I meant to post these images a while ago. In the rowing machine at a gym if I just do a relaxed stroke, it ends up being a flat and even force curve like you see here.
If instead I row hard, the legs have much more power than the arms, and so during the first half of the stroke there is a large hump of force from the legs expanding, while the 2nd half has about half this force while the arms and back complete the stroke.
During that first portion of the stroke when the legs are pulling hard, the arms experience the full tension on the rope as well even though they aren't doing any work, and it's a bit like being on a stretcher. In the mechanism that we have with the leg motion linked through a pulley, the arms only experience half of this tension force when the legs are pushing. (see viewtopic.php?p=1375676#p1375676
) I think that makes it easier and with a more uniform force stroke on the drive when we are rowing hard, but sadly didn't have time to install a torque sensor to measure this.
Does it make our rowing any easier? Who knows!
An update on the rowing rig is that some aspects of it are working excellent. After 150km or so it feels so good to switch over from pedaling to rowing, or rowing to pedaling. I thought that I would be doing about 75% rowing and Anne-Sophie just 25%, but in the end it's been about 50:50 split. We both have sore knee joints after a while and the change in motion is so welcome. I'm really happy about this which was one of the design goals of the setup.
Mechanically, we screwed up big time in not initially building the row->crank linkage with a White Industries freewheel. I'd posted before about how one of the pawl springs broke during the initial rides in France
Removing the broken spring and two associated pawls got us rolling fine again, but on Monday after another ~1000km the remaining springs failed, only now we're in southern Croatia with no large cities in site, at 6:00pm on a national holiday. Google showed one result for bicycle store about 30km further on so we ride there, expecting to find a commercial bicycle shop that might be open the following morning. Instead it's a house in a residential block with this small sign on the front
Not feeling too hopeful we rung the doorbell, and sure enough an older gentleman comes out and lets us know that it's his son's business, who's out with friends but will call right now. We get served hot drinks and fruits from their orchard and then 15 minutes later his son Danijel is over. He's got a full service/repair shop in his garage and has a side operation both repairing and restoring bicycles.
I explain the situation and show the broken freewheeling doublecrankset, and he has the perfect attitude of "well, let's see what we can do". Some hacking and grinding later and he's got the original seized freewheel off the custom adapter, and happens to have a replacement 16T single speed freewheel to clamp on it place.
By 8pm everything was fixed. We tried soo hard to offer any kind of payment but he wouldn't take it. The treatment that we've received in Croatia like this has been astounding. We greased the threads before screwing this freewheel on so that in the future now we'll be able to remove and replace it easily enough. The plan is to pickup a couple replacement freewheels at a bike shop in Belgrade to have on hand in case we have any further problems, and then we'll be able to do on-the-road repairs if this happens again. And in the meantime it gets us rolling and rowing again which is great.
StuRat wrote: ↑
Jun 26 2018 8:52pm
It's those experiences that become the memories.
Indeed. And a huge thank you to Danijel and his family who treated us so well.
Previously competed in the Suntrip race on a back to back tandem solar powered row/cycle trike
. 550 watt solar roof, dual Grin All Axle hub motors, dual Phaserunner controllers, 12 LiGo batteries, and a whole wack of gear.
Now back in Vancouver learning to be a dad with my Big Dummy Frame (yes This One
, thanks ES!) with GMAC 10T rear hub motor, Phaserunner controller, and 52V 19Ah EM3EV pack
My website: http://www.ebikes.ca
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