Steel Hubs in Bumper Plates Coming Loose – How to Avoid It

The steel inserts / hubs (I’m going to juts call all of them a “hub” here for consistency) of bumper plates are known to loosen after enough heavy use. Home gym users don’t normally see this at all. It takes a lot of dropping, day after day, month after month, with heavy enough weight, for it to even begin to happen. 

And it does happen more often when it’s dropped on bare concrete or onto an wooden top surface platform than it does when dropped onto thick rubber flooring or a modern lifting platform with a rubber top surface where the bumpers hit.

Inset Hub (Not Sticking Out)

One of the simplest things that you can visually identify is whether the hub is inset into the face of the plate, or in other words the rubber is sticking out the face farther than the hub. You don’t want the steel hubs of bumpers banging against each other on the bar, or for that matter, banging against the shoulder of the barbell or against the collars.

All you need is rubber sticking out the face just slightly. Here are examples of a couple bumpers I have in my gym…

The steel hub is pretty much flush with the face. That thin rubber lip around it isn’t doing much. Not good.

Contrast with this one:

A much larger rubber lip that is clearly sticking out above the steel.

So you want one like the second example, where the rubber will hit instead. The rubber does not need to stick out very far. After all, it’s not the primary direction that the force will go. You just don’t want steel-on-steel (or steel-on-iron, or you’re using some 5lb, 2.5lb etc plates on the end). That’s one thing that causes them to come loose.

Anchors on the Hub

Once the steel is protected as above, you might be fine, but it it’s not fullproof. Rogue’s HG bumper hubs have been reported to come loose under enough use, and they are inset really well. 

The next step up is a hub that is anchored into the rubber somehow so that it pretty much can’t ever move in any direction.

Here are the economy bumper plates sold in the US that have an anchoring system for the hub. 

MODEL COLOR SHORE
DUROMETER
(hardness)
ANCHORING
SYSTEM
WEIGHT
ACCURACY
WARRANTY
Fringe Econ Black or
Color
85* / 90 for 10lb/15lb yes  10 grams 1 yr 10lb & 15lb,
3 yrs others
Vulcan Econ Black or
Color
88 yes  1% 1 yr 10lb & 15lb,
3 yrs others
Vulcan Alpha Color Flec unknown yes  1% 1 yr 10lb,
3 yrs 25lb,
4 yrs others
Intek Champion
Black unknown yes  2% 2 yrs
Rep Econ Black or
Color
unknown yes  none 6mo 10lb & 15lb,
others are
3 yrs home,
1 yr commercial

Below is a view of Vulcan’s anchoring system, which is the only one we could get a pic of. I know, sad to see a nice looking bumper cut in half. The things we do for science.

Vulcan Strength’s rebar anchoring system. The rebar welded to the hub prevent the hub from popping out the face and from rotating in either direction.

Another shot of it, showing that they are indeed welded on:

Fringe Sport does the same type of anchoring system as Vulcan. Here’s Peter, the owner of Fringe, talking about it starting at the 1:50 point.

Rep Fitness sent me this quick drawing of their anchors that stick further into the rubber:

Illustration of Rep Fitness bumpers. The hub has anchors sticking deep into the rubber.

Intek Strength also confirmed with me that all of their bumpers use a similar anchoring system.

A Note on Rubber Hardness

The “shore durometer” rating is an industrial rating of hardness that you’ll see advertised for some bumpers. It uses the “shore A” chart, in case you search online and get confused.

To give you an idea, here’s the Shore A chart for various applications:

  • 70 – Car Tires
  • 75 – Crumb Bumpers (Hi Temp)
  • 85-90 – Economy Bumpers
  • 92-94 – Competition Bumpers
  • 95 – Shopping Cart Tires (so hard you probably thought they were plastic!)

Rubber stiffness is a trade-off that has to be just right. Too stiff and it doesn’t act as a good shock absorber and it wears out quickly. Too soft and it bounces too much and the 10lb and 15lb bumpers will taco and break. 

One unique thing that Fringe did to help the situation with the steel hubs was use a softer rubber just around the steel hub. This acts as a shock absorber. 

Another Solution: Crumb Bumpers

Hi Temps are known for being super thick and bouncy. 

I recommend getting the version that Hi Temp supplies to Rogue, because Rogue is known for quick service and taking care of customers when equipment fails down the road.

Hi-Temp bumper plates made for Rogue Fitness

A few issues with Hi Temps. These may or may not be a problem. Just be aware:

  1. Diameter: They are all 17.5″ diameter, not the 17.72″ (450mm) that is standard. You won’t be able to mix them with other brands, and the starting bar height is 1/8″ lower.
  2. Hardness: They’re soft and they bounce, almost as much as car tires. Not great for touch-and-go sets. On the other hand, you can do unlimited cheat reps once you’ve got the thing bouncing.
  3. Thickness: You won’t fit more than about 3 45lb plates on each sleeve (315lb).

Pricey Solution: Competition Bumpers

All comp bumpers are made in a way that they don’t have issues with the hub separating.

The two-piece hubs are made in a way you can see in this pic before the hub is installed.

A steel hub goes into each side of this style of competition bumper and are screwed together, sandwiching the rubber between them as an anchor.

One-piece hubs in comp bumpers are anchored in another way. Basically they’re all good. It’s just two ways of doing it.

However, comp bumpers are more expensive. Durability-wise, they are about the same as econ bumpers that meet the requirements I’ve gone over so far in this article. Comp bumpers are more expensive because there is more steel involved, and because they are usually calibrated to very tight weight tolerances for competition purposes.

Also, the bounce is very minimal, because they are so hard. You’re more likely to start pulverizing low quality concrete than you will with econ bumpers, even under rubber.

Fringe’s Vaughn bumpers are very well priced and get great reviews.

Fringe Vaughn bumper plates, available in Pound and Kilogram denominations

My Recommendations

Based on all the above, the Fringe econ bumpers should be at the top of your list. They also have colored bumpers of the same design.

 

Fringe makes their 10lb and 15lb OneFitWonder bumpers with extra-stiff rubber to prevent them from taco-ing, which is denoted by a shore durometer rating (basically a hardness rating) of 90. Their 25lb+ sizes have a lower shore durometer rating of 85.

As mentioned in the video further above, Fringe’s hub also has a knurled texture where it contacts the rubber to help prevent slippage, and it’s glued together as well.

Fringe also makes their 10lb bumpers 440mm diameter, compared to 450mm on all other sizes. That helps protect the 10lb bumpers. The 5mm difference makes them 2.5mm higher off the floor when you load any heavier bumpers with it, so that the 10lb don’t absorb as much of the impact. 2.5mm is really slight. They do still absorb a small amount of impact, with the give in the heavier bumpers as they hit the floor, not to mention the give in the rubber flooring, and that’s perfect.

Fringe promotes the heck out of their bumpers, calling them the best econ bumpers in the world, but I don’t think they do a great job explaining why on their product page. Hopefully my explanations here help. So I can’t help but recommend them.

As a second choice, look at the Vulcan Alpha bumpers, a nice color flec design that are usually priced better than Fringe’s colored bumpers, depending on the shipping. The quality seems to be just as good.

Vulcan Alpha bumpers

The Alpha bumpers are so popular that Vulcan Strength can’t keep them in stock. For the last two years they have had backorders selling out before they can restock them. As a business person that kind of inefficiency drives me nuts, on principle. They’re losing out on so much business by not having them ready to ship. I’m guessing the factory in China is incapable of making them any quicker and there’s no other factory who can do it? Anyway, what you have to do is just order them and sit back for up to a month. Don’t just keep waiting for them to come back in stock first, or you’ll never get on the list.

 

Have you run into any bumpers that are coming apart, or that seem to last through anything? Share your comment below!

 

  • Was this Article Helpful?
  • yes   no

About the Author:

David Kiesling
David founded Adamant Barbell in 2007. He is into weight training, Crossfit, nutrition, hang gliding, snowboarding, mountain biking, and hackysack. He also owns a hang glider repair business.

Leave A Comment