Is it cheaper to buy a complete built bike or build one from the frame up?
I recently had a chance to check out the Specialized SL8 Pro Ultegra Di2 complete bike at my local bike shop and it got me thinking, is it cheaper to build one from the frame up or buy the complete bike. So I decided to do a cost breakdown of what the individual parts cost, both at MSRP and at some of the deal prices I’ve seen lately. Let’s start with the what you get when you buy the Specialized SL8 Pro Ultegra Di2 model
Specialized SL8 Pro Ultegra Di2 Parts list:
- Frameset: Tarmac SL8 FACT 10r Carbon
- Fork: FACT 10r Carbon
- Wheelset: Roval Rapide CLII
- Front and Rear Tires: S-Works Turbo, 2BR, 700x26mm
- Inner Tubes: Turbo Ultralight, 60mm front, 80mm rear
- Crankset: Shimano Ultegra R8100 with 4iii power meter
- Shifter Levers: Shimano Ultegra Di2 R8170, hydraulic disc
- Brakes: Shimano Ultegra di2 R8170, hydraulic disc
- Brake Rotors Front and Rear: Shimano RT-CL800
- Front Derailleur: Shimano Ultegra Di2 R8170, braze on
- Rear Derailleur: Shimano Ultegra Di2 R8150, 12 Speed
- Cassette: Shimano Ultegra, 12-speed, 11-30t
- Bottom Bracket: Shimano threaded BSA
- Chain: Shimano Ultegra 12-speed
- Saddle: Specialized Power Pro, hollow titanium rails
- Seatpost: S-Works Tarmac SL8 Carbon
- Handlebars: Roval Rapide handlebar, carbon
- Tape: Supeacaz Sticky Kush
- Stem: Tarmac integrated stem, 6-degree
- Battery: Shimano DN300
- Front Derailleur Wire: EW-SD300 900m
- Rear Derailleur Wire: EW-SD300 1200mm
- Battery Charger: EW-EC300 charger
A few assumptions were made
The website talk about the Di2 parts like battery and wires and it didn’t say exclusively that it includes a battery charger but I figure you will need one anyways so those are all on the list. Also it doesn’t say which rotors are used but from the photos I assume they are Shimano Ultegra RT-CL800’s
Comparing the Tarmac SL8 Pro Complete Build with Built From the Frame Up
These are the retail prices if you pieced the bike together and paid the MSRP pricing:
| Part | MSRP |
|---|---|
| Frameset: Tarmac SL8 FACT 10r carbon | $3,500 |
| Fork: FACT 10r carbon | Included with frameset |
| Wheelset: Roval Rapide CLII | $1,850 |
| Tires: S-Works Turbo 2BR, 700x26mm (pair) | $140 |
| Inner tubes: Turbo Ultralight | $16 |
| Crankset: Shimano Ultegra R8100 with 4iii power meter | $640 |
| Shifters: Shimano Ultegra Di2 R8170, hydraulic disc | $1,074 |
| Brakes: Shimano Ultegra Di2 R8170 | Included with shifters |
| Rotors: Shimano RT-CL800 (pair) | $122 |
| Front derailleur: Ultegra Di2 R8170, braze-on | $260 |
| Rear derailleur: Ultegra Di2 R8150, 12-speed | $410 |
| Cassette: Ultegra 12-speed, 11-30t | $94 |
| Bottom bracket: Shimano threaded BSA | $18 |
| Chain: Ultegra 12-speed | $48 |
| Saddle: Specialized Power, hollow titanium rails | $160 |
| Seatpost: S-Works Tarmac SL8 carbon | Included with frameset |
| Handlebar: Roval Rapide carbon | $300 |
| Bar tape: Supacaz Sticky Kush | $45 |
| Stem: Tarmac integrated, 6-degree | Included with frameset |
| Battery: Shimano DN300 | $185 |
| Front derailleur wire: EW-SD300 900mm | $28 |
| Rear derailleur wire: EW-SD300 1200mm | $28 |
| Battery charger: EW-EC300 | $50 |
| Total | $8,968 |
Specialized Tarmac SL8 Pro: $8500 - Specialized Tarmac Ultegra identical build at MSRP: $8968
It looks like you save $468 by buying the complete bike compared to paying the retail prices for each of the parts.
Finding deals on parts to bring the price below the complete bike cost
I did some searching and the best deal I could find at the time of writing this was a Shimano Ultegra Di2 12 speed groupset which included all of the Shimano parts on the list below. The one thing that is missing is the power meter but 4iiii has a deal where you send in your left crank arm and they will install a power meter for $275. This would make it the same as the power meter on the complete Specialized Tarmac SL8 Pro. The price I found was Jenson USA for $1999 for the groupset which they claim is a 25% discount off the MSRP. Shimano Ultegra R8100 Di2 Groupset - Jenson USA
| Part | Market Price | Best Deal Found |
|---|---|---|
| Frameset: Tarmac SL8 FACT 10r carbon | $3,500 | $3,500 |
| Fork: FACT 10r carbon | Included with frameset | Included with frameset |
| Wheelset: Roval Rapide CLII | $1,850 | $1,850 |
| Tires: S-Works Turbo 2BR, 700x26mm (pair) | $140 | $140 |
| Inner tubes: Turbo Ultralight | $16 | $16 |
| Crankset: Ultegra R8100 with 4iiii power meter | $640 | $275 (4iiii send-in power meter) |
| Shifters: Ultegra Di2 R8170, hydraulic disc | $1,074 | $1,999 (full Ultegra Di2 groupset) |
| Brakes: Ultegra Di2 R8170 | Included with shifters | Included in groupset deal |
| Rotors: Shimano RT-CL800 (pair) | $122 | Included in groupset deal |
| Front derailleur: Ultegra Di2 R8170, braze-on | $260 | Included in groupset deal |
| Rear derailleur: Ultegra Di2 R8150, 12-speed | $410 | Included in groupset deal |
| Cassette: Ultegra 12-speed, 11-30t | $94 | Included in groupset deal |
| Bottom bracket: Shimano threaded BSA | $18 | Included in groupset deal |
| Chain: Ultegra 12-speed | $48 | Included in groupset deal |
| Saddle: Specialized Power, hollow titanium rails | $160 | $160 |
| Seatpost: S-Works Tarmac SL8 carbon | Included with frameset | Included with frameset |
| Handlebar: Roval Rapide carbon | $300 | $300 |
| Bar tape: Supacaz Sticky Kush | $45 | $45 |
| Stem: Tarmac integrated, 6-degree | Included with frameset | Included with frameset |
| Battery: Shimano DN300 | $185 | Included in groupset deal |
| Front derailleur wire: EW-SD300 900mm | $28 | Included in groupset deal |
| Rear derailleur wire: EW-SD300 1200mm | $28 | Included in groupset deal |
| Battery charger: EW-EC300 | $50 | Included in groupset deal |
| Total | $8,968 | $8,285 |
This brings the price of the built bike to $8285, $215 less than buying the complete bike
Custom build lets you choose every part
The other main advantage of a custom build is that you can choose all of the parts on the bike. By going custom on the build, you can choose the items that are very subjective like seats, handlebar shapes, stem length, tires, and even the wheelset. If you are someone who spends all of their time in the mountains, you may like a wheelset like the Roval Alpinist CLII over the Roval Rapide CLII. So many of these items can be customized to the places and the way you ride, so price isn’t everything when deciding to build your own bike from the frame up.
Conclusion
At the time of writing this, there wasn’t a huge amount of cost savings to be had for building a bike rather than buying the complete Specialized SL8 Pro. By buying the groupset, you can save about $215 from the complete bike, but this is assuming you have all the tools to build and know how to build it yourself. You might spend $150-250 for a local bike shop to build the bike for you so all that savings might be lost. The best reason for building up your bike custom is that you already know what parts you like the best and this gives you the freedom to choose every part out individually. Buying the complete Specialized SL8 Pro is great choice for people wanting a complete package already built. Some times bike shops will also offer some free maintenance if you buy the complete bike from them so that is a plus also. Whether you build it yourself or buy the complete Specialized Tarmac SL8 Pro, you’re gonna be getting one of the newest and most advanced bikes on the market.
Update: The Tarmac SL9 (2026)
The SL8 has since been replaced by the Tarmac SL9, which launched only in S-Works trim at first. That makes this math more interesting for SL8 shoppers. Outgoing SL8 completes tend to get discounted, while part prices don’t drop, so the gap between buying complete and building it yourself usually gets wider as a model year ages. If you’re shopping now, price a discounted SL8 complete before you price parts.
The same “is the premium worth it” math shows up in my Dura-Ace vs Ultegra R8100 cost per gram breakdown and the CAAD13 vs SuperSix Evo Hi-Mod comparison. And if you want to see what a frame-up build actually looks like, here’s my 2026 SuperSix Evo build.