"She's a strong rider but needs some more gears to be able to push it on the downhills. "

Just remember that you also have to go uphills. It usually doesn't make a lot of sense to spin downhill IMO. I can always go at least as fast by tucking aero and coasting.

It usually doesn't make a lot of sense to spin downhill IMO. I can always go at least as fast by tucking aero and coasting.

Doesn't it depend on the hill, though? People always say it's better to coast downhill, but let's say you're on a long, gentle downhill. You're not going to coast down too fast, but with some big gears, you can really fly. ( let's say a 2% grade? )

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"People think it must be fun to be a super genius, but they don't realize how hard it is to put up with all the idiots in the world."

54, 55, and 56 tooth chainrings are readily available. The Shimano SuperRings look pretty cool, as do the FSA TT chainrings. I run a 54t FSA to match my FSA carbon cranks. These size rings should be readily available from your tri-aware LBS.

A 54 x 11 on 650c is good for 36+mph at a reasonable cadence.

I have heard rumors of bigger rings, but only for guys like Bjorn. They would most likely be a special order.
http://www.trisports.com/shimduracetr.html

http://www.trisports.com/trichainring.html

Take a look at http://www.analyticcycling.com/...eedCadence_Page.html

My wife runs a 54/42 chainring, 12-23 8 spd cassette on her 650c tribike. We calculated and calculated to see if putting a 55 up front or an 11 in the back would be beneficial. Then we asked around at our LBS to get their input.

Our conclusion was that the extra force required to push these harder gears would not take advantage of her excellent cardio and cadence ability and could possibly have a bad effect on her run.

If she truly does spin out of her 53 then get her a 54. I think 54 comes standard on many 650c bikes.

Thanks for the help. I'll try a 54 and switching her to an 11-23 versus the 12-23 she's running now. Her pedal cadance is right around 80 so a little lower than some still in the range. She spins out even on slight downhills, I've still got 3 or 4 gears to go (53/39 12-25 700c) and she's spinning like crazy. Thanks for all the advice.

I run a 53-39 front with a 11 x 23 cassette and for almost every occasion it works great. Yes I can spin it out on a 40+ mph downhill but at that speed it uses less energy to coast rather than pedal to gain more speed. I don't really see a need for a larger front chain ring.

But then again, I like the idea of compact cranks on a bike with 700c wheels.

I run a 44/55 front with a 12/23 cassette. If I know the course is smooth I will run a 12/21.

jaretj

I normally run a 55/44 on my bike with 650 wheels. But I have been known to show up with a frying pan looking chain ring every once in a while. I took the 62 out last week and gave it a run and I remember why I used to like it so much. If there aren't any super big climbs, the 62 allows me to stay in the middle of the cassette most of the time on flats and small rollers. That means I still have room to go up or down on the cluster depending on if the road goes up or down. I was still spinning the same cadence when going hard (high 80's) but with the big ring, I was in the middle of the cassette and going 27 as opposed to being at the bottome of the cassette. The first little downhill we hit, I was able to accelerate up to 38 and still pedal while the others didn't have the gears to do that. That gap was all that was needed and it was never closed up the rest of the interval (5 miles). Coast all you want, if you don't mind getting second.

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Mike Plumb, TriPower MultiSports
Professional Running, Cycling and Multisport Coaching, F.I.S.T. Certified
http://www.tripower.org

I used to ride a 55/42 chain ring combo and 11/21 on the back, with 650. I like to downhill as fast as I can so thought about going to 56 or more on teh front to try and beat 100km/hr (63mph) on a descent. (maxed at 97km/hr for now...damn)

I'm also a real wuss for pushing the pedals hard so I've actually gone the other way and given up on top end downhill speed and gone for better chain lines and higher candence on the flat and rolling hills. I now ride 53/42 (gonna get a 40 soon) and 12/21 at the back, soon to be swapped to a 12-23 or 12-25 (depending if I get the 40 up front or not)

Remember that front deraillers don't like it when the chain rings differ by more than 13 teeth. The chain tends to drop off on down shifts and can be difficult to pick up when shifting up. Particularly with short chain stays on 650 bikes.

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TriDork

"Happiness is a myth. All you can hope for is to get laid once in a while, drunk once in a while and to eat chocolate every day"

If she is spinning out that fast, maybe she needs to work on her cadence. I would consider spinning out to mean 110+ RPM, which for my 650C 53/11 means over 35mph.

Quote "That gap was all that was needed and it was never closed up the rest of the interval (5 miles). "

Hey, does this mean that if you were my coach, my intervals include coasting downhill? I can do that!

:-)

I am running a 56-44 on my 650's. I also runa 23-11 cassette. I have been riding this set up for two years and still can't come close to spinning this out. To give you an idea, my best 9 mile TT is under 20 minutes. 19:51. Unless I go downhills, I can't really justify using the 11 on my cassette. I usually switch between the 14 and 16 for most courses. However, I am a much better flat/rolling course rider than a hilly rider/.
I would recommend switching to a 54 tooth big ring. Anything else might be a little much on hilly courses.

I always have this same question when I hear about 62-tooth chainrings. To those that use them: do you pedal really slowly, or are you really spending most of the time at 25mph+? 62 x 12-23 x 650 at 90 rpm's is a range of 19 - 36mph, the middle of the cassette is 25-29mph. (I suppose I'm just concerned about being a big wimp for using a 53 on a 650 bike :) )?

Chris

I used to use a 55/42 on my 700 bike and usually race on 11-23. I find that I can make up some of what I lose on the uphill (did I mention I SUCK at climbing) by spinning up on the downhill before going into coast mode.

I've hit 56 mph in races and 72 on a descent that about scared the crap out of me. Since then, I don't go for top speed (PR) anymore, but still like to catch folks on the downhills.

My new Rotor Crank adorned race bike is 54/39 and I like the ratios. With 11-23, I sometimes have trouble on climbs, but then I'm gonna suck there anyway... Yeah, yeah, work on your weakness, I know. Problem with the Rotors is that they start to feel lumpy above 110 rpm.

I think you're gal should spend the upcoming winter spinning a smaller gear and will come into next season faster for it.

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Cousin Elwood - Team Over-the-hill Racing
Brought to you by the good folks at Metamucil and Geritol...

Use a gear-inch calculator ( http://www.panix.com/...pcgi-bin/c41strt.cgi ) and plug in some different chainrings and cassettes and you'll find what you need. It'll show all sorts of things, including gear-inches and cadence / miles per hour.

I'm a bit surprised she's spinning out, though, because with 650 wheels and a 53-11, at 90rpm you're doing about 32mph, and at 110rpm you're doing about 42mph! Of course, where I live on the coast it's flat as a pancake so there's no "downhills".

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http://irondad06.blogspot.com/

http://irondad.blogspot.com/

I run 55/42 with a 12-25 casette for training and 11-23 for nearly all competitions.

Considering that 55/42 is a bit smaller than 53/39 on a 700c bike, there's nothing special about this. If 56 or larger would work with a 42 chain ring I would probably go up even further.

Simon

it's not that she's spinning out, as in can't pedal any faster it's just that when put in the situation of a good tailwind, a fast pace group, and a mild downhill, she's having to spin a little faster than she'd like and she's already in dropped to the smallest cog. Plus she's pretty light so on some big downhills it would be nice if she could accellerate to speed faster before coasting so she doesn't get passed in the beginning of downhills. I used to run a 53/42 with 11-23 on the back on my old 650 softride but I spin pretty fast and am comfortable at over 100rpm. She's not that comfortable that high.

Thanks for all the advice, I know she'll really appreciate the gearing coming down from Hawi this year. It's her first Ironman and first Kona (hey might as well knock them both off in one shot:)

The 62 ring sure sounds impressive. I think I'll make a fake 80t outer ring and just mount it on my bike for looks!