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Discussion Starter · #1 ·
Thinking of doing a 10 mile time trial fixed, Eddy Merckx style bike (but with front brake). What gearing would you use? The course has several turns, a slight hill over about 400 yards, and typically a 10 mph tail wind at the start and 10 mph head wind at the end. Would you gear attempting to estimate your average speed, then figure about 95-100 rpms at the average? Better to gear too low or too tall? Thoughts? Thanks.
 

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A very interesting problem

The hazards are:

-on the one hand, you gear too low, and you spin out and go slower than you could on the downwind stretch and the downhill.

-on the other hand, you gear too high and bog down on the climb and the headwind section, thereby losing speed and time in two critical sections, especially the finish.

The answer depends in part, of course, on how wide a range of cadences you're confortable with, though I know since you ride fixed a lot you're better than the average roadie in that respect.

I suspect I'd gear around that upwind finish leg. Estimate what speed you can sustain there at the end of the effort, and go for 90 rpm or so there. You'll be a little undergeared for the downwind start and especially the descent, but you can probably handle that much spinning (a 400-yard hill at 30 mph will take less than 30 seconds). You'll be overgeared for the climb, probably, but for a quarter of a mile you can stand up and gut it out.

This approach may get you to about the same number as your average-speed suggestion, of course.
 

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Somebody as fit as you are can work very hard to maintain cadence for 2.5 miles. I'd try the last quarter of the ride, including the headwind, looking for a gear that you can barely keep at 90 rpms. On race day, you know adrenaline will get you to the finish spinning close to 100.
 

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Discussion Starter · #4 ·
thanks

Spinfinity said:
Somebody as fit as you are can work very hard to maintain cadence for 2.5 miles. I'd try the last quarter of the ride, including the headwind, looking for a gear that you can barely keep at 90 rpms. On race day, you know adrenaline will get you to the finish spinning close to 100.
Thanks, I'm going to give it a shot April 16. Spin and mash, spin and mash... ;-)
 

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Let us know how it goes

Fixed said:
Thanks, I'm going to give it a shot April 16. Spin and mash, spin and mash... ;-)
BTW, the two responses you got show that there is near-unanimous consensus on this issue among all roughly-60-year-old fixie riders in Glastonbury, Connecticut. You might want to hold out for a broader opinion sample ;-)
 

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Discussion Starter · #6 ·
silent majority?

JCavilia said:
BTW, the two responses you got show that there is near-unanimous consensus on this issue among all roughly-60-year-old fixie riders in Glastonbury, Connecticut. You might want to hold out for a broader opinion sample ;-)
Good point, but knowing people around here, if anyone disagrees, I'd imagine they would pipe up. ;-)
 

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Back in the 1990s.

For what it's worth, I did two 40 km time trials fixed, using a 3 : 1 ratio (81"). Course was flat and there was no or very little wind. On the identical course under similar conditions, my geared rides before and after my fixed experiment weren't any better or any worse.
 

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JCavilia said:
The hazards are:

-on the one hand, you gear too low, and you spin out and go slower than you could on the downwind stretch and the downhill.

-on the other hand, you gear too high and bog down on the climb and the headwind section, thereby losing speed and time in two critical sections, especially the finish.

The answer depends in part, of course, on how wide a range of cadences you're comfortable with, though I know since you ride fixed a lot you're better than the average roadie in that respect.

I suspect I'd gear around that upwind finish leg. Estimate what speed you can sustain there at the end of the effort, and go for 90 rpm or so there. You'll be a little undergeared for the downwind start and especially the descent, but you can probably handle that much spinning (a 400-yard hill at 30 mph will take less than 30 seconds). You'll be overgeared for the climb, probably, but for a quarter of a mile you can stand up and gut it out.

This approach may get you to about the same number as your average-speed suggestion, of course.
I'll chime in belatedly.... I was holding out for lack of anything insightful to add, but I'll go ahead and add it anyway...

I think the 400 yard hill, up or down, is a pretty minimal factor in the 10 mile ride. Any gearing that is optimized for the flats will work fine enough for that short hill, in both directions, unless it has a horrendous grade. The bummer is that the tailwind is at the start... rather than the end, but it's workable, too.

I think one factor is the distance of the headwind stretch at the end.... 5 miles of headwind would warrant some respect in the gearing, but a mile or less maybe not so much.

Option 1: Respecting the headwind (a 3+ miles or more of it): I think the effort for this section needs a dominant consideration in the gearing. A prolonged, over-geared slog into a headwind at the tail end of a TT could drive your time way up. In this case, slightly undergearing for a typical, flat-out effort on the flat may be worthwhile to avoid blowing up on the headwind finish distance.

Option 2: Headwind, schmeadwind ( a mile or less of it): In this case, the tailwind will not be of much help either, I'm thinking, so gearing for a typical, flat-out effort on the flat ought to do the deed.

In both cases, the climb will be out of the saddle for a bit, and the descent will spin-out a bit, but neither is very long...
 

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I think a fixie would be a superior TT machine if the course was a false flat the entire way, there was no wind (or at least, no tailwind), and only gradual turns. But if you're thinking of using a fixie in a TT, winning probably isn't the number one priority.
 

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PS: The use or yards in describing the hill made me think that referred to its length, rather than its elevation. 400 vertical yards would be different...
 

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Impossible to tell you what kind of gear would be right since I'm not sure of your abilities. However, too light is better than too much gear and, if you know when to pedal hard, the hill is a non-factor. If it were me, I would do a 54x14 and float the gear a bunch on the fast parts of the course and hammer hard just before the hill and over the hill and coming back with the head wind. You could actually be faster on the fg than on a geared bike.
 

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I'd want to hear from Peter before declaring consenus. If he disagreed, I might well change my mind.
 

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Discussion Starter · #13 ·
you're faster

Sherpa23 said:
Impossible to tell you what kind of gear would be right since I'm not sure of your abilities. However, too light is better than too much gear and, if you know when to pedal hard, the hill is a non-factor. If it were me, I would do a 54x14 and float the gear a bunch on the fast parts of the course and hammer hard just before the hill and over the hill and coming back with the head wind. You could actually be faster on the fg than on a geared bike.
You are undoubtedly faster, but the principle is what I'm after. Last summer I was time trialing about 25.5 mph for 10 miles, but on a full on TT bike. I'm probably giving up 2 mph on aerodynamics alone. So, assuming that, the question, I think, is do I gear for the average speed, probably about 23 mph on this bike with these conditions, or more so for what looks like the hardest part, about 3.5 - 4 miles into the wind on the finish leg.

I would love to be able to push a 54x14 the entire way.
 

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Fixed said:
You are undoubtedly faster, but the principle is what I'm after. Last summer I was time trialing about 25.5 mph for 10 miles, but on a full on TT bike. I'm probably giving up 2 mph on aerodynamics alone. So, assuming that, the question, I think, is do I gear for the average speed, probably about 23 mph on this bike with these conditions, or more so for what looks like the hardest part, about 3.5 - 4 miles into the wind on the finish leg.

I would love to be able to push a 54x14 the entire way.
Well, if you put aero bars on there (and maybe the brake on the aerobar instead of the bull horn, this could be pretty effective. For many years, the Brit 10 mile TT records were all done on a fixed gear. It's fast. You can float the gear a lot. Use a slightly smaller gear than you think is max and go for it. As I said, if you float the right parts and hammer the right parts, you will be faster than on a geared bike.
 

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Spinfinity said:
I'd want to hear from Peter before declaring consenus. If he disagreed, I might well change my mind.
I should have said "substantial majority" rather than "all."
 

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Hey, Doug, I want to hear how it goes. Me I'd crank back just about one click on the cog from what's the max I think I could get up the worst hill on the course. Let her rip!
 
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Hey Fixed, have you done your TT yet? I just did a 12-mile TT fixed as part of a duathlon yesterday. The course was rolling but the hills weren't too steep, and I used an 81-inch gear (42x14). I waffled all week about what gear to use. I live in a pretty hilly area and typically ride a 70-inch gear for just getting around, but I spin out downhill. I was very happy with the 81-inch choice because the course had lots of long, gradual downhill sections. Of the cyclists I was around during my ride, I was passing most on the downhills and holding my own going uphill, and my bike leg ranked 26th out of 161. Although I've done flat TTs with my fixie on auto racetracks, this was my first one on the open road, and I can't imagine going back to using gears for a TT unless it was mountainous. However, I'm mostly a recreational rider and have nothing big at stake. If you like riding fixed, you'll love the TT fixed. Be sure to update us on how it goes.
 

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Discussion Starter · #19 ·
interesting

vw_steggie said:
I have no information to offer on setup, but the guy who rides this bike is my fixed-gear hero:

http://www.fixedgeargallery.com/2008/sept/2/MikeHayes.htm
I have a Cervelo P2C, which has rear opening horizontal drop outs. I suppose I could run it fixed, too. Problem is, I've done out and back time trials here where I averaged 32 mph one way and 20 the other. Don't know how that would work fixed.

I have one coming next week, April 16. I was going to do it on my Pista, removing the bullhorns and installing drop bars. If I'm going to mess with doing it fixed, I think I'll stick with the classic bike setup. These are just a club kind of thing, anyway, and the rules for the more important events I do fixed all require the classic type fixed bike.
 

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Discussion Starter · #20 ·
next week

foothillsbass said:
Hey Fixed, have you done your TT yet? I just did a 12-mile TT fixed as part of a duathlon yesterday. The course was rolling but the hills weren't too steep, and I used an 81-inch gear (42x14). I waffled all week about what gear to use. I live in a pretty hilly area and typically ride a 70-inch gear for just getting around, but I spin out downhill. I was very happy with the 81-inch choice because the course had lots of long, gradual downhill sections. Of the cyclists I was around during my ride, I was passing most on the downhills and holding my own going uphill, and my bike leg ranked 26th out of 161. Although I've done flat TTs with my fixie on auto racetracks, this was my first one on the open road, and I can't imagine going back to using gears for a TT unless it was mountainous. However, I'm mostly a recreational rider and have nothing big at stake. If you like riding fixed, you'll love the TT fixed. Be sure to update us on how it goes.
Doing it next week. Wind is much more of a factor than hills, for these. What kind of speed did you average with that gearing?
 
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