I'm a relatively fit hobby cyclist and want to set myself a challenge for (mid) 2024, competing in a 6-hour TT challenge. It's a relatively flat to moderately hilly 18 km loop (1% average gradient, 185 m) and only paved roads, as you would expect. I am not planning to use any specific gear like skinsuits, aero bars due, I'm just going to do this on my endurance road bike in the best fitting kit I have and the result/rank isn't the main focus.

Here's the course profile:

enter image description here

I know that I can finish because it did comparable-length rides on my own, both indoors on Zwift and outdoors but since the indoor season is coming up soon, I want to do the majority of structured training over winter and on the trainer. Workouts on the road are not my thing because it is hard to find roads for steady efforts and keep focused.

"Relatively fit" means I'm doing endurance sports (running, cycling) for the past 10 years, current at ~3,8W/kg FTP at 37 years of age and I know can sustain about 2,5W/kg for 5-6 hours - I'm for sure not winning my age class but I want to take it seriously and not just show up with whatever form I'm in at the day of the event.

Based on these numbers and using bikecalculator.com, I'd be happy if I can do about 8-9 laps (~150-160 km). Judging by this year's results, I'd be somewhere solid on top of the bottom third but anything beyond dead last and riding the full six hours with good feeling counts as success. I am aware that my bike will be a limiting factor in this scenario. At least I know that being in the saddle for so long shouldn't be a problem position-wise, especially because a climb and descent loosen things up lap-per-lap, the course has a long straight, hills and there are a few technical bits due to the countryside location of the race.

That's the bike I am using (2018 Ridley Fenix SL, size S):

enter image description here

As I learned, it is not per se a lazy endurance frame and its STR ration of 1,41 rather sporty, even though I feel more upright and not really aero on it, but that's not the point of the bike, anyway. I had two bike fits and the position works well for me on long rides (the worst being 6+ hours on the trainer). I think, the fitter has somewhat compensated the geometry by keeping spacers on the stem but I have ridden about 10-15k+ over the last 3 years with this fit and wouldn't really want to change anything about it. There were observations that the saddle is tilted forwards but that was also a result of the fit since I seem to be a bit tail-heavy on the bike and even wheelied off trying to get back on the bike on ascents - and actually ride quite a lot of hills.

Here's my current power curve, nothing extraordinary, just as an indication where I'm at:

enter image description here (The huge step over 5-6 hours must be an artifact of a stopped activity or something like that, I can't recall any 10-hour rides this year)

So, my ambition is just to be prepared and focus my indoor training rides on getting the best possible result with 2-3 workouts per week - I also commute approx. 2 hours per week. I'm not really keen on subscribing to any paid service (other than Zwift), so I'm asking for some general advice on what I should focus on.

Quite honestly, I don't have the biggest experience with structured training, last year I did a 2-hour hillclimb and mostly did 60/90-minute sweetspot units with occasional higher-intensity workouts and simulated climbs. That worked out pretty well because it was close to the actual challenge.

Is that something I could continue with or do I need to put in longer units at moderate intensity to avoid falling off the cliff half into the race?

(Of course, fueling will be yet another topic but I think that's something we can ignore here for now)

  • 1
    Yeah, it's a bit vague ... somewhere in the middle. I'm aware that I'll never get to a competitive pace but a little more than just riding for six hours at whatever tempo I survive. Most realistically, I'd be aiming for a consistant finish around my endurance/tempo pace. Let's say ~70 percent of my threshold power which should be roughly 170 watts at my weight. I don't think I'm that far off because I had Zwift rides that showed at least a normalized power around that for 6+ hours, but without bonking throughout the course this time, ideally.
    – DoNuT
    Sep 6, 2023 at 19:20
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    Are you actually comfortable with aero hoods for that long? That's pretty rare, if you're really getting your forearms horizontal, though a short toptube+stem and bars with long tops would help a lot
    – Chris H
    Sep 6, 2023 at 20:46
  • 1
    @Criggie that's one of the nice things about TTs. On the day, it's you against the clock, and you don't know the result until afterwards unless everyone overtakes you (and not even that in a course of laps).
    – Chris H
    Sep 6, 2023 at 20:47
  • 1
    @ChrisH Yeah, I pretty much ride every flat section like that. Just feels nicer than the drops, but I must add that my bike is far from aggressive, so not very stretched out. Plus, the course has a climb and descent back into the valley, so it'll be a solid mix of all bar grips, anyway. And climbs generally suit me. Others may grind up on TT bikes with heavy gears, I'll just dance up with compact gearing. But let's see how much I like the climb on the 9th iteration.
    – DoNuT
    Sep 6, 2023 at 20:52
  • 1
    @DoNuT that's a decent reason. And if you enjoy the TT, you have a mechanical way to do better next year (though of limited benefit given your default position). IMO clip-on bars don't make a TT setup. I had some on my tourer until recently, and would have put them on my MTB for a 200km ride if the screws hadn't seized.
    – Chris H
    Sep 6, 2023 at 21:06

2 Answers 2


I'm not a coach, and this may not be the best forum for answers. The folks on TrainerRoad's forum seem more than willing to help outsiders. Long triathlon bike legs are similar to your intended effort, so riders in your situation should also consider the Slowtwitch forum. That said, here's my effort.

A 6-hour ride done continuously will probably be in your endurance or tempo pace. For reference, here are some power zones. Also, top Ironman competitors do a 4-5 hour bike split (where they cover a century), and I believe they race at the high end of the tempo zone - but they are also fitter than you are I. And their bikes are a lot faster.

Zone Range as % of threshold power
Active recovery <55%
Endurance 55 - 75%
Tempo 76 - 87%
Sweet spot 88 - 94%
Threshold 95 - 105%
VO2max 106 - 120%
Anaerobic capacity >= 121%

This TrainerRoad forum user posted their training plan for Unbound XL. They had one or two long endurance rides on the weekend (up to 8 hours in a single ride), and 1 VO2max workout and 1 threshold workout during the week. It is relatively few workouts per week. Bear in mind that Unbound XL men's winner finished just short of 23 hours, whereas your event is slightly shorter.

I can't do an expert assessment of this plan. At face value, it seems like it could be informative for your goal. The general structure should hold.

This part of the answer was added later. This poster, who I believe is a coach, posted on the TrainerRoad forum, also recommended long tempo intervals, ~80-85% FTP. The conventional wisdom I picked up for general road cycling is that we want to avoid zone 3. It's not as hard as doing a sweet spot or threshold workout, hence it doesn't stimulate as much adaptation. But it's more fatiguing than zone 2.

However, in general road cycling, few of us are trying to hold steady zone 3 for a long time. Races aren't often decided just by that type of effort. Many marathon and half marathon runners are aiming to hold tempo for as long as they can, and it turns out that tempo workouts are common for distance runners. Elite Ironman triathletes are, I think, aiming to hold zone 3 for the bike leg.

Your power at VO2max acts as a ceiling on your threshold. All athletes, even ultra athletes, want to do at least some VO2max. It does seem to me like you could periodize your training, e.g. do some longer threshold/sweet spot work on two days a week over the winter, and add VO2max in the spring.

Therefore, I don't know exactly what to advise in this situation. Perhaps my initial advice was sub-optimal. There should be some coaches who have experience with cyclists who do long- but not ultra-distance events.

Here is a suggested set of progressions for threshold work:

3x10 > 3x15 > 5x10 > 2x25 > 6x10 > 3x20 > 1x60 > maybe more if you want

Sweet spot intervals can be longer. On forums, I've heard people say they can hit 90 minutes of continuous sweet spot. Now, I don't know if everyone can hit this sort of duration. For example, can any healthy man potentially hit a sub 3h marathon if they train hard enough?The original poster there thought so, but they may be wrong! Nevertheless, long sweet spot workouts can be highly beneficial for your endurance at high power.

I'm not familiar with progression for long tempo intervals, aside from just adding time relative to sweet spot. Because of the principle of specificity, I would probably advise to try to get a few sessions where the OP could do very extended tempo work.

Last, I think the long endurance rides would be important as well. They train your body and mind. You may not have to hit a full 6 hours for an endurance ride, but push as close as you can - in contrast, it would probably be impractical for most people to do a 24-hour or more training ride to prep for Unbound XL. I don't know what typical guidelines for cycling are, but I vaguely remember runners targeting at least half their race distance, and that poster echoed the advice.

Somewhat related, time to exhaustion (TTE) is a different concept from threshold power (or whatever other power). Adding time in zone trains TTE. One alternate FTP test by Kolie Moore basically has you hold about your FTP until failure, which basically estimates your TTE at FTP. My TTE was a pathetic 30 minutes last I checked, although my excuse is that I may not have been fully recovered from earlier rides. You might consider doing this test. I assume you want to increase your TTE if possible, in addition to increasing your threshold. Some readers may have have heard that FTP is the power you can hold for 60 minutes. It's not. It's an estimate of the power you generate at lactate threshold. We don't measure lactate threshold outside of a lab, so we estimate it using various other tests. People can typically hold their FTPs for 30 to 70 minutes.

  • Thanks, that's a lot to digest but confirms some thoughts I had. Realistically, with a job and in the evening, I'll probably do the shorter/more intense workout throughout the week and aim for the longer rides on the weekend, be it on the trainer or outdoors if the conditions allow it. I know myself, as soon as it is outdoor season (and another 2+ months to the race), I tend to just enjoy myself on longer rides without a goal, but I think I can use those to get close to the target pace, on a 3-4-5 hour ride which is in my comfort zone.
    – DoNuT
    Sep 6, 2023 at 19:33
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    Quick note that 3x15 isn’t missing and 2x20 wouldn’t fit in that progressing because its total of 40 min in the zone is less than 3x15, but jumping from 10 to 20 min in each block is a big leap
    – Paul H
    Sep 6, 2023 at 22:31
  • @PaulH thanks for the heads up. I agree that 20m blocks are a lot. I successfully did 4x10 earlier in the year, but then I tried 2x20 and I had a terrible time.
    – Weiwen Ng
    Sep 7, 2023 at 12:38

From this image:

enter image description here

your saddle has a significant forward tilt.

Your arms are likely to get sore and tired on long rides from having to continuously push yourself backwards to hold yourself on that saddle. You really should try to get the nose of the saddle up some and not force your arms to work so hard on long rides.

Also, a Ridley Fenix is not really an "endurance" frame. It's a pro-level race frame used by riders like Andre Greipel in races like Paris-Roubaix. The "endurance" aspect of the Fenix is its design for racing on Belgian pavé, taking larger tires than most road bikes and not as being stiff so it doesn't ride as harsh as a race frame designed for smooth roads.

But make no mistake about it - it's a racing frame. With its short chain stays/wheelbase, relatively steep head tube angle and little trail, it handles like a race frame. It's quick and responsive. It's not a bike you can relax on and ride no-hands easily, for example. And that can get tiring during hours-long rides.

It does have a relatively tall head tube, so it can be hard to set one up really aggressively and get a really aerodynamic position, and that tall head tube does lend itself for use as more of an endurance bike with a more upright position.

But it's still likely to be a lot tougher on you mentally on long rides than an actual endurance bicycle.

How would I know? I have one, set up pretty much just like yours - but with the stem flipped up for an even more upright position. The chainstays are so short that it feels like I'm going to flip over backwards when I hit a local 16% grade. And I can make it at most about 2 seconds riding no-hands before the bike makes a directional decision of it's own.

  • Thing is - I have that bike since 2019 and that position is the result of two bikefits, ridden since mid-2021 or so. I didn't ride a 6-hour TT on it but certainly enough long rides between 3 and 6 hours without any sore hands. So, changing anything in my fit is the last thing I'll do. Plus, I'm pretty sure I can ride with no hands for 1 kilometer including turns, which is something I'm not able to do on my other bike, a 2000s alloy frame on 23 mm wheels. I know it is a "classics" bike and Ridley's marketing text but it is rather comfortable and I sit rather upright, hence "endurance"...
    – DoNuT
    Sep 13, 2023 at 4:29
  • ... appreciate your input Andrew, but except it being not being suited for time-trialing due to its "classics nature", the bike is not really the problem, here. I've ridden about 25k on it and had no issues whatsoever, so I wouldn't even level out the saddle. ;)
    – DoNuT
    Sep 13, 2023 at 4:48
  • But you are right, based on geometrygeeks.bike, my size S has a STR of 1,41 (vs. a Specialized Roubaix in comparable size is at 1,5), so it is probably sportier than I anticipated but that has been somewhat compensated by the not-so-slammed stem and the saddle not being as far out. However, it worked well for me but it probably means that I'm not having as much of a hard time if I ever want to switch something more aero, not coming from an actual endurance bike.
    – DoNuT
    Sep 13, 2023 at 6:11
  • The distinction between "endurance" and "race" here is quite strange. Yes, those bikes are used in races like Paris-Roubaix but Paris-Roubaix is an endurance race that took 5 hours 28 minutes for the winner this year so 6 hours would be just barely above the time limit.
    – ojs
    Sep 13, 2023 at 7:32
  • @ojs Yeah and Ridley nowadays clearly markets it as endurance bike. It seems it has been born as a bike built for Lotto Soudal that survives cobbles, that probably explains why it is maybe a bit more aggressive than other bikes because a pro team demanded it. But, with generally wider tires and technology improvement, people are smashing through Parix-Roubaix with aero frames these days. Anyway, it fits me and my riding well, TT is just an experiment but only 1% of my 2024 riding, so I'm not too concerned about using the Fenix for it. :)
    – DoNuT
    Sep 13, 2023 at 7:51

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