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Discussion Starter · #1 ·
Looking for a stiff chain stay. Looking at the Henry James site. Whats the differance between a HOX4CS and a HOX5CS. Found those listed in the frame kits but can't find them on the spec sheet.
Some back ground, Going to build a new belt drive frame and come to find out if the stay is too flexy it will cause the belt to pop. The belt will ride up the rear cog and snap back down on to the cog and you get a popping noise. So looking for a stiffer stay. Hope to build a 29er but will do a 650B.
Any suggestions on a stay?

Tim
 

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Eric the Red
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The difference is length. The HOX4CS is 415, vs 455 for the HOX5CS. I don't think they are very stiff, I've got a set on a single speed frame that flexes enough to derail the chain.
Bringheli and Nova have the Dedacciai Zero Due s bend stay. It's strong, stiff and has a great bend to it. You can get great tire clearance without bending or dimpling and still have heel/crank clearance. Long enough for 29ers. Great stays.

http://www.cycle-frames.com/bicycle-frame-tubing/DEDACCIAI-MTB-SBND-CHAINSTAYS.html
 

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Tim,

Place the split in the seat stay instead, as it is subject to less lateral torsion than the chainstay.

Although a lap joint or dropout junction will suffice, a gate joint or SS coupler are preferred.

As you've already learned, the chainstay will require some manipulation for the chainwheel, even with the oval section stay recommended above. I would suggest using a .75" sg tube for the stays that can be mitered and capp'd for chainwheel clearance, still retaining the strength you need for proper belt use.

Based on my experience, the most common cause of the "popping" noise is from improper belt tension, not from torsional play due to the frame. Based on recommendations from the techs at Gates, I've had to increase belt tension 2x the recommended numbers for heavier or more powerful riders.
good luck,

rody
 

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Discussion Starter · #4 ·
Rody
Its already in the seat stay.
read these 2 threads
http://forums.mtbr.com/showthread.php?t=617192
The first frame that I hacked up. Basicly a prototype. This will be the second frame.

http://forums.mtbr.com/showthread.php?t=632000
This is the thread were Velobike tells every one whats doing the popping.

Yes I have the belt tension as far as I can go to the point that I think the BB bearings are draging. New frame will have sliding drop outs and the stiffer stays plus more clearance for the front ring.

Tim
 

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Tim,

Thank you for the links, I had an opportunity to read them prior to my original post.

Two issues that continue to revolve around MTBR that create mistrust and a virtual black eye on the products are the belt drive and 650b wheels. In each case, almost every person that has had a negative experience have been conversion projects of frames that were never designed/intended for the specific product, or a serious lack of education in proper setup and execution.

Whether your local bike mechanic or a tool/die maker, no one will argue that the right tool for the job makes the work a pleasant experience. So too is the application of the belt drive...a frame designed for the system will always perform with greater efficiency than one adapted for it.

Having completed numerous conversions and new frame fabrications, I feel that I have a strong perspective on what is required in this frame design and application. The second thread that hypothesizes on frame flex causing belt mis-alignment is not incorrect in it's supposition. Production frames still have a way to go in belt efficiency. To avoid chainwheel/chainstay interaction in the production environment, they simply lengthened the tapered chainstays to move the tire bends away from the bottom bracket. Predictably, this allows for more torsional flex over it's length. As more chainwheel size options open up (getting smaller), you'll see shorter/stiffer stays and less belt travel associated with it. As you are building a new frame from the ground up and have the experience of others to learn from, this should never be an issue for you. Anticipate the forces and accomodate for them.

Poor designs will always suck, regardless of the skill of the fabricator. Don't follow the herd, lead it.

rody
 

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Discussion Starter · #6 ·
Rody
Exactly. I have learned from mine and other experiences. That's why I need the stiff stays. I'm all about experimenting. After I get the frame back from paint I intend to put the bike on my old Cat Eye training stand (the one were the front wheel locks in the stand) and see if I can get the belt to pop. I will also try out one of Velobikes snubber/tensioners. Just to see if I can get it to quite down.

Tim
 

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edoz said:
The difference is length. The HOX4CS is 415, vs 455 for the HOX5CS. I don't think they are very stiff, I've got a set on a single speed frame that flexes enough to derail the chain.
That's not what I want to read! I'm about finished with a 29er singlespeed using HOX5CS stays, and when doing rear alignments, they seem very flexy. I dimpled the inside horizontally for tire clearance. I've been having iffy feelings about these already. :madman:

I'm going to ride it before paint, and see how it goes. If it's too flexy, I'm debating of putting some 0.040" flat sheet on the inside, reinforcing the dimple area. I'm not diggin' that idea either. I don't really have room for a cross brace, as the chainstays are short (16-5/8" in the shortest position), and the brace would be going into the dimpled area, further displacing the forces to the dimple. ...sigh... live and learn.
 

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I find it amazing to read all this.
For approximately a year, everyone was moaning at the company Rohloff for being so awkward and not selling carbon drive hubs to the public - they only sold belt compatible hubs to manufacturers who have passed a frame stiffness tests. Now it seems, a year or so later, that we have all experienced that they were correct to do as they did.

I wish I had listened to their reasoning before going belt-drive on my singlespeeder.

Why don't gates seem to be able to back up their marketing bull with facts? It seems as if we are all doing their R&D for them! I'm not a guinea pig.
 
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