Tuesday, August 28, 2012

More on Matched Filters and Cycling

My group lunch ride got me thinking about how applicable the engineering concept of matched filtering is to cycling again. There are subtleties in group riding dynamics that may be non-intuitive to some riders. Maybe I can explain some of these subtleties with a story. The names of the characters have been changed to protect the innocent.

A tri guy, a scull boy and a climber freak went for a ride one day on their lunch break. It was agreed that intervals would not be the theme of the day, but rather go more for steady pace, maybe a team time-trial type of effort.

Tri guy was on a TT bike, which generally raises all kinds of warning flags in group rides, but scull boy and climber freak had him dialed. No worries. Tri guy posts some impressive results in Olympic distance tri's and can hold a pretty hard pace for hours at a time, but doesn't fare so well in sprinting or on sustained climbs. His aero position on the TT bike makes him a rocket on descents.

Scull boy is a fast twitch specialist and has done well on the velodrome track in the past, but spends most of his days on the water now. One day per week on the bike, peak fitness maintains not.

Climber freak tends to be biased towards fast twitch and sucks least on terrain that goes up. He can also put out some pretty mad anaerobic Watts for his age too, at least for anything longer than a sprint.

It was never discussed, but after a while, the ride gravitated towards maintaining average speed at all cost.  Mid ride, the trio began hitting variable terrain. Some flats, climbs, descents, headwind, tail wind, bit of everything. This got the climber freak to thinking, "if we're trying to optimize our average speed, is there an optimal way to stage riders in the paceline rotation relative to terrain?" Climber freak posed a suggestion to the other two. Neither liked it. What do you think climber freak suggested?

A term needs to be defined before we can begin analyzing this scenario. The term is "work." Cyclists use this term a lot. The term is frequently used correctly, but too often it is misused. What does it mean to do "work" in a peloton? And how is "work" quantified?

I define work as the difference, in Watts (real time) or kiloJoules (over period of time) between a rider pulling at the front of the pack and the average of the riders not at the front of the pack. For those who ride with power meters, you know that your power drops substantially when pulling off the front and you slip back into the pack. The difference in Watts is the work riders at the front are doing to keep the pace up. It is not their total power.

A numerical example may help explain. On flat terrain, an average size rider on regular bike may have to generate 400W to hold 28mph. A rider tucked close in behind him may need to produce only 300W to go the same speed. Thus the rider pulling at the front is doing 100W of work, which is 100W more than the rider drafting him needs to produce to go the same speed. This is substantial. The rider pulling is likely going deeply anaerobic, while the drafter is sub-threshold. This is why a rotating paceline can maintain a much high speed than a single rider can. Riders recover in the pack and then go anaerobic briefly at the front.

So what happens when you go uphill? The work the rider up front drops dramatically. On a 12% grade, the speed may drop to 8mph at 400W. There is almost no drafting benefit at this speed, thus the rider behind him will be producing upwards of 390W. Even though the rider up front in working really hard, just as hard in the 28mph flat case, he is doing almost no work, maybe only 10W. The power differential is very small. Riders hanging onto his wheel are getting almost no benefit by staying there, and unless they are of similar fitness, will soon find themselves separated from this rider.

Then there are downhills. What happens to our definition of work there? Turns out on a moderately steep downhill, the pulling rider can hammer at 400W while everybody in tow behind him are coasting or even hitting the brakes. In this case, the rider up front is doing 400W of work, which is a huge amount, as those in the draft are doing nothing.

So far, this should be pretty obvious to everybody. The range of work one can do is almost nothing going uphill to almost all of it going downhill. Now it is time for a quiz. Can you match the type of terrain each of the three riders in our story should pull on? Remember, the goal was to keep the 3-man team time-trail together and complete the course as fast as possible:

1. Tri guy (on TT bike)   a. climbs
2. Scull boy                     b. flats
3. Climber freak              c. descents

It may not seem intuitive, but the rider that can least handle the climbs (scull boy) should pull on the climbs. Why? Because he will do the least work there, even though it feels like you work like hell setting pace on a climb. But whatever Watts he generates, so too will the others. Then when the terrain flattens out, the next rider can do actual work, where scull boy's power will drop. This is especially true on the descents. Scull boy should never work on the descents, as he most needs the recovery, even though he could potentially just coast on the front and go almost as fast as working. But this does not optimize the group's speed.

The tri guy with his TT bike slips through air much easier than scull boy and climber freak on non-aero bikes. This becomes very important as the speeds go up. Tri guy can go fastest on the descents, doing disproportionate amount of work, and because of this speed, forces the other two to put in some effort too to stay with him.

The climber freak gets all the terrain in between, namely the long, flat boring parts that just need to be hammered out. The other two can tuck in behind him and recover there. You do not want to put climber freak up front on a climb, as the rider that pulled to the climb will promptly get popped off, then the group has to slow down to let him get back on. Let climber freak kill himself on the flats, where it is relatively easy for the other two to stay in his draft and recover.

So you see, there is a strategy that can optimize a circuit time with differing abilities and equipment among the riders. Understanding the definition of work and matching riders to the terrain, and thus work they can contribute, will net a fastest time around a varying circuit.

Sunday, August 19, 2012

D2R2 2012: "I Suck!"

I nearly had to back out of D2R2 this year. A week before, I got tagged to attend a DARPA workshop in Washington, D.C. the day before D2R2. I'd have to go to DC from work on Thursday, then straight from airport to Deerfield late Friday night. The hassle and potential lack of sleep didn't seem worth it.

My flight was late getting back to Boston Friday night. DaveP reserved a room at the Red Roof Inn in South Deerfield. I figured maybe I could be in bed by 11pm. Having a terrible time sleeping in strange places, that didn't leave many hours to try to get some sleep in with a 6am event start time.

Heading west on the Mass Pike, I ran into torrential thunderstorms. Traffic slowed to a crawl. I couldn't help think about those camping overnight at the venue. The good thing was this front would clear the hot, humid air out.

En route, Dave sends me a message saying the hotel over-booked rooms, and all they had left was a single bed smoking room, and they would not allow a roll-away into the room due to fire regulations. I sometimes have trouble discerning when Dave is being facetious.  I had dealt with planes, trains and automobiles over the last 36hrs, so surely he was joking.

Dave left a room key at his car so I wouldn't have to wake him. Sure as shit, the room was a single. Dave was totally zonked, so I went to the office to fix the situation. I had a lot of pent up stress from the last 36hrs and was ready to unload.

At first the desk clerk told me there was nothing they could do, D2R2 cleaned them out of rooms, and unless you pre-pay with credit card, they don't guarantee room selection. That sounded like BS to me. I thought it was a rhetorical question, but I asked them to give me my own room. They in fact just had a cancellation and a room opened up. My stress level dropped a few orders of magnitude.

I managed to get nearly 5hrs sleep, which was 2 more than the night before. So in two nights, I got about one night's worth of sleep. Better than nothing. I had picked up a quart of milk and Cheerios in a bowl for breakfast on my drive in. Little did I know, the cereal bowl was cracked top to bottom in two places. I filled it up and milk spewed all over the place. Son of a bitch! I thought the stress of the last two days was behind me. Kitting up and a quick cup of Starbucks Via had me on my way.

I wasn't sure who I was hooking up with. At least Dave, Alex and Paul I thought.  Paul's loaner bike fell through last minute, so we heard he wasn't making it. It would be just a four-some, Dave, Alex, Alex's friend Bill and I.

It was raining and overcast at 6am. It wasn't cold enough to warrant long layers though. This was perfect for me, a chronic overheater. It was expected to clear and be very pleasant later in the day. We rolled out at 6:15am at a cordial pace. What a change of pace going from the urban jungle that DC is to dirt paths, cows and cornfields in 12 hours.

The gravel was quite spongy from the heavy rain over the last 12hrs.  I regretted packing bike with aggressive 35mm tires when Sandy sent update out on Friday stating course was firm and fast. The other three had 28mm road tires. But my tires pressed much less deeply into the soft gravel, so I suspected I had to work less hard in these conditions. Soon we learned that even though conditions permitted good traction and control with skinnies, there are other benefits of going with larger volume tires.

Spongy gravel

Let the flats begin. The East Rd descent is one of the best parts of the course, a couple miles of swoopy, one-lane, totally white knuckle descent. Dave and I absolutely bombed it. The rain meant tacky surface, no looseness. The descents this year were the fastest ever. Bill didn't fare as well, pinch flatting near the bottom. It didn't take long to get going again, but a slug of riders passed us in the process.

Alex after bottoming out on East Rd.

Maybe this was the way to go this year. He did the whole 180k
with 10psi and 30# bike!

Just before Archambo Hill Rd, Dave's rear tire exploded just riding along on pavement. Not sure why. Almost looked like a tube failure, but could have been a latent pinch flat or maybe tube was caught in tire bead. Tear was more perpendicular to rim bead and on inner side of tube.  So we quickly put a new tube in, only to find Dave packed short valve stem tubes for deep dish rims. Argh! He was so fortunate Alex and Bill packed long valve stem tubes even though they had shallow rims. I was running balloon tires, so my spare tube was way too big. We essentially had to fix this flat twice, killing way too much time in the process. I think it was Clara Kelly that flew by saying it was not a good place to stop (right before Archambo). Legs were nice and tight heading into the 27% grade. I think I saw Clara again later in the ride, fixing a flat.

Not gonna work

A little while later on Deer Park Rd, there was this nasty little plummet with fist sized rocks scattered about. Dave and I bombed it with reckless abandon, but Dave flatted again. Same rear wheel, clearly a pinch flat this time. Pressure after first flat may have been on low side.  Lucky for Dave, Alex packed multiple LVS tubes. We were suspicious of tire and rim at this point so we gave it a careful go over, completely removing the tire, which was almost impossible to get on and off (requiring heavy lever use putting bead back on). By now, we had killed more than an hour fixing flats, and the ride wasn't even half over yet! One rider flew past yelling "Carnage!" There were several riders fixing flats after that little plummet.

Hillman Rd

I felt tell-tale signs of cramping coming on. This had me deeply worried. This last flat stop helped recharge my electrolyte battery or whatever gets out of whack in me and causing cramps. The lunch stop was just a bit up the road too. We took a fairly long lunch lunch break. As always, the sandwiches and other food were awesome. There must have been a few hundred riders there, as all the route options converged there around noon. Over 800 riders were pre-registered.

I felt like a new man heading up Stage Rd from the lunch stop. Short lived though. By the time we got to the top of Sweet Pond Rd, I was hanging on by a thread. Then there was the Alexander Rd climb that just wouldn't end. How I stayed in contact with the other three is beyond me. I should know better than trying to hang with much younger slow-twitch freaks who weren't slowing down at all. We still had 30+ miles to go with two spanker climbs.

N. County Rd

When we turned onto Nelson Rd, I was done. No cramping, but I couldn't turn the pedals any harder than a light endurance pace. Dave, Alex and Bill were out of sight in minutes. Dave and Alex killed the climb, leaving me for dead. I wouldn't see them again for a long time. Bill waited up for me. This was a good thing, as Bill wasn't navigating by GPS and later depended on me for guidance. I was dreading Patten Hill.

I was sure this would be the year I failed to clean Patten Hill. I came close to stopping in years past due to cramping, but this year it seemed fatigue would do me in. Turning 50 the next day, I concluded I was getting too old for these shenanigans. Once we turned onto Patten Hill Rd, Bill bolted and was gone in a heartbeat. The grade approaches 20%, paved at first, then gravel. At times, the only way I could push my 34x32 minimum gear was to stand. The bike nearly came to a stop between each down stroke. There were walkers, and I didn't want to join them, even though I made little to no progress on them by riding the climb. I could handily slay Alex and Dave on this climb in a fresh-legs scenario, but the slow-twitchers slay me 7hrs into a hill-fest ride. I thought to myself how badly I suck.

As I approached the summit, there was a pretty good crowd up there at the food stop. Volunteers were ringing cowbells for arriving riders. I was so deeply into deathmarch territory, I was surprised I was still even alive. After being complimented on how awesome of a job I was doing, I blurted out "I SUCK!"  That drew a few chuckles. I'm sure I looked like death. I was surprised my ride mates were still there after taking an eternity to climb this last beast.

My stomach was in a major funk by this point.  The watermelon was the only thing I could stomach. Two pieces and the others were already rolling. I had to hang on for dear life for the last ten miles. Somehow, on the uber bony Hawks Rd, I found a little mojo. Maybe it was the horse smelling the barn.  We hung with three other riders maintaining a solid pace over the rutted rollers through this section. I was having a little fun again.

Square Lot Rd. What is Alex afraid of here?

I rolled in with 7:57 moving time on the Garmin, three minutes faster than 2010, the last time I rode D2R2. Not my fastest, and definitely one of the slower total times due to the flats earlier in ride, but who cares.  The weather could not have been more ideal for me. Other than a little sponginess early in the ride, the course was in mint condition too. It was probably my most enjoyable D2R2 even though I can bank on suffering immensely towards the end of the ride.

This event continues to grow in popularity. Sandy Whittlesey and the army of Franklin Land Trust volunteers continue to put on a stellar event. The post ride meal under the beer tent lets riders reflect on the all-day challenge.  Bill commented how rides like this let him down a pint of Ben & Jerry's guilt free. This seed grew bigger in bigger in my head on the drive home, until I capitulated and picked up a pint of Cherry Garcia. A fine way to cap off an awesome day.

Icecream headache! Nearly 1000 calories and two days worth
of saturated fat.

Thursday, August 9, 2012

CIGNA 5k: 18 Minutes to Debilitation

When I ran the CIGNA 5k race last year, I speculated that with two hours of running per week, I could possibly finish sub-18 minute. Running hasn't quite gone to plan this season. I was somewhat serious about it earlier this summer in preparation for the Mt Washington foot race, but then I developed an injury that put the kibosh on that. I had to lay low for several weeks and never ramped back up to the 2-3hrs running per week I was doing leading into Mt Washington. In fact, I've only run 49.5hrs so far this year, or exactly 1.5hrs per week average.

Most of the running has been at a recreational pace of 7:30-8:00min/mi. Only over the last three weeks did I do some focused interval work with my triathlete friend Dan M. Following a Daniel's protocol, we ran a block of four 1200m intervals with three minutes recovery in between each 1200m. That's not much recovery, and 1200m is run at VOmax. But if you can run this at a consistent pace for all four intervals, you can very accurately predict time in various race distances.

Last week Wednesday, I had a superb 4x1200m workout, averaging about 4:14.5 minutes per interval with only a few seconds variation between them. Daniel's book said this was good four a 17:57 minute 5k. My goal was to break 18 minutes, so theoretically, I should be able to do it.

Leaving work for the race, it was torrentially pouring out. It did not look like this would hit Manchester, so I would have to suffer through hot, muggy conditions, unlike last year when it was pleasant. That was sure to cost some seconds. CIGNA is a "corporate" race, where area companies field large teams. I had to ditch my company singlet and scare everybody with my pasty torso.  Thermal implosion was nearly certain, so the BAE logo had to go.  Like last year, I warmed up by running down the finishing hill and back up. One mile total at easyish pace.

Still got screwed lining up. A couple hundred runners fill in the last seconds before the start, pushing me back to about row eight. Still much better than 30 rows or so back like last year. We had a one minute warning, but no 3,2,1 go! Just the mayor firing the gun and catching everybody by surprise.

I stayed with Dan the first mile, who ran this nearly a minute faster than me last year. Either a) I was going out way too hard, b) Dan was having a bad day, or c) I was having a very good day. Turns out it was mostly a & and a little b. My first mile was 5:34.

The second mile is mostly down hill and should be at least 10sec faster than the first, but I was at least 10sec slower. This was very bad, as that meant I was probably going to implode on the last mile, which climbs.

One thing I notice in my running is that I seem to go downhill very well, which totally surprises me. I would never be able to descend well off-road, but I can really let it rip on pavement and surge past a lot of people hanging with me. Then when it kicks up, I get passed again. This is not the Hill Junkie way. What gives?

The third mile lasted for infinity. My core body temp reach critical, and I didn't think the finish was going to come soon enough. It started to spit rain, which did nothing but drive the humidity to 100%. There's a punchy one-block climb about 400m from the finish. Several kids running with me immediately dropped me. I caught nobody.  I crossed the mat at exactly 18:00 minutes. Assuming I was a couple seconds back to cross the starting mat, I should have met my sub-18 goal.

I punched it so hard to beat that 18:00 mark, that I had to pause hanging over the finishing chute rails for a moment. A couple volunteers rushed over to see if I was ok. I was breathing too hard to explain to them that I do this to myself all the time for fun.

Results were posted shortly after I got home. Imagine that, 5200 finishers and results up just like that! I was pleased to see my mat time was 17:58. This was within one second of Daniel's prediction! I like it when things work out like that. This put me at 5th in the 45-49 age group. I turn 50 next week, and this finish would have won the 50-54 age group this year. Something to shoot for next year. Maybe I'll even run more than 1.5hrs per week.

This run did some damage. When I got home, I was debilitated. The stairs were almost impossible to negotiate. My calves were completely locked up, and my quads refused to perform eccentric contraction. I screamed sitting down at the dinner table.  How can 18 minutes going hard do this? With D2R2 and a Colorado trip coming up soon, it's time to shift the focus back to the bike for a while. After that, I may entertain doing a couple 10k races this fall.

Monday, August 6, 2012

Taint Damage

Last Friday, Paul L and I hit a brand new trail network over in Charlemont, MA. Some riders may be familiar with this area as being part of the Hilltowns road race or D2R2 randonnee.  The terrain is steep. Charlemont Trails will be hosting a grand opening next weekend, and you can learn more about it on their Facebook page (scroll down for hi-rez maps).

I knew of the efforts at Charlemont for some time from NEMBA's Singletracks magazine. When Paul suggested we check it out on my off-Friday, I jump at the chance despite forecasted oppressive heat. Armed with maps and some play-by-play directions from Harold G, we headed off into the woods.

I kind of chuckled at the average pace of some of the Strava tracks I looked at from these trails. I think none of them averaged over 5mph. Plus Harold's estimated times for various loops and segments seemed extremely generous for "advanced" riders such as Paul and I. I figured we could cover the whole system in three hours.

It didn't take long to realize we were in for a hard day. Did I say the terrain was steep out there? Climbing was rarely less than double-digit grade. The tight trails partially benchcut into extremely steep slopes forced you to 100% concentrate on the trail. There wasn't fear of death exposure, but you'd certainly go for a long slide or tumble if you slipped off in many places. It seemed like for the first hour we did nothing but climb and we hadn't even rode five miles yet!

Many of you may be familiar with the phase "on the rivet." Way back, saddles were covered with leather riveted to the base. There was often a rivet at the nose of the saddle. When a rider was said to be "on the rivet", it meant they were head down, in time-trail position, forward on the saddle, going all-out. Well, climbing steep-ass grades puts you "on the rivet" for a different reason. If you don't keep your weight low enough and far enough forward, you end up wheelying over or losing steering control. Thus you must slide so far ahead on the saddle that it violates your nether regions. I must say the persistent, steep climbing at Charlemont left me with some taint damage.

Navigation was challenging even though the map was awesome. The only problem was there were not enough markings on the ground to orient one's self. Plus, there were more paths on the ground than on the map, thus you never knew if you were taking the right one or not. I'm sure it is obvious to the locals which path not to take, but to first timers, not obvious at all. We were constantly stopping to look at the map, back track, forward track, backtrack, then try another way. After a while, we just rode our freakin bikes.

One thing that is very easy to implement and provides huge navigational aid is to put waypoint markers at junctions. It only takes a small number on a tree and the map to do this. This would be more beneficial than the smattering of trail name signs in place now. Unique numbers provide absolute position on a map. That with a slight sense of direction goes a  long way in allowing one to navigate.

After reaching the height of land on the north side of Rt 2, we were hopefully in for some real treats heading back down.  The trails we planned to hit were Red Zone, TV Tower, West Side and more. Some of these trails are unidirectional. The descending was good, but it wasn't the kind of fast, flowy descent you would hope for after methodically picking your way up for over an hour.  The trail tread quite literally follows the nap of the earth. The undulations were quite fierce and required great focus to not get pitched over the bars. It was definitely a different kind of riding style than what I'm accustomed to.

Then there were the switchbacks. I pretty much suck at them. Paul was on a 29er dualie with a much longer wheel base than my 26" bike. Yeah, that pretty much made up for my suckiness. After Paul went "wide" on one particularly tight 180, I managed to stay ahead of him for the next dozen turns or so. This section was fun. You still couldn't let speed run out, but the every present risk of slipping over the edge, clipping a tree, or botching a switchback created a nice adrenaline factor. I bet we rode over a hundred 180-degree switchbacks while there that day.

After topping off water at the Zoar Outdoor Center where we parked (get permission to park there), we headed across Rt 2 to ride the Berkshire East trails. Route following looked easier, but I was quickly imploding due to heat and intervals workout earlier in the week.  Plan was to head up Bozrah and Hawks, then down E. Stranged Moose and Billy's World. Didn't look like this loop got much traffic. The climb nearly killed me, but the descent was quite sweet, around 800ft drop on very narrow singletrack with tons of switchbacks. It was a pretty good way to cap off the ride.

So my GPS showed about 21mi in 3.8hrs moving time. That is the slowest MTB ride I think I ever engaged in. And it kicked my butt.  So what's my overall impression of the Charlemont Trails? The area has huge potential. We did not ride everything there despite riding nearly 4hrs and spending well over 5hrs out on the trails. Marking needs improvement and may be a work in progress. Grand opening isn't until this weekend, after all. The trails could use some more buffing out too, to achieve more flow. There is a trend towards flow these days, although that can take great effort to achieve in New England terrain. Would I go back? Yeah, probably, armed with solid GPS track and more victims in tow. You have to bring your A-game climbing legs to really enjoy Charlemont. I haven't ridden anything quite like Charlemont in New England, so check it out if you want to try something unique.