Minuteman Road Club

I'm heading over to the Pat Bell TT in Southboro tonight if anyone else is interested?

http://www.patbelltt.com/home.html

Just curious -- I've thought of doing it on my road bike just for kicks.... Do you have a road bike or a TT "rig".

Road bike for me. There is a wide group of riders that show up for this ride. Some are on TT bikes w/ aero helmets. Others are riding bikes with clips for pedals.

So just for kicks I headed over to the Pat Bell course for a quick solo ride after work. The big question I have for some of you Tri/TT guys is how much time savings is a TT bike worth (over my stock road bike w/ no attempts at any aero equipment) on this course at my avg. speed? Just curious. Some observations I made:

1) 12 minute warm-up = not enough. Arrived at 4:30 and had to be home in Franklin by 6, poor timing...
2) I started my computer at the "electrical box" on 85 and stopped it at the "Faye School" sign on 30, but my total measured mileage was 11.34 miles, not 11.7 as the website says. I didn't see any opportunity to shortcut the course, am I missing something? Maybe I need to recalibrate my computer, although it is GPS based, so I wouldn't expect that much error.
3) The hill on Rt. 30 at mile 7 hurts I didn't pre-ride so I didn't know what to expect. I think knowing the course will help me to better meter my effort in the future.
4) I have no delusions of grandeur , but I was definitely humbled by looking at some of the times posted by MRC'ers on the Pat Bell website. Good job!
5) It was a ton of fun (after it was over), and I'll be back on a Tuesday night for sure.

My stats:
Measured distance: 11.34 miles
Time: 31:39
Avg speed: 22.2mph (if 11.7 miles), 21.5mph (if 11.34miles)
Max speed: 34.0mph
HR Avg/Max: 168bpm/176bpm (my Max HR is ~185bpm)
Avg Cadence: 89rpm

Any words of wisdom for next time? Any insight into the relative time savings of a TT bike for this course and my speed? Thanks.

---Chris

I would think that you could knock off a minute- minute and a half using tt/ aero bars.

you could probably knock off an additional 30-40 seconds by doing a good warm up.

I hope to make a few appearances this year on Kimball's ole tt bike. If Orapin were in shape you could watch her devour the Hills !

Hey Chris,

Fluid Mechanics 101: Your drag force is proportional to the square of the velocity. So, reducing this force will have measurable effects on your TT speed.
Frame shape/geometry has an impact on speed but it's number 5 on my list in terms of things you can do to go faster. Here they are in order of importance/impact to your speed:
1) TT bars: your body creates the most amount of drag force because it presents the largest amount of area to the wind. So creating a small profile/frontal area to the wind is crucial. If you make no other investment in equipment for time trialing, make sure it's a good set of bars that are adjustable.
2) Warm-up: should be 30-45 minutes and include several short (~3-5 min.) intervals at TT pace. This will release the buffering agents into your bloodstream that will aid in processing lactic acid which will enable you to turn the gears faster.
3) Wheels: next in line for drag force reduction is the rotational drag created by your wheels. The front wheel accounts for something like 65-70% of this. So, if you're short on $$ and want to make an aero wheel purchase, start with the front first and get the rear later.
4) Clothing: A skinsuit or closely fitting jersey can help. Something that flaps in the wind like a parachute will slow you down.
5) Frame: the last major piece in the drag force reduction can come from the frame. I list it near the end because it presents the smaller frontal area to the wind compared to your body.
6) Misc: aero helmet, shoe covers, bottle holders - all contribute some amount of drag but they're neglible at 22 mph compared to the other things mentioned about. But, they become much more significant as you approach 30 mph. Again, drag force is proportional with the square of the velocity (or speed).

Hope this helps!

Pretty much agree with the points Rich makes above but will put my own spin on things especially the frame.

I agree that from a air resistance perspective the frame is low on the list but what I think is much more important about the frame is the geometry. Slapping a set of tri bars on a road bike has limited effect. You may feel fast but that's about it. If you get low and aero on a standard 73deg road bike you are closing your hip angle to a point where you loose power and pedaling efficiency. This is why TT and Tri bikes have steeper seat angles that rotate the body position forward and allow you to get into a good low aero position without closing the hips. All this said a new bike can be a lot of cash and a lot of headache to get past the wife/husband so i would still go for a set of tri bars and move your saddle as far forward as you can (note: as you move your saddle forward you will need to raise the post to keep the same distance from the bottom bracket) until you've decided you want to get into this aspect of the sport. Dave Corso posted a very interesting Endurance Nation article on tri bike fit that explains a lot of this on one of the forums. I will look for it later and add in the details. (details now added: https://www.box.net/shared/xu23878c8t)

From an air resistance perspective Rich's point are all good especially the benefits of them if you are not going 22+ MPH. The more recent thinking from the guys in the wind tunnel at MIT is that aero helmets are more effective than an aero front wheel. An aero front is more effective than a rear as Rich says and a loosely fitted race number can take several seconds of your 40K time this is why some people are now gluing their numbers on.

Lastly. Skin suits, shaved legs, shoe covers, an all consuming passion for numbers and a total lack of personality are required to be a time trialist. Anyone fancy doing the Charlie Baker with me next week

Not much useful techie input, since I don't ever time trial EXCEPT to improve my ability to hold a high power level for a long time on my road bike. If, like me, you're only doing TTs to improve your prospects of being in a winning break in a road race, then IMHO you should do the TTs on your road bike. If you're going for the numbers, then see the previous posts...

BTW, the Charlie Baker TT course is a good one, and very safe. And this year they repaved the two sketchy parts of the course, so it's as smooth as butter for the whole 9.75 miles.

Smudger wrote:Anyone fancy doing the Charlie Baker with me next week

John, I did it last night for the first time since '07. That's why you saw me in Concord center last night. You should be able to better your PR this year because of the newly paved section on Monument St!

Good point made by John about the seat tube angle.
It takes a bit of trial and error but I got it to where I knew precisely how far forward to move my saddle on the rails, how high to raise the seat post, and how far to tip the nose down. I wasn't aware of the revelation regarding helmet vs. aero wheel wind drag. I wonder what Steve Hed would say about that.

Charlie Baker next week: Rich Person and I were actually talking about that today at lunch. If the weather cooperates, our plan is to ride there from Cambridge, do the TT and then continue the commute home. It'll be the longest Wednesday of the year in terms of daylight so why not?

I have long said that TT bars on a road bike can actually slow you down because of the power loss associated with the new position. It's more aero but who cares if you can't push hard.

My best times on the PBTT are using my regular everyday road bike, no aero anything. My best time with aero bars is about 45 seconds slower.

Great stuff... I know exactly what you mean about hip angle, it's obvious to me even on my road bike that I can't generate as much power when I am tucked way low, so at what point (ie. lowness of tuck) does the reduced power balance out the aero benefits? Hard to say... Probably different for every person.

John, great link, lots of good info. Thanks.

Wow, I didn't realize TT-ing was so complex. I will give it a whirl. If nothing else, Zone 5 workout

I pretty much agree with Rich also...

I've done some comparisons on my non-aero road bike vs. same road bike with aerobars/disk rear/zipp808 front/skinsuit/aerohelmet/shoecovers ... and the aero gear (in my case) helps a lot. On the order of 1.5 minutes, mayyybee 2 minutes on a fast calm hot day. I don't ride in exactly the same position aero/non-aero, even tho it's the same bike, my position is more forward when aero. Wattage loss is minimal (for me), around 10-20 watts tops, which is way made up for with the aero gear and increased aerodynamics. I've always had a fairly large difference between non-aero and aero gear rides, with my aero rides being 1.5 - 3 minutes faster, depending ont he course.

This probably means that my aerodynamics are not great when I'm non-aero, and they are excellent when I'm aero, and wattage is minimally impacted.

Others may have better non-aero positions, and not so great aero positions / wattage gaps. I have also known people, like M. Cole who were actually slower on aero rigs!

The course is somewhat technical, deceptively so, and riding it repeatedly will help your time.

As far as the distance, I'm not sure, but we measured it with an official measuring wheel some time ago. it was discussed in detail years ago, and 11.7 was what we settled on.

Good to chat about the TT - I miss it. Had knee surgery this past Thursday. Check out the photos of the chunks of cartilage they took out of my left knee. Those had been in there for 2-3 decades, seriously.

what does it say about me that I think those pics both really gross and really cool?

eew

Please post those things with a parental advisory - I don't want to feel like puking when I read the message board.

Yeah, somehow they don't seem so gross when they are YOUR OWN chunks o' cartilage... but when they belong to someone else, skeevie!