Purely a subjective impression, but my own experience is that the angle of the bike doesn’t make a massive difference and that it’s the increased resistance and/or reduced momentum (real or sumulated) that does.
In the past I’ve lived places where it was pretty much impossible to cycle outside during the winter and have spent months doing simulated climbs on Tacx RLVs (pre-Zwift!), only to book a holiday to Mallorca and find myself flying up the climbs. It does seem that virtual climbing is good training for real climbing and the experience can feel remarkably similar.
If you did your FTP on the flat and you are now attempting to climb a steep climb with varied gradient, it’s not a massive surprise that FTP is different.
Setting the trainer to 0% will make the variance in resistance lower, but it will not reduce the amount of watts/effort required to go at the same speed as at 85%, if that makes any sense.
It does reduce the need to change gear though, which will increase your efficiency a bit, and you now have the freedom to set your own pace based on how you feel, rather than being forced to go hard in certain spots due to the increase in resistance experienced at 85% difficulty.
Yup, that all makes sense. This is an old thread, and in fact I now have a better trainer (Tacx Neo 2T). I’m finding now that my Alpe du Zwift power is a little nearer to my FTP, even at 100% resistance. It’s still, maybe, 5w lower than it might be on a simulated hill of the same duration with a more continuous gradient, and I put that down entirely to the frequent gradient changes on the Alpe.
Zwift seem to have mapped the Alpe at quite a high resolution in terms of gradient changes (which is a good thing obviously), and the switchbacks etc. mean there is more variation than there is on some other hills anyway.
The interesting thing for me is that I can put out just a tiny bit more watts on simulated hills with smoother profiles, but I actually doubt that I could do so on a completely flat simulated gradient (e.g. if I set the resistance to 0%). TBH I’ve never tried an all-out 50min+ effort on the flat and would dread doing so… I like having the reststance to help me push (and alternate between sitting and standing), but in terms of average power that’s offset a little by gradient changes.
Reviving this old thread with my two cents, for what it’s worth. I have climbed l’Alpe d’Huez in Zwift, in BigRingVR and IRL. I use a Wahoo KICKR and always set trainer difficulty to 100%, since, with virtual platforms, 0% is meaningless when climbing as it will make any climb “flat”. When compared to IRL, Zwift is ok, but not reliable and/or comparable in terms of the time it takes and the power numbers. BigRingVR is not perfect, but much closer to IRL on all aspects, gradient, power and of course, the view. I have been using Zwift since the beginning (I was a beta tester) and I no longer use it due to it being way too optimistic with “achievements” (speed, power, distances, etc.) compared to reality. It’s a good social/gaming platform, but cannot be relied upon for serious training. These are my personal observations and your mileage may vary. Cheers!
I normally climb the Alpe on Zwift using a KICKR Bike at 100% difficulty and was wondering how much easier it is than IRL.
Do you have a rough idea of how much harder it is IRL (5%? 20%?)? I know weather and temperature will be a factor, as will the road surface, but if I went to France, how much harder should I expect the climb to be?
What people tend to forget in comparison of virtual versus real life, you tend to be alot fresher indoor, unless you are staying at the foot of mountain you tend to need to ride there, it’s rarely flat… plus there’s beers the night before, riding the day before… that bit might just be me.
The other major one, riding it on a trainer is a fairly simple experience, real life, when you have a bloody big mountain that disappears off into the mist in front of you it tends to make people back off a little to ensure they don’t blow up as they are intimidated by it.
Importantly… I assume you are aware that Alpe du Zwift and BigRingVR’s simulations of the Alpe use different routes? Alpe du Zwift simulates something like the “tourist” ascent, while BigRingVR uses (I think?) the full TdF route, which is about 2km longer and 100m more ascent.
@BikePower if I had to give it a %, I would say it’s within 5%, maybe closer to 2%-3%. However, what @Lee_H is mentioning in his feedback is very true and will definitely affect your effort and your perceived exhaustion. Vehicle traffic (stress) is a factor on this climb and once you’re high enough, the views could also take your breath away, literally
@Neil_Bell I can certainly confirm the BigRingVR route is identical to the IRL TdF route. And you are correct, the Zwift route is almost 2 km shorter. It seems to be matching the old finish of the climb (still marked with a sign) at the water fountain in Vieil Alpe. Those last 2 km IRL can be the busiest in terms of traffic depending on the season, as you go through the streets of the town of L’Alpe d’Huez and unless you’re in a race, the roads won’t be closed to vehicles.
@Toby_Conant_ABR Box Hill is my type of climb (short and punchy), it would be great to hear your feedback on how it compares between Zwift and IRL. There is a good YT video from a guy who is quite strong and fast, which makes the time gaps slimmer, but does confirm the faster splits in Zwift, even considering external factors. My PR in Zwift for Box Hill is 7m35s. Your time up AdZ is similar to mine. I average around 1h05m, even though my PR is 55m51s, that was obtained with my TD set at 0%, which is cheating IMO
Well I’m not going to be riding up the real one for a while but my best time is 7.15 (can’t do that now) for the segment to the cafe but the zwift one finishes further along. My best zwift time is 9.30 which might not be the best I can do but pretty close I think. I guess the real and zwift ones are within a minute of each other for me, but will see if I can use a ln old ride to work it out
