SD Fixed

I feel that now, I've advanced enough that I'm not getting enough out of my bike, at least gearing wise. So I'd like to gear down (is this the right term). So, I have some questions:

Is it more desireable, or is there a benefit to changing the front or the rear of the bike?

If I change the front, can I change the largest ring only, or do I have to change both? Along with that, is it better to replace the whole crankset, or just the ring?

In the rear, what limitations are set by having a shimano Rx100 hub?

I live in a hilly area, so I don't want to go too crazy, but I feel that I can use the better ability.

TIA!

1oldRoadie

Before these questions can be answered you has to give a little more information.

Road or mountin'?

What chainrings (front) do you have now? (if you look on the gears themselves you can see a number stamped in them i.e. 39, 42 , 52,53.

How many gears do you have in back? 6, 7, 8, 9? And count the number of teeth on the largest one.

Are you wanting to go faster? or climb harder hills?

MichaelW

Changing the front will shift your entire range. If you have top gears which you never use, you can swap to smaller front rings to shift your gear range down. I used a 36/48 double for a while and liked it a lot.
If the size of the bolt holes is limiting your smallest ring, then you may want to change the crankset. Most road cranks have a Bolt Circle Diamter of 135mm (Campagnolo) or 130 (Shimano).
TA and Stronglight make cranks with smaller BCDs for smaller chainrings.

You can change your rear cogset to a larger set. You can either extend the range (and increase the gaps)between ratos or you can shift the entire range to a lower set with larger cogs. eg start from a 13t instead of an 11t.
For a largest rear cog, 28 is about the largest that road mechs can handle.

You can extend the lower range of your gears with a triple chainset. Road triples are usually 30/40/50 or 32/42/52, but you shouldnt feel obliged to stay with these ratios. My current triples use a 28/38/48 on one bike and a 26/39/50 on the other. You can play with various degrees of overlap.

When you want to play with gear ratios, use gear-inches to compare different ratios.

SD Fixed

My Front is 53?

I ride a Road bike and it's a pretty hilly ride. I'd prefer to keep my lower front as it's just OK for the hill climbs that I do. I would like to go faster.

1oldRoadie

Does the crank arm (attached to the pedal) say "sora" or "105" or something on it? And there are 2 gears in front or 3, and does the littler front ring have a 39 on it? If so it is probably a standard/normal road crankset. Changing it will cost $100 +/-.

What is the number of teeth on the largest gear on the rear wheel?

SD Fixed

It's a shimano 105 double on my 99 Cannondale r600.

1oldRoadie

Good bike, good components.

If the rear gears are original they are probably a 12-23. With the 23 being your power gear and the 12 your speed gear.

If you get a 12-27, then you keep your speed gear and get a better hill climbing gear. the cost is $20 to $50.

If you want to go faster on the flatland part of your ride, JOIN THE CLUB. and do what Lance does, keep your butt on the saddle 6 hours a day.

MichaelW

If you have a 53/12 you dont need any higher gear. This is about the top gear on a professional or elite amateur racers bike.
To go faster you need to spin faster, not push harder.

The only reason for changing your transmission would be to get more lower gears for hill climbing.
Time trialists on flat courses would fit a rear cog cluster with a smaller range for better fine-tuning of the gear ratios, but that is not neccessary with 9 speeds.

SD Fixed

It's the honest answers like this in life that I love!

jmlee

I agree with Michael, increase your spinning. It either takes a pretty strong person or a pretty steep hill to spin out a 53/12.

By my calculations, that puts you going about 65 kmh at a cadence of 115 rpm. We'll assume that you're doing that downhill (if not, I'll just start calling you Mr. Zabel). At that point, you'll gain more by improving your aero position than by trying to push a higher gear.

Since that is a max situation, everything else comes in underneath that. In other words, if you are running out of gearing, you should definitely look into increasing your cadence. On a 53/12, 40kmh (25mph) would give you a cadence of 70. That is gear-masher city. 90-100 is much more ideal.

To increase cadence, do leg-speed intervals, where, for 10 seconds at a time, you use a really low gear and spin your legs as fast as they'll go. Do this several times per ride, in addition to an overall conscious effort to ride in a higher cadence/lower gear. (Note, these are not power intervals. You should have no trouble spinning your legs completely out.)

Cheers,
Jamie

SD Fixed

Cadence!!!

How do I tell what my cadence is. I'd have trouble counting!!! Do I finally need to lookinto a bike computer to assist with this?

1oldRoadie

I write up a little cheatsheet and tape it to my stem.

I calculate the speed in each gear at 80rpm and then I write the numbers down in a column. This way I know that if I'm in my middle gear in back (in my case 17) I should be doing atleast 14.7mph to be doing the 80rpm cadance, etc.

After just a little while you know what 80rpm feels like. and you don't need your cheatsheet until you want to increase your normal cadance, or something.

WoodyUpstate

A cycle computer with cadence is a great help and will help your spin considerably.

I counted revolutions, taped a table to my stem, etc. to determine cadence. They all worked, but I found when I was hammering and concentrating during a ride I couldn't do the math effectively in my head. For $55 you can get an Avocet 45tt with cadence that will change the way you ride.

jmlee

If you have a cycle computer you can use the Excel sheets which I wrote up. They do all the calculating for you, providing a cheat sheet for your handlebar stem. But you do have to know your current speed.

In making the sheets, all you have to do is enter your gearing, your wheel circumference, and your desired cadences (if they differ from the givens). Then, do a little cut and paste manoeuver to get only the numbers you want. After pasting it into a new sheet, make sure you raise the font sizes to something you can read on the bike.

They may be downloaded for free from www.uni-bonn.de/~jmlee

make sure you download the sheet that applies to your number of cogs/chainrings.

Please read the instructions.

Have fun.

Cheers,
Jamie

SD Fixed

Thanks for that tip. Time for a new thread.. er, search engine time. And then I'll ask questions.

Time for a 'puter I guess.

SD Fixed

I should say, despite the fact I'm a little ownry here, you guys are all really helpfull!

Thanks (humble voiced)!

jmlee

William, if you don't have a computer already, then by all means buy one with cadence and forego the table business.

The only disadvantage with a cadence computer is that it requires more wires than a normal computer (since the cadence part goes to the crank/chainstays and the speed part goes to the front or the back wheel). They are also more pricey. For some, price and wires might cause them to prefer a table on the stem.

I am happy with my Ciclosport 414. It is a higher end model (including altitude). With this one, you have to buy the cadence part as an add-on (an extra 10 clams). I know that you can get them in the U.S., but you may find something from Avocet or Cat-eye cheaper.

If you are trying to raise your cadence, you may want to check out my website. I posted there some tips on raising cadence.

Best of luck,

Jamie

SD Fixed

URL?

jmlee

In my post above, but at www.uni-bonn.de/~jmlee

If I recall, the link to the tips page is pretty far down on the main page.

Have fun.
Cheers,
Jamie

Cadd

William, I have a $25 Specialized computer that DOES NOT tell me what my cadence is....but it's really easy to figure that out.

You don't even need a computer. All you need is any type of watch or stop watch.

Cadence is measured in Revolutions per minute. Just look at your watch and when the needle hits 12 (or the "seconds" digit hits 59) start counting. For every time your right foot hits the bottom count 1. Do this for 60 seconds and you'll have your RPM.

Usually, you'll bike at about the same RPM regardless of speed. Your body tells your legs how fast to spin. I usually spin the crank between 90 - 95 RPMs.

Or you can count your revolutions for 15 seconds and multilply that number by 4 and you'll get our RPM.

No offense if this seems too childish for you. Hope it helps.

Dutchy

Yep, that's what I do also. Count for 15sec times by 4, easy. Mine is usually 107rpm on the flat.

CHEERS.

Mark