I read somewhere once that aerobars are pointless until you are going faster than 23-24kph, which is ~15mph.

 



Perhaps not much but why not take advantage of every aero opportunity you can get?


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Once, I was fast. But I got over it.

I'm sure you did, but that's why we can't have nice things.

Yes, use the clipons.

At lower speeds the speed gain and watt savings are lower, but (somewhat counterintuitively) the time savings/mile is greater (since you get the benefit over a greater period of time).

There is no magic cut-off speed where aero benefits disappear. The idea that you have to be at least X fast to save time with an aero helmet/disc wheel/aero bars/etc. is a myth. Kienle saves less time with a disc wheel than the guy with the 6:30 bike split.

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

i'd try to get the pulse of the event. Sure aerobars are faster, but for what seems like a not really serious event do you really want to be "that guy" who used aerobars. To each his own, but sometimes going cannibal style is the coolest way to roll (especially if you win anyway).

Oh please.
You MAY (or may not) save more seconds at a lower speed thanks to aerobars, but it's always going to be a smaller percentage of your total time.

But that is of course not the question. The question is if the gains outweigh the costs.

While clip-ons only carry a small weight cost, more importantly, they reduce the power you put out at the given effort level (which is not true for all athletes on a TT/road bike, but for like 95% of them sure, and I guess for 99.99% of athletes on a fatbike with clip-ons - the weirdest and least familiar position imaginable).

The aero benefit is on the other hand a rounding error of total resistance, especially on a bike with the sort of rolling resistance one would expect from a fatbike. The drag would matter less than on a road/TT bike even at 20 mph, because it takes so many watts to depress the tyre as you roll. Plus the low speed.

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"FTP is a bit 2015, don't you think?" - Gustav Iden

I ride a lot of fatbike on snow.

I’d be more worried about losing any small amount of time I saved by being in aero getting up off the snow due to a toe dab, spin out, or crash from not having as good of control of the handlebars.

Even if it’s perfectly groomed 15’ wide skating track, seems like you’d be giving up a lot of control on a highly variable surface.

Have fun!

It's an interesting point. Are we looking for marginal gains not too far from what everyone else is doing or are we looking for the biggest gains within the rules?

Both are fine BTW.

If everyone else is wearing baggy clothes, mtb helmets with visors and massive wide straight handle bars why not turn up in full TT kit?

Are you trying to win or take part? I don't mean that in a provocative way. I'm certainly there to take part. But my MTB has a handle bar with a second parallel bar I can rest my wrists on in a headwind. It's intended for bike packing but I've always been interested in a long solo trial against the clock where it would be helpful.

From the fat tire riding I've done, I'd suspect that ideal tires and tire pressure would be way more important than aero concerns in the event.

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Genetics load the gun, lifestyle pulls the trigger.

i'm looking for at least top 5, so taking every possible advantage. its a winter multisport race, fat bike 10k, skate ski 10k, snowshoe 8k, then skimo. likely will be a past olympic skier in the field and many other very strong winter athletes. https://www.friendsoftuckermanravine.org/inferno

Sounds amazing. Good luck. I think the more unusual the sport the more scope there is for doing something different so, as you say, pull out every stop.

If I still lived in Washington State I wanted to try a multisport race that involved jumping on and off a noboard.

The difference between hoods and clipons at 15mph is ~9W. I haven't seen MTB tunnel data, but let's assume this is a reasonable proxy (the MTB clipon position likely isn't as low, but the baseline position on the grips is worse). If you can do 15mph on 250W (very doable on flat, non-technical surfaces), saving 9W (~4%) seems non-trivial.


The clipons aren't going to help on gnarly, rooted, technical single track; but across fields, fire roads, paved sections, etc. they can offer an advantage.

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

You and most people on this thread are missing the point when talking about the ground speed of a fat bike.

Ground speed is somewhat irrelvant. What is important is the true air speed of your bike plus body moving through the air and the barometric pressure of the air.

Let's say you are moving at 20kph into a 20kph headwind on a day that is 103 kpa barometric pressure?

You better believe that aerodynamics have a massive impact at least for your headwind legs! In XC ski races, drafting at 15-25kph has a huge effect given that largely the position of the skier is very non aerodynamic. So at similar speeds if you can get into a tight aero ball rather than being a sail in a typical fatbike position (not as bad as a skier or runner standing up, but close), then it is definitely a way to go faster.

Also I read that this is a winter multi sport event. I assume the bike leg is draft legal. So I depends on your strengths in the other sports.

I have done winter tris that were speed skating in a pack, then skate ski and then run. I would get in the speedskate leg and essentially do zero work. I would sit in the top 3-5 in a pack of 200 people that would whittle down to 20 or so, but I would just stay in top 3-8 and do nothing but stay out of trouble from all the crashes (if you fall, you lose the pack and the moment you lose contact, you have no hope). Before every turn I would crank up the pace to force the pack into an accordian affect which essentially ensured that coming out of the turns, many would get dropped

At the end of the speedskate, I would sprint like crazy in the last 1 minute and transition fast to exit onto the ski course ideally in first place but if I knew there was one of the guys who is a faster skier, I would try to start the ski on the tail of those guy/s. But if I could get on the trail in first place, I could control the ski course and surge exactly at the best spot to make a gap and then TT solo to make a gap work and pad gaps foor the run. But if I was with a faster skier/s I would just sit in and do NOTHING for the entire ski. Just draft draft draft.

After that it was a foot race, and the foot race had almost no tactics other than running on ice with sheet metal screws screwed into running shoes for traction. I am sharing this because these winter tris are hyper tactical in terms of what you do with who is around and how to use them to maximize speed and position with the least amount of energy. Depending on where the fat bike leg is and who you have around you and which sports are your strength, you may want to completely draft the fat bike, or you may need to put down the hammer and gap people who are stronger on other legs.

In these winter tris, my strength was on the speed skate and skis, but I would try not to use any real juice on the skate and just put a few short surges in to whittle down the pack to jettison good skiers and good runners who are not great skaters, but I would never try to get away from the top skaters. There was no chance to get away from them and would be a stupid waste of energy, so I would put these random surges in to bait the strong skaters who can't run well to ratchet up the pace incrementally to hurt good skiers and runners who can't skate.

it is a staggered start at 5 second intervals, based on bib #. hopefully i should have a low number based on last year's results. earlier start time and less traffic should yield the smoothest and fastest snow. not sure if drafting is allowed, but on previous years races (on road bikes rather than snow,) it was not draft legal. the strong competitors are all excellent cyclists on the road but have no fat bike experience, so i think i need to capitalize on every second here. i think i have tire selection and pressures down, something they could possibly struggle with. i'll probably test the clip ons next week in the weekly TT to see if there is any effect. even if it is slight, i think it's worth it because it is going to be 2 loops, and windy section will total 1 mile.... as for the ski, even if i ski low 30's for 10k i'll probably lose a few minutes to the best skier. and also transitions will be key, but i'm keeping that secret.....

I think the answer here is not straight forward and analogies to road riding are only partly applicable. Rolling resistance on a fat bike is much much higher that rolling resistance on the road. A consequence of this is that a 5% change in rolling resistance on a fat bike is much bigger deal in terms of watts than a 5% change in rolling resistance on the road. Tied in with rolling resistance is grip which can very easily be make or brake in the snow. Going aero will impact your weight distribution and if you don't account for this by adjusting the rest of the system I could see it making the whole system worse. Conversely putting more weight over the front may let you run a faster rolling front tire and that could amplify the gains of using clips.

Ultimately you need to keep in mind that a TT bike would be utterly useless on the course you are talking about (unless you have this bike When a TT bike and a fat bike have a baby... The Fat Trek Equinox is born - Bikerumor) so while you want to go aero you need to be careful not to compromise what makes the fat bike the better bike to start with. A bet you could optimize the system with a bit of testing though.

The aero bars are going to be faster. If the course is groomed well then being in a reasonable (NOT the complete road TT foldover) aero position shouldn't make you fall. I've done it, and I'll frequently just move my hands in and grip the bars on either side of the stem. Just get your arms in and get a little shorter. It's faster.
If it is ALL groomed you will be tucked more and therefore faster by just flipping your stem and dropping it on the steerer tube if you can. That won't be the ideal position for getting through technical singletrack fast though.

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Andy Tetmeyer (I work at HED)

Hello jflan and All,

Fun to weigh in on problems that have limted information.

You may find an angle in the answers you have not considered.

With so many disciplines to consider ... preparation for this race seems the primary focus.

And with only 15 days left before the starting gun ... time is short.

Adding something unfamiliar like aero bars to your bike at this late date is problematical ... since you are looking at top 5 currently without aerobars.

If you can get in a few rides to accomodate to the new position it might be fun to have the aero bars ...... but unless you are very comfortable with them .....

Eschew the bars this year .... but definitely maybe check them out and practice much earlier next year.

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Cheers, Neal

+1 mph Faster