Having trouble with long tempo and sweet spot intervals


I’m not on TR, but I figured I would ask here since there’s a good concentration of training knowledge. All my cycling career, I’ve tended to be a very good breakaway rider, so on Sufferfest, my 4DP score shows 1min intervals as my strength and threshold as a relative weakness. I decided to do some structured training to address that.

I’ve been finding 3x15 or 2x20 threshold intervals to be very challenging to complete. I am guessing that I may need to keep at it a while - time to exertion is related to but separate from FTP, and I need to work on this bit. Am I on base?

By way of background, I was a cat 3 way back when. I’ve had ups and downs, but currently in decent shape. I got my FTP up to 228W this winter. I have about 20 years cycling experience, but I haven’t really got into structured training before, and I haven’t deliberately sought out long durations at sweet spot or FTP.

Been doing these for about 4 years now.

Few things that helped me along the way:

  • Correct FTP
  • Breath control / relaxing
  • Nice high cadence (for me, some where around 95rpm takes the edge of pushing the pedals)
  • Nice smooth pedalling technique
  • Mentally & physically breaking the intervals up. For e.g for 15 mins do 5 min in drops, 5 min on hoods, 5 min on bars.

What system are you using to set you FTP? A pure tempo effort you should be able to hold with some focus for several hours and a pure SS effort for about an hour with a lot of focus. If you are unable to hold it, it suggests to me your FTP might be too high. Some people for instance excel at a ramp test as they have good MAP but it overpredicts their FTP.

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I’m using the shorter 20 minute FTP test as programmed in Zwift.

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Your ftp is overestimated. You should at the very least be able to do 60min tiz without much difficulty. I did 2x60 sweet spot today, it’s achievable with a correctly set ftp


At a 228W ftp, I assume you are saying that 3x15 or 2x20 around 225-230W are challenging.

One approach to consider is starting at 5x8 or 4x10 at 85-90%. If outside shoot for 195-210W and it will likely be better to start lower end of power and then work on going longer. Make the first interval around 195W and increase the power a little on each interval after that. Over time you can extend those out to 45-60 minutes total. Don’t worry if they are only 10 or 12 minutes long, eventually take them out to 60 minutes total (e.g. 5x12 or 4x15 or 3x20).

However there is another approach, one I’ve come to prefer. Skim this article and pay attention to the workout formats:

The last workout is Steady State Intervals - e.g. 2x20 and READ THE NOTE UNDER IT as this classic interval format is both your weakness and opportunity to get similar adaptations with a different format.

Instead of doing threshold intervals, and before doing some longer sweet spot, I’d suggest doing a few weeks of the Significantly Over/Longer Under intervals in that article. Essentially its 3 sets of a 12 minute interval that starts with a 45-sec acceleration a good bit above threshold (say, around 115-125%), and then 135-seconds around 85%, repeated until you do 12 minutes. I progress them by taking the unders from 85% to 90% and sometimes 95% if fitness is going up quickly. After a couple weeks of those, take a break, and come back doing some longer sweet spot intervals.

One of those two approaches will likely put you on a better path than trying to jump directly to doing 3x15 or 2x20 threhsold intervals.


I’ll give an example of what I tend to do to get into shape. My ftp is between 350-380 depending on fitness during the season (based on 95% of 20min). I won’t give %ftp because I don’t go off of that. I know my legs well and they get fitter through the 2-3month block, so I just ride off of wattage instead and I know where I’m at based on how those watts feel.

I usually start with 3 weeks at 300w for 2-4x15min or 2-3x20min. This is easy to accomplish but it’s work.

Then 3 weeks at 330w with similar intervals. Still not too challenging if I’m recovering well.

Lastly, I’ll do 2-3 weeks at 360w for 2-3x a broken 30min (based on a climb with two stop signs. I end up doing 11min, 1off to cross safely, 13min, 1 off, then 6-7min). These feel hard, but I can repeat another rep 30mins later. I do them in a big loop.

I’ve done this block maybe 3-4 times in the last few years. I do it outside on climbs. I’m more of a punch rider but I’ve got a ‘big engine’ triathlete style.

I won’t train ftp intervals outside of this block. When racing, I do a 3min on → 1min off x 5-8 reps maintenance workout once a week at 20min max power for the on reps.

I think you’re having so much difficulty because you’re diving right into such hard wattage. Ease into it and it’ll be easy. Especially given your ftp comes from a 20min test


As a good breakaway rider you might want to use 90% of the 20-minute average power from the Zwift test. If Zwift used 95%, your 20-minute power was 240W.

Your ftp is likely in the 90-95% range, or 216 to 228 watts. You might want to split the difference and lower ftp to 222 watts.

Those two things:

  • lowering ftp a little if you aren’t sure where its at
  • doing intervals at 85-90%, or starting with those over/unders I mentioned and then going to 85-90% intervals

will likely put you on the path to success.


I coached a very good 800 meter runner. He was very good at the shorter faster reps and had a great 400. Had a decent mile but the further up he went the more he suffered. We tried to work thresholds and guys who were much slower would destroy him on threshold runs. No matter how we tried to build it up it just was something he was not good at. So it could just be something you’ll never be good at and will always suffer at. Some are good at it, some are not.

That said we can work to reach our ceiling. Maybe start with 3 min reps, then move to 4…5…6…etc. keep recovery at 1:1 then slowly reduce the recovery. If you can’t do 20 min do break it down… do what you can!

When I last used a shorter 20mins test and maybe because I using ERG (which isn’t the best on the Suito) I found 0.92 (as oppose to 0.95) would give me a more sustainable FTP number.

To be blunt. Perhaps bad coaching was a culprit there.

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60 min unbroken at sweetspot is doable, but challenging. You need to build up and get used to it physically but mostly mentally.

yes but I said 60min time in zone and not unbroken, so I maintain my original statement

I do occasionally do that 4DP test just to see where I am. The 4DP’s FTP estimate has been consistent with the FTP estimates from the Zwift 20 minute test. For people not familiar, the 4DP test is 2x max sprints, 5 min max effort, 20 min max effort, 1 min max effort, with warm up and rest in between each effort.

I’m open to my FTP being overestimated, but during my threshold blocks, my heart rate is hitting and not exceeding my estimate of my threshold HR. If I were actually riding above threshold, wouldn’t it climb above that level? For example, the current estimate I have is that my threshold HR is about 170 bpm, and here is the last 3x15 workout I did. My HR only got a few bpm above 170 at the end of the 3rd interval. (Threshold HR estimate from a combo of intervals.icu and the last 4DP test I did.)

HR is a funny thing. Whilst I’m no expert, hitting a THR estimate and not going over it could be a sign of overtraining and the FTP you’re training at being too high for you. Conversely however, it could also mean that higher efforts are getting easier and you’re getting fitter, but given what you’ve said about trouble with Tempo I doubt it.

Do tell. :roll_eyes:

A combination of things that you and others have said

When you are new to structured training, 3x15 and 2x20 threshold intervals are very challenging to complete.

Some combination of keeping at it a while, or slightly lowering your FTP / the % of ftp applied to the workouts and doing a mix of different workouts as you do more structured training will certainly help make them a bit more doable.

But 3 x 15 and 2 x 20 threshold intervals aren’t going to be a cake walk anytime soon. Yes, more doable as your training extends your TTE & improves your fitness overall, but the nature of the beast is that such workouts are meant to be just that - a workout!

This forum is one of the best places to learn about & discuss such matters.

Whatever happens, enjoy every ride.

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Oh it was definitely bad coaching. :wink: But he did run 1:52 in the 800 and a 49 in the 400 as a junior in high school. Even though he never broke a 6 min mile in 8th grade I am not under and presumption there was not a huge amount of untapped genetic talent there and he would have been successful with any “non bad” coach.

Putting bad coaching aside, the reality is not everyone is good at the same thing. Why are there different events in Track and Field? Why not just have everyone run the 100 meters and be done with it? We accept that the best sprinter may not the best at the marathon and vice versa. People are good at different things and that’s ok. I know the bike is the great equalizer that kind of muddies things a bit but the truth is some will be better at hills, some at maintaining threshold and some at sprinting. I mean that’s why there are different leaders jerseys after all right? Just my observation (from doing this a long time) but some just struggle with threshold. Some don’t. It doesn’t mean you don’t work at it… it just means it is going to hurt a bit more compared to your training partner.

I’ll try 4x10 at this FTP, but I completed 4x10 earlier in the year. It felt easy. Now, as I’m typing this, I’m remembering that this was done in early April, when it was cool outside. My apartment runs a bit warm in the summer, and I should maybe get an extra fan. I don’t think I’m seriously overheated indoors right now, but it’s possible this is affecting my performance.

I’ll read that in depth, but I’m basically hearing add more over-unders to train lactate clearance. Which makes sense. Honestly I don’t like over-unders either, but maybe that tells me something.

Then what do you suggest I do? Do the Kolie Moore FTP test and set numbers based on that?