Bike Fit for Power and Muscle Engagement

[CruzinCambridge]

A little while back I did a professional bike fit on my diamond frame bike and made small adjustments to my stem and seat position to get my fit dialed in. The fitter analyzed my power curve through my pedal stroke and moved my saddle a little forward and down to better engage my glutes in the 1-3 portion of the pedal rotation among other things. He took photos from the side and was able to measure my knee bend and hip bend see where my knee was relative to the pedal spindle drawing a virtual plumb bob on the photo.

Is there anybody doing anything like this on the Cruzbike? Hard to drop a plumb bob off the knee and hard to know where exactly three o'clock is in the pedal stroke on a Cruzbike. I spent most of the fall and winter playing with my boom to optimize the pedal stroke and clearance. When the bottom bracket is too close, I feel it in my knees, but I've noticed my current position doesn't feel like I'm engaging my glutes or hamstrings enough. I'm wondering if a shorter chainstay will effectively bring my saddle forward. I've been combing ebay for shorter cranks that will work with my setup so that will probably be my first move.

Anybody else have theories on the biomechanics of the front triangle setup of their Cruzbike?

 

[Always-Learnin]

A little while back I did a professional bike fit on my diamond frame bike and made small adjustments to my stem and seat position to get my fit dialed in. The fitter analyzed my power curve through my pedal stroke and moved my saddle a little forward and down to better engage my glutes in the 1-3 portion of the pedal rotation among other things. He took photos from the side and was able to measure my knee bend and hip bend see where my knee was relative to the pedal spindle drawing a virtual plumb bob on the photo.

Is there anybody doing anything like this on the Cruzbike? Hard to drop a plumb bob off the knee and hard to know where exactly three o'clock is in the pedal stroke on a Cruzbike. I spent most of the fall and winter playing with my boom to optimize the pedal stroke and clearance. When the bottom bracket is too close, I feel it in my knees, but I've noticed my current position doesn't feel like I'm engaging my glutes or hamstrings enough. I'm wondering if a shorter chainstay will effectively bring my saddle forward. I've been combing ebay for shorter cranks that will work with my setup so that will probably be my first move.

Anybody else have theories on the biomechanics of the front triangle setup of their Cruzbike?

Maybe give this a try? https://www.bikesmithdesign.com/Short_Cranks/

 

[Beano]

I'm guessing you should measure your hip angle on your DF when you fill 'dialed in' and try to replicate that on a Cruzbike?

 

[JerseyJim]

Is there anybody doing anything like this on the Cruzbike?

This is actually a really good question and I wish there was more of a science when it comes to recumbent body positioning. There are rules of thumb, but most of the time it's trial and error.

I recently replaced my seat pad and the new one is a little thicker than the previous one. As a result my knees were brushing the handlebar on my T50 so I had to extend the boom. I adjusted the boom for max knee clearance without over-extending my leg at the bottom of the stroke.

It turns out that I had not been extending enough in my previous position and I found more power in this new position. The difference was about 1 inch on the boom. I previously set up my bike based on the Cruzbike recommendations. Turns out I'd been limiting myself. I suppose it was safe for my knees but I wasn't getting the most out of my pedalstroke.

Actually come to think of it, I also got new bike shoes at the start of the year and that may also have contributed to my lack of extension. It's possible that the sole of my new shoe is a little thicker as I use MTB shoes.

It was nice finding more power, which increased my cruising speed, however I feel a bit cheated that I didn't discover it earlier. My original position was good enough but it wasn't optimized, which is a big difference. Now I wonder if I'm missing something else.

 

[CruzinCambridge]

@Beano Great Idea! I think I'm going to get my trainer out of the basement and try to film myself riding and see what my angles look like compared to my DF angles. Will post photos... but I probably won't get to this for a couple, three weeks. Ideally I'd couple this with power meter readings through the pedal stroke and compare the profile but that adds like $800 to this project.

@JerseyJim I've been playing with my boom a lot to get it dialed in and then (different post) my boom slid and I could feel that I was engaging my butt and hamstrings more. When I got my fit dialed in, I think I was optimizing for "feels good" (able to reach the pedals and get clipped in) and not "feels powerful. Now with more experience and confidence, I'm able to be more comfortable with more "saddle height." But that doesn't answer the fore/aft question which I'll have to get from photos.

 

[Rampa]

To find 12, top of pedal stroke, is really easy if you have cleats. It's where the pedal is when you pull it back towards you as far as possible with the steering straight. Once you have 12, you will then know where the other times are.

 

[CruzinCambridge]

@Rampa That's very logical, but is it correct? On my DF bike, the seat tube angle is 75 degrees, so when the pedal is closest to me is 15 degrees off 12 or 11:30. So I guess I could use that reference point and go 105 degrees to find 3 o'clock. Am I thinking about that right?

 

[Rampa]

I certainly don't have a better idea. But it may be a bit relative.

 

[benphyr]

Also impacting at full up pull:
-the knee will be forward somewhat and
-the pedal would be in rearward in relation to the knee
And both of these will be impacted by upper leg, lower leg length, foot size, location of pedal on shoe, foot angle, and what is comfortable to the user.

The “vertical” difference when at full up or down changes the least per angle change.

 

[benphyr]

I postulate it might be easier to take a picture from horizontal side view with the foot in approximately “forward” and “rearward” position. Draw a straight line from hip to bottom bracket pivot point. Then draw perpendicular line to get the absolute “forward” and “rearward” pedal locations. And then compare with what the picture shows. I have no idea if that would help us with respect to eyeballing the correct orientation, but it should give us a better reference point to use.

I have probably missed lots in my understanding....

 

[CruzinCambridge]

Okay... it took me a long time to get around to taking film of myself on my Cruzbike on the trainer... but what are winters for other than toiling in the basement on a trainer and making micro-adjustments to your bike.

Below a comparison of my DF bike fit to my recumbent film. The angle's a little low... which I should probably try to fix as it might make the angles a little shallow. It looks pretty clear that my reach is a little too long and I should shorten the distance to the BB. I'm a little worried it will bring my knee too far forward. It's hard to tell where 3:00 is... I just took a snap when my knee was farthest forward. Same on top and bottom of the pedal stroke... though it's odd that the top and bottom are not 180 degrees from each other.

Anybody have any thoughts on whether I'm doing this right? Regardless... I guess the think to do is make some small adjustments to the reach and see how it feels... especially as there's not much I can do short of getting a custom sub-165 crankset.

 

[Frito Bandito]

CC, I've never been properly fit on any bike so I won't even try to pretend I can make sense of the proper and/or best angles in relation to comfort or power. I just set my BB to where there was no pain anywhere in the pedal stroke. This allows me to put as much power as my legs can put without pain. Maybe it is because I am almost 55, but I could probably move the BB out or in 1/4" or half a centimeter or so and not experience any pain with my 165mm cranks. I am not sure how far in our out you can move your BB to get you into a better power delivery, but I'd be incredibly jealous if it were 1cm or more. I am intrigued by your progress though and love reading about what other riders are doing to progress so please keep us up to date.

This is somewhat related and my approach when riding. I think it was on Slowtwitch but there was a thread titled something like "Are you a pusher or puller?" Before buying my V20 I turned my roadbike into a triatlon/TT bike with my current Deda Tribar and clipons. I never really paid attention to which I was, but I came to the conclusion that I was a "pusher". Initially when my quads starting giving up the ghost I just slowed down until they recovered enough to go again. Later, when my quads gave up I started pulling to give the quads a break to recover. I'd pretty quickly run out of steam because those muscles were weaker so after pulling for a short while I'd go back to pushing. After buying my V20 I kept up the same style of switching between pushing and pulling in high efforts, and occasionally dropping my cadence to try to do both at the same time. I believe other riders probably do the same thing, but I noticed that I will scoot a little towards the BB at times, and tilt my hips more, which might mean my BB needs to be moved. Again, I'm a noob at the angles and how they relate to comfort, longevity and power.

 

[Mathew Fy]

Shorter crank arms help keep the Top of Pedal Stroke angle lower. Besides that, the adjustment we can make is boom length. I have mine set to maintain knee angle about 135-145, following this recommendation. I develop knee cap pain if I extend it out much further.
This source recommends extending out as much as 155, way too much for my comfort.
Or search the forum for "knee angle" to go down the rabbit hole.

 

[DavidCH]

It all depends what you want... max power or max aero. With the vendetta they are mutually exclusive. I've gone for more aero than power so then I don't have to grunt so much. I find myself hovering about the 50kph speed so aero savings are considerable.

 

[Frito Bandito]

It all depends what you want... max power or max aero. With the vendetta they are mutually exclusive. I've gone for more aero than power so then I don't have to grunt so much. I find myself hovering about the 50kph speed so aero savings are considerable.

That's awesome David! I need some more aero haha

 

[CruzinCambridge]

It all depends what you want... max power or max aero. With the vendetta they are mutually exclusive. I've gone for more aero than power so then I don't have to grunt so much. I find myself hovering about the 50kph speed so aero savings are considerable.

Interested in the idea that power and aero are mutually exclusive. I hear you Vendetta people talking about getting the BB up so that your legs are in line with your torso to increase aero. Do you mean by doing that, you're getting more "tall" on the bike - decreasing hip angle and increasing knee and ankle angle, taking you out of the "core" range of motion and decreasing power?

In the S30, I'm already sacrificing some aero... but better ability to draft with DF riders makes up for some of that defecit (they are grateful for even the half draft I provide).
I'm more concerned with power since I've got a few hilly rides (10,000 and 18,000 ft) on my calendar. My big concern is accessing more muscle groups to spread the load and minimizing the strain on my knees. In my biggest ride last year - 300K with 8,000ft of vertical - I was grinding at 60RPM to get up the hills in with a reasonably low 38/34 ratio. Trying to figure out if I can get more power without creating knee pain.
@Frito Bandito - you're right... I should start with a few millimeters not CM... and then a few more... and then if I see some knee pain, walk it back. And thanks for the link. Look forward to reading that.

 

[chicorider]

Interested in the idea that power and aero are mutually exclusive. I hear you Vendetta people talking about getting the BB up so that your legs are in line with your torso to increase aero. Do you mean by doing that, you're getting more "tall" on the bike - decreasing hip angle and increasing knee and ankle angle, taking you out of the "core" range of motion and decreasing power?

In the S30, I'm already sacrificing some aero... but better ability to draft with DF riders makes up for some of that defecit (they are grateful for even the half draft I provide).
I'm more concerned with power since I've got a few hilly rides (10,000 and 18,000 ft) on my calendar. My big concern is accessing more muscle groups to spread the load and minimizing the strain on my knees. In my biggest ride last year - 300K with 8,000ft of vertical - I was grinding at 60RPM to get up the hills in with a reasonably low 38/34 ratio. Trying to figure out if I can get more power without creating knee pain.
@Frito Bandito - you're right... I should start with a few millimeters not CM... and then a few more... and then if I see some knee pain, walk it back. And thanks for the link. Look forward to reading that.

Your goals are inspiring.

I have been on a V20 for seven years, and an S30 (same as yours) for almost six years. My approach to bike fit is highly untechnical, and driven almost entirely by trial-and-error and feel. For me, the most important setting is where to put the bb (while using 160mm cranks), to get the fullest sustainable leg extension. I fit both bikes by nudging the bb outward, outward, outward by small degrees until I felt mild pain. Then I nudged it back in by tiny degrees, going on full rides each time, until there was no pain. That has become my fullest pain-free leg extension for my natural cadence and power output on all terrains, from flats to climbs. It's a measurement that I value enough that I made my own tool to make sure that I will always have that extension (pictured below). The stubby bolt end fits into the bolt head of the boom steerer clamp, while the end of the aluminum bar just brushes either the bb bearing cup on the S30, or the bb shell on the V20c.

I know that doing things by "feel" lacks numbers, angles, and precision, but it is the only way I have been able to arrive at my end goal: sustainable power without pain (my last long ride was in October: 205 miles (330K), 10,000+ feet vert, in 10 hours ride time, 12 hours total. Fatigued legs? For sure. Actual pain? None).

The last reason to do this by feel, despite how tedious it can be, is that it is unlikely that any two riders will share identical ideal measurements. I don't know what my numbers and angles are, but I could probably figure them out and send them to you. But I'd be surprised if they became your best fit. I take the same approach to setting the headrest and handlebar spots: for the headrest it's backward, backward, backward until I've gone too far, and then forward in small amounts until I hit "just right." For the handlebar it's forward, forward, forward until too far, and then back in until my hands and arms feel most natural.

 

[CruzinCambridge]

I love this! Not only having fit measurements... but of course a hand-made metal fit stick. I only wonder if you've considered upgrading from aluminum to titanium! I'm heading out this weekend to get a yardstick and do the same. I've been doing it with tape on the boom... but as I'm breaking the bike down and setting it back up a reference will come in handy. As I'm breaking down my bike and setting it back up

It's a measurement that I value enough that I made my own tool to make sure that I will always have that extension (pictured below). The stubby bolt end fits into the bolt head of the boom steerer clamp, while the end of the aluminum bar just brushes either the bb bearing cup on the S30, or the bb shell on the V20c.

 

[CruzinCambridge]

I needed to post a quick update that in the course of changing pedals I moved the cleats back a centimeter just like everyone has said (not a full mid-foot mind you, just behind the balls of the feet) and OMG it's miraculous. Where before I was fine tuning to remove knee pain, with the changed cleat position it feels like there isn't even any knee strain. Note to self, stop being stubborn and listen to the kooks on the CB forums. I need to fine tune the position and see if it does anything to my top-end power and then more measurements.

 

[trplay]

Does anyone have any numbers showing in watts certain adjustments provide more/less power?