To V20c as a lifelong DF roadie

chicorider

Zen MBB Master
Thanks for the great write up vosadrian. I agree, it seems I am on a very similar path as you were, at least I hope so! I never did race road bikes, although Cat 2 racers in my groups were not uncommon. I think Cat 1 are probably too fast for my abilities, this being more of a weekend sport for me, as I work long hours during the weekdays.

Like you, I have a feeling I will pick it up quickly as well, and I’m rather anxious to do so. I live in Miami, which is flat as a pancake. We have one bridge that is 4% for about a quarter mile that’s it (actually, the 4% section is even shorter), so that shouldn’t be an issue. What we have a lot of is wind. Riding along the coast or in the Everglades where there is nothing taller than a blade of grass for miles in any direction means we contend with strong 15-20mph wind all the time. It seems like a place where a recumbent would thrive. I had no idea Sydney was so hilly! Must be nice to have that level of variety. I’m glad you still get to ride your DF from time to time, I hope that is also in my future, although I’m told that may not be the case.

Your Strava ride is impressive! 24mph average over 40 miles while only spending 180w average tells the whole tale. Looking through my Garmin and Strava, if I should average 180w, I would probably average 18-19mph, not much more. Then again, I’m no Cat1 racer! Impressive numbers, thanks for sending! I’m looking forward to seeing what I can do on a Vendetta…I am glad to see from your figures that you do seem to get a good workout. Zone 3 Hr average is great, I was concerned if not be able to get out Zone 2 while riding normally.

What do you use for bike shoes? I’m told some normal road shoes (SPD SL), and other use a mod-cleat position shoe (often hand-modified) with mountain pedals. Given the different body position, what do you find is the most comfortable and efficient? Also, given the greater need to put a foot down when first learning or when avoiding a crash (given the more limited maneuverability), would it make sense to use a mountain/SPD cleat and shoe?
A pedal suggestion: go for something double-sided. Some people use Speedplays. I use Shimano XTR SPDs. I started with single-sided Ultegra road pedals, and fiddling with the pedal orientation while also trying to get rolling through an intersection quickly became a pain. I use Shimano RX8 gravel racing shoes. Lightweight and plenty stiff. Also easy to walk in. But most important, for me, is the recessed cleat. When I put my left foot down at a stop (while still being fully reclined), I have good grip on the asphalt with the rubber sole. Exposed road cleats, by comparison, are pretty slippery. The last thing you want when you put your put down is to have that foot skate out from under you. Down you go, in front of everybody. But at least the only thing that hurts is your pride.

Here are a few of my recent Strava posts, just to give you more perspective.



 

brokemyback

Well-Known Member
Good point on the shoes. I touch down with my left heel. It is hard plastic with a small rubber heel pad, which is now worn completely off.
 

gaspi101

Well-Known Member
Thanks for the g
A pedal suggestion: go for something double-sided. Some people use Speedplays. I use Shimano XTR SPDs. I started with single-sided Ultegra road pedals, and fiddling with the pedal orientation while also trying to get rolling through an intersection quickly became a pain. I use Shimano RX8 gravel racing shoes. Lightweight and plenty stiff. Also easy to walk in. But most important, for me, is the recessed cleat. When I put my left foot down at a stop (while still being fully reclined), I have good grip on the asphalt with the rubber sole. Exposed road cleats, by comparison, are pretty slippery. The last thing you want when you put your put down is to have that foot skate out from under you. Down you go, in front of everybody. But at least the only thing that hurts is your pride.

Here are a few of my recent Strava posts, just to give you more perspective.



This is super helpful, thank you! Going shoe shopping, I guess! Too bad, I love my DMTs...But it looks like that RX8 might be a great choice...looks like I'm going shoe shopping! Question: What's your take on "mid-cleat" shoes...I'm seeing a lot of people with home-modified shoes that have the cleats at the center of the shoe...my recumbent "guru" says that it's necessary to have it in the middle so that it lines up with the femur, so you can drive the power down....But I'm still skeptical of that, since we apply power in a sweeping and arcing direction...what's most comfortable and efficient? Also another question: what makes the XTR pedals ($180 here) so much better than their regular dual-sided SPD pedal (about $40)? I never could tell the difference between my Shimano 105 SPD-SL pedals and those that were worth a lot more...Thanks for the strava links...now I'm gonna stalk your ride data a little bit...
 
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gaspi101

Well-Known Member
Don't want to rain on anybodies parade but be aware of front flat crash and do your best to avoid it. Tubeless seems to work well for most.
Actually that's a really interesting issue. Are recumbents more or less prone to crashing when getting a flat than a DF roadbike? If so, I might want to consider tire liners, like I used to do when riding in rough terrain...adds a bit of rolling resistance, but means no flats ever
 
Thanks for the great write up vosadrian. I agree, it seems I am on a very similar path as you were, at least I hope so! I never did race road bikes, although Cat 2 racers in my groups were not uncommon. I think Cat 1 are probably too fast for my abilities, this being more of a weekend sport for me, as I work long hours during the weekdays.

Like you, I have a feeling I will pick it up quickly as well, and I’m rather anxious to do so. I live in Miami, which is flat as a pancake. We have one bridge that is 4% for about a quarter mile that’s it (actually, the 4% section is even shorter), so that shouldn’t be an issue. What we have a lot of is wind. Riding along the coast or in the Everglades where there is nothing taller than a blade of grass for miles in any direction means we contend with strong 15-20mph wind all the time. It seems like a place where a recumbent would thrive. I had no idea Sydney was so hilly! Must be nice to have that level of variety. I’m glad you still get to ride your DF from time to time, I hope that is also in my future, although I’m told that may not be the case.

Your Strava ride is impressive! 24mph average over 40 miles while only spending 180w average tells the whole tale. Looking through my Garmin and Strava, if I should average 180w, I would probably average 18-19mph, not much more. Then again, I’m no Cat1 racer! Impressive numbers, thanks for sending! I’m looking forward to seeing what I can do on a Vendetta…I am glad to see from your figures that you do seem to get a good workout. Zone 3 Hr average is great, I was concerned if not be able to get out Zone 2 while riding normally.

What do you use for bike shoes? I’m told some normal road shoes (SPD SL), and other use a mod-cleat position shoe (often hand-modified) with mountain pedals. Given the different body position, what do you find is the most comfortable and efficient? Also, given the greater need to put a foot down when first learning or when avoiding a crash (given the more limited maneuverability), would it make sense to use a mountain/SPD cleat and shoe?

If I lived where you live, I would rarely ride my DF. The DF is only better than the V20 on steeper climbing. The V20 also seems to cope well with strong wind... even strong cross wind with my 90mm wheels is managable. Does not seem any worse than my DF with 50mm wheels. In a head wind, the V20 is much faster than DF. Less so in tail wind. I live in a valley in the "Hills District" in Sydney. I have an almost 100m elevation climb just to get out of the valley every ride. I ride off my driveway to a 10% climb for 5 minutes. I should start my Garmin after that to get the average up!! :)

That ride I posted was just what I happened to do yesterday. I have much faster rides in the past. On flat roads I could be over 25mph and have several rides like that in my history. The ride yesterday still had some elevation and slow bits. I think if I pushed it on good flat roads in light wind, I could do 27-28mph for a couple hours. Unfortunately there is not much road like that near me. But I rarely ride more than a couple hours, so I don't think I would be that quick on the longer stuff some V20 riders do. My setup seems to get me 25mph at around 180W on flat roads. Note that I am not flexing my riding ability here. Just highlighting what the bike is capable of. My personal power levels on the V20 are pretty ordinary as I seem to suffer a larger power loss than most compared to my DF.... but I seem to be pretty aero so still get good speed. My DF FTP at full ftiness is around 300W. If only I could do that on the V20!

I use the same shoes on my DF and V20. Nothing special with cleet position. I use Garmin Vector pedals with Look Keo cleets. My cleet position on my S-works shoes is with the cleats as far back as they go on the standard shoe. I did this to manage some achilles issues on my DF years ago, and just use the same on the V20 with no issue. If I was starting again with pedals I would consider speedplay that can clip in on each side. The Keo cleats are OK, but you sometimes have to be careful getting clipped in on hills to avoid the pedal being upside down. But they are certainly workable if not ideal.
 

Frito Bandito

Zen MBB Master
MTB shoe wearer here. Not the most aerodynamic and kinda heavy, but I like that they don't slip on pavement when I stop. A bonus is that I don't walk like I have dog doo between my toes like with the road cleats. While you clear that image my cleats are set back a bit towards my heels, but not all the way. I can push pretty hard for up to about 3 hours before hotfoot starts becoming an issue. 1 time when that happened I stopped the ride and moved the cleats back to the max but it didn't help me then, and I wouldn't be surprised if it was already too late. I did try a ride starting with the cleats all the way back and it felt like I was losing power and was a bit uncomfortable. Maybe with more training in that position would help?

I use Shimano 1-5 PD-ES600 pedals. Light and small, and weighted in back so the top always faces me for ease of clipping in. No flipping the pedals with my toe while my imaginary riding partners race off without me off the line.
 
As a road bike rider, I am used to road cleets. I've had a few slips because of them. I don't do much walking on them. I get on my bike and ride with as fewer stops as possible, and then I get off and remove my shoes. Certainly if you walk around more than me on your cycling shoes, there are better options.

On thing to consider is that IMHO, pedal power meters are the best option for a bent due to desire for shorter cranks. So the pedal type may be limitted to those that support PMs if that is your desire. Look Keo is the best supported by PM options... but there are others also.
 

gaspi101

Well-Known Member
My setup seems to get me 25mph at around 180W on flat roads. Note that I am not flexing my riding ability here. Just highlighting what the bike is capable of. My personal power levels on the V20 are pretty ordinary as I seem to suffer a larger power loss than most compared to my DF.... but I seem to be pretty aero so still get good speed. My DF FTP at full ftiness is around 300W. If only I could do that on the V20!
Yowza. My FTP is 220w… not as strong as you! but I’m reading that lower power output is to be expected on a recumbent because you can’t use gravity to assist with mechanical advantage, and you cant dance on the pedals. Fair tradeoff, I suppose.
I use the same shoes on my DF and V20. Nothing special with cleet position. I use Garmin Vector pedals with Look Keo cleets. My cleet position on my S-works shoes is with the cleats as far back as they go on the standard shoe. I did this to manage some achilles issues on my DF years ago, and just use the same on the V20 with no issue. If I was starting again with pedals I would consider speedplay that can clip in on each side. The Keo cleats are OK, but you sometimes have to be careful getting clipped in on hills to avoid the pedal being upside down. But they are certainly workable if not ideal.
Nice. I suppose I will try with my shoes and pedals and see how it goes…might end up changing for gravel spd shoes and clears though, as others have indicated it’s important for safety when unclipping and not having your foot slide on the pavement
 

gaspi101

Well-Known Member
As a road bike rider, I am used to road cleets. I've had a few slips because of them. I don't do much walking on them. I get on my bike and ride with as fewer stops as possible, and then I get off and remove my shoes. Certainly if you walk around more than me on your cycling shoes, there are better options.

On thing to consider is that IMHO, pedal power meters are the best option for a bent due to desire for shorter cranks. So the pedal type may be limitted to those that support PMs if that is your desire. Look Keo is the best supported by PM options... but there are others also.
Interesting…can you tell me why shorter cranks are preferable? I usually ride a 172.5mm on my roadbike…planning on going with a Sram Force groupset, and the cranks can go down to 165mm…was also planning on getting the crank-mounted power meter…$200 less than the garmin power meter pedals…. what do you think
 
Yowza. My FTP is 220w… not as strong as you! but I’m reading that lower power output is to be expected on a recumbent because you can’t use gravity to assist with mechanical advantage, and you cant dance on the pedals. Fair tradeoff, I suppose.

Nice. I suppose I will try with my shoes and pedals and see how it goes…might end up changing for gravel spd shoes and clears though, as others have indicated it’s important for safety when unclipping and not having your foot slide on the pavement

I think my FTP at full fitness on the V20 is around 240W. Here is a V20 ride I did with 230W average power for just over an hour. I probably could have pushed it over 240W for an hour if that had been the aim: https://www.strava.com/activities/6217062859 . That was a windy day but with some time spent drafting other bent riders. Average speed of 28mph. No wind and solo I expect 27-28mph.

There are some bent riders who are pushing 350W FTP.... so I am far from the best on a bent. I can't remember the german guy, but he does well over 300W for rides over 30mph.

FTP on my DF peaked just over 300W. But I may have been fitter at that time than I have been since getting the V20. With some of the bunches I ride with, I needed to be at that level just to stay with the bunch on some of the climbs. Some 5-10 minute climbs being done at 350W. I think my current DF. Strava says I am currently at 275W FTP just coming out of winter where I live. Should get back to 300 by the middle of summer. Some of my mates are much higher than me.... but I am pretty light and small and aero for a DF rider, so I am generally competitive with them.

I have slipped over on my V20 once due to the cleats. I had come to a full stop, and was waiting for some lights with my foot on some sandy surface, and it just slipped and I toppled over. No damage to anything except my ego as the cars waiting at the lights beeped their horns to poke some fun at me. It was not dangerous, and I have learned to be more careful so it does not happen again. I can't see how the clears could cause a dangerous situation, but they could cause a low/no speed topple and a small injury. In up hill starts, you have to be prepared to get some momentum before you clip in to avoid slow speed issues trying to clip in a stubborn cleat.
 
Interesting…can you tell me why shorter cranks are preferable? I usually ride a 172.5mm on my roadbike…planning on going with a Sram Force groupset, and the cranks can go down to 165mm…was also planning on getting the crank-mounted power meter…$200 less than the garmin power meter pedals…. what do you think

Now I run short cranks on my DF also. I run 165s on my DF and 155s on my V20. I would like to try a set of 145s on my V20.

I am a little unique, but many bent riders run short cranks. My situation is that I have a hip issue that does not like me to put my knee close to my chest. Short cranks on the DF enables me to get lower in the drops before this issue causes me problems. It is actually quite common for many DF riders to move to shorter cranks. It allows you to get lower in the drops at the same hip angle so you get more aero. Most riders find it gives them a smoother pedal stroke and they do not lose power. I gained FTP on my DF when I went to shorter cranks dues to smoother pedaling. I used to run 172.5 cranks on my DF but will never be going back. For me, my knees and hips hurt less, I pedal smoother and higher cadence and make more power.

On the bent, there are some other reasons. For a start you are more aero as you knees go less high and your heels go less low.... so less frontal area. Most riders find it helps their knees and hips by reducing the angles they operate at... so generally better for your joints. You tend to spin a little quicker also as you are moving through a smaller circle. I think it mays also help with power a little at reclined hip angles.

Most of the quicker bent riders are riding cranks 165 or shorter. Indeed most pro TT riders are running short cranks also.
 
My advice would be to not buy a PM for your bent if you are going crank based until you get to a level where you can determine what crank length is best for you. If you find you want a crank less than 165, you probably will be unable to get a crank based PM. This is where pedal PMs are great. They work on any crank. It is hard enough to get short cranks without a PM, so best to not limit yourself to that. I would spend the extra for a pedal PM.... does not have to be Garmin. Plenty of options. Just pick the one you like best.
 

gaspi101

Well-Known Member
Now I run short cranks on my DF also. I run 165s on my DF and 155s on my V20. I would like to try a set of 145s on my V20.

I am a little unique, but many bent riders run short cranks. My situation is that I have a hip issue that does not like me to put my knee close to my chest. Short cranks on the DF enables me to get lower in the drops before this issue causes me problems. It is actually quite common for many DF riders to move to shorter cranks. It allows you to get lower in the drops at the same hip angle so you get more aero. Most riders find it gives them a smoother pedal stroke and they do not lose power. I gained FTP on my DF when I went to shorter cranks dues to smoother pedaling. I used to run 172.5 cranks on my DF but will never be going back. For me, my knees and hips hurt less, I pedal smoother and higher cadence and make more power.

On the bent, there are some other reasons. For a start you are more aero as you knees go less high and your heels go less low.... so less frontal area. Most riders find it helps their knees and hips by reducing the angles they operate at... so generally better for your joints. You tend to spin a little quicker also as you are moving through a smaller circle. I think it mays also help with power a little at reclined hip angles.

Most of the quicker bent riders are riding cranks 165 or shorter. Indeed most pro TT riders are running short cranks also.
I’m so glad you wrote this now, I’m discussing parts with my LBS at the moment, and I was going to tell them to get a 172.5 crank…I’ll go with a 165 instead. Everything you said makes sense. thank you so much
 

gaspi101

Well-Known Member
My advice would be to not buy a PM for your bent if you are going crank based until you get to a level where you can determine what crank length is best for you. If you find you want a crank less than 165, you probably will be unable to get a crank based PM. This is where pedal PMs are great. They work on any crank. It is hard enough to get short cranks without a PM, so best to not limit yourself to that. I would spend the extra for a pedal PM.... does not have to be Garmin. Plenty of options. Just pick the one you like best.
fair enough, I’ll hold off the power meter for the moment…or I might run the cyclops power meter in my ancient zipp 808s for a bit
 

gaspi101

Well-Known Member
I think my FTP at full fitness on the V20 is around 240W. Here is a V20 ride I did with 230W average power for just over an hour. I probably could have pushed it over 240W for an hour if that had been the aim: https://www.strava.com/activities/6217062859 . That was a windy day but with some time spent drafting other bent riders. Average speed of 28mph. No wind and solo I expect 27-28mph.
This is crazy impressive. Good on ya!
 
I’m so glad you wrote this now, I’m discussing parts with my LBS at the moment, and I was going to tell them to get a 172.5 crank…I’ll go with a 165 instead. Everything you said makes sense. thank you so much

I think the 165s are a good starting point. I think Cruzbike sold the V20 with 165s standard in their full made up bike (that is what mine came with). I then changed to 155s after about 6 months. You can get cheap 155s and 145s one ebay made by BBK that fit the SRAM GPX BB that was standard on the V20. I am curious to try 145s and see how that goes. @LarryOz is the fastest V rider around here, and I think he rides even shorter than 145.

The problem is locating short crank sets. Most common name crank manufacturers do not go shorter than 165. So you need to modify longer ones, or go to lesser known options like BBK. The BBK are good quality and light. Not as pretty as some, but do the job wheel, and standard compact chain ring bolt set, so you can run many different chainrings on them, so you can still get good quality chainrings or Q rings if you like.
 

gaspi101

Well-Known Member
I think the 165s are a good starting point. I think Cruzbike sold the V20 with 165s standard in their full made up bike (that is what mine came with). I then changed to 155s after about 6 months. You can get cheap 155s and 145s one ebay made by BBK that fit the SRAM GPX BB that was standard on the V20. I am curious to try 145s and see how that goes. @LarryOz is the fastest V rider around here, and I think he rides even shorter than 145.

The problem is locating short crank sets. Most common name crank manufacturers do not go shorter than 165. So you need to modify longer ones, or go to lesser known options like BBK. The BBK are good quality and light. Not as pretty as some, but do the job wheel, and standard compact chain ring bolt set, so you can run many different chainrings on them, so you can still get good quality chainrings or Q rings if you like.
Nice. Ok, will keep all of this in mind, will start off on a 165 and see how it goes. I’d love to see some science concerning shorter crank lengths…I know that in a DF, the idea is to have length that corresponds to leg length such that you don’t over or under rotate your hip flexor muscles…same theory should apply to recumbents, I would assume, except that the risk of injury from over-rotation I imagine is lessened…

Edit: So apparently there is some actual science: http://www2.gcc.edu/dept/math/jackson-m/posters-f09/t. baker et al. - poster.pdf

“This study found no significant difference in delta efficiency between any of the three crank lengths. The mean DE of the 115mm, 140mm and 170mm cranks was 0.30±0.067%, 0.32±0.081% and 0.31±0.084% respectively. It was found that for the lengths of cranks tested there was no statistically significant effect of crank length on DE at the α =.05 level of significance (p = 0.37).”

And while the science suggests no measurable distinction, it appears the anecdotal evidence is toward shorter crank lengths, and there’s even a calculator (which I shall use): http://www.recumbents.com/wisil/misc/crank_angle.asp

Thoughts?
 
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chicorider

Zen MBB Master
Nice. Ok, will keep all of this in mind, will start off on a 165 and see how it goes. I’d love to see some science concerning shorter crank lengths…I know that in a DF, the idea is to have length that corresponds to leg length such that you don’t over or under rotate your hip flexor muscles…same theory should apply to recumbents, I would assume, except that the risk of injury from over-rotation I imagine is lessened…

Edit: So apparently there is some actual science: http://www2.gcc.edu/dept/math/jackson-m/posters-f09/t. baker et al. - poster.pdf

“This study found no significant difference in delta efficiency between any of the three crank lengths. The mean DE of the 115mm, 140mm and 170mm cranks was 0.30±0.067%, 0.32±0.081% and 0.31±0.084% respectively. It was found that for the lengths of cranks tested there was no statistically significant effect of crank length on DE at the α =.05 level of significance (p = 0.37).”

And while the science suggests no measurable distinction, it appears the anecdotal evidence is toward shorter crank lengths, and there’s even a calculator (which I shall use): http://www.recumbents.com/wisil/misc/crank_angle.asp

Thoughts?
When I saw you ask the crank length question, I thought, "Oh, here we go..." There's voodoo in this question.

These bikes put more strain on the knees than a DF, so dialing in the fit, including crank length, is important. Since the back is supported against the seat pan, you now have a solid surface to push against, kind of like doing a leg press at the gym. This is great for putting down power, but if the fit is off, you'll feel it in the knees. The rule of thumb is to have cranks short enough that when the pedal is coming over the top and heading into the power stroke, that knee is bent no more than 90 degrees. To apply power with the knee bent more than that can create strain. On a DF bike, the knees bend more than 90 coming over the top of the stroke, but you aren't putting down power at that point, partly because you have nothing to push against. It's almost like you're waiting for gravity to carry the leg over the top of the stroke, and by the time it does and you're ready to apply power, the knee is then in a better position to handle it. Having cranks on a bent that are a centimeter too long can be like riding a DF with the saddle a centimeter too low.

Up against that is crank leverage. I'm short, at 5'5", and I ride 160mm cranks. I started with 165, but they were a little long. I rode 160 happily for some years, but then some people here on the forum started experimenting with crank arm length and reporting their findings (I will let you to decide if you want to go searching for that rabbit hole). "If 160 was better than 165," I began to wonder, "would 155 be better than 160?" There was only one way to find out. I found an inexpensive used set of 155s on eBay that fit a spare bb that I had on hand, and I gave it a whirl. On the flats, they were great--a smoother pedal stroke, and maybe a tiny bump in speed. I definitely noticed a speed bump on downhills as the shorter cranks extended my ability to spin that 52/11. I even picked up a few downhill KOMs that eluded me with the 160s. But on the climbs--and I do love to climb--I noticed a decrease in leverage. Just as the 155s extended my downhill spin range, I had to spin an easier gear on the climbs. I felt slower, and climbing fairly quickly has always been my thing. I rode the 155s for a while longer--long enough to fully acclimate to them--then switched back to the 160s for the sake of comparison. It didn't take me long to know that I was "home" with the 160s, and I've stayed there since.

This is not me telling you that you should ride any particular length crank, but that there can be some trial and error with this particular metric, involving body mechanics, riding style, route tendencies, etc. I was glad that I experimented with those 155s (I sold them for just about what I bought them for); doing so confirmed that I have found my personal best crank arm length for my body and the kind of riding that I do.

Rotor and Aerozine make nice short cranks, and Praxis does as well, down to 160. One cool thing about Aerozine is that they use a flipchip at the pedal end that gives you a 5mm difference, depending on which way you have the chip flipped. It's like buying two crank lengths in one.
 

Jeffers

Performer Low Racer
When I saw you ask the crank length question, I thought, "Oh, here we go..." There's voodoo in this question.

These bikes put more strain on the knees than a DF, so dialing in the fit, including crank length, is important. Since the back is supported against the seat pan, you now have a solid surface to push against, kind of like doing a leg press at the gym. This is great for putting down power, but if the fit is off, you'll feel it in the knees. The rule of thumb is to have cranks short enough that when the pedal is coming over the top and heading into the power stroke, that knee is bent no more than 90 degrees. To apply power with the knee bent more than that can create strain. On a DF bike, the knees bend more than 90 coming over the top of the stroke, but you aren't putting down power at that point, partly because you have nothing to push against. It's almost like you're waiting for gravity to carry the leg over the top of the stroke, and by the time it does and you're ready to apply power, the knee is then in a better position to handle it. Having cranks on a bent that are a centimeter too long can be like riding a DF with the saddle a centimeter too low.

Up against that is crank leverage. I'm short, at 5'5", and I ride 160mm cranks. I started with 165, but they were a little long. I rode 160 happily for some years, but then some people here on the forum started experimenting with crank arm length and reporting their findings (I will let you to decide if you want to go searching for that rabbit hole). "If 160 was better than 165," I began to wonder, "would 155 be better than 160?" There was only one way to find out. I found an inexpensive used set of 155s on eBay that fit a spare bb that I had on hand, and I gave it a whirl. On the flats, they were great--a smoother pedal stroke, and maybe a tiny bump in speed. I definitely noticed a speed bump on downhills as the shorter cranks extended my ability to spin that 52/11. I even picked up a few downhill KOMs that eluded me with the 160s. But on the climbs--and I do love to climb--I noticed a decrease in leverage. Just as the 155s extended my downhill spin range, I had to spin an easier gear on the climbs. I felt slower, and climbing fairly quickly has always been my thing. I rode the 155s for a while longer--long enough to fully acclimate to them--then switched back to the 160s for the sake of comparison. It didn't take me long to know that I was "home" with the 160s, and I've stayed there since.

This is not me telling you that you should ride any particular length crank, but that there can be some trial and error with this particular metric, involving body mechanics, riding style, route tendencies, etc. I was glad that I experimented with those 155s (I sold them for just about what I bought them for); doing so confirmed that I have found my personal best crank arm length for my body and the kind of riding that I do.

Rotor and Aerozine make nice short cranks, and Praxis does as well, down to 160. One cool thing about Aerozine is that they use a flipchip at the pedal end that gives you a 5mm difference, depending on which way you have the chip flipped. It's like buying two crank lengths in one.

Excellent explanation Craig!
I had a similar experience deciding between 172, 170, and 160mm.
And found 170mm to be the best setup for me.
“You never know what is enough unless you know what is more than enough.”

Height 5'10"
X-seam 42.5"
Inseam 33"
Weight 160#

Height 178cm
X-seam 108cm
Inseam 84cm
Weight 72.6kg
 
Actually that's a really interesting issue. Are recumbents more or less prone to crashing when getting a flat than a DF roadbike? If so, I might want to consider tire liners, like I used to do when riding in rough terrain...adds a bit of rolling resistance, but means no flats ever
I had some luck the other day…
Rain obscured my vision a bit and I hit this lip at about 30 mph and instantly flatted, sealant spewing out the damaged tire. I was able to stop quickly and remain vertical.
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Maybe tire inserts would have saved me? Maybe if I was on a DF I could have let the bike float over the bump? To answer your question, I think we’re more prone to crashing due to the fact that we tend to hit bumps harder.

BTW, the tire lost its seal when the rim tape tore. Later on that day the (unrecognized) damaged sidewall split and the tube blew out the hole, several hours after the ride.
 
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