--GIANT DH REAR SWING ARM OFFSET?--

[waynebergman]

I have a theory about the 2004 Giant DH Team frame and wondering if others have found this to be true or know a bit more about the Giant frames than my self. Other years of this model may have the same issues.

I think Giant has made there swing arm assembly & drop outs offset from the center line of the bike. When I look at my Ringle hub and 12mm axle that came stock on my bike I noticed that there is no dishing on the wheel but yet it needs it to have the wheel sit centered on its axle stops. If it was to sit in a normal set of centered drop outs and swing arm the wheel would sit off center but in the Giant frame it sits just fine as the drop outs seem to be offset so you do not have to dish the wheel.

So if any modification are made to your Giant DH frame drop out area to accommodate the 10mm axles many of us are all putting on these bikes from our DD hub motors the wheel may will sit off center by a lot unless to take into account the drop outs are not centered on the center of the frame. The right side of the tire (drive side) will rub on the drive side chain stay if you are running a large dirt tire. This is the case for me so I am now running a smaller width tire till I sort out a solution. The HS3540 DD Hub has got such a large diameter flange coupled with a very narrow flange width it does not make it a good candidate for dishing the wheel enough to get me centered. Or at least I don’t think it’s a good idea. I hope others can chime in on this. I feel there should be some angle to the spokes coming out of the hub on the way to the rim or I will loose lateral stability in the wheel.

I think many who have chopped out the old drop outs in there frame and have used epoxy to set in the Doc style drop out solution will be able to center things as they go, and have probably with out realizing the offset built into the swing arm I am describing here made it work making sure things are lined up before final epoxy treatment.

I want to mention this to others that may be fabricating a drop out adaptor up to make there frames work with our standard 10mm style axle to keep this in mind. Don’t just use the old drop out locations as something to put a centered wheel in and think you will siting in the center of your drop outs. You need to come to the left side quite a bit like at least ¼” with your drop out placements or else dish the wheel more that what I think is a good idea for these crazy sized hub flanges we are dealing with.

At this point this is just a theory I have and look forward to others input here and again just a heads up for others traveling down this road and a place to sort out this issue as I see this Frame is a popular choice for e-bike fun………….wayne

 

[markt108]

you need to tweek the rim on your hub to make it sit central the frame but losening off one side of the spokes and tightening the other if you do it equally you should get it more in a line that what i have done seems to have done the trick

 

[waynebergman]

As I mentioned Mark, I need to go at least 1/4" to the left and I am not sure that is a good idea dishing these over sized hub wheels sets this much. Are you sure you can dish a wheel built from such a narrow flange width that much? I think it would make the wheel laterally very weak although this would be different on a regular style hub. I am not sure but just my gut feel.

 

[MadRhino]

Common issue, with almost all DH bikes, for 80% of the frames have an assymetric swing arm. Dish the wheel, a quarter of an inch is nothing to worry about. I've been dishing some enough to need 2 spoke length and have to lace right side inside the flange and left side out.

 

[waynebergman]

Thanks for the tips. Good info. I had no idea most DH bikes did this. I will get some shorter length spokes by about 5 mm for the left side and relace and go. The drive side should be ok as is as they seemed a bit long anyways. Sorry about rambling on and on at the start of the thread. I found it hard to explain what was going on.

 

[binlagin]

My motor is sitting way out of whack in my frame, I'm hoping dishing it will solve the problem. But I first must make sure my dropout adapters are square.

 

[waynebergman]

I just installed some shorter spokes on the non drive side. I went with 5mm shorter spokes on the non drive side and I was able to dish the wheel nicely to get it centered in the swing arm now. So my dirt tires are back on the bike and all is well.

 

[crusoe]

I'm noticing the same, had to lose my 2.5 mudders with my HS and the 04 DH Comp. I have an HS3540 also and was wondering what size wheel you laced it into? I need to figure out proper spoke lengths, but if it's the same setup as you your sizes it should work great.

 

[waynebergman]

The rim was a 24" but I did not measure its effective diameter from eyelet to eyelet as spoke length formulas require. I just went with 5mm shorter on the one side and it worked out. Grin tech in Vancouver cut the spokes for me. Good luck with it all. My bike has now got close to 600 kilo's on it and working real good. I think the Giant DH is a good choice for an electric bike. Feels safe on the road and super fun on the trails. I think Duc is also in the middle of lacing up his old motor to a new 24" for his giant.

 

[moonshine]

hey guys, i'm in the process of mounting an x5404 into my 03 dh comp and i forsee a lot of issues with wheel sizes, lacing, and alignment in the 135 dropouts... To start, does anyone know what the max OD is for the rear wheel? I wanted to put a 26" surly large marge rim in...but i'm afraid the rim won't be strong enough (at least thats the vibe i've been getting). So i was leaning towards a 21"x1.85" excel rim (dimpled or non-dimpled?). GCinDC is lacing a 19" with 2.75" wide tires and says he's at his max. I have 26" sun double wides with 2.75" wide tires as well...and im good. So...if i run a 21"x1.85" will the tire wall height take me OVER the OD of a typical 26" DH wheel??? i plan on having just a normal set of treads on the tire for the 21" (as in not dirtbike treads...). Any help/insight would be GREATLY appreciated.

 

[Duc998]

I'm in the same boat. I'm hoping my 26" rim with 2.2 tyre will fit but it looks too tight. I might have to drop to a 24". I'll find out later this week once I get is laced and dished to the center.

 

[shorza]

Thank Duc, I am in the same boat, '04 DH Comp. About to get my motor laced, but not sure if I should go a 26" or 24" yet. I'll be waiting for your verdict.

 

[moonshine]

The plan right now is to get my hubzilla laced into a 26" large marge rim. I mean...everyone's been saying its for light ebikes and stuff, but, i don't intend on taking 10' drops. Also, its has a triple box design and is meant for xC and DH. I'm getting the NON-offset version. I originally wanted to get the hubzilla laced into a 19" excel MC rim, but i don't want the OD to be 24" or 25", nor do i want the added weight of a MC rim/spokes/tire/tube. The large marge is light and once JRH is finished with it (12ga spokes) it'll be plenty strong enough for the streets and some trails. I also, like the idea of having the original 26" size rims. My 03 DH comp came with sun double wide rims (46mm) with 2.7" tires on them and they obviously fit (albeit somewhat lose in the rear). The max you can do with an excel is 19" and not too many tires out there (only one, the shinko 244 on GC's) that i see will work. GC's vids show very very little clearance with the 19". So i'll probably put some larry tires on there.

 

[binlagin]

I really wish I went with an MC wheel.

With my Axel Rim - DX-32's inside my Cromotor, I've had to dish it a good ammount. just to run Hookworms much less any other tredded tire.