Specialised Demo 8 - a good conversion ?

J

Jestronix

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150x12mm Dropouts ! With clamps to tighten the axle , does seem a match made in heaven ?

http://www.pinkbike.com/news/2011-specialized-demo-8.html

obviously putting a rear hub on this would ruin the real purpose of this bike, but I'm having thoughts about this as a nimble downhill turned into an uphill :)

things that stick out for me are

* tough frame - designed to take hard hits
* wide 150 dropout - makes for wider hub choices (what motor with 12mm ?)
* 12mm axle with clamps - good but are they tough enough ?
* insane suspension and brakes

Thoughts on this as a conversion ?

Or is this a mid motor dream?

Fitting a bettery pack could be interesting
 
Maybe on mid motor... no on hub motor. The axle is round 12mm so a hub motor axle wont go in there if the flats are 12mm, plus the whole axle slides out of the hub to get the wheel in and out, which again won't work with a hub motor. The pinch bolts are just there to keep the axle from sliding out, not to hold any torque. With most crank drives, the clearance between the BB shell and the motor is an issue, so you might end up with the motor pointed straight down the way the frame is in that area. Maybe a Tangent drive and a backpack battery?
 
Tats said:
Building a demo 8 2 2010 vintage - 135mm rear and 73mm English bb. Likely easier
Click to expand...

After looking further the 2010 is a better option. Also I don't like how low the crank is on these.
 
Voltron said:
Maybe on mid motor... no on hub motor. The axle is round 12mm so a hub motor axle wont go in there if the flats are 12mm, plus the whole axle slides out of the hub to get the wheel in and out, which again won't work with a hub motor. The pinch bolts are just there to keep the axle from sliding out, not to hold any torque. With most crank drives, the clearance between the BB shell and the motor is an issue, so you might end up with the motor pointed straight down the way the frame is in that area. Maybe a Tangent drive and a backpack battery?
Click to expand...

Not a good candidate really, the crank is so low on these to then have a motor pointing down would be silly
 
No,, the clamps are useless to you for a hub motor. What you are looking for is a frame with removable dropout plates. Then you can fabricate whatever you need and simply bolt it to the swingarms.

Sweet bike for a mid drive of course. Assuming the BB is not so damn exotic you can't use a bolt on mid drive kit.
 
I have built one with a cromotor and put over 30 000 Km on it, riding both on and off road. This was my third bike and proved a very good ride. You have the easier model to build, and the best choice of motors with 150mm. Use the axle clamp screws to secure custom steel torque plates. The frame can clear 3.0 tires, making it a good choice to speed. The only downside that I found on this bike is the numerous suspension bearings, all of them to be replaced once a year if you ride winters. Also, use a Cane Creek Angle Set to slacken the fork angle + 1.5.

PS. I just had a look at my Demo 8 and made me think about some of the mods that I had made.

Extended dropout length. Build your torque plates integrating brake, tensioner, and mud guard mounts. Make them 1 inch longer. The bike is designed pretty compact for it is made for pro racing. Even building a large frame, you will like to extend its wheelbase with both head slack and dropout extension.

It is a great quality of this bike to be low. Unless you will be riding rough trails, build it even lower with 24 inch wheel and a shorter crank (160 mm crank lever is fine on 24 wheels).

Don't be shy to build it for speed. Mine was doing 106 Km/h and felt like it would be fine to double that speed. Because it does feel so confident, you will soon be aggressive on it. Use a big motor and low resistance controller, I fried a few motors and controllers before fitting it with a cromotor and 18x4110 modded controller that made it reliable. Use a simple 3 speed switch to make it safe to cruise to let friends ride it.
 
With all the better quality , newer MTB's having a 12mm x 143 rear drop out. ( Through Axle )

We really need someone here to make custom made Drop Out's/Torque Plates.

The only person I read about here in the U.S. area is someone in Seattle that makes some for a certain Giant Bike, ( can't find him/his ad for them lately )

As Mad Rhino said, make the plates to add some wheel base, incorporate the Disc Brake Tabs on that plate and incorporate the Derailleur Hanger on the Drive side plate.

I will also add , when making the plates, make the slots horizontal .
 
Ahh,,, I did not realize that type dropout would be so easy to add a custom motor plate to. That changes EVERYTHING.

Thanks for your post Mad Rhino. Now I want to see a picture of the plates.
 
A Demo 8 is never easy to make torque plates for. I only said it is the easier model to do. On mine older model, I had no place to screw and had to open the swingarm tubes to insert the steel dropouts into them. One full week of shaping steel plates to a perfect fit. With this model of the Demo 8, there are places to screw and very solid too. Nevertheless, making the torque plates does require some fine crafting skills because the screws are not on the same axis as the motor axle, much like hand crafting brake adapters for post mount. Many would require machining facilities to make a perfect fit with a 3D shape.

It is well worth the trouble building this bike though. The Demo 8 is among the best DH bike's handling ever made. The kind of bike that is making you a better rider, feeling confident at first try. Speaking of first try, I had posted a short vid of one of my former staff and fellow rider, trying my Demo 8 for the first time. The build was not even finished, still far from what it became after being completed 5 yrs ago.

[youtube]7FbKBMhk6pQ[/youtube]
 
I guess I should have said possible, vs easy. I think though, the OP does need at least a picture of your solution.

Otherwise, it remains a No.
 
I can find that. A friend of mine has one of this model that he built last year. He made the torque plates by himself very neat in a couple days without my help.
 
Tats said:
Building a demo 8 2 2010 vintage - 135mm rear and 73mm English bb. Likely easier
Click to expand...

This I want to watch, the 2010 is looking sweet, particularly the option for fitting batteries in the frame. Maybe with a bit of work a nice moulded battery case.

I want to see how you deal with the torque plates. Oh are the dropouts square in both sides ?
 
If you are not going high power, I mean low enough that it can be held with a plain torque arm, why would you build on a big DH frame in the first place ?

You should be looking at lighter bikes. Enduro and Trail MTB are many with comparable components group as a Demo, and most are in a weight category that is more suitable for low power build.
 
Mostly comfort for a bumpy bike path commute - 8 inch travel is much better than 6 - and they're super strong. The other thing is price - locally DH bikes are significantly cheaper than xc or trail. They are very much out of fashion so you can get a real bargain. Most high quality DH bike owners look after them too so they also tend to be better condition too.
 
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