When a ride on the road bike gets long, intense, or both, one thing matters above all: energy. Blood sugar levels play a crucial role in this. But what exactly is the glycemic index (GI) ? And how can you use this knowledge for better fueling during training ?
By Vincent Augustin 2 minutes read time
Published: December 20, 2025
The glycemic index (GI) indicates how quickly a carbohydrate-containing food raises blood sugar levels . Glucose, with a GI of 100, serves as the reference. The higher the GI, the faster blood sugar levels rise – and the faster energy is available.
High GI (>70) : e.g., white bread, glucose, rice cakes
Medium GI (56–69) : e.g., bananas, oatmeal
Low GI (<55) : e.g., lentils, apples, whole-grain bread
During intense rides or races, the body primarily relies on carbohydrates as an energy source. Depending on their glycemic index (GI), these can be metabolized more or less quickly.
Before training : A low to medium GI prevents blood sugar spikes and resulting energy crashes. Ideally, take 1–2 hours before starting.
During training : Quick energy is crucial. A high GI ensures rapid glucose availability – important for long rides or intervals.
After training : A high GI can help to quickly replenish glycogen stores – especially during short recovery periods between training sessions.
Blood sugar levels fluctuate throughout the day and during physical exertion. When cycling, performance is closely linked to the availability of glucose – especially during prolonged or intense exertion.
Stable blood sugar protects against performance drops (“bonk” or “hunger hit”).
A rapid drop in blood sugar levels can trigger dizziness, concentration problems or nausea – the classic “flat foot in the body”.
No additional fueling is needed if glycogen stores are well filled.
Water or an electrolyte drink is often sufficient.
From the 60th minute onwards, you should regularly consume energy – about 30–60 g of carbohydrates per hour .
Good sources:
Energy gels (high GI, quickly available)
Rice bars or dried fruit (medium GI)
Banana (natural mix of glucose and fructose, medium GI)
Sports drinks with glucose & maltodextrin
Tip: For longer tours, pay attention to a combination of glucose + fructose in a ratio of 2:1 – this increases the maximum absorption capacity to up to 90 g of carbohydrates per hour.
Those who race should test their fueling during training . Digestion, GI tolerance, and personal preferences vary.
Breakfast (2 hours beforehand) : Oatmeal with banana and nuts (medium GI)
During the journey :
One energy gel every 30 minutes (20–25 g carbohydrates, high GI)
Additionally, half a bar or a banana every 60 minutes.
500–750 ml of fluid per hour, possibly with electrolytes
After the ride : white bread with jam or a recovery drink (high GI)
The glycemic index isn't dogma, but it's a helpful tool – especially for athletes. Those who manage their blood sugar intelligently can perform better, last longer, and recover faster. The motto is: low GI before training, high GI during and after .
For all ambitious cyclists, fueling is an integral part of training, not an add-on.
Almost every road cyclist remembers this moment: You're rolling slowly up to a traffic light, everything is relaxed – and then you simply tip over . Not quickly, not spectacularly, but agonizingly slowly.
Ein Tubeless-System funktioniert nur so gut wie die Dichtmilch, die darin zirkuliert. Sie dichtet kleine Einstiche in Sekundenschnelle ab – aber nur, wenn sie noch flüssig und wirksam ist. Wer sie vernachlässigt, riskiert, dass der Reifen bei der nächsten Panne nicht mehr selbst abdichtet oder schleichend Luft verliert. Die gute Nachricht: Dichtmilch nachfüllen oder wechseln ist einfacher als viele denken.
Die Tour de France 2026 ist entschieden: Tadej Pogačar fährt zum fünften Mal in Gelb nach Paris und schließt zu den Rekordsiegern auf. Das Finale über den Montmartre entschied Mathieu van der Poel um eine halbe Radlänge – gegen seinen eigenen Sprinter.
