Penn State's mentor group - CLOSED! (Page 21)

Kath2163 - 2010-04-21 7:14 AM

From what I am reading here, it sounds like a compact crank on a tri bike is the best way to go. Is that correct? 

zionvier - 2010-04-21 1:04 AM

A lot of the time it just takes hearing it over and over again to learn about it all.  Definitely don't feel funny asking a question about anything you're not clear on.  We all started in the same boat with this stuff and remember not understanding what the difference an 11T  vs 12T cog makes.

Some basics:
the T stands for "tooth", if you ever don't know what you have, you can just count the teeth looking things that stick up that the chain grabs on the cog on your cassette in the rear.  More teeth = larger cog = lower gear = easier gear.

low(er) gear = you spin the pedals fast and you still go slow.  You use a low gears to get up mountains... much like if you have a 4wheel drive car... you'll have 4wheel High and 4wheel Low... if you put it in 4wheel High you can still go fast, but in 4wheel Low the engine will be rev'ing and you'll still be going slow, like if you're out off-roading trying to get up a steep climb ;-) )

Basically: The closer you get your front sprocket tooth count to match the rear cog tooth count the lower the gear you are in.  So if you were in the big sprocket up front (50 teeth for instance) and you were in the big cog in the back (25 teeth for instance) you have 50/25 = 2.. so for every rotation of your pedal, your tire rotates 2 times.  But if you were in the 50 up front and an 11 in the rear, 50/11 = ~4.55, every rotation of your pedals would mean your tire rotated 4.55 times.  When you're going fast, if you don't want to have to pedal faster to go faster you would need to make that equation larger... 50/23 = 2.17, 50/21 = 2.38... etc.  Now for each rotation of the pedal that rear wheel spins faster making you go faster.  But obviously we also want it to be easier to pedal sometimes.  So you have two choices... Option 1 which you do all the time: get out of the big ring up front and go to the smaller one... 34 tooth on the compact doubles... so now you have 34/25 = 1.36.  Option 2, combined with option 1: go to the small chain ring up front AND make that rear cog bigger (like what we've been talking about... give yourself a 27 instead of just a 25)  34/27 = 1.26 

That same tooth division is the same on motorcycles... except they have it where the rear cog is bigger than the front.  My motorcycle has a 14 up front and a 48 in the rear (I'm making those up, but I believe they are pretty close to being true).  14/48 = 0.29.  But that's because my motorcycle engine can "pedal" at 8000+ rpm and if you had a 50/25, my rear wheel would be spinning 16,000 times per minute instead of 2320 times/minute... I'd be dead before I knew it what happened   We as humans can't do 8000rpm... we like the 90rpm a little more, so we need more help.


Hope some of that helps... I'm an engineer, so I hope it didn't sound too technical or "mathy".  But you can do some simple math and find out a mathematical number to judge how big of a difference going from a 25 to a 27 or going to a 29 like dharris13.  Then compare that number to the difference you feel changing from your 23 to 25... How much does 34/25 = 1.36 vs 34/27 = 1.26, a 0.1, difference make?  Quite a bit.

zionvier - 2010-04-21 1:59 PM Quiet day today.... is this everyone's rest day or something?!  I'm feeling a little fatigued from the last two weeks of workouts.  I need some motivation to get out for an easy recovery run or something after work.  What's everyone's workout plans for the day?.... make me feel lazy and motivate me

dharris13 - 2010-04-21 12:44 PM

Your logs look real good! Keep up the awesome workouts!! Your running base seems so amazing. I hope to get there sometime. I was actually looking in to a 50k at the end of this year. How long did you build to be at 15 hours running a week?

Today is an hour and half ride...if my back loosens up :/

Tomorrow will be a nice workout day though! 1.5 mile speed continuous swim in the morning...then a 13-14 mile run!!

calimavs - 2010-04-21 2:22 PM No rest day for me, I have track tonight. I'm going to try to take it easy and NOT hurt myself,

dharris13 - 2010-04-21 1:00 PM

Yeah good call. We are less than 10 days awat from wildflower!

WittyCityGirl - 2010-04-21 2:48 PM
Question that I just posted on the IMLP thread:

Would someone look like a wuss for posting a 15mph average on the bike of an Ironman if it meant not totally bonking on the run?

I think in my head that this is a question similar to "is it okay to walk during a road race"... I think I need to look at last year's splits!

WittyCityGirl - 2010-04-21 4:48 PM Thanks for the gearing post (that I got to read during work because the boss FINALLY got out of the office during a work day <- boss at the office puts a damper on my BT time).

Question that I just posted on the IMLP thread:

Would someone look like a wuss for posting a 15mph average on the bike of an Ironman if it meant not totally bonking on the run?

I think in my head that this is a question similar to "is it okay to walk during a road race"... I think I need to look at last year's splits!

PennState - 2010-04-21 6:35 PM That really is coming up soon. Excited?

PennState - 2010-04-21 3:35 PM That really is coming up soon. Excited?

dharris13 - 2010-04-21 6:29 PM

Not even close to a wuss!! IMHO you do what you have to do to cross that finish line in 16:59:59 or less. Swim at your own pace, bike your own pace, and run your own pace. You will be an IRONMAN!

IdealMuse - 2010-04-21 7:11 PM This gearing talk is timely as I'm trying to figure this out for my bike as well, but I'm still very overwhelmed and only just starting to understand gearing. My training group coach says 12-25 is good for IMOO but I read a lot of people go with a 12-27. Some suggest at 27 is *NEEDED* Campy doesn't seem to have that gear ratio or at least the guy at the bike store said my available option would be 13-27. I don't want to lose too much of the top end of my speed range either though... I have fairly strong legs, but I am also carrying some extra body weight (181 currently) I apparently have I think a 11-23? Don't want to invest too much more in this bike so I don't think a compact crank is really and option right now. Any words of wisdom? (It's a Campy Veloche 10 speed standard crank) Please make my head stop spinning.

JoshKaptur - 2010-04-21 8:55 AM

It totally depends on the course profile and your strength as a cyclist.  My gut feeling is that for most MOP women, a compact DEFINITELY makes sense.  Or, ask yourself this way... how many times have you been in your biggest/hardest gear and wished you had a harder one?  How many times have you been in your easiest gear and wished you had an easier one?

Compact will gain you some easier gears and lose you some harder gears.

As an example... I ride a HIM at just under 20mph unless there's a lot of climbing... and I have a compact casette.  That basically makes me FOMOP (front of the middle of the pack) who is happy with the compact.  If I was just bike racing, I'd get a standard front because I could handle it and I'd want to eek more speed out of my descents.  But with the goal of saving my legs for the run, I've never wanted a harder gear in a tri and rarely do I want it in training.