Marin’s Hawk Hill Jr mountain bike that grows from 24″ wheel to 26″ wheel

Whilst we were at the 2018 Cycle Show Trade Day at the NEC (you can read our write up here) we didn’t spot the Marin stand until we were dashing for our train home. We were therefore pleased to catch up with them when we returned on the Sunday, so that we could take a closer look at a sweet 24″ wheel mountain bike that we spotted on the stand.  The Marin Hawk Hill Jr had caught our attention for two reasons – firstly, it’s got rear suspension (which is still quite rare on this size bike) and secondly it appeared to have large clearances for the wheel size.  We were keen to find out more…….

Marin Hawk Hill Jr full suspension kids mountain bike

Marin Hawk Hill JR 24" wheel kids full suspension mountain bike

The Marin Hawk Hill JR full suspension mountain bike is an interesting concept as it is designed to appeal to parents fed up with frequently having to replace their kids bike as they grow.  The Hawk Hill JR is supplied with 24″ wheels, but has sufficient clearance between the wheels and the frame / forks to allow fitment of 26″ wheels, meaning the bike can be upgraded for minimal cost (especially as 26″ wheels are currently out of favour and can be picked up quite cheaply).   Standover height for the Hawk Hill Jr is 621mm, suggesting the bike will be suitable from about age 8 plus, depending on your child’s leg measurement.

Clearance on the Marin Hawk Hill JR Mountain Bike

The Hawk Hill JR has been designed to be a scaled down version of  Marin’s adult bike of the same name.  The air sprung front X-Fusion Velvet RL 26″ front suspension gives 120mm of travel, which is more than most other 24″ wheel mountain bikes.  Compression and rebound adjustment allows fine tuning as the rider gains weight.

Full Suspension on the Marin Hawk Hill JR

Rear suspension is provided by an X-Fusion O2 Pro R.  On Marin’s website, the optimum rider weight for this shock is given as between 36 – 68 Kg.

Marin rear suspension on the Hawk Hill JR

It’s worth noting that a child on the 90th percentile will be 36kg just after their 8th birthday and someone on the 50th percentile by 10 and a half, but if your child is on the 5th percentile they won’t reach this weight until they are 13 and a half.  As Marin are using an air fork it should be possible to do some fine tuning to dial it in for lighter riders. However, if your child is a featherweight they may not feel the full benefit of the rear suspension.

The bars on the Marin Hawk Hill JR are pretty wide coming in at 720mm, so this allows for a bit of tweaking – you can trim them down to a size that feels comfortable for the child.

The wheels are double wall rim with stainless spokes and tubeless ready which is a nice touch and come shod with 2.25″ wire beaded tyres from Vee Tyre.

Vee tyres on Marin Hawk Hill JR

As you’d expect from a forward looking company like Marin, the drivetrain is pretty fresh for a child of this age. Keeping things nice and simple, there’s an own brand narrow wide 30T chainring with suitably dimensioned crank arms for kids. This couples up to a 10-Speed SunRace 11-42T cassette, with the well respected Shimano Deore shifter and rear mech ringing the changes. All in all it’s a sweet setup that gives plenty of ratios and should allow for most challenges to be overcome.

Rear Cassette on the Marin Hawk Hill JR

Stopping power comes courtesy of Shimano BR-M315 hydraulic disc brakes, with a 180mm rotor on the front and 160mm on the rear combined with matching levers.

Disc brakes on the Marin Hawks Hill JR kids mountain bike

The bike is set up to take a dropper seatpost if you want to upgrade from the quick release seat post supplied (unfortunately Marin don’t state the dimension of the seat post on their website).

Saddle on the Marin Hawk Hill JR

Price wise, the Hawk Hill Jr comes in at £1,350, but you do get two bike sizes for the price of one in that, meaning it compares favourably with other full sus kids bikes on the market.

This is certainly a bike to get people talking.  The ability to buy one bike and then just swap the wheels as your child grows will no doubt appeal to those who don’t like the continual hassle, expense or environmental impact of bike shopping, whilst the full suspension and cool frame should appeal to young shredders keen to have something a little bit different out on the trails.

Where to buy the Marin Hawk Hill Jr

The Hawk Hill Jr is currently available for pre-order at Tredz, for £1,350 .

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Disclosure:  We belong to Tredz affiliate scheme, so if you buy your bike through the link above we will get a small commission, which will help to pay for our train fare to the Cycle Show.  It doesn’t affect what we write about, this is the honest view of what we saw. Thanks for your support in helping us keep Cycle Sprog pedalling along.



Hi I was wondering how much would you sell it for


Hi Karlie, Thanks for your message – we are not a bike shop, so you’d have to contact your local Marin stockist to discuss availability and pricing of this bike. Hope you manage to find one. Karen

grant murray

I bought this because it could be upgraded to 26 inch wheels. Tredz sent me wheels that did not fit then quoted some that do – at cost of 500 pounds. Other specialists quote 260-315 to build wheels from scratch. SO I would personally discount the upgrade option.


Hi Grant – I have had the following information back from Marin for you:
In terms of the upgrade. The wheels need to the following axle spec:

Front Wheel – 15×100 axle

Rear Wheel – 12×142 axle
Typically these can range depending on the level of wheel the customer wants to buy. These can start from £150.
Hope this helps Karen


Hi Grant, This is disappointing – I hope Tredz offered you a full refund – they have a 365 returns policy.
I have emailed Marin to ask for the exact details of which types of wheel fit the Hawk Hill – it should certainly be cheaper to upgrade the bike than to buy a similar quality one twice over for 24″ and 26″ wheels. I’ll post any response I get here. Karen

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