Liam Hallam is a sports science graduate. He is also a keen cyclist as well as being a lover of the Derbyshire Dales and Peak District.
The Planet X Uncle John Cyclocross Bike
The Planet X Uncle John is marketed as a multi-use frameset: at home as a lightweight cyclocross racer, yet with the ability to adapt to become a quality commuter bike or winter trainer. This review will assess its ability to deal with all of these demands.
CX is gaining huge popularity across the globe; however not everyone can justify the purchase of an ultra-lightweight carbon-fibre top-of-the-range cyclocross bike which could set them back thousands of pounds/dollars/euros. The Planet X Uncle John aims to offer a great value alternative and therefore could be considered as an option for a first cyclocross bike.
Value-for-Money Cyclocross Frame
Great news! You can buy a triple butted lightweight aluminium frame with carbon fibre cx fork for less than £300 ($450 USD) and have a choice of red or blue colour too! This is fantastic value for money and opens up having a cyclocross bike to the masses.
Definitely great value for money for a cyclocross frame set.
My Uncle John Build Up
I've owned my size large Uncle John for 3 years and have it built up as below. (With original spec in brackets where adjustment made). The bike was purchased without wheels and tyres as the result of a special offer at the time.
Groupset. Shimano 105 10 speed
Chainset. FSA Gossamer CX with 44/ 36 chainrings
Handlebars. Planet X Superlight Team 44 cm
Stem. ITM Millennium 110 mm (Planet X Superlight Team 100 mm)
Seatpost. ITM Millennium Carbon (Planet X Superlight Team)
Saddle. Selle Italia Prolight (Planet X Team- Fizik Arionne Replica)
Brakes. Planet X Frogs Bollox
Wheelset. Mavic Ksyrium SL
Tyres. Challenge Grifo
Read More From Skyaboveus
Out on the woods, the spiritual home of the Planet X Uncle John
Planet X Uncle John Frameset Specification
The frame is made from triple butted super light aluminium and tips the scales at a reasonable yet not considerably light weight of 1980 g in my large size. A relatively light high end cyclo cross frameset would be expected to weigh around 1500 g however would likely cost over twice as much.
The Planet X Uncle John frame has clearance for 38 mm tyres. UCI regulations set that the max width for racing tyres is 32 mm therefore this allows for excellent mud clearance capabilities, especially when you consider that the frame also uses a traditional seat stay set up as opposed to a mono stay which decreases mud clearance.
The frame is also unlike many budget cyclo cross frames as it includes mounts for disc brakes and cantilevers. Disc brakes are a new addition to the cyclo cross world and give greater quality braking which is a step forward for cyclo cross as mud and water severely effects braking performance.
The Planet X Uncle John frame and forks also have braze on's in place for the mounting of mudguard fenders to give adaptability of purpose as well as featuring two sets of bottle cage mounts- while you shouldn't need a bottle in a cyclo cross race these bottle cage mounts are uncommon on high end cyclo cross frames and allow the frame to be used for other purposes like as a commuter bike or winter bike.
Disc Brake Mounts on a cyclo cross frame
Mud Clearance on a Planet X Uncle John
The important bit- how does the Planet X Uncle John ride?
With so many people now used to riding carbon fibre bikes it's somewhat refreshing to jump onto a relatively stiff aluminium bike and feel how much fun they really can be. One way I would describe the Uncle John is responsive. However it also feels confidence inspiring.
The position in a size large feels upright due to it's 170mm headtube which is raised even further by the fact that the frameset does not take a modern integrated headset which raises the height of the handlebars. Planet X have now adapted the frame to accept integrated headsets which should now lower the front end and provide a racier feel.
The frame and fork feel resilient with every pedal stroke despite my old Mavic Ksyrium SL wheels now being slightly on the spongey side. (Ironically I never liked them on my road race bike as they felt dull and lifeless).
Out on the trail the Uncle John simply urges you to go and find some singletrack and simply have fun. The handling is responsive and urges you to push your boundaries further.
Planet X Uncle John Geometry
What size Planet X Uncle John Frame do I need?
The below table from Planet X shows the geometry of the Uncle John frameset and a recommendation of what size frame is required based on height and the information is taken from the Planet X Website
Uncle John Frame Sizing from Planet X
Head Angle (degrees)
Head Tube (mm)
Effective Top Tube (mm)
Seat Angle (degrees)
Seat Tube length (c-f)
Chainstay Length (mm)
Standover height (mm)
Recommended Rider Height (Feet)
5ft3 to 5ft7
5ft8 to 5ft11
5ft10 to 6ft2
6ft1 to 6ft6
More Planet X Uncle John
I love my Planet X Uncle John
I ride my Uncle John with a great big smile on my face. I'm lucky in that locally to myself we have some great riding for which you don't necessarily need a mountain bike. I can ride a local 14 km singletrack loop which is closed as a technical red route with confidence on my Uncle John as I overtake mountain bikers and they look on in amazement that i'm on a 'cross bike and they're on a top of the range full suspension bike.
Could you use this as a winter bike or commuter?
Having owned this frameset for three years I can categorically say yes this could be a great winter bike. It has a comfortable racy yet slightly upright position that you can adapt for long distance comfortable riding. The responsiveness of the frameset means you could use it for fast training sessions and the braze on's and bottle bosses mean you can fit mud guards to ensure you stay relatively dirt free and hydrated on your rides.
Updates and upgrades for the 2012 Cyclocross Season
Stuff you might need for Cyclocross
Mountain biking helmets on January 03, 2012:
Hi, I think your site might be having browser compatibility issues. When I look at your website in Safari, it looks fine but when opening in Internet Explorer, it has some overlapping. I just wanted to give you a quick heads up! Other than that, fantastic blog!
Liam Hallam (author) from Nottingham UK on September 08, 2011:
Thank you Martie for your feedback. It's great to know others' thoughts
Martie Coetser from South Africa on September 07, 2011:
This is a well-written and worthy-to-read review of the Planet X Uncle John Cyclocross bike.