Looking to drop a lot of money in a very short amount of time.
Anyone have experience with this set-up? Any issues with either crank stiffness, reliability, breakage…or general thoughts on power measurement while MTBing?
I know lots of MTBers who train with power on the road, but none off-road.
I’d be very keen to hear any reports on the MTB SRMs, too. I’m concerned about their longevity and general toughness.
I had one at one time. Power is too variable even on long climbs on the dirt. 500- no 200- back to 400, uh-oh I should be watching where I’m going! Not the same as having an SRM on the road bike.
I know a local guy who does 24 hr races and stuff on his MTN and has a Powertap SL built up on a 26" (I think tubeless) rim.
I’m bumping my own thread as I figured out the magical answer.
Damn sensor “usually” needs a custom bracket, esp on high swing arms.
Duh. Should have figure that out on my own…
I cannot even begin to understand what a MTBer would do with a power meter. There is no constant pace, and the terrain (and conditions) are far too variable to make power readings usefull in any way. “Oh look, for 3 seconds I was able to generate 700W…awesome! But then I only generates 5W. Must have been a downhill section” Great, now what does that tell you?
On a road bike? Sure. On a MTB? Only if you want to win the poser of the century award.
On a road bike? Sure. On a MTB? Only if you want to win the poser of the century award.
Um…my buddy Larry who has one…well, I bet he would kick your ass on any MTN bike race up to and over 24 hours. X-Country races (not downhill). On the right trails they can be used properly, long inclines for instance.
I race xc - competed nationally at a decent level for the last 10 years, and I’m sorry - I really don’t understand the value of power meter readings on a MTB. No two courses are the same, and even on the same course conditions change from day to day. You might have sustained climbs of 30 seconds or more, but it will never be on a constant grade, and conditions and line will always dictate changes in cadence. Plus, different tires would mean different power numbers, even in a perfect world.
I’ve races my share of Canada Cups and Norba’s, and now race 8hr and 24hr endurance races. I’ve been around, and I have never seen a power meter on a mountain bike.
XC is about ability to work at threshold, tactics and bursts of power that are entirely dependant on the terrain…you are never going all out for an entire race, except in short track, and even then numbers would be absolutely useless. Tactics are huge, so power numbers while you’re waiting to pass or sucking someone’s wheel up a climb are irrelevant. Power numbers on singletrack are irrelevant. Power numbers on downhill sections are irrelevant. And power numbers in a mass start are irrelevant, because you’re going all out, mano e mano, to get your line first.
Power numbers on a MTB are like and AVG HR reading…it means absolutely nothing, because of the constant spikes related to terrain.
If nothing else, the power data would be pretty useful to look at after the fact, to determine what you may need to do differently in your training.
How often do you look at your PM in a crit or points race? Me, pretty much never-but I still find the data useful after the fact.
I would think that looking at your average power per lap over the course of an 8 hour or 24 hour race could be of some benefit in the early laps, just to make sure you’re not going out too hard–but that’s just speculation on my part, as I’m not doing anything that long.
Um…my buddy Larry who has one…well, I bet he would kick your ass on any MTN bike race up to and over 24 hours.
Larry would kick is ass? Chip - that’s an absurd blanket statement. Not because I (or anyone else here) may be fast, and not because your buddy Larry may be fast, but because none of us know each other or ‘buddy’ Larry. This may be a triathlon board, but let’s put things in perspective…your buddy Larry is not the only xc MTB racer in North America, fast or not. There are probably some pretty fast xc dudes here on ST. I know of a few.
As an xc guy first, tri geek second, I call that statement absurd on behalf of us MTBers. I grew up racing with, and against, guys like Roland Green, Seamus McGrath, Ryder Hesjdel, and other names you might recognize if you know your xc racers. Don’t get me wrong, I’m not saying that I was faster than them, but we ran the circuit together for enough years that I have a pretty clear understanding of where I stand.
Your buddy Larry might be a fast rider, and good for him if he is. The fact is unless he’s racing continental cups, don’t assume that he’ll kick the ass of anyone you talk to on a message board. You don’t fully know his race history, or mine, or anyone else’s here, and that is what makes it such an absurd statement.
I would think that looking at your average power per lap over the course of an 8 hour or 24 hour race could be of some benefit in the early laps, just to make sure you’re not going out too hard–but that’s just speculation on my part, as I’m not doing anything that long.
But your average power is affected by so many factors that it is still useless information. Lap times are a far better indicator. Power readings on any given lap can be highly affected by course conditions, line taken, riders in front of you (waiting to pass) or racer tactics.
Power numbers, like heart rate, vary SO much that the actual average would be useless. You are never, ever at a steady state. In a short 42k xc race I will have major HR fluctuations between 120 and 212 bpm. The same would hold true with power numbers. The only thing of interest might be peak numbers on a bitch of a climb, and only if you didn’t lose traction, and only if you didn’t spin it…but not spinning would be poor riding.
On a MTB you don’t necessarily want high power numbers. You want high cadences and fast speeds, but you never want to actually be grinding the kind of gears that would give big readings.
I agree “mostly” with what you’re saying and came the same conclusions about having it offroad…although nearly every “fast” MTBer I know these days uses power on-road.
I qualified for Norba Nationals (Endo) this year and didn’t go b/c I didn’t want to get my ass kicked too bad. While I agree MTB is “mano y mano”, many of the races that I do are won by pacing (Ice Man, Chequemegon 40, Leadville 100, etc). HR is mostly useless to me…mostly b/c mine is pretty darn low and most of my races are long enough where drift sets in. Here’s a great example of what happens to my HR during a 12 hour race (3rd, I stopped each lap to drink a beer). 305 dies after 10 hours, btw…but as you can tell, I don’t change much - I’m the Energizer bunny.
So, I’m considering options and the SRM MTB is still curious to me, although I certainly understand (now) the limitations and practicality is brings to MTB. I guess I’ll just have to train on the road like all the other guys…
BTW - Lemand-style start…sprint to the single track…then settle into pace (fairly technical course). Starting at 8:30ish (time, not clock)…we were riding with lights.
For those out there that don’t have experience racing MTB’s, that’s a great visual example of what happens during a race. For a trained xc rider, the HR is all over the board, showing intense efforts and periods of quick recovery. Power numbers would be even more skewed than HR though, because of the many brief periods where the rider is not even pedaling. i.e. railing turns, tech flow through stuff, dh sections
Every now and then I will put on my Polar 520 and graph a race at my Wed night series - only about 15k, and just for fun - but it’s fun to see, even if it only shows a partial picture. Unfortunately, the HR graph is entirely dependant on the sample rate at that distance - on my Polar it ends up being every 30 sec, so a graph only shows my HR reading every 30 seconds…or more. A lot can happen in 30 seconds that doesn’t show up on the graph, so you’re actually only getting an incredibly static snapshot of a very dynamic race. Maybe that one moment is an intense effort, and maybe it’s an easy recovery section.
Occasionally, I do like to see what my max HR was at the end of a race though…just for fun. I generally race xc by feel, without an HR monitor, so it keeps me aware.
Out of curiosity…what is the sample rate for that graph? I have a Forerunner coming in the next few days, and am anxious to know what to expect on long rides.
GearGrinder:
come visit in april if your into endurance racing. new race with great prize purse.
O
I use the Garmin in “Smart Recording” mode…which I have no clue how it actually works. It claims it adjusts based upon speed, hr, etc.
You have the option to set it to record every second, but this limits the recording capability to around 3.5 hours.
Sadly enough…out of curiousity, I looked at my road ride on Friday and it “zig-zagged” more than my MTB ride on Sat because of all the darn stop lights!!!
well, that’s why I said ‘maybe’ as far as a PM’s usefulness for pacing. Still, if you’re just using your PM for pacing and doing intervals, I think you’re missing a big utility of a power meter.
When I first started using it in road races and crits about 5 years ago, I heard the EXACT comments that you’re making now; and you’re right, a PM is of very little use DURING a race–there are a few specific instances, but generally they aren’t that useful. Yet, you see an increasing number of folks racing with them. Especially in MTB, where many of the races are on the same courses each year, it would be nice to know the specific demands of the race course before you get there. Memory is often shady in this respect, but the power file doesn’t lie.
Especially in MTB, where many of the races are on the same courses each year, it would be nice to know the specific demands of the race course before you get there.
That could be helpful. I’ve never really raced the same venue more than twice a year (except on a Wed night series, but those aren’t serioous races). To me, a better indicator of the demands of a course comes from downloading a course from Motion Based…if you have an accurate HR graphing with readings every second, then between the HR graph and the elevation profile you can basically preview the course, and even develop a pretty accurate race strategy.
I don’t have a Garmin (yet) but I have been known to “preview” the courses through motion based. You don’t need any device to look at the info.
Sadly enough…out of curiousity, I looked at my road ride on Friday and it “zig-zagged” more than my MTB ride on Sat because of all the darn stop lights!!!
You can adjust the auto pause feature to stop recording whenever you drop below a certain speed…eliminating those zig-zag’s and rendering a pretty useful reading and graph.
come visit in april if your into endurance racing. new race with great prize purse.
www.dirtsweatandgears.com
Looks like a good early season test. The prize purse is sure to attract some good talent.
Is it all daylight racing?
The trusty sunset calendar calls for:
Sunrise: 5:58am
Sunset: 7:31pm
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