Carlosss

Hi everyone, new in these forums!

It's been almost a year since I first went to the velodrome and now that I have plans to train more seriously and race in the sprint disciplines I'm thinking of getting a cadence meter to track progress and help with gear choices. I will need both cadence sensor and compatible bike computer, but am quite lost in terms of what's out there simple and at a reasonable price (there are just too many GPS, power, HR, etc. units that I don't want or need).

Ideally I'd want the following features for the cadence compatible computer:

• Instantaneous, average and maximum cadence
• Be able to export cadence history data to my phone/laptop post-training
• Wireless sensor, therefore with ANT+ transmission?
• Cheap, i.e. no additional features and fancy screens that will push the price up (plus cannot look at the screen while cycling anyways)

Question: should I get speed sensor too or is it just completely unnecessary considering I can calculate speed from cadence data?

From what I've seen Garmin's and Wahoo's speed and cadence sensors are the most common? I'm sure there must be a ton of good alternatives that work just fine as well? What about the actual computer unit that I'd need to attach to the seat post (for example) that gathers all of that cadence data? That's where I really don't know where to start looking. I need help!

Please share your own experiences with what you use and/or recommend. Your help is very much welcomed

queerpunk

The Garmin 500 sounds right up your alley. It's both simple, and high-powered - able to accommodate a lot of other functions and features, but pretty easy to set up and use for simple displays. Used, they tend to run under a hundred bucks. And they're small and very reliable.

And, yeah, the GSC-10 (garmin's speed/cadence sensor) is good. I suppose you don't need the speed sensor, but hey, they're one unit - might as well use it.

carleton

Hi and welcome to the forum and the sport!

Yes, you will want a speed sensor because:

1) It's a pain to have to calculate your speed.
2) You might forget what gear you were using for an effort. When you train a lot, you it's common to change gears a couple of times per session.

I would look to get separate speed and cadence sensors. Put the speed sensor on the fork and the cadence sensor on the chainrstay by the crank. Why? Because if you have a combined speed/cadence sensor mounted on the chainstay, it assumes that your rear wheel magnet won't move because you have a road bike and your wheel's position is fixed. On a track bike, your rear wheel's position changes with each gear change...up to nearly 2 inches. This could affect if the sensor picks up the magnet or not. Yes, you can remember to move the magnet, but you will forget sometimes.

If the speed sensor is on the front wheel, then it's in the same position every time.

Mount the magnet on the brake track of the front wheel using outdoor double-sided tape. Why? Because if you mount it on the spokes of your training wheel, you may not have the same position available on your race wheel. The brake track is the same location on all wheels and you never use your brake track on track bikes. So, if you put magnets on the brake tracks (both sides) of all of your front wheels, you never have to think about anything. Just put the wheel on and boom...speed sensor activated.

Bontrager used to make separate ANT+ speed/cadence sensors. Not sure if they still do.

carleton

Also, Carlosss, many head units record data every 1 second. That's the sampling rate.

Every 1s is fine for road use where you are recording data for 30 mins to several hours. But, on the track your events can be less than 30 seconds. So, you'll ideally want more granular data.

Think of a high speed camera recording vs a low speed camera. You'll get more data from a sprint event with the high speed camera.

So, if in your research you find a head unit that records faster than every 1 second, then that's a very good thing.

Also, I wouldn't use your smart phone as a head unit. A lot of manufacturers are offering Bluetooth-to-smartphone options for head units (I think Wahoo does this). You don't want your $600 smart phone out on the track. If it falls off or you bump into something, that can be expensive.

As QP mentions, the garmin 500 is a solid option. Remember to turn off "get speed from GPS". It's silly and very inaccurate. It calcualtes your speed based on GPS readings which are spotty. On a 3hr ride, it's fine. But, if you are doing a 3K and it says your max speed was 60mph, that's not worth anything Use sensors for speed, not GPS.

carleton

Read this thread for other info: https://www.bikeforums.net/track-cycl...computers.html

It's not just about power meters. Feel free to comment there, too.

Poppit

We use Garmin 520s, the new style cadence sensor straps to one of the cranks with a rubber band, the speed sensor straps to any one of the hubs with it's own integral rubber band. They're dead easy to swap between wheels and bikes although if you're running discs or 3/5 spokes it's a bit trickier to fit the speed sensor.

Carlosss

Thanks guys, that's a lot of info!

I've been reading a bit more on Garmin Edge units and yeah, the 500 seems like a very solid unit! Is the newer model 520 much better or no major benefit in my situation? Getting a used 500 for under £100 surely is a much better deal than getting a new 520 for £200 right? (plus it's well above what I wanted to spend).

What is the rate of update for the cadence and speed sensor in the Garmin Edge 500/520? I have also seen the Garmin Edge 25 which is ANT+ compatible and can too export data, but considering I could get a used 500 for the same money or less it's probably not worth... And who knows how fast/slow it is taking cadence/speed measurements... Has anyone used/heard of it?

In terms of the actual sensor you're right Carleton, keeping a record of all the gears for every single effort so I can then calculate speed would be too crazy. Hadn't thought about that!

So yeah, will get both speed and cadence meters. The latest one from Garmin has extremely good reviews so I'll probably go for that one. Like you said Poppit an extra benefit is that the speed sensor attaches to any of the hubs, so no need to get anything to the fork and front wheel. That is using normal wheels which, which I am using (at least for the time being, and probably for quite a while because I have no plans on getting disks/3-4-5 spoke wheels any time soon).

That being said, is there any benefit from the conventional magnet "ticking" cadence/speed sensor over the internal accelerometer style of the latest from Garmin? The old GSC-10 seems to be out of stock every by the way, Queerpunk.

carleton

Track training and racing often involves cadences much higher than roadies achieve. It's normal to touch +150RPM in a race (if you are using a small gear). And if you are doing cadence training on rollers, your cadences can be over 200RPM.

I'm not sure how the accelerometer sensors handle that. I've never used them. I know the magnet ones work. Maybe look for reviews that focus on high cadences.

jfiveeight

I much prefer the magnet based sensors. They are immediate, accurate, and less expensive.

houleskis

I have both types sensors (the GSC-10 on my roadie and the accelerometer on my track bike) and a Garmin 500. Here's my reviews FWIW


GSC-10: Much more responsive and syncs with my Garmin much more easily. As Carleton said, the magnet will move when changing gears. Luckily, the magnet setup is pretty straight forward so it shouldn't be a crazy issue to move it around when you change gears but it is an additional thing to do. Also, given that the sensor is zip tied to your bike, it won't be too easy to move should you want to use it on multiple bikes. I would advise getting another GSC-10 if you went that direction.


Accelerometer: Only have 2 rides on it so far so YMMV. So far, I've had issues pairing the sensors with my Garmin (if anyone else has fixed the problem let me know!). I generally can't have bike computers visible on the track so it's hard to see if it's pairing properly. Also, a lot of people have these sensors on their bike at the track so I can't tell what signal I'm picking up! In other words; I need to debug. Otherwise, the setup is dead easy. Simply strap them on and you're ready to go. If you want to use them on multiple bikes swapping them is a piece of cake as well. Performance wise, while accurate, it doesn't seem as responsive as the GSC-10.


As for the bike computer, the Garmin 500 is awesome. Yes, the more fancy ones have bigger colored screens, Strava updates, more data fields per screen, better maps, etc, etc but I've never been left wanting. You can also get power should you ever get a power meter. Best bang for the buck IMO.

Doge

Where does the PowerTap hub fall down?
I guess I need to make sure there is a track version, but speed, cadence, power are all there.
Saw the track version cost more - oops. I bought several @ $299 and now that price is gone. Still I'd think esp on track where weight is not an issue (thinking that 6.8kg thing) then a nice set of wheels with one seems OK.

Now waiting for the corrections...

carleton

Powertap records every 1.25s, so it has the slowest recording rate of them all. SRM is the fastest at 0.5s.

Edit: That could be different now for Powertap, but when I last had powertap (on road and track bikes back in 2009-2011) that was the case.

Doge

Good info.

What do you need - for Cadence (OP) and Power?

I assume the .5 sec SRM also needs more data storage.

carleton

Total ride time for a track day is typically less than total ride time for a typical road ride/race.

The storage requirements are minuscule these days. I've known people to never erase their head units. 15 years ago, portable storage could have been pricey, but now, it's pennies.

carleton

I recall there being an SRM "Scientific" track model that recorded at 10Hz (10x/second for the non-tech folks). That probably seemed like overkill at the time, but I'd go for it now

Doge, when you start analyzing splits from your son's files, you'll start longing for higher resolution

Doge

Just that SRM units are not pennies.

I do not think they are more accurate, just better sampling (precise).

Is that needed in light of the other options that are generally 50% less costly.

I could imagine in you could sync your time against another rider and compare jumps - that would be cool. But (and I really want to know) why does a track rider need .5 sec sampling?

Doge

Think we were posting at the same time.

I have video that does 60 frame/sec :-)

carleton

For pursuiters, I think a high-resolution SRM is the most useful training tool. You get speed, cadence, HR, time, distance, power, and temperature every 0.5 seconds.

Data is only good if you analyze it, right? What do they say about a tree falling in the woods being heard or not?

Power meters and the file analysis are what (I think) helped propel the British to the top in the 2008 and 2012 Olympics. Before then, power meters were not systematically used by a team. The Brits even had a guy on staff who's only job was to analyze files (and wink at Victoria Pendleton (he later married her)).

I think Sprinters can get away with all of the above without Power meter cranks. Just take speed, cadence, HR, time, distance, and temperature every 0.5 seconds with a $400 head unit and you are good. Every sprint effort is maximal. There is very little need for pacing in most sprint programs.

carleton

There exists software where you upload a GoPro video (let's say from a crit or a points race) and sync it with a power file and it then spits out your video with tachometers, speedometers, etc... for all of your metered data. Now THAT is cool. I can never remember the name of it.

It's because the efforts are SO SHORT. Let's say a sprinter is doing a standing lap in training. That's 17-18 seconds. That could either be 18 data points or 36. But even for pursuits where each lap is 15 seconds. That could be 15 data points or 30.

Another thing that happens is the fluctuations in speed and cadence when you enter and exit the turns. The waves are more regular when you have higher resolution than if you get a tick ever second.

If you are going to analyze his files, you won't just look for averages over 4 minutes. You will probably look at 125m splits, which are 7.5s long.

carleton

Why 125m splits? Because that's how you compare him to the best:

Doge

Data is only good if you know how to change it - in the way that is better.

I get the analyze part - but DRIP (Data Rich, Information Poor) is an issue in many areas besides cycling.

For me (not you) .5 sec vs 1 sec is good for eWang. I wouldn't know what to do with it - or how to get it changed. At the time there is a coach that does (and can communicate that so I believe them), I'd spring for a SRM.

carleton

The head unit set the sample rate, not the power cranks. I used the SRM head unit with Dura Ace cranks and got all the data I needed...ever 0.5"

It's not eWang (not sure why you keep using that term).

Look, man. You have little or no experience on the track yet have opinions in every thread. Would that be considered DRIP?

brawlo

Bontrager don't make those any more. I tried long and hard to find one NOS. I had little success finding other options until I went to Bike24 and found they had a few different ones. Obviously the new generation of Garmin sensors are out there (I have a Garmin 510 with the combined GSC10 sensor but sought to separate for reasons that Carleton poined out) but I came across some issues with them from a sprinter's point of view. I can't recall specifics but I do know they got crossed off the list of options. I ended up with a set of Sigma sensors and they have not been a problem at all and were only about $AU15 (+shipping) for each sensor as they were on special at the time.

Carlosss

It seems nowadays they can all reach cadences up to 240rpm from what I've managed to find... Is that in line with your own experiences?

Very interested on this. What's the cadence sampling rate with the Garmin 500? Once per second? And is that the same for both GSC-10 and accelerometer?

So the Sigma sensors that you have are both magnet-based with fork-mounted speed meter and chain stays-mounted cadence meter? How quick is the sampling rate? Although if it is good for you as a sprinter it should be good for me too

MarkWW

Bontrager ANT+ Digital Sensors | Trek Bikes