Polygon Siskiu D24 Full Suspension Kids Mountain Bike

The Polygon Siskiu D24 is the perfect pony for moving little rippers up to a full squish, but without taking a heavy blow to the pocketbook – it’s that illusive mix of great performance at a decent price. With confidence-building modern geometry; well-tuned air spring, kid-friendly suspension; as well as the ability to easily upgrade to a dropper post and a tubeless setup, the Siskiu comes ready for action now and for years to come.

In this review, we put the Siskiu D24 to the test, but we also point out the differences and upgrades available on the more expensive D24X, which shares the same frame as the D24.

young rider catching air on the polygon siskiu 24 full suspension kids mountain bike

Polygon Siskiu D24 Overview

RATING: Highly Recommended

MSRP: $1,299

BEST FOR: Quickly progressing riders who want to hit harder blue and black trails, as well as some lift-served mountain bike parks

SPECIFICIATIONS

SEAT HEIGHT: 27.8″ – 32.7″
WEIGHT: 30.4 lb.
BRAKES: Tektro Mechanical Disc
FORK: Suntour Raidon 32, Air Spring, 120mm Travel
REAR SHOCK: Suntour Raindon R, Air Spring
GEARS: 8 speed (1.5 – 5.4 gain ratio)
SHIFTER: Microshift Acolyte Trigger
DERAILLEUR: Microshift Acolyte, Medium Cage, Clutch
TIRES: Vee Tire Flow Snap 24 x 2.4″ – Not tubeless ready (but rims are tubeless ready)
HEAD TUBE ANGLE: 66
WHEELBASE: 1,028.2 mm
FRAME: Aluminum Alloy

PROS:

  • Low price point for full suspension with modern geometry
  • Lightweight for price and build
  • Tune-able air sprung fork (with lockout) and rear shock
  • Thru-axles for increased stiffness and rigidity
  • Internal routing for dropper post
  • 1x trigger shifters for quick and easy shifting
  • Pre-taped tubeless ready rims

CONS:

  • Mechanical disc brakes not ideal
  • Does not come with tubeless ready tires (only rims)

Polygon Siskiu D24 Full Suspension Kids Bike Review

Kelly from Haven Outdoors authored this review for Two Wheeling Tots. Kelly is an avid mountain biker and a father of four and certainly knows his way around bikes and kids.

After a fun spring and summer of hitting single track with the kids, it’s hard to fight the urge to constantly want to upgrade their bikes (okay well, mine as well). I’ve seen firsthand how better tires, more responsive brakes, or upgrades in drivetrains have allowed us to take on harder and longer trails.

So when the opportunity arose to test out Polygon’s new full-suspension kid’s bike, we were stoked. After 5 years of consistently riding single-track, our 10-year-old has been itching to ride the more advanced blue and black trails. The Siskiu D24 was the perfect pony for the task.

Getting to know the Siskiu was pretty easy besides the hard-to-spell name. With minimal transition time, my son quickly became one with this bike, as if he had been riding it all year. The Siskiu unapologetically delivered as he eagerly and repeatedly hit higher jumps with endless enthusiasm.

What type of rider is the Siskiu D24 best for?

The Polygon Siskiu D24 is an entry-level 24″ full suspension kids mountain bike. Its modern geometry delivers endless fun for young groms, without completely blowing the budget.

As a true full-suspension rig, the Siskiu D24 is best suited for riders ages 8 to 12 (more info on size below) who are quickly progressing and want to hit some of the harder blue and black trails, as well as ride some lift-served mountain bike parks.

young rider riding downhill on a full suspension 24 inch bike

Who is the Siskiu D24 not ideal for?

Full suspension bikes allow riders to tackle rowdier and rougher terrain, but that extra fun also brings extra weight. For the rider who still has a slower trail speed and is not hitting the harder blues and blacks, a lighter front suspension bike is likely going to help them progress better on the trail.

The Siskiu D24 comes in at 30.4 pounds, which is certainly on the lighter side considering it’s full squish. But when your kid only weights 75 pounds, it can be a lot of bike for a new rider.

After riding single track for 5 years on both rigid and front suspension mountain bikes, my 10-year-old son continued to push himself to hit harder lines, so I was quite confident that he was ready for a full-suspension pony. A couple of years ago, when we were still working on basic technique and endurance, I would have never considered moving him up.

For riders ready to tackle more intense downhill, as well as those who have the extra budget, I would recommend moving up to Polygon’s Siskiu D24X. It shares the same killer geometry we came to love on the D24, but with several upgrades, including hydraulic disc brakes, a Shimano 10-speed drivetrain, as well as suspension improvements. All of these upgrades are well worth the extra $400 in my book (more details about the differences later in the review).

What size child fits on the Siskiu D24?

The seat height on the D24 ranges from 27.8″ – 32.7″. Polygon’s recommended height for the Siskiu is 4’2″ – 4’11” (50″ to 59″).

My son, shown throughout this review, is 58″ tall with a 27″ inseam. Even though he is on the higher end of the Siskiu’s range, it was still a great fit for him with plenty of room for him to ride through another season.

side shot of a child riding a full suspension kids mountain bike

We have thrown some smaller kids on the D24 for a bit as well and the bike is also comfortable for them. I would attribute this to the bike’s super low standover, yet longer reach and wheelbase. The 10-year-old rider below is 53.5″ tall and had no issues with maneuverability or control. (Different kid, even though they’re basically wearing the same outfit!)

young child riding the Polygon Siskiu full suspension mountain bike
Being lighter in size, this rider did feel the weight of the bike more than our taller tester, but that didn’t stop him from thoroughly enjoying the Siskiu. If he was ready technically, I wouldn’t hesitate to purchase a Siskiu for a kid on the shorter end like him.
boy cruising through a turn on the Polygon Siskiu mountain bike

Siskiu D24 Geometry and Performance

Polygon nailed the geometry of the Siskiu D24 and created a true do-everything trail bike that allows kids to feel comfortable pedaling uphill while still being super fun, playful, and confidence-inspiring on the downs.

With a head tube angle of 66 degrees, the Siskiu is steep enough to keep the bike fun and fast on green and blues but slack enough to feel confident and comfortable when the trail gets a bit steep and rowdy. The effective seat tube angle sits at 75 degrees which puts the rider up over the bottom bracket for great positioning while seated and getting power to the pedals.

boy riding on a dirt trail while on the polygon siskiu full suspension kids mountain bike

Standover height (598.4 mm) is nice and low to help young riders with body/bike separation, as well as easy on and offs. Wheelbase (1028.2 mm) and reach are long for a good stable feel, yet the chainstays are nice and short at 400 mm which keeps the D24 super playful and quick through corners.

Performance

Straight out of the gate, the Siskiu did not disappoint. Within the first few miles of our inaugural ride, plans to hit our favorite local single-track as well as lift-served bike parks with jumps and gnarlier terrain were quickly in the works.

Courage to take on jumps and drops that previously seemed intimidating was quickly summoned as the Siskiu graciously put our young riders at ease. New jump line? Absolutely. Challenging rock garden, gnarly steep downhill, tough rooty section? Let’s go!

boy riding up a steep jump on a 24 inch full suspension kids mountain bike

Climbing

Let’s talk about climbing. I don’t know if there are many kids that actually enjoy climbing. And as many adults can attest, climbing on a full-suspension can be less than awesome. Polygon, however, makes climbing as efficient as possible on the D24. A bike that is clearly built for having a good time also disguises itself as a decent climbing bike as well.

boy riding up a hill on the polygon siskiu kids mountain bike

The suspension is active while climbing, giving the rider great traction through more technical bits of trail. But it doesn’t bob up and down getting up long fire roads either. Considering most suspension systems work terribly under lighter-weight kids, no complaints here considering the entry-level price of the Siskiu.

Descending

Headed downhill, the Polygon Siskiu D24 is a ripper. My kid said he had never had so much fun on a bike in his life. From mid-trail launches to chatter downhill rocky bits, smiles and confidence were easily had.

catching air off a jump on the polygon siskiu full suspension kids mountain bike

The suspension works really well and seems to have a nice plush feel off the top for great small-bump sensitivity, but without wallowing out on big hits or g-outs. There is just enough mid-stroke support with a good bit of ramp-up at the end of the stroke without feeling harsh.

riding down a rocky section of trail on the polygon siskiu kids mountain bike

Looking forward, Polygon was also smart to include internal routing for a dropper post. While he’s not quite ready yet, I’ll likely add one next season.

Polygon Siskiu D24 Components

While those looking for a rig with higher-end quality components should upgrade to the Siskiu D24X, for those already pushing the budget to get a full suspension rig, the components on the D24 offer solid performance for the price.

polygon siskiu 24 inch kids mountain bike leaned up against a fence

Weight

In terms of weight, the 30-pound pony could certainly be felt, but even after several hundred feet of elevation gain, it wasn’t a major complaint. (Although we did keep most of our rides under 6 miles.) Considering many front suspension kids’ mountain bikes weigh more than the Siskiu D24, Polygon’s efforts to keep the weight down certainly made our longer rides possible.

As a quick comparison in regards to weight, for the price, the Polygon D24 is right on the mark with other brands. Unless you are willing to shell out top dollar, you won’t find a lighter, well-spec’d full suspension 24″ bike on the market for under $1,300.

These other bikes, certainly have a lot more going for them spec-wise, but in regards to weight, the Polygons don’t have anything to hide.

MSRPWeight
Siskiu D24$1,29930 lb.
Siskiu D24x$1,69930 lb.
Commencal Clash$2,899+30 lb.
Spawn Rokk$2,955~29 lb.
Trailcraft Maxwell 24$3,299+24 lb.

Suspension

The Siskiu D24 comes spec’d with a Suntour Raidon 32 air shock with 120mm of travel and a Suntour Radion R rear shock. Neither are considered ultra-high-end, but both offer rebound adjustments to get the job done, and do it well.

You can run the pressures low enough on both front and rear to be supple off the top but still have enough in the tank for when it comes time to rebound. Both come back with enough energy and speed to be ready to go in time for the next set of chatter, rocks, or other bumps that poke their heads up out of the trail.

There is also good midstroke support for when your kid sees a jump or small feature in the trail where they can push into the bike and get some pop to boost into the air.

Drivetrain

The drivetrain is a 1×8 Microshift Acolyte (trigger) that shifts smooth and crisp. We had no issues with the drivetrain during testing, although it would be nice to see a bit more range. Within the 8 gears, the D24’s 12-42t cassette provides gain ratios ranging from 1.5 – 5.4.

close up of the microshift acolyte trigger shifter and derailleur

For those who need a bit more range, the upgraded Siskiu D24X does bump up the range to 10 gears (along with a Shimano drive train), but only offers a higher range with a gain ratio range of 1.5 – 6.3.

Tires

Having ridden the Siskiu’s Vee Tire Flow Snaps tires on other mountain bikes before, we were pleased to see them as they’ve always performed great for us. Tons of grip and traction and pretty fast rolling. They are also pretty durable.

side shot of the Polygon Siskiu kids full suspension mountain bike

Nothing to complain about with the Entity wheelset either. They come pre-taped if you end up wanting to go the tubeless route. As an FYI, the Flow Snap tires on the D24 are not tubeless-ready, but the Flow Snaps on the D24X are.

Brakes

The brakes on the Siskiu D24 are where I have some complaints. While the Tektro mechanical brakes are labeled as short lever reach, we found them to be rather big and clunky. The reach can be adjusted, but we found that they really needed to be adjusted tight into the bar before you get any bite out of the pads.

close up of a child braking on the polygon Siskiu mountain bike

There is plenty of stopping power once you get them locked up, but the power it takes to get there is more than we’d like to see on a bike for aggressive kids. Even an adult’s hands would be tired after a long descent after pulling those levers in for multiple miles.

I understand they were trying to hit a price point on this bike, but I don’t feel like this is an area to try and save a few bucks on. That being said, the brakes as they are would not stop me from buying or recommending the D24.

As a parent who would invest in a good full suspension bike like this for my own kids, I would rather pay an extra hundred bucks out of the gate for some good stoppers. Sure, I could (and likely will) upgrade to hydraulic brakes on my own, but going through the hassle of purchasing and installing them is a bit of a pain. I understand Polygon has to have some differences between the D24 and the D24X, but in my opinion, the brakes are not the place.

Polygon Siskiu D24 vs. D24X Comparison

Coming in at two price points, the Polygon Siskiu D24X allows parents to buy the ultimate rig from the get-go, while the D24 allows parents to save upfront and upgrade components as needed later.

Based on our experience, we would absolutely upgrade to the D24X if our budget allowed, but wouldn’t hesitate to get the D24 if our budget was already stretched.

D24D24X
MSRP$1,299$1,699
ForkSuntour Raidon 32, Air Spring, 120mm TravelX-Fusion Velvet 26″, Air Spring, 120mm Travel
Rear SuspensionSuntour Raindon R, Air SpringX-Fusion O2 Pro, Air Spring
BrakesTektro Mechanical DiscTektro Hydraulic Disc
DrivetrainMicroshift Acolyte 1×8-speed, 12-42TShimano Deore 1×10-speed, 11-46T
Gain Ratio1.5 – 5.41.5 – 6.3
TiresVee Tire Flow Snap 24×2.4″, Tackee Compound, Wire BeadVee Tire Flow Snap 24×2.4″, Tackee Compound, Tubeless-Ready
WheelsEntity X15 Disc, 24mm, Tubeless Tape Installed, 15×100 / 12x142mmEntity X15 Disc, 24mm, Tubeless Tape Installed, 15×100 / 12x142mm

Polygon Siskiu D24 Bottom Line

If your little grom is ready for full squish, but your pocketbook isn’t, the Polygon Siskiu D24 is the Goldilocks bike. Spec’d out enough to withstand a beating, but without hitting the high-end price point. With a well-thought-out modern geometry and fine-tuned suspension that actually works with lightweight kids, the Siskiu delivers on the downhill, without too many compromises on the uphill.

This bike has plenty of standover and the frame is routed for an internally routed dropper post if you choose to upgrade later on. The bike stays planted due to a longer wheelbase and long front center, but stays playful and quick through the corners thanks to short chainstays. The only thing holding the D24 back on the downhill would be the mechanical Tektro disc brakes.

Brakes aside (if you can afford the $400 upgrade to get the hydraulic brakes on D24X do it!), Polygon has done a great job at creating an awesome bike for little rippers who have taken their skill to the next level and have outgrown the hardtail.

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