patentcad

Right, I know, you're reading the title thinking that old fart Pcad wants to know your racing age.

Incorrect.

Your big chainring tooth count. I have ordered a 55. In training for TT's it seems to me the difference between a 55 and a 53 is only on click of the rear derailleur, but more speed on the descents, which did strike me as a key factor in going fast on rolling TT courses. I considered a 54T, but that seemed rather pointless, so I opted for the Big Mama 55.

UT_Dude

Unless you're regularly spinning out, stick with the 53 for now. Maybe eventually a larger chainring to run a straighter chain, but no need to rush into it.

waterrockets 

Yeah, bigger rings are for bigger power. A 53x11 will get you 38.7mph at 100rpm and 53.1mph at 130rpm.

How long are you going to be going over 40 in a race? Personally, I'd be able to put out good TT power anywhere south of 130rpm for an extended period.

merlinextraligh

53x11 is 39 mph at 100 rpm. Unless the course has really steep prolonged downhills, I doubt you'll be spinning that out.

A short downhill above 40mph probably better to catch your breath for a seocnd.

Conversely, with the bigger front chainring, you may find yourself going to the small ring on climbs more often which is a bit of a hassel.

Our TT's down here are pretty flat, but I rarely find myself inanything bigger than 53x14

Snap

I rode a friends TT bike yesterday with a 54 chainring and 180 crankarms. I felt like my cadence was way to low for the whole ride. I think I'm going to run a 53 with 175s. I haven't had a problem spinning out with a 53-12.
+1 to Merlin. TTs here are flat.

Andy

cheezhead

You should choose the size of your front chainring based on what gear of your cassette it puts you in while hammering on the flats. The idea is to have as straight of a chainline as possible to reduce friction. If you have a 53 and you find yourself always riding in your 13-12-11, then it's time for a bigger chainring. If you have a 55 and you're always riding in your 21-19, then you need a smaller chainring.

Also take into consideration that different size chainrings will slightly affect your cadence because the gear-inches don't line up perfectly. If you like to TT at a specific cadence, you might want to keep this in mind.

cslone

I switched froma 53 to a 55 for a few weeks. I switched back because I could never get comfortable with that gearing for some reason. The cadence always seemed too high or too low.

DrWJODonnell

Knowing what PCad is talking about, I am using one of two setups (with the first more likely): 54x39 with a 11-25 DA cassette, or a 54x39 with a the 11-26 SRAM.

I use the 54 in all of my racing (it is on the SRM crankset) and I like it because it gives me just a wee bit more top end, but I don't have to change the derailleur setup, nor do I have to go with the 42 for the small (54/39 shifts just fine...at least with Ultegra and Dura Ace FD). I am thinking 55 would cause you to have to be in the be big ring only, or need the 42 inner ring. Using the bigger range of cassette you will be able to handle both climbs and descents, say if you were to do a TT like, oh, say silvermine.

ratebeer

1 The mechanical efficiency drops as your rear gear gets small (by a whopping 2+%)
2 Larger rings mitigate the need for these smaller rear gears

1 Although best performances are often at high cadence, oxygen efficiency may be better at 74 rpm
2 So it might be very beneficial to be nowhere near spinning out when you're at your race's most critical junctures

The amazing brains of Joe Tucker say: pcad did the right thing

patentcad

Thank you, my confusion is complete. No matter. Pcad's slowness will defy any pathetic attempts on his part regardless, but the hand-wringing on BF is well worth it.

roadwarrior

I hate to break it to you....

but a friend of mine's sister in law rides a 56 FSA tt ring on her tt bike.

Seriously.

cat4ever

I just went from a 53 to 54 for no good reason except that I got rid of an 11-21 cassette and am now using a 12-23.


Like that made sense.

UT_Dude

I shall sum it up for you. You don't need one. Save your $$$$. Better yet, give your $$$$ saved to me, and i'll make you faster.

FatguyRacer

Why don't we all be honest and just say we like/use the 54 & 55t rings cause thats what the pros do.
Who doenst think that big pie plate chain ring with a 11-21 corncob out back on a TT rig looks cool?

patentcad

I rode that Silivermine course and the descents were long and pretty ballistic. The 55 made sense to me. But that might mean do the opposite. I'll pay for the 55 and hang it in the garage as a reminder of my stupidity. Which is not particularly necessary, but helpful nonetheless. Hopefully Dr. W. is in a charitable mood on the 16th and will sign an autograph for me. I'll tell him it's for my daughter who's a big fan.

DrWJODonnell

Get Mike G's hancock. He is the one who will slaughter us all. If you want, buy me the FSA 56 Carbon TT ring and I will use it at silvermine. Then I can tell you whether you should have used it or not.

patentcad

Mikey G. is my peloton pal (he's the nicest guy in the world, great dude), I can get his autograph any time. On the other hand Dr. W. is sort of like Howard Hughes, a mystery man whose exploits I only hear about through BF, even though I spend many weekends chasing his team mates @ 30mph. It will be big fun to meet you there WJ. I know what your bicycle looks like. Look for my Cdale.

I hope to get at least one more ride in on the Silvermine course before that race on my Zippified Slice. I actually have yet to ride that Slice with the Zipps. That should be faster.

CrimsonKarter21

Kind of a seperate question, but; what about foot speed?. I like 165's on the track, and I'm not a super-powerful mashing-type rider (yet), and I like high cadence as well as moving my feet fast. Does anyone think it could hamper (already slow) sprinting speed?

patentcad

Chris Walken for President? I like that.



I would never refer to Mr. Walken as a Fred. Now that man is badass. I take him in the Chuck Norris vs. C. Walken WWF Slamdown on Pay Per View.

nitropowered

I know a guy that used a 60t ring

patentcad

I think that was Christopher Walken.