My Big Fat Giant

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Obiwan007   1 kW

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My Big Fat Giant

Post by Obiwan007 » Feb 18 2015 9:43pm

Some may have noticed me hinting about my newest project on other threads over the last few months. Thought I better start my build thread before I got to far into the project. So my aim is to build a high powered electric heavy duty down hill fat bike. Full dual crown, high travel forks in what I beleive to be the best off road bike for electric conversions; the Giant DH Comp. I began, some time back (shortly after finishing my last project) to research the possibility of doing this. It difficult to build a regular full suspension fat bike and there are few components on the market to fit the bill. Also, those that do exist are pretty spendy. Nevertheless I have been haunting craigs,pink, ES, the bay, and other places for months now to acquire the foundation parts for the build. Here is what I have so far:

Giant DH Comp, complete bike with really good components but trashed wheels, 18" (medium, I know it's not the large but more on that later)
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Risse Racing Trixxy dual crown forks. These babys are, as far as I know, the only dual crown forks on the market that will fit a full 4" wide fat tire.
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V2 Cromotor. This motor was one of methods last ones and I got to meet up with him to pick it up and he and Mathew kindly took me on fun ride in their neck of the woods. I have since opened it up to put a heat sensor in it and did my custom disk flip mod as well as the freewheel mount modification that allows a 3-speed freewheel.:
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Lyen 18 fet controller

A pair of 100mm wide Weinmann double wall fat tire rims. Just finished lacing up the front wheel today:
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Brakes are off the original bike and they are hayes prime experts 203mm

I don't have tires yet but they will be the Vee Rubber V8s:
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The rest I will get as I go along including a CA V3 (got to get a couple of these since I just upgraded my wife's motor in the "Electric Jeepster" to clyt 4060 and she now wants temp sensing and throttle mapping), and a Kiwi TA from Scott.
So obviously a 4" tire will not fit in the swing arm of the DH Comp. But my guy at Quality Heliarc has already looked at the project and will be modifying the front of the swing arm as well as the back to result in clearance for 4" tire in the front and 160mm symetrical drop out in the back. My first Giant with this mod is still going strong?
Also I am re-doing the battery box on this bike with a little help from some friends. The new battery box will be just slightly wider but will extend to the bottom of the down tube. This will provide additional space along the sides of the down tube for batteries. Also it will have an integrated mounting channel that fits the down tube and clamps firmly in place with no frame modifications. Additionally, it may be able to fit the controller inside, but if not it will have controller mounting on the bottom built-in. Because of the additional room it will provide enough space to make the 18" frame viable for 72-96V. We will be designing the box in SolidWorks for both the 18" and the 19" frames and in the end they will be orderable from MSM sheet metal. I'm still going to have the magnet cover in the back to cover the charging ports. One final thing to look for in this build will be some new, universal brake switches that I think you will all like. Tiny, easily adjustable, and works with any brake system you care to use. More on that later. To design the battery box in SolidWorks we needed a good, solid model of the 18" frame and a friend of a friend offered to digitally scan it for us. Here is a picture of the scan in progress:
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Most everything I have done so far is the same as stuff I did in my previous Giant build so I have not chronicled it here. That build can be found here:
http://endless-sphere.com/forums/viewto ... =2&t=55605. As I go along I will try to take pictures but I often forget so sue me :o. Let me jus finish this opening post by saying thanks to all those on this list who have taught me so much over the last couple years and to Justin for making it possible.

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Obiwan007   1 kW

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Re: My Big Fat Giant

Post by Obiwan007 » Feb 18 2015 9:54pm

Whoops! Almost forgot about the batteries. Just took delivery of 6 of these little honeys on sale:
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Now I know that they are exactly the same as two smaller batteries but the form factor and the wire elimination will provide a form factor that works perfectly with the battery box we are designing. I'm starting with 6 but will likely make the harness for 8 and add two more later. At 10s I will hook them up to get 20s3p for 13.5Ah with 6 batts, or 20s4p for 18Ah with 8 batts. Plus they are nano-tech so I am hoping they will be somewhat more durable than the Zippys I have been using up till now. Plus they were on SALE! Anyone have any experience with these?

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Re: My Big Fat Giant

Post by recumbent » Feb 19 2015 2:16am

Wow, those are awesome looking rims, and double walled at that. Had you considered the moped sized rubber? And would it fit. I'm just amazed at what's available to us ebikers.
Ebike in use:
LWB Recumbent bike, Sram i-9 internal gears.
Power: 58V, 16 amp/hr, lipo batteries.
max speed: 52 km/h (30 mph),
max range: 40 km's, incl stop&go few times, minimal pedaling.
New build: Delta recumbent trike

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Obiwan007   1 kW

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Re: My Big Fat Giant

Post by Obiwan007 » Feb 19 2015 2:27am

Hey recumbent, I used the moped rubber on my firs project, the Electric Jeepster. Build thread is in my sig. Like em but they are really heavy and they are only three inches wide. So not really fat tires. I have wanted to try something like this for a long time and am finally getting to do it.

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Re: My Big Fat Giant

Post by BoomerChomsi » Feb 19 2015 3:10pm

Looking very good so far...mate!

Your bike dropout is 150mm? if so you are a lucky man 8)
I already like your build, just home made and not plug and plug build 8)
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Obiwan007   1 kW

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Re: My Big Fat Giant

Post by Obiwan007 » Feb 19 2015 3:59pm

Hey boomer, no my drop out is 135 stock. I am getting it modified by Quality Heliarc in Reno NV. I had this mod done on my first Giant so I could use a Cromotor with a 3-speed freewheel. It opens the dropout to 155mm and essentially takes out the asymetry of the stock frame. Others here on ES have had the same mod done since he is willing to do it via the mail and has all of the jigs and fixtures ready to go. There are pics and pricing of the process in my build thread that is in the sig of my posts. This time out he is going to modify it further to provide clearance in the front portion of the swing arm too.

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Obiwan007   1 kW

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Re: My Big Fat Giant

Post by Obiwan007 » Feb 19 2015 4:02pm

So I did a little testing of these batteries and they all look good with one exception. One battery had a single low cell. About 150ma difference. That seems like a lot. Should I return it before I try charging and balancing. Don't want to void the warrantee.

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Drunkskunk   100 GW

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Re: My Big Fat Giant

Post by Drunkskunk » Feb 19 2015 4:08pm

Looking awesome so far!
That Risse fork's triple clamp was still in prototype phase when I built mine. I had a few conversations with them about getting a Big Foot fork with one custom made. I think they were doing the original for Salsa, and I wanted to beat them to having the first FS Fat bike. So I went with a slightly modified Marzocchi Monster, then later an unmodified Marzocchi Super Monster. The super monster can take up to 4.8", but they are only available used.
Buy the ticket, take the ride.
Monster Bike:http://endless-sphere.com/forums/viewto ... =6&t=38667

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Obiwan007   1 kW

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Re: My Big Fat Giant

Post by Obiwan007 » Feb 19 2015 4:31pm

Hi Skunk. Good point, the super monster is in fact another triple clam that would work. I had forgotten about that one. In my research it appeared that they were about as rare and hard to find as Sasquatch. I found this Risse fork on craigs pretty close to me and got it cheap then sent it to Risse where they did a full upgrade of the internals to the 2015 model and replaced the lowers. I'm pretty happy with them although I have not ridden on them yet. Fitting these wheels past the locknut of the lower is very close but then there is about 3/16" clearance on both sides so I think I will be fine with the 4" V8 tires. My only complaint is the color (anodized purple) I'll likely powder coat the uppers white to match the frame.

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Re: My Big Fat Giant

Post by cheekybloke » Feb 20 2015 10:19am

Cant wait to see this one finished mate, been keeping a close eye on this and your other dh comp build.
I have a dh comp at the welders for a full on frame chop .As i have an 18" it is just not long enough, does not want to go round a corner on flat ground etc.
So it has had 75mm added to the downtube which gives 68mm added length on the crossbar and a little height on the seatube(not measured that bit yet).
Also this has steepened the steerer angle which helps a lot.
The whole front section will be batt. enclosure with the tubes removed.
Monster T forks come up quite often on e bay , i grabbed a pair for this build for 160gbp.
I will be using a L.R. big block on mine hopefully with 3 speeds.
Darren


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Obiwan007   1 kW

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Re: My Big Fat Giant

Post by Obiwan007 » Feb 20 2015 11:50am

Darren thanks for the info. Wow! That's an extensive frame mod. Would love to see some pictures. Do you have a build thread? Are both the down tube and top tube being removed? Are they welding in a box frame for the batt compartment? How about the dropout, are they going to widen that too. I recommend it. What is an L.R. Big block? If it is as wide as the Cromotor you're definately going to want the extra width. If you are using the Kiwi adapter from Scott (I reccomend those too they are great) remember that they take up about 5mm of dropout space. I see monster Ts for sale now and then but the Super monster Ts are really hard to find in my experience. There are guys out there that have standing adds to buy any and all components from these cool forks. Unfortunately, the standard monter T won't handle 4" tires unmodified as far as I know.

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Re: My Big Fat Giant

Post by cheekybloke » Feb 20 2015 2:44pm

Obiwan007 wrote:Darren thanks for the info. Wow! That's an extensive frame mod. Would love to see some pictures. Do you have a build thread? Are both the down tube and top tube being removed? Are they welding in a box frame for the batt compartment? How about the dropout, are they going to widen that too. I recommend it. What is an L.R. Big block? If it is as wide as the Cromotor you're definately going to want the extra width. If you are using the Kiwi adapter from Scott (I reccomend those too they are great) remember that they take up about 5mm of dropout space. I see monster Ts for sale now and then but the Super monster Ts are really hard to find in my experience. There are guys out there that have standing adds to buy any and all components from these cool forks. Unfortunately, the standard monter T won't handle 4" tires unmodified as far as I know.
Hi Obiwan,
Yes both the top and downtube are being removed for more batt. space and yes it will have a box welded in.
As for the motor it is a mid drive.
http://endless-sphere.com/forums/viewto ... 28&t=57720
the big block version of this kit.
So no dropout needed thanks.
The brace on the Monster T is removable so you could cut a new one with more clearance for the tyre and it is flat so an hour with a grinder and some flat plate would do it.
No build thread as yet, just waiting for frame and motor to arrive as i have most of the bits already.
I do know that a 20" mc tyre will fit on a 24" mtb rim and fit in the rear of a 135mm dh comp rear end and the tyre is 3" wide as i have some .
Darren

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Obiwan007   1 kW

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Re: My Big Fat Giant

Post by Obiwan007 » Mar 02 2015 8:18pm

Just got my frame back from the stripper today. Had the white powder coat stripped off in the chemical tank and then the whole thing bead blasted. Total cost $33.00. Turned out pretty good.
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Getting all of the bearings out of the linkage was a real bitch. Can I just say that pressed-in bearings and red locktite should not ever be in the same room together! So, next step will be to get it to Rob at quality Heliarc for the swingarm mods. Talked with a friend today that is an experienced auto pain guy and I'm thinking about getting a good, tough auto style paint job on this bike as opposed to powder coat. It should be considerably less expensive. What is the wisdom here on the sphere? He has the facilities to do it right...booth, oven, quality gun. Thinking possibly Imron paint.

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Re: My Big Fat Giant

Post by motomech » Mar 02 2015 10:33pm

That frame could be mounted on a pedestal as sculpture.
Motomech

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Re: My Big Fat Giant

Post by Ch00paKabrA » Mar 03 2015 9:26am

Obiwan007 wrote:Just got my frame back from the stripper today. Had the white powder coat stripped off in the chemical tank and then the whole thing bead blasted. Total cost $33.00. Turned out pretty good.
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Getting all of the bearings out of the linkage was a real bitch. Can I just say that pressed-in bearings and red locktite should not ever be in the same room together! So, next step will be to get it to Rob at quality Heliarc for the swingarm mods. Talked with a friend today that is an experienced auto pain guy and I'm thinking about getting a good, tough auto style paint job on this bike as opposed to powder coat. It should be considerably less expensive. What is the wisdom here on the sphere? He has the facilities to do it right...booth, oven, quality gun. Thinking possibly Imron paint.
Frame looks beautiful. Is this a friend doing you a favor in painting it? The only reason I ask is that around here powder coating is much less expensive than painting. I have the same frame in Large and to paint it, all the body shops (except Maco) wanted over $600.00. To powder coat it was less than $200.00. I just dipped it with 3 cans of Plasti-Dip for now.

My opinion is that paint always looks better than powder coat because of the depth and luster that can be achieved so if you can get a good price on it, go for it. Everything around here is ridiculously expensive though, lowest I could find to bead blast was $100.00.

I like your project. I have a DH frame kicking around in the basement that I was considering doing this to. Now I will wait to see how yours turns out. :D

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Re: My Big Fat Giant

Post by Drunkskunk » Mar 03 2015 10:31am

That frame looks stunning in raw Aluminum. Paint will look far better than powder coating, but it will be more likely to get chipped and scratched. You have a third option as well. you could get it polished and anodized in any color you wanted. I have no idea what that would cost on a full frame.
Buy the ticket, take the ride.
Monster Bike:http://endless-sphere.com/forums/viewto ... =6&t=38667

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Obiwan007   1 kW

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Re: My Big Fat Giant

Post by Obiwan007 » Mar 03 2015 4:41pm

Yep, friends going to prep and shoot it for free. Still considering powder though. The cost of powder depends on if they have the color in stock and if they are shooting that same color any time soon.

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Obiwan007   1 kW

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Re: My Big Fat Giant

Post by Obiwan007 » Mar 03 2015 7:36pm

Been pricing the paint. Damn! The highest quality, toughest paints are going to run $150.00 just for the paint. Looks like powder is going to be my best bet if I can get it done reasonable.

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Obiwan007   1 kW

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Re: My Big Fat Giant

Post by Obiwan007 » Apr 24 2015 6:01pm

Although I have not posted in a while I have been making progress. Got to go and see the swing arm surgery underway the other day and got these never-before-seen views of the internals of the DH Comp frame:
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I found it interesting that the Stubbs on the dropouts were so short. Also, the welding did not penetrate into the material of the Stubbs from the factory. Anyway, after extending the arms by 1" (with internal sleeves) he will be welding everything back together with better penetration. Should be done and ready by this weekend. Got my tires and tubes and put the from tire together here:
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I'm pretty happy with how it looks. Once the frame is back and done there will be lots to do. Fame and wheel measurements to order spokes, powder coat, first assembly steps, etc. my biggest problem at this point is going to be getting the battery box done. I need a Solidworks model of the frame to build the battery box on. I got the frame digitally scanned but can't seem to find a way to convert the point cloud scans converted to solid works surfaces. Apparently Solidworks has some add-on that will do this but it is EXPENSIVE! Been trying to find someone who knows how to do this. Any help on the Sphere? After that we have what we need to model the parts on the frame model and then send it out to the factory floor for production. After that,....well Bob's your uncle. All other components are on hand. Should have the whole project done in a week or two. Yea, I know, glass is half full.

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Re: My Big Fat Giant

Post by BoomerChomsi » Apr 25 2015 4:39am

Looking good, any picture of your battery storage system?
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Obiwan007   1 kW

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Re: My Big Fat Giant

Post by Obiwan007 » Apr 25 2015 10:37am

No pics of the battery storage yet because it only exists in my head. It will be similar to the one on my previous Giant project (see my signature) except that instead of using a tray that sits on the down tube I'm using a shaped channel that extends down to the bottom of the down tube. Also it will be slightly wider so there is room for a 5s battery to fit between the down tube and the sidebar the box. This increases the real estate within the box by a lot but still does not require any frame modifications other than removing two brake cable guides. While we are at it we will produce models to fit both the 18" and 19" frames possibly the 17" frame too. Then the battery box solution for this bike can be ordered by anyone who wants one.

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Re: My Big Fat Giant

Post by BoomerChomsi » Apr 25 2015 1:53pm

Thanks for your reply!

Keep posting! 8) good luck with your nice build.
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Re: My Big Fat Giant

Post by mikebikerad » Apr 28 2015 9:04pm

I'm anxiously awaiting to see how this goes!!! keep chugging. I have some old beat up Risse Racing tripples laying around, thanks for the heads up on the fit in case I try to replicate your efforts sometime in the future.

With a taller sidewall tire like the V8 you might hit the tire on the crown unless you already have stiff springs. Maybe my Risse's were just in bad shape but were squishy. This would be another badass fork for the fatty: http://risseracing.com/store/product_in ... cts_id/362

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Obiwan007   1 kW

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Re: My Big Fat Giant

Post by Obiwan007 » Apr 30 2015 10:07pm

It turns out that my frame was not completed this weekend :cry: However, since I was there any way I was able to take some more pictures of the fascinating process. Keep in mind that most of the components here are simply tack welded in place for stability while moving things about. Here:
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Robb explained to me that he may add a gusset at the rear of the swingarm triangle to add some extra stiffness just in case the additional 1" of length is adds unaccounted for stresses. He will be widening the front part of the "wheel box" too. He also explained that in the areas that got the internal sleeping he will be filling those gaps so that it will look indistinguishable from the original fit and finish. Going back this weekend. Hope it's done.

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