Confusing it with sweet spot 2 × 20
Same notation, different session. Sweet spot is ridden at 88–94% of FTP with 5 minutes' recovery; threshold 2 × 20, at 95–100% with 10 minutes. If you want a session you can repeat often, sweet spot is the one.
CyclingThreshold and sweet spotIntermediate 75 min
Threshold 2 × 20 min
The 2x20 threshold session: two 20-minute blocks at 95–100% of FTP, with 10 easy minutes between. 40 minutes at threshold in a 75-minute session. The most classic session in power-based training, for riders who've already done some sweet spot.
Session profile7 blocks
At a glance
- Duration
- 75 min
- Main target
- 95–100%FTP4 Z4 · Threshold
- Time at target
- 40 min
- Estimated load
- 81
- Structure
- 2 × 20′ at 95–100% FTP, 10′ recovery
- Level
- Intermediate
- Equipment
- Power meter · Smart trainer
The session in detail
FTP
Time in zone
- Z125 min
- Z210 min
- Z440 min
What the targets mean
| Target | Zone | Time | FTP 200 W | FTP 250 W | FTP 300 W |
|---|---|---|---|---|---|
| 95–100% | 4Threshold | 40 min | 190–200 W | 238–250 W | 285–300 W |
| 50–60% | 1Recovery | 10 min | 100–120 W | 125–150 W | 150–180 W |
Put this session on your bike computer or watch
Wattson works out the targets from your FTP and sends the session to your Garmin, Wahoo, Coros or Suunto.
What this session is for
Two by twenty targets your FTP itself, the power you can hold for about an hour. Your threshold is the point beyond which lactate builds up faster than your body can clear it. Riding for a long time just below that point, at the top of Coggan's level 4, pushes your body to raise it: that's the power behind time trials, long climbs and breakaways.
Why 20-minute blocks? Hunter Allen, co-author with Andrew Coggan of Training and Racing with a Power Meter, sees little value in threshold efforts shorter than 10 minutes. Two 20-minute blocks give you 40 minutes at the target intensity, with a single break. No study has tested this exact format: it rests on very established practice and on the logic of the intensity.
Who it's for
Intermediate riders, after a few weeks of sweet spot 2 × 20, which is ridden a notch lower. An up-to-date FTP is essential: 40 minutes at 95–100% leaves no margin. If you're preparing for a time trial, a hilly sportive or a breakaway, it's the session that most resembles your race effort.
When to do it
One threshold session a week is usually enough, with at least one easy day before and after. Avoid the day before a long ride or a race. To build up to it, start with 3 × 10 minutes, then 3 × 15, before 2 × 20; after that, move to 3 × 20, or to Seiler's 4 × 16.
How to do it
Warm-up
15 min5′ at 45–55% FTP + 5′ at 56–65% FTP + 5′ at 66–75% FTP
15 minutes building from 45 to 75% of FTP, in 5-minute steps. Outside, use the warm-up to reach a road with no junctions or descents, or the foot of a 20-minute climb.
Main set
50 min2 × 20′ at 95–100% FTP, 10′ recovery
Two 20-minute blocks at 95–100% of FTP, or 238 to 250 W for an FTP of 250 W, with 10 easy minutes at 50–60% between them. Start at the bottom of the range for the first five minutes, then settle in. Keep a steady cadence and a position you can hold for 20 minutes: it's often your neck or back that goes before your legs. If you can't hold the second block, drop 2 to 3% rather than stopping.
Cool-down
10 min10′ at 40–55% FTP
10 very easy minutes at 40–55% of FTP. Note how the second block went: if you had to back off within the first few minutes, your FTP is probably set too high, and a new test is due.
How it should feel
Hard but controlled: the pace of a one-hour time trial. The first block feels manageable; the end of the second takes concentration and a degree of stubbornness. Twenty minutes is about how long it takes to regret updating your FTP. Guide: 7 to 8 out of 10.
Common mistakes
Riding to an inflated FTP
At 95–100%, an FTP that's a few per cent too high makes the second block impossible. The session then becomes an accidental test: if you crack every time, retest rather than forcing it.
Starting above the range
On fresh legs, 105% feels easy for five minutes. You pay for it over the next quarter of an hour. Start at the bottom of the range, and only nudge up halfway through the second block if you have something left.
Bailing instead of adjusting
Stopping a block at minute 14 throws away most of the benefit. Dropping 2 to 3% and finishing keeps the session in the right zone, just a little lower.
When to skip it
Before you start
- A recently measured FTP.
- A few weeks of sweet spot or shorter threshold blocks behind you.
Skip it if
- You're tired, or a long ride or race is planned for the next day.
- You have doubts about your health: get medical advice before sustained hard efforts.
Origin and evidence
Level of evidence
Established practice, no dedicated studyLevel 1 of 5
A classic of power-based training, tied to level 4 (threshold) of Andrew Coggan's zones, from 91 to 105% of FTP. Hunter Allen, co-author with Coggan of Training and Racing with a Power Meter, sees little value in threshold efforts shorter than 10 minutes, hence the long blocks. No scientific protocol is attributed to this exact format, and no controlled study has compared it with other threshold sessions. The 95–100% range, the 10-minute recovery, for lack of a reference value, the warm-up and the cool-down are Wattson choices. Bottom line: very established practice, indirect evidence.
Sources
- Allen H., Coggan A., Training and Racing with a Power Meter, VeloPress
Frequently asked questions
What power should I ride a 2x20 threshold session at?
At 95–100% of FTP: 190 to 200 W for an FTP of 200 W, 238 to 250 W for 250 W, 285 to 300 W for 300 W. It's the top of Coggan's level 4, which runs from 91 to 105%. Start at the bottom of the range and keep the top for the end of the second block.
What's the difference between 2x20 threshold and sweet spot 2x20?
Intensity and recovery. Sweet spot is ridden at 88–94% of FTP with 5 minutes between blocks; threshold, at 95–100% with 10 minutes. Sweet spot is less tiring and can be repeated more often; threshold is closer to a time-trial effort.
How much recovery between the two 20-minute blocks?
Here, 10 easy minutes at 50–60% of FTP. There's no reference value: it's a Wattson choice, long enough for the second block to be ridden at the same power as the first. If the second still falls apart, it's more likely your FTP that needs revisiting.
How do I build up to a 2x20 threshold session?
Through block length, at the same intensity: 3 × 10 minutes, then 3 × 15, then 2 × 20. Once 2 × 20 is under control, move to 3 × 20 or longer blocks, and retest your FTP after 4 to 6 weeks: if it has gone up, your targets follow.
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