🔥 Got a Burning Question?

Not sure how JACK works? Wondering if it’ll fit your bike or handle your weekend haul?You’re in the right place. Below are answers to our most common questions, short, simple, and straight to the point.

💪 How much weight can JACK carry?

JACK has been lab-tested and road-tested to safely carry up to 5kg.
That said, if you're riding smooth roads and feeling confident, you can push that limit slightly at your own risk. Just keep in mind: heavier loads can negatively affect your bike’s handling. We don’t officially recommend exceeding the limit.

🔧 How do I install JACK?

You wont need any tools. Watch our official installation video for a full walkthrough.There are also great install videos in different languages on YouTube, made by JACK users worldwide.

🚴 Can I fit JACK to carbon handlebars or stems?

Yes, JACK works with carbon. Just treat it with care like any carbon component.

Tip: Check under the spacers regularly to make sure no grit or dirt has gotten underneath, as that’s what causes wear.

🥊 Does JACK work with Redshift suspension stems?

Yes. There's a user-generated video on YouTube showing how.

📏 Does JACK work with Ø26mm handlebars?

Yes. Many customers use the 25.4mm shims for 26mm bars. Some have even gently filed down the shims to get a better fit.

📏Does JACK work with Ø35mm handlebars?

Yes, with an added part. One of our brilliant Kickstarter backers designed a 3D-printable 35mm shim you can get made at your local print shop.

✅ Is JACK compatible with my bike?

Most likely, JACK fits around 90% of bikes, including old-school cruisers and modern commuters, road and mountain bikes. It’s designed for handlebar stems that clamp to:31.8mm / 25.4mm / 22.2mm bars.

There are a few specific spacing requirements. Check the compatibility diagrams on the product page to be sure.

💥 What if JACK breaks?

If you manage to break JACK we want to see it! Seriously, send us a pic, it’s rare and we’d love to know how it happened.

If anything wears out or breaks, we stock spares for every single part. If you’re out in the wild and a strap fails, JACK is designed to be field-repairable. Use any strap, rope, shoelace, wire, even a t-shirt to get back on the road.

📦 What’s in the box?

  • JACK (the rack) with removable fabric base
  • Pairs of handlebar shims: 31.8mm, 25.4mm, 22.2mm
  • Tapered inserts for 25.4mm → 22.2mm bars
  • Five stem loadstraps (sizes XS to XL)
  • Adjustable steerer retention strap with O-ring + rubber strap tidies
  • Two 1.2m bungee straps with snake-head buckles
  • Instruction manual

🌍 Where is JACK made?

JACK is made in Shenzhen, China, where one half of the WholeGrain Cycles team is based. We work with highly skilled, ethical manufacturing partners who maintain high quality standards while keeping JACK affordable and accessible.

❓ Still have questions?

💬 Send us a message using the form below and we’ll get back to you as soon as we can.