1 2

Shoulder Boulder/Chest Fly Attachment

4.9
Rated 4.9 out of 5 stars
17 Reviews
$324.99 CAD

Build boulder shoulders & poppin’ pecs with this compact attachment.

Shoulder Boulder/Chest Fly Attachment
Notify me when available

Specifications

What's Included

The Shoulder Boulder - Hydra Lateral Raise Attachment:

  • 1x Hitch pin
  • 2x Rubber stoppers
  • 1x Threaded knob
  • 2x Metal shim

Shipping & Returns

We get it — shipping heavy gym gear raises some important questions. Here’s exactly what to expect:

Flat-Rate Shipping: Most orders ship for much less, but no matter how big your setup gets, you’ll never pay over $199 CAD for shipping in Canada. Some conditions apply for rural or Northern addresses.

Shipping Time: Orders ship within 1–3 business days and usually arrive within 3–7 business days (during sales events, delivery may take up to 2 additional business days).

Fulfilled from our Calgary or Toronto warehouses. Local to either city? Pick up in-store and skip the shipping fees!

Returns: All Bells of Steel products are backed by our 30-day return policy. If you don’t love your order, send it back — simple and stress-free.

Product Features

  • BUILD 3D DELTS

    Ditch the dumbbells and get more out of every rep! The smartly positioned weight horns increase tension at the bottom, where dumbbells fall short, targeting your delts more effectively. Perform lateral raises, single-arm front raises and rear delt flies to leave no delt undone on this full-shoulder solution!

  • UNLOCK CHEST FLIES

    On dumbbell chest flies, your biceps steal the show and pushing to failure feels more like gambling than training. But thanks to the Shoulder Boulder’s design, that sweet burn stays focused on your chest muscles. Plus, the 360° dial sets the ideal starting position AND acts as a safety catch—because your pecs deserve better odds than the roulette table.

  • COMPACT SHOULDER & CHEST STATION

    Why let a bulky machine take over your home gym? The Shoulder Boulder Lateral Raise Attachment mounts directly to your power rack and occupies a fraction of the footprint of a rear delt/chest-fly machine. This keeps your Castle of Gainz clutter-free; after all, the best gym is one you can actually walk through.

Product Details

Build boulder shoulders and poppin’ pecs for that iconic V-taper look!

Dumbbell shoulder and chest isolations suffer from inconsistent resistance, but the Shoulder Boulder’s design provides smooth, controlled movement with a superior resistance profile.

A standalone rear delt/chest fly station takes up a whopping 5-foot x 5-foot footprint (or more), while this rack attachment mounts to your rack to save space. Easily adjust its height on your power rack for the ideal fit.

This nifty unit uses weight plates, saving you money. Plus, easily micro-load the smaller muscles of your shoulders to minimize injury and get better gains!

While it doesn’t beat a cable machine for chest flies, the Shoulder Boulder comes in as a close second. Set it low & wheel over a bench (or mount a Seal Row Pad) for better chest flies that keep the tension exactly where it belongs: on your pecs.

With the new tightener knob and updated UMHW lining, the new 3" x 3" Shoulder Boulder fits securely on any 3" x 3" (75mm x 75mm) rack.

The 2.3" x 2.3" Shoulder Boulder is compatible with any 2.3" x 2.3" Cable Towers, All-in-One Trainers, or Power Racks with 2.3" x 2.3" (60mm x 60mm) uprights. 

IMPORTANT: For user & equipment safety, ensure your rack or cable tower is bolted down or otherwise secured. Tighten the spin lock before each use. Locking on your weight plates with collars is highly recommended.

PRODUCT SPECS

Shipping Details

This product will be shipped in 1 box:


1x SHBLD-RA-HDR

  • 20" x 17" x 6" / 51 cm x 42 cm x 14 cm
  • 39 lb / 18 kg

You can find the SKU on the front of each box.

Manuals and Assembly

4.9
Rated 4.9 out of 5 stars
Based on 17 reviews
Total 5 star reviews: 16 Total 4 star reviews: 1 Total 3 star reviews: 0 Total 2 star reviews: 0 Total 1 star reviews: 0
100%would recommend this product
Slide 1 selected
Write a Review (Opens in a new window)
17 reviews
  • ST
    Samuel T.
    Verified Buyer
    I recommend this product
    Rated 5 out of 5 stars
    2 hours ago
    BOS Shoulder Boulder

    This was easy to put together, easy to install, and man does it do a number on the shoulders! Solid piece of equipment, and it is extremely smooth to use. I haven't used it for chest flyes yet, but so far I really like it. Also, I'm pretty sure I can use my ankle strap to attach the cable to it instead of using plates only.

    Was this helpful?
    Bells of Steel Canada
    2 hours ago

    Thanks for the awesome review! We are stoked to hear the Shoulder Boulder was easy to assemble and install and that it is already lighting up those shoulders.

    Smooth operation and rock solid feel is exactly what we were going for, so it is great to know it is delivering. Once you try chest flyes you might unlock a whole new level of burn. And we love that you are already thinking creatively with the ankle strap setup. That is the kind of versatility we like to see.

    Appreciate you taking the time to share your experience. Keep crushing it. Yours in strength, The B.o.S. Crew.

  • JF
    Jack F.
    Verified Buyer
    I recommend this product
    Rated 5 out of 5 stars
    3 days ago
    Cant wait to use it

    Its very high quality. I have a monster g12 from Force Usa, the original version. My machine has 2×2 " tubing, so im having extra shims 3d printed to take up the slack. I also added a sleeve adapter to take the 5/8'" stud up to a 1" to fit into my smith machine. So , there is a little more I need to put in to it to make a perfect fit for my machine, but in the end I already know it will be worth it. Its really an amazing compact device. Untill my 3d prints are done , I have it mounted on my attachment wall . Looks great with all my innovative gear. Perfect addition.

    Was this helpful?
    Bells of Steel Canada
    Yesterday

    We love the dedication here!

    First off, thank you for the awesome feedback on the quality. Hearing that it is pairing up with your Monster G12 and already earning a spot on the attachment wall is seriously cool.

    Major respect for dialing in the fit with custom 3D printed shims and a sleeve adapter. That is next level home gym tinkering right there. While it is designed around standard specs, we always appreciate seeing customers get creative to make great gear work in their unique setups.

    It sounds like once those prints are ready, it is going to be a perfect match. We are pumped it is already looking right at home with the rest of your innovative lineup.

    Yours in strength, The B.o.S. Crew.

  • JB
    Jeff B.
    Verified Buyer
    I recommend this product
    Rated 5 out of 5 stars
    3 months ago
    Fantastic!!!

    Just bought this and it’s great! Big time space saver since my gym is just a bedroom. It’s going to be a bit of a learning curve to figure out the setup for all of the different exercises but so far a 10/10.

    Thanks for making it to fit the uprights on the All-In-One trainer. Keep it up with your future ideas!

    Was this helpful?
    Bells of Steel Canada
    3 months ago

    Hey Jeff,

    We appreciate your 5-star review of our 2.3" Shoulder Boulder! The option to make it 2.3" was definitely something we had in mind when we first came out for the 3" version and we're glad you could snag a copy to use on your All-In-One. Here's to some boulder shoulders incoming!

  • DB
    David B.
    Verified Buyer
    I recommend this product
    Rated 5 out of 5 stars
    4 months ago
    Mr

    I love the Shoulder Boulder Attachment more with my 2 Ancore Units. Its smooth and eliminates the dead weight zone when using the small change plates. I mount the Shoulder Boulder on my rack above the Seal Row Pad for Reverse Flys as I try to strengthen my "rehab-ing" shoulders. I attach the Ancores to the front leg and the lower crossmember using quick sliding rack adapters. Now I really need to find the room to mount a single post rack to permanently attach the shoulder boulder to so I can use this every day. Unfortunately, I have to remove this from my rack for daily lifting exercises.

    Was this helpful?
    Bells of Steel Canada
    3 months ago

    Thanks for the fantastic 5-star review, David! We're absolutely thrilled to hear that the Shoulder Boulder/Chest Fly Attachment is working so well with your 2 Ancore Units and delivering that smooth performance you're looking for.

    It's awesome to hear that you're finding it eliminates the dead weight zone with small change plates—that's exactly the kind of functional improvement we aim for with our attachments. We're also really glad to hear that you've found such a great setup for your reverse flys above the Seal Row Pad, especially as you work on rehabbing those shoulders.

    Yours in strength,
    The B.o.S. Crew.

  • PS
    Peter S.
    Verified Buyer
    I recommend this product
    Rated 5 out of 5 stars
    4 months ago
    Best Chest/ Shoulder attachment

    The Bells of Steel chest and shoulder attachment is the best on the market! I love the easy to use and versatility it offers for any rack not just BoS. Add that extra ummpf to your workout without compromising space.

    Was this helpful?
    Bells of Steel Canada
    4 months ago

    Thanks a bunch for the stellar review, Peter! We're pumped to hear that the Shoulder Boulder/Chest Fly Attachment is a game-changer in your workouts. Easy to use and versatile? Just how we like it! Big thanks for the photo and video, too – they really bring your words to life!

    Yours in strength,
    The B.o.S. Crew.

Show More
The Bells of Steel Shoulder Boulder/Chest Fly Attachment is a black mechanical device with adjustable arms and knobs, ideal for chest fly exercises to build the Shoulder Boulder look.
Bells of Steel

Shoulder Boulder/Chest Fly Attachment

$324.99 CAD

Build boulder shoulders and poppin’ pecs for that iconic V-taper look!

Dumbbell shoulder and chest isolations suffer from inconsistent resistance, but the Shoulder Boulder’s design provides smooth, controlled movement with a superior resistance profile.

A standalone rear delt/chest fly station takes up a whopping 5-foot x 5-foot footprint (or more), while this rack attachment mounts to your rack to save space. Easily adjust its height on your power rack for the ideal fit.

This nifty unit uses weight plates, saving you money. Plus, easily micro-load the smaller muscles of your shoulders to minimize injury and get better gains!

While it doesn’t beat a cable machine for chest flies, the Shoulder Boulder comes in as a close second. Set it low & wheel over a bench (or mount a Seal Row Pad) for better chest flies that keep the tension exactly where it belongs: on your pecs.

With the new tightener knob and updated UMHW lining, the new 3" x 3" Shoulder Boulder fits securely on any 3" x 3" (75mm x 75mm) rack.

The 2.3" x 2.3" Shoulder Boulder is compatible with any 2.3" x 2.3" Cable Towers, All-in-One Trainers, or Power Racks with 2.3" x 2.3" (60mm x 60mm) uprights. 

IMPORTANT: For user & equipment safety, ensure your rack or cable tower is bolted down or otherwise secured. Tighten the spin lock before each use. Locking on your weight plates with collars is highly recommended.

Shoulder Boulder/Chest Fly Attachment

  • 3" x 3" (5/8" & 1" Holes) - Hydra & Manticore
  • 2.3" x 2.3" (5/8" Holes)
View product

  • $199 MAX SHIPPING

  • PROUDLY CANADIAN SINCE 2010

  • EXCELLENT WARRANTY