Recumbent-DF transformer

[ccf]

Has anyone ever designed a bike that could be transformed quickly from a recumbent to a DF and vice-versa? The use case would be a hilly century or double-century, where I'd want to have a DF when climbing big hills, but a recumbent for the rest of it. I'd want a bike that could be transformed on the road in less than the amount of time typically spent at a rest stop.

-Cliff

 

[RojoRacing]

There'd be zero use for that because the only thing holding back a bent from climbing fast is it's weight and not the body position so a transforming bike would be even heavier in both forms and even slower in both forms.

Now a transforming bike just because you'd like to ability and freedom to stand up on the climbs would be a different story in which case I'd prefer a bent to ElliptiGO design.

 

[Rampa]

But someone did do it anyway!

 

[ccf]

the only thing holding back a bent from climbing fast is it's weight and not the body position

A bent has a low-speed limit that is higher than a DF because I can balance at lower speed on a DF than on a bent. On long steep hills with a bent I must either climb fast enough to not fall over, or stop and rest, or walk. On the hills that I can get up, I have to put out above-threshold power, which isn't good for a 100mi or 200mi ride. On a DF, I can go slower without falling over, which means that I can climb long steep hills without nearly blowing up.

 

[ak-tux]

There'd be zero use for that because the only thing holding back a bent from climbing fast is it's weight and not the body position so a transforming bike would be even heavier in both forms and even slower in both forms.

Now a transforming bike just because you'd like to ability and freedom to stand up on the climbs would be a different story in which case I'd prefer a bent to ElliptiGO design.

I agree to a large extent with @RojoRacing here. Unless off course, the recumbent position is really extreme and the grade really steep +15% (or steeper) which would then put the rider in a disoriented position, the weight and stiffness on the drive train is what matters.

Hypothetically speaking, if it was possible to build an S40 or S30 at around 7.5 or 8Kg (<17.6 pounds), I really can't see why it cannot contend with a DF of similar weight unless the grade was ridiculously steep enough for the recumbent to loose traction.

See Marco's Rev-9 (8.5Kg) https://biciclettereclinate.blogspot.com/2017/12/la-rev-m-superleggera.html

 

[LarryOz]

There'd be zero use for that because the only thing holding back a bent from climbing fast is it's weight and not the body position so a transforming bike would be even heavier in both forms and even slower in both forms.

I respectfully disagree - I think body position, BB to rear height differential, hip angle, and total recline angle all come into play - yes weight too, but that is easy to make equal for testing. I think Marco's design where BB is very low and hip angle is more open comes closer to climbing as well as a DF. It might also be that some people can do it and some can't. I am building up a P5 to test this theory, and will add weight to it to match the Vendetta and see where the numbers come out at. More later

 

[Balor]

Yea, biomechanics is extremely complicated, even so far as extremely well-known of DF bicycles - the jury is still out about optimal pedalling style, chainring shape, etc. At least there is no consensus that I know of.
Introduce drastically different position into play and it gets even murkier. While bracing issues is my favourite theory about why 'bents don't climb' (for a LOT of people), there can be other reasons like blood pressure, gas exchange or even lactate shuttle.

 

[ed72]

Anybody ever see an opera singer belt it out in a reclined position.

Mechanical aspects aside.....

Lung perfusion varies by position (prone, supine, upright). Lower lung perfusion in the recumbent position would also explain lower heart rates reported by many. Heart rate is controlled by the Medulla Oblongata, which uses CO2 levels, temperature, etc. to set the desired heart rate. Aside from neuro muscular adaptation when converting to bents, I believe (my opinion) that lower lung perfusion explains my lower FTP on a bent vs upright; however, I have only been on a bent for 13 months. I have worked very hard at it and have seen enormous improvements. Age could be a factor.

Plenty of riders experience lower power levels on a bent compared to an upright but there are a few youngsters who report no such loss. My money is on age, lower lung perfusion, and improper muscle recruitment

 

[ccf]

The Switchbike, though interesting, isn't what I have in mind. In the perfect world I'd be able to transform my Vendetta into a Domane and back again in minutes.

 

[Gary123]

Thats a pretty cool bike though.