Chr0m0ly 

A fellow on the steel is real FB page posted this thing!

With the video from Alan Duignan, found this info about the SDV system. Quite a few links in there as well to the actual company website and an employee from that bike company even commented on this blog post:

https://tadpolerider2.wordpress.com/2015/10/12/sdv-drive-with-oval-pedal-motion-a-more-efficient-drive-system/

[img]blob:https://www.bikeforums.net/ff2c86d2-7e10-46fe-8c71-9245f408133b[/img]
https://m.youtube.com/watch?v=EpiEX2...ature=youtu.be

scarlson 

More like WTF drive! All those moving levers remind me of Walschaerts valve gear on a steam locomotive. And my goodness, just watching that guy pedal makes my knees hurt. Looks like fast transitions top and bottom, sharply transitioning to a linear power stroke. Kind of an extreme oval ring, in the orientation that Chris Froome had them clocked, opposite of Biopace. But the feet aren't moving in circles, so the knee angle change would be less. Hm.

Drillium Dude 

Now we know the answer to the question: "How do I make my bike heavier, uglier, and more complicated with no discernible benefit?"

DD

scarlson 

Thought the answer to that question was di2

USAZorro

There has to be a less complicated way to move the pedals a bit more towards the rear for time-trialling. The Q-factor on that looks astronomical too.

Chr0m0ly 

I wrote exactly that on the FB page.
reminds me of a stair climber.

stardognine

Wouldn’t it be easier, to just hook up a few Husky-dawgs up front, & let them pull ya? 🙄😁😉 And what’s up with that headset? 🤔 This is apparently the end-result of hoarding, with too much free time & spare parts.

davester

Wow, I've got to get me one of those! If you read the original article on this system from 2002 (https://www.hupi.org/HPeJ/0013/sdv.pdf) they claimed to have measured something like a 20% power increase, something that would be quite useful in sprints...if you believe it. Also, the system would be so distracting to your competitors that you'd flash past them while they were gaping.

Chombi1 

Why?.......

Nemosengineer 

1. Just because you can doesn't mean you should.

2. Three chains, five chain wheels, two bottom brackets, six pivoting links, do not equal a paragon of mechanical efficiency regardless of how you pedal it.

3. "Fig.3 delivers 1.35 times lager output power than that by a conventional drive represented by Fig. 1".
"The cadences for LMPs of the SDV drive vary from 20.8 rpm to 38 rpm as heart rate increases and those for the conventional one vary from 35.3 rpm to 88.9 rpm as heart rate increases".
There is no free lunch as the above quotes show, SDV drive is a friction monster.

: Mike

Lascauxcaveman 

Oh, man, I sooooo wanna ride that bike. Just once. Don't wanna own it.

I'd like to try a swing bike, too. And one of those set up with the steering to work backwards. But the one in this post I'm pretty sure I could ride without falling and hurting myself.

RiddleOfSteel

Oh hey now wait a second! I resemble that remark, and I will have you know that it is a magnificent system. I run it on my Davidson Impulse (Ultegra 10-speed in this case) and it is flawless.

The real answer to that question is hydraulic disc brakes!

Prowler 

Sounds great. Make mine Yeungling. I suppose in the confines of the Nautilus, greater beer output/square foot is a big plus. Thirsty times....

clubman 

This video is 18 years old. I guess they didn't make it into production. Small mercies.

Chombi1 

There looks to be enough chainrings and chains down there to grind your ankles to hamburger if you are not careful.....

RobbieTunes

Has been replaced by the elliptical bike, in a way.

tricky 

Hey now! Every mountain biker (and soon CX'er) out there would beg to differ. :-D

jackbombay

SDV, Uhhhhhh, new one to me, thanks for posting it!

I would love to ride 50 miles on it to really get a feel for it, but I'm sure that will never happen.


I'm plenty happy with rim brakes on many of my bikes, but hydro discs are the cats pajamas, there is no debating that. GEtting them bled properly can be a hassle, but once set up they need zero attention, and I feel I could slow the rotation of the earth with them if I decided to do so.

tricky 

Yes! I wouldn't want anything else on my mountain bike. When setup correctly (I'm still learning. Just learned that you want to continue using organic pads if that's what you used on the rotor previously, for example) they are much less effort and provide more modulation than cable actuated discs. I am building up my CX with some SRAM drop bar hyrdos and am excited for that, but do need to buy a new bleed kit.

RiddleOfSteel

Ok ok ok, I will relent! Or rather, caveat or qualify my disc brake comment to road bikes (and anything close). MTBs look sick with discs, and have for a long time. And CX/gravel stuff looks just fine with them as well, largely because they were made from the outset to be that way (IMO). Road bikes being as svelte and light as they have been for so long--the discs encroach on that lithe, all-about-the-ride-quality nature. Again, IMO.

tricky 

I see where you're coming from! Something about the classic lines of a C&V road bike are so lovely and caliper brakes are part of that. As much of a disc advocate as I am, I don't see a need for them on a sunny day road bike. But don't get me started on electronic shifting. The only reason I ever would want to charge my bike is for e-assist on a bike I am using to replace a car. Turns out you and I have opposing views on electronic shifting and disc brakes and both of us have luddite streaks.

RiddleOfSteel

Is it luddite, or just proven? Lol. I took a well-used first generation Ultegra Di2 groupset (from ~2012-2014!) that I got from Bike Works, put it on my Prologue, and it has worked perfectly. I barely charge it, and that's once every three months just to top it off--it takes no time to do so. My Campagnolo EPS battery died because it was five years old and not properly cared for (aka charged to full every three months) when it was on the shelves.

I've always loved the Di2 brifter shape. It looks wicked and feels wonderful.

jackbombay

I wish the video of the SDV drive was better, I want to see it move slowly so I can see how power gets from the pedals to the drivetrain.

Bianchigirll 

That video is horrible. It is like just watching someone rev up a car engine to check out a new carburetor. Is there an actual demonstration video somewhere?

It looks needlessly complicated.

UKFan4Sure

But how much would you lose in the extra weight?