mr:referralID=57a28aef-5461-11de-8759-000423bb4e95

 

[John Tolhurst]

Ideally you would leave it as it is to retain the solid tetrahedral structure, and the direct linkage between handlebar and crank. I can't decide which is more important! What I can say is that achieving the stiffness between grips and pedals is more difficult that maintaining the ridgid triangle. At least I think it is.

If you are going to go custom, you could look at a new pair of bars, that gave you a longer reach, if nothing is around like that.

 

[WhiteSilvio]

johntolhurst wrote: Ideally you would leave it as it is to retain the solid tetrahedral structure, and the direct linkage between handlebar and crank. I can't decide which is more important! What I can say is that achieving the stiffness between grips and pedals is more difficult that maintaining the ridgid triangle. At least I think it is.

If you are going to go custom, you could look at a new pair of bars, that gave you a longer reach, if nothing is around like that.

Just a thought.
Is doing what Doug suggested, or I think he suggested, and coming off the TFT with a suitable "member", any different to the way the Freerider handlebar is arranged?

I'm assuming that the Freerider handlebar and mount doesn't compromise the integrity of the front "power triangle"? Or indeed introduce a lack of stiffness between the grips and the pedals?

I have to say that I have looked at my Silvio, since VeloLEV suggested the repositioning of the hand(s) position, and although I have to say "breaking" the power-triangle doesn't seem like a good idea from a structural point of view, I did wonder if the straighter arm/superman stance could lead to benefits ergonomically and possibly from a power generating point of view.
The problem as I see it is that moving the bars forward would also require them to be raised (if a horizontal handlebar member is used) to allow for clearance of the knees. This would vary from rider to rider, but that is the way I see it without actually experimenting/tinkering at all. (Too much work for the moment).

Any thoughts, anyone?? :?

Regards John R

 

[JonB]

WhiteSilvio wrote: I'm assuming that the Freerider handlebar and mount doesn't compromise the integrity of the front "power triangle"? Or indeed introduce a lack of stiffness between the grips and the pedals?

I have a Freerider and i think you assume wrong. I think that the Freerider setup does introduce a little less stifness between the grips and the pedals.

 

[VeloLEV]

Again I appreciate all the excellent input. I did consider the fact of front derailleur issues, but looking again at the image it becomes much more obvious. Sometimes hearing the words and thinking for a week or more brightens the mind. :mrgreen: I did also consider adding a stem and it is feeling more plausible for sure. It would look more like this:

---and would accomplish a similar result. The R&D continues...

 

[WhiteSilvio]

VeloLEV wrote: It would look more like this:

I think that is a pretty good idea. I imagined that you would use a stem from a regular steering setup and slide it on to the TFT. I haven't measured anything to know if it would work easily but I reckon it is important that the front triangle remains intact.
I'd really like to see what you come up with VeloLEV and look forward to seeing some graphical evidence.
And hear what the result feels like.

Best of luck,
John R.
PS Just tried this with a "spare" handlebar stem. The 30mm diam. handlebar end fits reasonably neatly on the TFT tube (could need a very thin shim to add some grip), but the other end off the DF steering stem is a little small and not capped in the same way. I guess it's 1.125in. (measured the inside as 28.55mm). Could really do with two capped 30mm ends so the angle rise wouldn't be a problem, (probably would help) and you could use "standard oversize" handlebars. Do you have such devices in your shop or are all the steering stem ends 1.125in.?

 

[super slim]

Would an option be to have shorter cranks (155mm ) instead of 175mm (Std) so that the knee does not rise so far. The handle bar stem could then be pushed down 20mm. This would keep the line from the shoulder to the handlebar closer to the line of hip to pedal, so more of the resultant arm pulling, results in extra force on the pedals.
See the photo of Maria in the 12 hr race with extended arms AND legs.

The disadvantage is that the cadence would have to be increased by 175/155 or from 80(175) to 90 (155) for the same power, if the pedal force is the same.