when i use bike computer to train ,it will record some data . i want to know which data(instant speed ,riding time ,cadence or other else ) do you need most when you are riding ?

When I'm riding, I look at cadence more frequently than anything. HR is second. I almost never look at speed. Time is nice so I can eat, drink, stand, etc. by the clock if I want to. If I'm following a cue sheet, I need to know distance traveled. I even have a second device that shows distance traveled as a backup. I hate getting lost, losing time, or doing extra miles. Uploading for exercise analysis, I want to have at least time and HR. Now that I use a GPS device, I can upload route, speed, time, elevation, temperature, and HR. For me, more information is better. OTOH I know some champion riders who have no cycling computer at all - nothing.

I look at my cadence the most, and keep an eye on my HR. If I'm going downhill I'll look glance at my speed for the yippee factor, and of course the time/distance so I know when I should be heading home.

There are heaps of bicycle computers on the market ... why make a new one?

It depends on what you're wanting to train.

Cadence is great if you want to train your pedaling speed.

Heart rate is good if you want to train your fitness.

Power is want you want if you want to train to go faster.

But, that's simplistic.

Pull in as much data as you can for purposes of training analysis. Although you're clearly at a point where you don't know what you need or what it all means, you will soon be able to amalgamate all that info to paint a full picture of your ride efforts, strengths and weaknesses.

A basic cyclometer will give you speed/time/distance, and you can stake out a route on which you can compare rides. You push yourself to go faster, and make extra effort to cover the route in shorter time.

Add a cadence sensor, and you can start to look at your pedaling speed and optimize your output, but you still need time and distance.

Other metrics like elevation and current speed can help you further dial in your effort and to motivate you. Speed is simple, and variables like wind and position impact it greatly, but At the same time, it's the key performance metric. Going faster than before/everyone is the ultimate performance goal.

When riding my bike on the trainer in the basement, I've got two pages on my Garmin Edge 500; one page has Time, Speed, Cadence, Heart Rate Zone, Heart Rate and HR Percent of Max. The second page shows the Cadence and the Heart Rate graph; but I only check this page once or twice during a training session just to see where my HR's been.

Power, power vs. cadence is the key. Your power and cadence should remain stable regardless of the gearing you are in. Eventually you should get to a point where you can feel the numbers on a training ride. Where, you know what 85-90 cadence feels like, so you won't need to check often. Pick a power number and stick to it, uphills, downhills, flats, headwinds, doesn't matter, stick to that power number.

Sounds interesting Paul. Excited to see your product. What type of computer are you making exactly? The competition is fierce, good luck!

I have a Garmin 500. It allows me a few pages and a ton of metrics to look at. I have 2 main pages, one for outdoor riding and one for training on the indoor trainer. The indoor trainer page has elapsed time and HR zones. The other page has speed, avg speed, time of day, distance and cadence.

I'm sure everyone is different.

Good Luck.

Well said! Very well said...

Only let me add: A heart rate monitor connected to my IPhone has made a big difference for me in two ways:

First: It showed me that I really wasn't going as hard as I thought I was. It pushed me to up my effort into higher zones. (Actually, my cardiologist was the one doing the pushing. When I showed him the results from the monitor he 'encouraged' me to increase my average to 75% max heart rate over an entire ride of 60-90 minutes -- I had been only averaging about 70%)

Second: It provides me with a history (even a bar chart showing each day) showing ride duration, distance, speed, heart rate -- and how many times I have ridden. Its a motivator. Actually, the biggest motivation are the holes it shows when I don't ride. So, on a day when I just don't feel like it, it motivates me to get out there knowing that, if I don't, the log on my IPhone will always show a hole for that day...

These days I mostly use the computer on my bike for the clock: "OK, I have to be back by 6:00pm, I can ride for another 25 minutes..." The other time I use it is when I ride with my little 8 year old buddy: "You're doing 15 mph!... 16mph!... 17... You better slow down! Hey! Slow up! Wait for me!" (Which of course only makes him peddle harder!)

Power.

Most good head units can display more than one parameter, so the question is really moot.

I have a power meter and I use a Garmin 500 as a head unit. For intervals I show: 1) 10s power; 2) lap power; 3) lap time; 4) cadence. I record HR but don't look at it during the set.

Current speed, distance, and cadence for general riding, add HR for training.

Ride time.

I do not think this is good training advice.

Why not?

Would saying something like it depends on your goals be better? That seems a bit high level. My advice is high level, but at least gives a metric and method to follow that many top cyclists already subscribe to.

I train with power so I keep time, lap time, power, cadence, and HR all on my main screen. I have a second screen with total miles, average speed, total climb etc, but usually only look at that at stops.

Depends, MTB and CX race, just time and hr for CX and time and distance for mtb. I have power on my road bike so training wise power and hr and time for intervals. For road races just hr power and distance and for crits just hr and time. Cadence is unnecessary unless in the garage on trainer doing cadence drills. I ride where I'm comfortable and over the last 4 yrs my cadences has risen from 80-85 avg to 90-95. During gravel races/ training rides I look at HR and distance only.

Well I guess I have no idea how one would accomplish your advice. My power descending a 6% grade is about 15% of what it is going up the same hill. My cadence is way faster. My speed going down hill is typically maxed out for conditions- road surface, technical-ness of descent, traffic, etc, so it's not as if it's even an option to have my power output going downhill the same as uphill.

Why would you want to attempt to ride the same power and cadence at all times in all gears? What would be the advantage of that?

As Heathpack points out, what you prescribe doesn't make any sense, and no "top cyclist" on Earth engages such a training program.

Training is a series of variable intensity workouts designed to develop and improve certain skills and elicit certain physiological adaptations. "Picking" a power level and sticking to it "at all times" is simply impossible, and even if we imagine it were not, it would still be loser because it would not make anyone a better cyclist

FYI everyone should probably note that OP has been banned, so no one should expect him/her to join back in or benefit from this conversation.

It's not even close. The most important parameters for training are power and heart rate. Power doesn't lie. But your heart rate can fluctuate for lots of reasons, but power only does if you are not working hard enough. You can't hide from power data. If you can't display power, then watch heart rate and average speed unless your days purpose is cadence driven, then watch cadence, too. But, with experience, you will develop natural cadence tendencies. If I ride 100 rides, my cadence on average will never vary more than 5 RPMs. 90-95. That's my natural zone.

To give Roarau the benefit of the doubt, I read his post to mean that when riding a power-based interval, you need to achieve the target wattage and adjust your gearing and cadence accordingly. If my target is 300w and I'm on a 6% hill, I'm going to be in the small ring; if I'm on a flat road, I'm going to be in the big ring going much faster, but the power output should be the same.

Now, if Roarau is saying that every ride, every day should be at the same wattage, then you guys are right: that makes no sense.

Yeah, sorry should have been more clear. Stick to a power zone / cadence for X period of time. During X, stick to it no matter the conditions, this is key. Obviously deciding to do this on a ride with a multiple massive descents would be stupid.

Power zone training is critical in getting faster.