Benefits of bigger 700c/27.5"/29" wheels on kids bikes
We've pioneered the use of larger wheels on kids bikes for years and a common question is "What are the benefits of larger wheels on kids bikes?". Benefits include: performance (handling & acceleration) financial & practical;
- Handling: especially in MTB & CX the larger rolling radius smooths out the terrain - rolling over problems, not in and out of them! Larger diameter wheels are also more stable (gyroscopic) improving the riders confidence.
- Acceleration: lightweight 700c/27.5"/29" wheels spin up much faster than mass produced children's 24"/26" etc, especially helpful for kids with less power. Tyres and tubes are also lighter.
- Practicality: component sharing with parents and siblings - borrowing mums/dads race wheels, tyres, tubes etc - no more odd sized kit, everyone on the same size. Easier on holidays too.
- Financial: they won't outgrow their 700c/27.5"/29" wheels (only a frame and cranks) so moving to a larger size frame, as they grow, can actually cost less than buying a whole new bike.
With these advantages in mind, the HUPcc range of framesets have all been developed using 700c/27.5"/29" wheelsets for riders aged approx 6 years old and above. This is how we did it...
The BIG Wheel Design Challenge
Designing a complete range of youth-specific bikes means understanding the key differences between kids and adults, such as their relationship of leg length to torso. This leads to 4 key areas of frame design that need to be addressed: reach, toe-overlap, stand over and stack height. Add to those, the requirement for all frame sizes to use 700c/27.5"/29" wheels (to benefit from the well proven advantages for smaller riders) and you need careful, considered geometry…
With shorter torso’s and longer legs (relative) the kids need different geometry to an equivalent height adult. In essence a shorter top-tube, so they can still reach and operate those controls without difficulty. Typical small adult frames have a top-tube that is too long, creating all sorts of reach and confidence issues. However, the current reliance on very short stems for Road/CX bikes (compensating for a long the top-tube) isn’t the perfect solution (as it can create ’twitchy/nervous’ steering). But frames with genuinely short top-tubes, allow the use of longer stems for more balanced and predictable steering. The carefully designed, youth-specific HUP geometry achieves just that: shorter top-tubes, better fit, increased control.
It’s also important to eliminate toe-overlap on youth cyclocross bikes in particular, so they can confidently negotiate technical sections of the course without the risk of their shoes clashing with the front tyre when steering. It’s a common issue with adult frames, but we’ve been very careful (especially on the smaller frame sizes) to remove that risk, so they can simply concentrate on the course.
We’ve created super low stand overs (especially on our 37cm & 13" frames) using contemporary sloping top-tube geometry, making it practical for small riders to use full-sized wheels and all the benefits that come with adult wheels.
However, those very appealing 700c wheels can lead to a high stack height (height of the head-tube, over the front wheel) which isn’t necessarily that helpful for bike fit. Riders with short legs will have a very low saddle height (possible thanks to short seat tubes) but a high stack on a Road/CX bike will lead to a poor bike fit position (bars much higher than the saddle) creating the MTB style riding position - not ideal for road, track or cyclocross. With a combination of FSA headset, head-tube depth and fork rake, we’ve managed to lower the stack height on our HUP drop bar bikes, compared to the existing youth frames, which is great for improving rider position. That low-stack is a favourite with youth riders, they tend to favour the ‘slammed’ position, just like the pro peloton does.
But when it comes to the HUP enduro, it runs a much higher stack, for good reason. Tilt your bike downwards on the descent and the high stack actually helps short-torso junior rides stay in control, easily reaching the bars at any angle, so they can deal with the features and terrain they are riding easily. Further helped by the use of Riser bars.
It was also important to ‘future-proof’ the range as much as is possible, an important consideration for parents wanting to preserve the value of their investment. The latest technical standards have been used such as flat/post mount disc brakes, Shimano thru-axles, an 1 1/8” tapered fork steerer and internal cabling (with ‘easy to install cables’ design for novice mechanics). The full length outer cable design also reduces ongoing maintenance to a minimum. The HUP evo on 142mm/100mm OLD, the HUP enduro on 148mm/110mm boost OLD - both the very latest in their categories.
Finally, it was important to create class leading tyre clearances for obvious reasons such as the ability to deal with Winter mud, but also to allow the flexibility to fit 650b wheels and larger Gravel or MTB tyres on the HUP evo. This gives the opportunity to build a highly effective Gravel Adventure bike (or MTB XC bike for the younger riders), something the previous cantilever brake frames couldn’t manage. For these reasons, HUP cyclocross frames have a huge 55mm tyre clearance. The HUP enduro is built for 2.4" wide enduro tyres, huge grip!
We also had firm opinions about where our frames should be produced. After building 100’s of race bikes from many brands over the years, we had certainly learnt where we didn’t want them made. As the home of high-end bike production for decades, Taiwan was our first choice and finding a factory that was already producing bikes for several well-known UK and US brands was very useful. Their experience and quality was instantly evident. All frames are hand fabricated and hand painted. Then all bikes/self-build bundles are hand-assembled in the UK, giving us the freedom to build to the riders requirements, using our own unique range of youth-specific bike components.