Which part of my bike should I upgrade first?
In value order: free position changes, then what you wear, then your tyres and chain, then your helmet, then wheels, and the frame last. For most riders the best-value paid upgrade is a skinsuit, and the best free one is narrowing your arms and getting your head down.
That order is close to the reverse of how most people actually buy. Below is the reasoning, with the numbers.
The order, and why
1. Position (free)
Narrowing your armrest pads is worth roughly 3 watts and costs nothing. Getting your head down and your forearms parallel costs nothing either. Nothing you can buy competes with free, and a good position is also what makes the expensive kit work properly later. The catch is that a position you cannot hold for the whole event is not an aero gain, it is a way to lose time in the last 10 km.
2. What you wear (£8 to £350)
This is where the value is concentrated. A skinsuit instead of a jersey is around 12 watts for £230. Shaving your legs is around 5 watts for the price of a razor. Aero overshoes are around 6 watts for £35. Loose fabric flapping in the wind is the single biggest thing separating a club rider from a fast one, and it is the cheapest to fix.
3. Tyres and chain (£25 to £80)
A slow tyre can cost you more than a slow wheel, and a dirty chain is a few watts you are simply throwing away. Both are cheap, both are replaceable in an evening. Neither is affected by how fast you are going in the way aero savings are, so they matter relatively more at lower speeds.
4. Helmet (£180 to £250)
A time trial helmet is around 8 watts over a normal vented one for about £250. That is decent value and it is the point at which spending starts to get serious. An aero road helmet gets you about half of it for a bit less, and is more use outside a race.
5. Wheels (£700 to £1,200)
Deep wheels work. A deep front is around 6 watts, a disc rear around 5 watts on top of a deep rear. The problem is the price. At 0.008 and 0.004 watts per pound they are five to ten times worse value than the clothing above them, so they make sense once the cheap things are done and not before.
6. The frame (£2,500)
A dedicated TT frame saves the most of anything on the list, around 20 watts, and is still the worst value on it at 0.008 watts per pound. Buy it because you want it, or because you have run out of other things to buy. There is more on this in is it worth upgrading my bike?
Side by side
| Order | Change | Watts | Cost | Watts per £ |
|---|---|---|---|---|
| 1 | Narrow your armrest pads | 3 W | Free | — |
| 2 | Shave your legs | 5 W | £8 | 0.62 |
| 3 | Clean and wax your chain | 6 W | £25 | 0.24 |
| 4 | Aero overshoes | 6 W | £35 | 0.18 |
| 5 | Skinsuit instead of a jersey | 12 W | £230 | 0.052 |
| 6 | Time trial helmet | 8 W | £250 | 0.032 |
| 7 | Deep front wheel | 6 W | £700 | 0.008 |
| 8 | Dedicated TT frame | 20 W | £2,500 | 0.008 |
| 9 | Full disc wheel | 5 W | £1,200 | 0.004 |
What changes the order
Your speed. Aero savings rise with the cube of speed, while tyre and chain savings do not. At 32 km/h the chain and tyres climb the list. At 45 km/h everything aero pulls ahead.
What you already own. This is the big one. If you already race in a skinsuit, the 12 watts above is not available to you, and your next best buy is something else entirely. A generic list like this one is only a starting point, which is why the tool asks what you are currently running and ranks the upgrade from your actual setup.
Your event. A road race with a bunch to sit in rewards aero kit differently from a solo time trial. Draft for most of the day and the watts you save alone matter less.
The honest caveats
These are indicative figures, mostly from published wind tunnel and rolling resistance testing, with some of our own estimates flagged on the sources page. A wind tunnel resolves to about ±2.5 W at 40 km/h, so treat anything smaller than that as directional. Savings also overlap, so you cannot simply add them all up. The tool applies a diminishing-returns discount when it combines them.