Plates

[Mmll]

Hi Rip,
I have 4 questions:
1. Do iron plates usually have a shorter diameter than bumper plates?
2. There are some bumper plates im interested in buying. Their diameter is 450mm with a 51mm ring diameter...is this a conventional size for deadlifting? Eg the deadlifts people do at starting strength gyms etc.
3. If i deadlift with these bumpers, will i be making it too easy on myself? Im just wondering if they are too big meaning that id be lifting from a higher than ideal position off the ground?
4. The bumper plates have a steel internal ring...is this normal for bumpers?

Thanks so much.

[Mark Rippetoe]

1. Standard plate diameter is 45 cm, iron or bumper.
2. By "ring diameter" I assume you mean the inside diameter (ID) of the hole in the middle. Approximately 2.00 inches is also standard.
3. These are the same plates everybody uses. We make it harder by putting more weight on the bar.
4. Bumper plates have a steel or iron core, around which the rubber is formed. You are seeing that part of the plate.

[Mmll]

Thanks a lot.

I was also hoping to make a platform with the dimensions you've previously suggested but i havnt got the space for an 8 foot by 8 foot square platform.
So, if i use b grade plywood or better, and have 3 layers of just 1 sheet of 8 foot by 4 foot...with two 13kg 1 square metre gym mats on top...would this protect a garage floor to a similar level as the 8 foot by 8 foot design? If not, do you think it would still be enough for protecting the floor? i currently deadlift 175kg for set of 5 and improving. The thickness of each of the sheets i was planning on buying are 0.75 inches. Thanks

[Mark Rippetoe]

The plans for the platform are in the book.

[Logan1]

1. The only bumpers I can think of which aren't 450 mm are Rogue Hi-Temps which are 445 mm.

2. Some manufactures may use larger inside diameters to compensate for lower tolerances. The plates I in my home gym have 50.4 mm IDs, which I prefer to the ones with larger inside diameters.

3. The urethane 45s I have are 53 mm wide. Although most bumpers are narrower, High-Temp 45s are 3 3/4" wide. At higher strength levels, the larger diameter or the plates will limit how much weight one can put on the bar. They can also could case the bars to bend slightly more. Be happy if you get strong enough that the bar bends noticeably more with bumper plates.

One of the many nice things about owning your equipment is knowing how much you are actually lifting instead of hoping the weights in are close to the stated amounts.

[skid]

Asking the obvious question - Why are you building a platform if you are buying bumpers? I've got a 3/4 inch rubber mat that have seen 600 lb deadlifts smashed using narrow calibrated plates with no damage to the floor below. Are you planning on Olympic lifting and dropping the weights from overhead?