Dave : Equipment

Testing, testing, and more testing

Dave — Tue, 21 Aug 2007 10:19:00 GMT

In winter 05/06 I was on a quest to answer the question: which bike is more efficient, a Trek Fuel or a Salsa Dos Niner? It just so happens that one uses 26" wheels while the other uses 29" wheels...

These have proved to be rather popular posts, most of them getting over 10,000 hits and still counting. To this day, it is the only published attempt at quantifying the difference in wheel formats using power. I could be flip and say it doesn't really matter anyway, we're just riding bikes for fun, right? Well, based on the popularity (infamy?) of these posts it clearly matters to some folks out there. Probably you ;)

My stable has grown - it now includes a FS 29er (again), lots of 26ers, and soon a 55er (26+29=Siren Fifty-Five). And if that isn't confusing enough, there's an outside chance I'll be testing a new entry to the wheel size mix, the 650B/27.5" by Kirk Pacenti.

So guess where my interests lie now? Yep, learning the strengths of each of these formats. It's a technical nightmare as James at CN has learned. Realistically, the only power meter I trust on an MTB is the Power Tap. The major (MAJOR) hitch is they don't have a disc compatible hub yet. I've been leaning on them for a few years but I'm only once voice. If you are interested in the same hit with an email. The Lev is rear disc only...so any testing on that bike is limited to terrain where a rear brake is optional.

Fun things to look forward to, more charts and geekdom.

So with all the downtime in the last 6 weeks, aside from moving and a few other things...I've got my music situation dialed in. Some folks get cable TV, I get a monthly music service with Rhapsody. Their top plan is called Rhapsody to Go but it requires specific MP3 players to utilize it - it always seemed overkill to me. Well my trusty little Creative Nano finally croaked and forced my hand...so I got a Rhapsody compatible player. All I have to say is I'm glad that Nano bit the dust. In the past once I found the music I liked online, I had to buy it somewhere. It wasn't so much the money but the time that was a PITA and kept those efforts to a minimum. Rhapsody to go - so far - has changed all that. I can now upload anything from Rhapsody's catalog to the MP3 with a 30 day license - this even includes custom stations. Pretty sweet deal considering I work at a desk and use Rhapsody most of the time already...the new MP3 just upped my music addiction.

Ain't technology somethin'? I guess this means I'm no retro-grouch. Gimme gears, suspension, music, and power baby. That and a touch of crack makes for a lot of flow.

Lights for a night or a month?

Dave — Wed, 17 Jan 2007 11:39:00 GMT

I have this dream of a super bright light that will go all night without a battery change. Too much to ask for?

A side benefit of this quest is a light that will burn for, uh, weeks. Yea, no BS here - doing GDR this summer? Put one of these on your bars as the main light and something silly light for your helmet (for around camp and nightime repairs) and you're good to go.

These charts show the potential dual useage of this setup I've got cooking in my brain.

The light is run by the bFlex as mentioned in the last post. The bFlex allows configuration of max current (light intensity), and within each setting there are 5 levels. The light levels are listed on the chart as "lumens", each grouping of runtimes are values for specific battery configurations. The battery weight is approximately 6 ounces for 2400 mAh. Yea, kinda techy but that's how to read the chart.

For the above chart, this shows that you can have 668 lumens for ~ 5 hours with a 12 oz battery. That's twice the light I had on my head at Moab (and 320 was plenty). 392 lumens can be had for 11 hours with the same system.

Now, take a look at what happens when we throttle back the max current setting to 350 ma.

For reference, a single 3W Luxeon puts out about 80 lumens. I used two of these for KTR this year and the night went great. Throw was a touch short on the descents, but totally doable. Looking at the light blue lines, at 123 lumens you get about 70 hours of runtime, while at 200 you get about 40. GDR nutz: how much weight do you typically allow for batteries? It's certainly feasible to have a sub 2lb setup that will last the duration of the event, provided you finish in a month ;) It's also possible to use AA battery packs and use expendible batteries...but not having to worry about batteries I'd think would be quite an advantage.

Keep in mind this is all within the same light but with different settings. I don't think there is anything remotely close to these capabilities on the market...dunno why, that market space is soooo big ;)

The best thing? The above projections are based on the P3 Cree and in a couple of days I'll have the P4s which are roughly 10% brighter. When they show up I can turn this gedanken experiment into reality.

Unintentionally stirring the pot

Dave — Sat, 11 Mar 2006 15:29:00 GMT

It's a rainy morning here in southern Arizona, the first in 140+ days so no complaints...

So. My quest to determine which bike is faster for me, the Dos 29er or the Trek Fuel, kicked up a bit of a ruckus in places. The Cyclingnews piece in particular got folks talking, er, yelling? In case you missed it, it's this one:

http://www.cyclingnews.com/mtb.php?id=news/2006/mar06/mar03mtbnews

Then yesterday g-ted posted a link to bikemag, which features an article on Old Pueblo and the bike test.

http://bikemag.com/features/columns/030806_mike/. Mike Ferrentino doesn't exactly have a gentle writing style...

It has really baffled me why so many folks get so worked up over my little quest. How many folks are riding 29ers strictly for racing & speed? Very few. It's as though readers see my test and think it's a slam against their belief system. Some bring up points that would be valid if I was doing a blanket across the board study...but I am not a research facility!

Entertaining in a "gee this doesn't make me so proud to be a human" sort of manner. Here's a random collection of the links I found to MTBR threads concerned with the testing, either directly or indirectly. From initial reactions, to "where'd the love go", to "I'm outta here", to "wait a minute, we ride these for fun!".

Phew! Someone finally got it in the end.

http://forums.mtbr.com/showthread.php?t=170033

http://forums.mtbr.com/showthread.php?t=170202

http://forums.mtbr.com/showthread.php?t=170114

http://forums.mtbr.com/showthread.php?t=170650

This one is about the 96er. Anything 26" gets attacked here.

http://forums.mtbr.com/showthread.php?t=170773

http://forums.mtbr.com/showthread.php?t=170061

http://forums.mtbr.com/showthread.php?t=171388

http://forums.mtbr.com/showthread.php?t=171890

http://forums.mtbr.com/showthread.php?t=170790

http://forums.mtbr.com/showthread.php?t=170491

http://forums.mtbr.com/showthread.php?t=170411

http://forums.mtbr.com/showthread.php?t=166486

http://forums.mtbr.com/showthread.php?t=155598

On the endurance racing MTBR board:

http://forums.mtbr.com/showthread.php?t=141317

Funny thing is, I love riding my 29er. 26er too, for that matter.

Every thorn has it's rose

Dave — Wed, 22 Feb 2006 01:25:00 GMT

Drum roll please...as you look at this plot, keep the following in mind:

This compares a Trek Fuel 26" wheeled bike and a Salsa Dos Niner 29" wheeled bike
Bikes were similarly equiped - near identical weight
Identical tread pattern, Specialized Fast Traks all the way around
I changed the crankset on the Dos to accomodate a 30T middle ring to more closely match the Fuel's gearing

The data is the result of daylight laps at the 24 Hours in the Old Pueblo race. When I say race, I mean it was full on...see the OP race post if interested. The upshot of this was that I did everything possible to go as fast as possible, within the limits of the event. No prior subjectivity could have skewed the results. The displayed lap times are the time on the course. Pit times are not included. I threw out the night laps for publication because of the eyesight issue - the 9th and 10th laps are extreme outliers due to extenuating circumstances.

OK...giving this a minute to sink in...each point represents the x, y pair of average power and lap time. In other words, the dots in blue show the relationship between power and lap time when riding the Fuel. More power = faster laps. Make sense? The black lines show a linear regression (done by MS Excel) to illustrate a trend, or predicted values. The two pink squares show what happened on the Dos Niner.

I added the red rectangles to show the "what if" scenarios. Consider the case where average power over a lap is 188 watts. Based on this data, a lap time of 67 minutes would be predicted for the Fuel, while the predicted time for the Dos is just under 69 minutes. Looking at it from another angle, for a lap time of just under 69 minutes, I'd have to average 175 watts on the Fuel but 186 watts on the Dos.

So there you have it. It's cut and dried in my mind. The 29ers in my testing have lost in rolly, twisty singletrack, and also on climbs. They might fare better on downhills, and almost certainly in sand and maybe even rocky stuff...but right now I'm losing interest fast.

Anyone interested in a tricked out Dos Niner with a Power Tap hub?

26 vs 29 singletrack shootout: tie

Dave — Sat, 11 Feb 2006 01:23:00 GMT

Well now, (AHEM!), looks like I jumped the gun yesterday in revealing results. That's what I get for seat of the pants analysis.

The testing of 29er vs 26ers continues on. Quick recap: the first round of tests looked at how climbing on the Dos 29er compares to climbing on the Fuel 26er. Those results showed a small but repeatable advantage to the Fuel for climbing dirt roads. That wasn't a big surprise to me, however, many took it as a direct attack on their lifestyle ;) We're just talking about a slightly larger wheel size, right?

This round of tests was done on a 3.2 mile singletrack loop in McDowell mountain park outside of Fountain Hills, AZ. If you've done the Mesa NORBA nats, you've ridden this trail. Swoopy, twisty, fast in spots, steep rollers, bad braking bumps in spots, a few very tight turns. It starts with a ~ 3 min big ring climb, finishes with a more rolling but trending downwards section of whoops and twisties. I call the latter section the "descent" in this analysis.

I did the rides on 2 different days separated by a 5 day period. The first ride tested the 29er, the second ride tested the Fuel. The results for each test are broken down by overall time, average power, and normalized power. Here's how it turned out:

Other relevant data not reported in the above sheet: energy expenditure was identical across bikes and runs at 185 kJ & 184 kJ for the Dos, 185 kJ and 182 kJ for the Fuel.

At first I thought based on average powers that the Fuel was significantly faster on the descent portion - which is completely non-intuitive. The Dos felt like it held speed better in turns, so I expected the Dos to be faster on the descent. If we just look at average power, that conclusion would stand. However, normalized power comes to the rescue. Normalized power was just enough higher in the Fuel tests to indicate I had a bit more snap in the legs on that day. In rolling terrain, it is very important where you put the power down, and how much at a time. On the Fuel's day, I just had a bit more to give on the steep ups, and rested more on the descents. The averages were the same, but Pnorm tells all...another factor that may have attributed to faster times on the Fuel was that I got 3 runs in on the Dos 5 days prior, so I was more familiar with the trail. The Fuel did feel faster in the tightest terrain, oh wait, that's subjective, nevermind.

Here's a chart showing how the distribution of power changed between the two rounds of tests. There's a considerable shift to the right for the Fuel's test, which simply means I was feeling better that day.

As for the climb - look how tight the data is between the first run on the Fuel, and the second run on the Dos. Looks identical to me.

Round 2 conclusion: it's a tie.

So what's next?

One test will be similar to this one, except at a much more relaxed pace. These runs were at a XC like pace, far above that of an endurance race. What happens if power spikes are much lower & most of the riding is in the saddle? Will the bigger wheels conserve energy somehow in the twisty/rolly stuff under those conditions?

How about some pure downhill runs? There aren't any around here I can think of, that'll probably have to wait until late-spring back in Colorado. The great thing about a bunch of downhill runs means I get to do a bunch of climbing :)

Signing out for now, fire away, but keep it civil.

Braaaap!

Dave — Sun, 05 Feb 2006 12:35:00 GMT

Just outside of Phoenix is McDowell mountain park, part of the Maricopa county park system. Lots of trails here, and best of all, they have an actual mountain bike specific competitive trail system. Can you say manna from heaven? That means that just a few miles from town, you can go out mid-day on a weekend and ride as fast as you want without fear of horse/hiker issues. Is this legend bitchin or what?

I've chosen the sport loop for 26/29 testing. 3 spicy laps yesterday on the 29er (Dos) was just about more fun than I could handle. They are short - only 3 miles - and all singletrack, an opening short big ring climb, then lots of twisty, rolling, whoopy stuff. So much fun at speed. The Dos was like riding on rails yesterday, those big wheels hugged the dry terrain like velcro and flew through the turns. Each lap was within 1 kJ, so the data is tight!

What is really interesting is that a slower warm up lap at roughly 24 hour pace used 12% fewer kJ over the same distance. That's something I've always suspected (that going fast is inneficient) but never quantified. So think about this, if you will: in a 24 hour solo event, how much sense does it make to go out hard? The faster you go, the more inneficient you get and you also chew into your valuable glycogen stores at an accelerated rate. Somewhere there is a balance between too fast and too slow for the first daylight stint...part of the balance is mental for sure...where do you think that balance is? Many good 24 hour riders have wildy differing pacing strategies, maybe there is no one size fits all answer, but for sure, last years natz was an example of too fast ;) Pretty cool - the 26/29 comparo project is teaching so much more than wheel size related stuff.

Supercaliber Anticipation!

Dave — Sat, 21 Jan 2006 12:43:00 GMT

Ryan Atkinson shared the current status of the Gary Fisher Supercaliber 29" race day bike on the MTBR forum, including an artists rendering of the frame. It looks to be a great design - but will take some $$ to bring up to race readiness. The current plans include:

- another prototype ready in a couple of weeks
- May/June delivery
- Reba Race
- SRAM X.9
- Bontrager Race GXP crank and Race wheels
- Avid Juicy 7 brakes
- $2859.99 (about half msrp of the Trek Top Fuel)

So let's see...throw on some superlight AC wheels, twisties, Race Face turbine crank w/20/30/40 and round it out with miscellaneous carbon bits and now we're ready to rock.

But wait - isn't that a 29er??? Sure enough it is...but I'm still intrigued. The jury is still way out for me - at least I have escaped the initial emphatuation stage where objectivity goes out the window in place of lust.

Speaking of objectivity, the first few weeks in Feb I'll be doing some 29er/26er testing on a rolling, desert singletrack course, the competitive loops of the McDowell Mtn park area in Fountain Hills, AZ. I'm even going to plan in a day of SS testing - at least as best I can with gearies. This is the kind of terrain I'd expect the 29ers to rock.

An update to the previous test: I got a rear Fast Trak for the Fuel and re-rode the same route. Energy expenditure dropped 3% from the previously reported values. I'm still using the beefy Weirwolf up front. I also re-rode the route on the 29er, this time with higher psi in the tires (38) and enough air in the relish shock to effectively lock it out. Energy expenditure INCREASED. Ouch.

Take away points: first, although higher PSI lowers rr on the road, the same is not true for off-road. Second, my Fuel climbs better on smooth dirt roads than my Dos - I have no doubt of this. The real question of course, is which is better under the condtions in which YOU ride or race? You won't find that answer here...but I'll keep you posted on what works best for me.

First results of 26 vs 29 inch wheels

Dave — Mon, 02 Jan 2006 20:04:00 GMT

Note (added 2/3/06): comments to this post have been disabled due to malicious spammers. You know who you are. Contact me through the "contact me" link if have something you'd like to add. If there is enough interest, I'd consider opening a public forum for the issue.

Note (added 2/12/06): this test looks at comparisons for climbing relatively smooth but variable pitched long dirt road climbs. For an analysis of rolling, twisty singletrack, check out http://teamhealthfx.com/blogs/dave_harris/archive/2006/02/10/510.aspx.

Thanks!

-------------------------------------------

Which one of these are faster? This is the question of the hour. Every 29er fan would have you believe 26" wheels are "kiddie" wheels and also that 29" wheels are faster. Time to cut through all the subjectivity and put some numbers on the problem. The short answer: for this comparison, the 26" wheels outperformed the 29" wheels, but it's not an overwhelming difference. Then again, the margins between winning and losing are often quite small...

I've got a Salsa Dos Niner and a Trek Fuel 110, both setup with power tap hubs. In the past week I did the same ride twice (4 Peaks road from hwy 87 to hwy 88 and back), a 60 mile dirt road/jeep trail route with approximately 11,000 feet total climbing. Two sections of the ride are compared: the first climb, which is partly rolling with some steep climbs and one long climb, rising about 4,000' in the process. The second section climbs from hwy 88 back to the high point; this climb is quite steep, climbing ~4,000 in 8 miles. There are a few short descents.

Bike setups: The Dos was setup with Specialized Fast Trak tires, tubeless ala Stans. The Fuel was setup with a tubeless (plus Stans latex) Panaracer fire XC pro rear and a WTB Weirwolf 2.3 front, tubeless ala Stans. The Dos is .6 lbs lighter than the Fuel, as measured by a Tanita scale (.2 lb increments). I started each ride with the exact same amount of water & food so as to eliminate rider weight changes. I assumed my weight to be the same on both days.

First off I just went out and rode the routes. I made no attempt to ride even paces for any sections of the ride, and in fact, the latter ride (on the Fuel) was done at a more spirited pace. I just planned on sorting out the data post-ride.

Next, I had to come up with correction factors for the power meters. Power taps are strain guage devices, and as such, have a small but significant precision variability. I performed a stomp test for each power meter (including my road bike PT), here's how they turned out:

Based on the stomp test, the 29" PT measures .86% high, while the 26" PT measures 1.75% high. This leads to correction factors of .9915 for the 29" and .9828 for the 26".

Now there's nothing left but to look at the data for each climb:

The road surface is sandy in spots, rocky in others, and fairly loose decomposed granite throughout.

Conclusion: in this test, the 26" wheels outperform the big wheels. The first "climb" has a lot of rolling terrain, I was interested to see how this would turn out. In the end, though, a consistent advantage exists for the 26" wheel, whether rolling or straight up climbing. On the steep climb ("climb 2"), one would expect a linear decrease in time for a linear power increase. IOW, a 10% power increase should decrease time by 10%. This is because the major resistance to overcome is that of gravity - a constant. Yet the Fuel saw greater speed increases than linear with power increases. I could feel this on the ride - any change in speed necessitates wheel accelerations, and the big wheels are simply slower to accelerate. The smaller bike feels much more "lively" or "responsive".

Another interesting detail is how closely the kJ tracked for each climb. Identical for the big climb! This is somewhat surprising given that the Trek was .6 lbs heavier.

Clearly, a test on a dirt road is only valid for similar conditions...so I'll do more tests off-road. But I'm becoming biased now. The acceleration issue of the big wheels is tough to overcome...I suspect they will be best suited for rocky/tech stuff.

One more data point: at Moab, I did a lap each on the Fuel, Dos, and the 292. I never did a lap on the 292 that was within a minute of the Fuel's lap time...

More to come!

26" or 29"???

Dave — Sat, 31 Dec 2005 12:32:00 GMT

Oh, that's a tough one. But in the end sponsorship arrangements made the decision for me...the team is sponsored by Trek & Gary Fisher. Trek doesn't yet make 29ers, and GF 29ers, although super fun really are better for trail riding, not so much racing. The Sugar 292 is currently the only FS option, and at near 30 lbs stock that's a lot of extra KJ over the course of a 24.

On the flip side, the Trek Fuel has been an awesome bike for me for 3 years now. It feels harsh compared to the Reba equiped 29ers I've ridden - but I think that is a result of the SID forks. They are designed for minimum weight, not maximum performance. As such, that's what you get - the lightest production fork. It feels like a jack hammer in your hands after awhile though...that's one of the biggest take home lessons of my foray into 29ers. Been riding SIDs for years - didn't know any better - but now I've seen the light. It was not lost on me that Eatough was riding a Fuel with a Reba fork rather than the stock SID when he won worlds 24 this year. If you can't beat 'em, join 'em!

It'll be interesting to see how more travel affects the handling of the bike. If it's too slow, I may end up shortening the travel a bit, for for now I think it's set at 115mm. Free-ride front end, baby!

I've come to really prefer the XO gripshift. Fast, precise shifting. The Dos was setup with XO and has worked flawlessly ever since. Still have XTR on the older Fuel - that option will be good for rain events.

The bike you see here will likely be the bike of choice for Trans Rockies. I've been considering the 29 option, but because of sponsors and a probable scarcity of 29er specific parts in Canada, the Fuel is going to be the machine. She weighs in at 24 lbs even with the Reba.

Test rides all weekend!

Fast Track 29er tire first impressions

Dave — Mon, 19 Dec 2005 11:41:00 GMT

If you don't ride & race a 29er this post will make abolutely no sense to you. You've been warned.

Tire selection for 29er race tires is limited at best. Switching over to tubeless 6 years ago was a big performance improvement. As far as cycling equipment innovations go, tubeless tires are on the level of suspension forks and clipless pedals. 29ers are a blast - but one of the tougher nuts to crack is tire selection. At this time there is not a single tubeless 29er tire available. The only tubeless option is some sort of conversion using non-tubeless tires. This involves a rim strip to seal the spoke holes and putting some sort of latex (or other chemical) sealant in the tire. Stans makes is a popular commercially available conversion kit for 26ers and 29ers.

This is not without significant risk, however. There seems to be no standard for producing 29er tires. As opposed to their little 26" cousins, 29er tires almost always fit loose. You can mount a 29er tire by tossing it across the room, it'll land on the rim just fine :) Also, the beads have been breaking or simply blowing off the rim when converted to tubeless. Not good!

Last time I checked Stans recommends only one type of tire for 29er conversions: wire beaded WTB. That's what I've been using all season. The race setup is a Nanorapter rear, Motoraptor front. They weigh in at about 760-780 g each. Ouch.

The big red S comes to the rescue. They've previously announced that they'll never make 29ers...but their defunct WC star was at one point interested in 29ers, so they set about designing a decent race tire for 29ers. The Fast Track is the end result of their work, and after one ride I'm jumping for joy.

Finally their is a viable 29er race tire. They are light. Compared to the wire bead WTBs, 300ishg lighter, and that's rolling weight. The weight difference is immediately apparent in moderate to high speed turns. The bike loses some of its longboat handling qualities. They are grippy, much more so than the nano/moto combo. The comparison ride was a snowpacked dirt road, and in those conditions the tires felt like velcro. They are supple. I ran them at 32R30F and at those pressures found them to be very compliant in the rough. They are not as high volume as the nano. On the Dos, rear tire clearance is an issue. With a nano on my Mavic Open Pro there is only about 3mm room between the top of the tire and the bottom of the wishbone. There is more than twice that now with the Fast Tracks. They come with an aramid bead, which as I understand it is considerably stronger than typical kevlar beads. I've taken the leap and mounted them tubeless. They aired up much more easily than any other tire I've mounted tubeless on 29ers, probably because they actually fit snugly on the rim. So far so good.

I'm thinking this tire outperforms anything I've used to date on 29ers...but I'll hold on that call until I abuse them on trails. But putting my bike in the 23 lb range by changing tires? How could that not be exciting! So long as that bead holds...

Life as a chronic geek

Dave — Thu, 24 Nov 2005 14:44:00 GMT

Chronic. The term conjures up visions of terminal smokers hacking their way through the day. I once worked with a gent that went by "chronic", and indeed he was (still is so I hear) keepin' it real. But as Miles points out, it's my new favorite word. It has a different connotation in my vernacular, just to clear any confusion.

The night before Thanksgiving and I finally found time to get the PT wheel set up on the Dos Niner. You'd think it'd be easy, right? Slap a tire on it, mount the harness and you're off. Some extra steps included a Stan's tubeless conversion and switching to a v-brake system from the Hayes disk. 3 hours later, this is what I have:

This is all very exciting...you see, if you don't have the data, it didn't actually happen. I've been flying blind since late July when I got the first 29er.

So this am it's off to give it a whirl, run it through the paces and pick up the metabolism in preparation for the gorging to come. 4 days in Moab are on deck...and everytime I spend time in that place the White Rim beckons. More than likely, tomorrow will be another trip around the WR. Not sure what it is about that ride - it's only jeep road, right? It sure does call loud and clear tho.

Any ambibuities in my useage of the term "chronic"? The geek part should be obvious.