BMS micro rack question

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BMS micro rack question

Postby GroundquestMSA » Nov 18, 2012 9:14 am

I tried my micro rack on the rocks for the first time yesterday. The frame is 8 1/4" with two hyperbars. I did a few 70' +/- runs on fairly clean rope. It worked great, but I can envision there being some difficulty on a longer drop with dirty rope. Since I'm light, and I've read that the micro rack shouldn't be fed, I think I'll have some trouble moving.

Is it normal for the rope to rub itself when the top hyperbar is engaged? Does that matter?
Do you normally use the control hand to manipulate bars with a micro rack? My efforts to do so had no effect on my speed. I didn't try spreading, just mashing.

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Re: BMS micro rack question

Postby Scott McCrea » Nov 18, 2012 10:52 am

Feed micro-racks in moderation and carefully. Keeping your hand on the bottom bar will prevent it from coming off when feeding.

Not sure I understand what you mean with the rope rubbing itself.

Yes, spreading the bars will lessen the friction and speed you up.
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Re: BMS micro rack question

Postby GroundquestMSA » Nov 18, 2012 2:15 pm

The rope rubs a bit at the third bar, where that there blue circle is.
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Re: BMS micro rack question

Postby NZcaver » Nov 18, 2012 4:45 pm

GroundquestMSA wrote:The rope rubs a bit at the third bar, where that there blue circle is.
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Yes, the rope can/will rub slightly against itself at that point. But because the rope is moving, it's not really an issue. It would only be a problem if a moving rope rubs against a stationary rope.

Regarding problems moving on a longer drop with a dirty rope - yes. Also unless you're a really big guy (and I don't think you are) I'm sorry to say you got the wrong micro rack. You should have got the 10.5 inch frame. The 8.5 inch frame is all but useless for many cavers in the US because you can't spread the bars wide enough to move efficiently on a dirty 11mm. I'm not small, and even I quickly switched my short frame from a longer one - for lighter people it's even more of a PITA. This is mentioned on the BMS website.

Another factor that may hinder you is that for some reason all the micro racks leave the factory ideally set for left handed use (in my opinion). But that I mean when you're using a micro and trying to reduce friction (not using the hyper-bar), the rope below should be feeding directly over the bottom bar and not curling around the frame of the rack down near the attachment point. Assuming you're right handed, I suggest you remove the lock nuts and switch the bars around so they swing up to open instead of down. Looking down at your rack, the rope would now being going over the bottom bar instead of under it. If you need the engage the top hyper-bar for extra friction, just bring the rope under the frame and wrap it over the hyper-bar.

I've been using my micro rack this way for years. Being a right handed person, I changed it around as soon as I figured out what was 'wrong' with the way it comes from the factory.
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Re: BMS micro rack question

Postby GroundquestMSA » Nov 18, 2012 5:55 pm

NZcaver wrote:Also unless you're a really big guy (and I don't think you are) I'm sorry to say you got the wrong micro rack. You should have got the 10.5 inch frame. The 8.5 inch frame is all but useless for many cavers in the US because you can't spread the bars wide enough to move efficiently on a dirty 11mm.


I'd be really big for a six year old maybe. I bought the rack used from another caver, just to try it out. Suppose I should have done more research first. I think it will work for me in some cases because I don't do enough vertical caving between rope washings. I successfully used it on 11mm static yesterday, but it wasn't Pit.

I see your point about the bar orientation. It seems like the rope will still rub the frame a bit if I switch them around. I'll try a few lefty rappels and check it out before I change anything.
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Re: BMS micro rack question

Postby Chads93GT » Nov 18, 2012 8:51 pm

Just add a 7mm quicknlink to the rack and the mini rack will be orientated as it was originally designed. No need to remove the bars and flip them. Just orient the rack so the hyper bars are pointing away from you. Not to the right or the left. Same as a 6 bar racks intended orientation. Yes. People will argue this point. Flame on. Lol
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Re: BMS micro rack question

Postby Chads93GT » Nov 18, 2012 8:56 pm

GroundquestMSA wrote:
NZcaver wrote:Also unless you're a really big guy (and I don't think you are) I'm sorry to say you got the wrong micro rack. You should have got the 10.5 inch frame. The 8.5 inch frame is all but useless for many cavers in the US because you can't spread the bars wide enough to move efficiently on a dirty 11mm.


I'd be really big for a six year old maybe. I bought the rack used from another caver, just to try it out. Suppose I should have done more research first. I think it will work for me in some cases because I don't do enough vertical caving between rope washings. I successfully used it on 11mm static yesterday, but it wasn't Pit.

I see your point about the bar orientation. It seems like the rope will still rub the frame a bit if I switch them around. I'll try a few lefty rappels and check it out before I change anything.


The rope will always rub the frame if the rack is oriented so you see the entire face of the bars and not the ends of the bars.

Also. I weigh 200 lbs. more with gear. And he 8.5" frame is useless for me on dirty 11mm rope
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Re: BMS micro rack question

Postby GroundquestMSA » Nov 18, 2012 9:59 pm

Chads93GT wrote:Just add a 7mm quicknlink


Or hook directly to the 1/2 round?

I'm not that concerned about the "turn your rack this way or that" battle. Either way works, so why make a fuss?
Are short frames only useful for those using small diameter ropes? The BMS site claims that they are intended for 10 and 11mm and designed for the caving community.
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Re: BMS micro rack question

Postby NZcaver » Nov 19, 2012 4:58 am

Chads93GT wrote:Just add a 7mm quicknlink to the rack and the mini rack will be orientated as it was originally designed. No need to remove the bars and flip them. Just orient the rack so the hyper bars are pointing away from you. Not to the right or the left. Same as a 6 bar racks intended orientation. Yes. People will argue this point. Flame on. Lol

Sit yourself down and prepare to be flamed, Chad! (Finding appropriate smiley...) :flamed: How 'the rack' (which rack?) was originally designed and in what orientation it was designed to be used (by whom?) is a matter for some debate, but you already know that. :laughing: Also bear in mind we are talking about a closed U-rack here, not an open J-rack. Most cavers normally connect this to their harness D-link via an oval screw link (or possibly a locking carabiner), meaning that the rack ends up approximately parallel with the body - not perpendicular. Unless you one of these people that uses a funny climbing harness with a belay loop thingy.

Chads93GT wrote:The rope will always rub the frame if the rack is oriented so you see the entire face of the bars and not the ends of the bars.

This depends a lot on the exact orientation of the rack, how far it is out from the body, and at what angle the rope goes down over the hip or thigh or between the legs (depending on rope weight below and friction desired and personal preference). I do believe frame rub could just as easily apply to a perpendicular oriented rack as a parallel one.
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Re: BMS micro rack question

Postby Scott McCrea » Nov 19, 2012 8:58 am

You can attach a U shaped framed rack directly to the 1/2 round. It's useful to make it nice an short, but you can't take it off easily.

Short frames are for heavier people. Long frames allow the bars to spread more, thus reducing the friction for lighter people. Long frames can be used by nearly anyone. Some light people struggle with short frames.

NZcaver is correct. As long as the two piece of rope that are rubbing, are both moving, there are no worries.

Many cavers using a caving harness (one with a half-round) with a J-shaped rack, use the wrong shaped rack. Twisted-eye (90 degree twist in the eye) frames are made for caving harnesses, assuming there is a link between the half-round and rack. Flat-eye racks are for directly attaching to the half-round or climbing style harnesses. John Cole told me, in person, that he designed the rack to be oriented perpendicular to the body. Using a rack oriented parallel to your body is like driving a Ferrari only using 3rd gear. It's safe, functional transportation, but you're wasting performance.
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Re: BMS micro rack question

Postby GroundquestMSA » Nov 19, 2012 9:59 am

NZcaver wrote:I do believe frame rub could just as easily apply to a perpendicular oriented rack as a parallel one.


That's true. I just got done trying left and right handed, perpendicular and parallel. The only way I was able to avoid frame rub without redirecting the rope in a way that added substantial friction was to rappel left-handed, with the bars parallel to my body and the rope between my legs. With a four bar rack on clean rope this didn't give enough friction, so in this case it really makes no difference how the rack is turned...the frame is going to get rubbed. The frame gets some rub whenever the hyper bar is engaged anyway.

Scott McCrea wrote:It's safe, functional transportation...


That's all I care about. However, since I normally run the rope between my legs with my J-frame, I don't see how the orientation makes enough difference to even mention.
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Re: BMS micro rack question

Postby Stridergdm » Nov 19, 2012 10:24 am

Scott McCrea wrote:You can attach a U shaped framed rack directly to the 1/2 round. It's useful to make it nice an short, but you can't take it off easily.


In fact I think I'm the only caver I know of that does this. I get strange looks, but.. it works for me and I've had no problem doing 200' pits this way.
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Re: BMS micro rack question

Postby NZcaver » Nov 19, 2012 1:29 pm

Scott McCrea wrote:Many cavers using a caving harness (one with a half-round) with a J-shaped rack, use the wrong shaped rack. Twisted-eye (90 degree twist in the eye) frames are made for caving harnesses, assuming there is a link between the half-round and rack. Flat-eye racks are for directly attaching to the half-round or climbing style harnesses. John Cole told me, in person, that he designed the rack to be oriented perpendicular to the body. Using a rack oriented parallel to your body is like driving a Ferrari only using 3rd gear. It's safe, functional transportation, but you're wasting performance.

FYI - John Cole designed the J-rack, not the U-rack. While I don't dispute your logic for operating a J-rack perpendicular for ease of adding and dropping bars, I'm sure you understand why a U-rack is not designed to be used in quite the same way.

P.S. - you need to tell MOS he's doing it wrong!

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Re: BMS micro rack question

Postby Scott McCrea » Nov 19, 2012 1:44 pm

LOL! MOS does lots of things "wrong."

John Cole, or not, there are many reasons why perpendicular J-racks are better and most apply to U-racks, as well.
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Re: BMS micro rack question

Postby NZcaver » Nov 19, 2012 2:33 pm

Scott McCrea wrote:LOL! MOS does lots of things "wrong."

Indeed! :grin:

John Cole, or not, there are many reasons why perpendicular J-racks are better and most apply to U-racks, as well.

Many reasons, other than adding and dropping J-rack bars on the fly? Pray tell?

For what it's worth, I own long J-racks in both orientations. They are still shiny because I virtually never use them. On the other hand, my U-racks and Stops are well worn. If I were doing long single-pitch drops more often, that balance would probably shift. Recently I've been using informal vertical sessions to introduce the benefits of the micro rack to local grotto members, who otherwise seem to mostly rely on the Piranha and the Figure 8. My point is that while there are many vertical caving 'standards' there are also personal requirements and preferences to contend with, and there is no magic one-device-fits-all solution for everybody.

Anyway, this discussion is about the BMS Micro Rack and nowhere in the literature can I find any official determination of one orientation being recommended over the other.
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