Baby Puke

There is data. I believe Southern Fox linked this video, and it is worth watching: But it's not all about big gears, there's a lot in there, and depending upon your reading it would not be hard to read some of it as contradictory. You still have to roll your own as far as what you race and train on, there's no cookie-cutter template that will work for everyone.

tobukog

Martin and (Povey) are great, and this video posted by Southern Fox more or less summarizes much of his views. The only thing that I don't like about the video is his part on crank length -- I've gone down to 150 -- and I sure hope more of my competitors don't see the part where he pretty much lays out the case that anyone under 5' 9" should be running under 165. There's actually a lot of research on track cycling, probably more than the road.

krispenhartung

This is absolutely fascinating, and exactly the type of information I was getting at. I just watched the entire video, but will need to watch again, probably twice. I'm trying to track down the slides as well.
p.s. Did they have this presentation at a skeet shooting range?! Good grief. Weird venue.

tobukog

I suggest you look at the sprint training seminar put out by Kolie Moore and WKO4. It provides a more practical look at applying these ideas for Sprint cycling.

krispenhartung

I will, out of curiosity, but my main focus is not sprinting, but endurance (sprinting in the context of mass start races, etc) and pursuit, I'm sure I can pick up some tips in the book, however. Thanks for the reference! :-)

krispenhartung

This by no means proves anything, but is just for discussion and commentary. I was just looking at my race data for the last week and a half. I looked at my fastest lap sprint in a Cat 4 points race, and then (after I upgraded to Cat 3 that night), a Masters Cat 1-3 points race 3 days later, again my fastest lap. This is a 400m lap, btw. During the Cat 4 points race, I was on restricted gearing (86 in), and my average fastest lap sprint cadence was 130rpm. On the Masters Cat 1-3 race, I was racing on 93 inch gearing and my average fastest lap sprint cadence was 125rpm. However, my average speed on the Masters race lap was 2.2 mph faster (at 34mph) than the Cat 4 (at 31.8 mph), yet my average power was 7% lower. Of course, much of this could have been related to the wind speed and direction at the time. However, if the difference is related to cadence and gearing, then I wonder what my lap time might be at 94 or 95 inches. I don't have enough Cat 1-3 data yet to draw any decent conclusions.

krispenhartung

I am looking at my data in WKO4 right now, actually, using one of Kolie's charts.

Baby Puke

Tobukog, I'm a little confused by your post: Are you saying that you disagree with the short crank thingy? Or are you saying you wish they hadn't laid that out so your competitors can benefit from the short crank idea? I do have one buddy who has gone below 165 (considerably) and is liking it, so there's anecdotal stuff around.

tobukog

I'm sorry. I'm currently running a 150mm and I'm loving them. This is one place where I disagree with Dr. Martin -- it's not just an aerodynamic / ftting gain. I'm hitting higher speeds near the end of my sprint, both in and out of the saddle. My foot velocity is actually a little slower than before, rpm a little higher, maximal torque a little higher (more than what's lost through foot velocity so it's not a wash).

So why did this occur? I can produce more torque in the saddle because the knee doesn't come up as high -- going from 165 to 150 allowed me to lower my knee by about 30mm at the top of the stroke. Out of the saddle, it didn't make that much of a difference but it was huge when you sit back down. At the end of a race, I used to spend an inordinate amount of time accelerating and maintaining out of the saddle. Now I can sit down and accelerate after the initial hit.

Morelock

Aerodynamically speaking, a shorter crank suggestion usually works under the assumption that a lower front end / cockpit is better.

In my testing, that's very often not the case (like everything of course, higher/lower/etc all depends on the starting place) and as tobukog suggested that going shorter lowered his knee at the top of the pedal stroke - this is possibly one of the main reasons shorter cranks can be bad for aerodynamics... more upper leg in the wind all the time. (another possible reason is that the rider generally goes farther forward - and up - in the saddle, which can also be bad aerodynamically, sometimes at least) On the flip side, going shorter does allow a more open hip angle all other things being equal, and many people produce more power (again, depends on where you start) so it's something to test for sure.

tobukog

Since you've spent time in a wind tunnel, you know how it goes.... That's one thing people forget -- many studies, usually performed on average height males -- might not apply to riders who are 6'3" or 5'5". It even applies to bike reviews (which are suspect anyways). A 56cm bike doesn't necessarily perform the same as the larger or smaller sizes.

Morelock

@tobukog absolutely. Bike sizing is something that gets no thought often, although I heard in an interview with Dion Beukeboom (on thetrackstand podcast) that they had tested different size GIANT bikes and sized down an unusual amount for his upcoming hour attempt because it turned out much faster (if you could get the reach from a smaller size, maybe aero pedestals under the pads > aero headtube) interesting stuff. In theory you also move the rider farther away from the top tube doing that though, which can be bad....maybe

John Cobb told me the first time I went that I'd spend an hour or two in there, come out thinking I'd figured something out, and then a day or two later realize all I had left with was more questions. So far, that's been spot on.

tobukog

Yeah, until you test you just don't know and even then it can open up a can of worms. My team mate, who is a wind tunnel guru (I think you've worked with him before) was testing water bottle placement positions on a smaller woman. Basically, the numbers showed that it didn't matter: no bottle, 1 bottle, 2 bottles, etc.... It was all the same cda. Maybe the triangle was so small that it didn't matter -- who knows.

taras0000

I mentioned this exact same "phenomenon" about setting up track bikes and road bikes the same. I out 165s on my road bike and experienced the same things you did. Despite the smaller crank, having your leg more extended at the top of the stroke allows more power output in your dead spot.

carleton

I've raced on 172.5, 170, 167.5, and 165mm. Only on 165mm can I "run on the pedals" where I hold high RPMs out of the saddle. With the other crank lengths, I would have to sit at certain RPMs in order to get more RPMs. Basically, the crank length limited how fast I could spin out of the saddle.

This might get better at even smaller crank lengths.

The downside of going shorter is that, for a given amount of torque (whatever your legs can offer each pedal stroke), the gearing must come down. My from-the-hip calculation is, to keep the torque feeling the same, go up 2 gear-inches when you go up 2.5mm in crank length or go down 2 gear-inches when you go down 2.5mm in crank length.

I posted the actual formula that I found in Bicycling Science (D. G. Wilson). But, I don't have it at hand.

The takeaway is: Pick the crank length that complements your pedaling style.

Divebrian

For me personally, I found this to be incorrect. Granted, I'm not your average cyclist and at 6' and 235 lbs, I'm built more like an NFL linebacker. I recently went down to 165 cranks and both my road and track bikes, my gearing stayed the same and my speed went up. I attribute this to a few different factors of power delivery, comfort and aero gains. There is nothing aero about me, but stick with me and I'll explain. Every time I have gone for a bike fitting, they have done things by numbers, angles, flatness of back, etc to give me the correct position. That position was my optimal position in the fitting studio, but didn't translate to real world. In the real world, it led to a very upright position that killed aerodynamics. Since I have a very large chest and wide shoulders, with longer cranks, my knees were hitting my chest, which caused me to open up my hips to give my knees room to go to the side of my chest, which then meant my knees now hit the inside of my elbows, so I flared out my elbows. To keep my knees and elbows in, I adopted a more upright riding style to get my chest further away from the top of my knees. When I went to shorter cranks, my knees didn't come up as high, so they no longer crashed into my chest. This meant that I could keep my knees in, which in turn brought my elbows back in and allowed me to maintain a lower riding position. With the shorter cranks, it allowed me to keep a lower position with my knees in and elbows tucked, knees in gave me a better power delivery and not smacking myself in the chest with my knees allows me to be more comfortable, which means I can maintain that position and power output for longer periods of time. As an extra benefit, I picked up a few more rpm's, which coupled with better aero properties and power delivery, allows me to maintain a higher speed for a longer period of time.

carleton

I would guess that your speed went up because your aero gains outweighed your torque losses for a given gear.

We are built about the same.

For guys our size, wind is our biggest challenge, not power production. I would suggest continuing to focus on aero gains to find speed. -5% frontal area will make you faster than increasing your squat 20%. Seriously. It took me years to learn that.

This is also why I went from 57cm frames to 61cm. Stretching out made my aero profile better. Arms went forward and back and head went down.

carleton

The lure of getting stronger is so tempting because it seems (and is) so attainable, especially for bigger riders who excel in the gym. My goal for this summer was to get my (non-sumo) deadlift to 500lbs (and I woulda achieved it if it wasn't for you meddlin' kids!).


But, air is the biggest enemy for bigger riders, *especially* at higher speeds.

Kaben

taras0000

Nope. You will need a large slot screwdriver or chainring tool to install them. The knurls are just slightly larger than the outside diameter of the hole, and as you tighten the bolts, they get pulled in. The tool is just to help the process get started, as once they have bitten into the back of the spider enough, they will stop rotating and jut get pulled in. IF you strip one that's already installed, you will have to hammer it out.

Kaben

Thanks! ( Fingers crossed i never strip one!)

taras0000

You shouldn't. It's REALLY hard to strip them, the backside nut that is. It's a pretty large, and coarse thread for the loads that it sees. You're more likely to strip the Allen bolt on the front, and those you just throw away, the backside will usually still be good as new.

IF you need to hammer the back nut out, then thread the front side in all the way, back it out a quarter turn, then hammer it. Proceed to back out and hammer in quarter turn increments until the nut can be pried/pulled/hammered out.

joe19582001

very nice reading.

cormacf

Thank you! I just rode for the first time yesterday and this post legitimately nailed almost every question / impulse I had!

cyclinganomaly

Carleton suggested that I post my videos here for the benefit of those who are thinking of trying a race.
You probably don't need to match my numbers to try a race, I've been racing on the road for a few years now. I have a cheap bike that I bought used for $200.

These videos are from my first night of racing, I was running 46-14.
Scratch Tempo
These videos are from my second night of racing. I bought a used chainring from a former teammate, I was running 49-14 this week.
500 Meter Chariot Unknown Distance Scratch