DH frames for freeriding

G

Grantmac

10 kW
Joined
Oct 22, 2018
Messages
888
Location
Victoria, BC
Given that peddling isn't as huge a consideration with a powerful (+2kw) mid-drive, is there any reason to not choose a DH frame (~2005-2010) as a general freeride build? Is the slack geometry that much of a problem?

Keep in mind my background is enduro motorcycles and a little trials thrown in.

Currently using a cyclone on a HT frame but finding the lack of suspension is not letting it hook up well over any loose or rough surface.

Thanks,
Grant
 
I think specialized big hit 2006 is a great frame to eletrification.
The squared design makes a dolphin batery under the down tube look aceptable
 
Grant,
a 200mm travel DH bike is a good choice, the slack head angle good for riding fast off road. In most cases, freeriders use DH bikes.

That said, any (decent quality) full suspension bike will be a major step up compared to a HT. you should take into account that generally the more travel a bike has, the more planted but less nimble it feels. After experimenting, I fount the sweet spot for the kind of riding I do is a 160mm rear travel frame withe a 180mm fork (see my signature). I'm from a MTB background, and tried to build my ebike feel as nimble as my MTB.

If you are looking for something that would feel the most like a motorbike, then a DH frame would be best.

Avner.
 
DH frame would be a great choice and the slack head angle can be sharpened a bit by lowering the preload of the front springs or sliding the fork tubes up in the crowns. And a longer rear shock can help raise the rear end.
 
Got my eyes on 2005-2010 bikes and I think probably single pivot to keep the anti-squat from being too strong.
Actually might take a look at a ~05 Kona Slab this week. I'm fortunate that DH bikes are plentiful and cheap here.

I was mainly wondering if the geometry makes riding tight lines or rough climbs difficult. The riding I want to do has a lot of root and rock steps.
 
Antenor,

I think specialized big hit 2006 is a great frame to eletrification.
The squared design makes a dolphin batery under the down tube look aceptable
Click to expand...


You first sentence concurs with what I have found: I have 2 Big Hit 3's and one Big Hit with the 24" rear wheel, all built up as single speed edirtbikes. They are not built up identical. If I discover a really good modification I am likely to switch the other two to a similar setup. Two of them have Fox 40's and the other Big Hit 3 has a Fox 34 at 150 travel.

If you get the Fox 40 shocks, you will notice the change in head angle immediately upon sitting on the new installation. But once out on the trail, likely you will not notice much to any difference in steering response and angle. When wheeling the bike in tight places, while standing, the limited steering angle will be noticed when jockeying the bike around.

I suppose most of us from a MtB background associate these 8" travel forks with downhill riding. Lame. You have got to learn what you can do with the Fox 40 forks and other likes when up hill riding. You can simply "headwall" a lot of rock and steps. I now find most of what one encounters while on Mtn bike trails of rocks and steps somewhat easier than what is on dirtbiker trails that go uphill through rock, steps and brush.

If you just want to go fast downhill on one of these bikes, take the motor and battery off as they are a hinderance.

If your reason for this choice of bike is the Dolphin pack, you will need a couple of these at least in parallel to get the amps burst that a single set of Multi Craft LiPO's will give you.
 
Antenor,

I think specialized big hit 2006 is a great frame to eletrification.
The squared design makes a dolphin batery under the down tube look aceptable
Click to expand...


You first sentence concurs with what I have found: I have 2 Big Hit 3's and one Big Hit with the 24" rear wheel, all built up as single speed edirtbikes. They are not built up identical. If I discover a really good modification I am likely to switch the other two to a similar setup. Two of them have Fox 40's and the other Big Hit 3 has a Fox 34 at 150 travel.

If you get the Fox 40 shocks, you will notice the change in head angle immediately upon sitting on the new installation. But once out on the trail, likely you will not notice much to any difference in steering response and angle. When wheeling the bike in tight places, while standing, the limited steering angle will be noticed when jockeying the bike around.

I suppose most of us from a MtB background associate these 8" travel forks with downhill riding. Lame. You have got to learn what you can do with the Fox 40 forks and other likes when up hill riding. You can simply "headwall" a lot of rock and steps. I now find most of what one encounters while on Mtn bike trails of rocks and steps somewhat easier than what is on dirtbiker trails that go uphill through rock, steps and brush.

If you just want to go fast downhill on one of these bikes, take the motor and battery off as they are a hinderance.

If your reason for this choice of bike is the Dolphin pack, you will need a couple of these at least in parallel to get the amps burst that a single set of Multi Craft LiPO's will give you.
 


I always wanted an offroad bike but the price of all the individual parts was far too high for myself so I let someone else take the hit of devaluation, so I got a 2017 kuberg freerider pro with a 12kw controller and a 14inch trials rear wheel from a trial centre, it was desperate for a full rebuild/service it took me around a month of potching in evenings etc and now it's all tidy I even bargained a new seat and plastics into the deal.

I'm not prepared to say how little or much I payed for this bike but even after a refurb it's much less than half the price of a 8kw pro model to me that's a no brainer.

A diy bike with all the latest and greatest will whoop my bike no doubt but it will be closer to an Alta mxr value than what can be obtained with a good dig in the preowned you may be lucky.
 
Ianhill,

I would say you have an electric motorcycle not an edirtbike build from simply a bike. I bet though it was fun to have built it.

I sometimes wonder why the Sur Ron which will soon have pedals available(?) was not posted in Electric Scooter & Motorcycle General Discussion?



The 3 LiPO brick batteries, which are in kid's nylon lunch box strap on the other side. For more Range 3 more batts can be attached to the left side.

Take note from the photo the length of the steer tube bars attached to the direct mount of the top fork crown. With ordinary DH bike hardware for the handlebars the direct mounts you may find something as long as 80 mm but even with this length while getting forward to lessen wheel ups on hill climbs I was bumping my knees near the bar end when making quick turning adjustments. Here I am testing an offset of 4" over 3" which I know works.
 
Dingus I got to agree it's no push bike, with the areas I ride it that's not an issue really it's rural off-road only.
That's a nice bike you have there some good components and the ktm seat backwards is just right up my street good improvisation :bigthumb: , Next upgrade for me will be a fox float x2 rear in time then the 40 fronts but at the moment the manitou is decent and progressive its set up for 200mm travel and has 36mm stantions so fairly stiff I'll run that into the ground first.
 
Only negative of DH frames is they generally have little space for a battery.
 
Code: 
  Tommm » Jan 13 2019 9:31am

Only negative of DH frames is they generally have little space for a battery.


Tommm, Oh do think outside the "triangle" and you can construct a lot of places to carry batteries.
 
Ianhill,

I do not know how Manitou forks compare to Fox 40 but one of these 3 eBay frames came with Rokshox Boxxer, what a dud it was.
 
DingusMcGee said:
Ianhill,

I do not know how Manitou forks compare to Fox 40 but one of these 3 eBay frames came with Rokshox Boxxer, what a dud it was.
Click to expand...

What eBay frames be that then ?
I've not used rockshox for a while now i got a basic one on my hardtail but I've not tried any of the more plush ones.

I've not tried a fox 40 myself to compare them but I'd think the fox should be better it's a later design but the manitou performs well with an average weight rider on a fairly heavy bike of 38kg so for their design it's got to be beyond their intended use but they hold up not issues so far.
 
I got the 05 Slab for ~$225 USD.
It's in okay shape with basic Bomber 888vf forks and Fox Dhk 4.0 other than needing a rear rim everything seems in order. Probably one frame size too big for a peddle bike but just right under power I'm hoping.

Dingus: you mention running single speed. Can you give some specs? I'm considering a single speed left hand drive and keeping the standard drive train intact.
My arms are too short for a stem that long but I am going to try mounting any weight as forward and low as possible to keep the front end down. For the riding I envision I can run a lot more sag much like a trials bike (~40%) since I will climb a lot more than I am going to jump for now.

Ian: the Kuberg is way too cool but I would be busted very quickly riding it to work. My intent is a duel use machine that can mostly pass as a "normal" ebike so long as I ride it mellow.

Thanks,
Grant
 
Hillhater said:
Tommm said:
Only negative of DH frames is they generally have little space for a battery.
Click to expand...
Any ebike, especially serious off road ebiles , ride so much better wothout the battery fixed to the frame.
A backpack battery is a huge step up from fixed packs, and often much more secure from theft.
Click to expand...

But where is best to route the cabling? Almost seems like from the front of the pack to the top tube would be best.
I've been considering a backpack battery for commuting to keep the bike more stealth plus I need to pack a few things. 20# of batteries really isn't much on your back.
 
With a mid drive, i route the power cable up the seat tube (external) to a connector under the seat.
Backpack cable runs down to the back of the seat for connection
Allow enough coiled cable to enable mount/dismount easy.
Recommend a easy pull connector incase of emergency. :wink:
All very stealth and makes super light bike handling.
 
I usual use the space on my back to carry my charger so I can charge at destination stay the night and head home next day, so for me the back pack idea never worked even with my scooters I've always done the same, 1kwh or there abouts frame mounted and a charger on my back to do a 30 mile round trip while traveling at decent speed.

If I made a ruck sack that had the charger bms and cells all secured inside then that would be around 10kg on my back up high when most of that weight could be down low in the frame not fatuiging yourself through your arms with shock loads etc, that's why you don't see it being used wide spread not for the want of trial but there's just a better way and that's get your weight as low as possible while keeping good ground clearance that gives the best handling ride along with wheelbase considerations.

To me the new ebikes like the specialized turbo Levo represent cutting edge mountain bike design while staying with in the realms of peddle assist bikes rather than motorbikes with peddles pretending to be a peddle bike but really its the vigger bikes more like the old school Yamaha peddle scooters in pushbike disguise on roads at high speed that are taking the risks and creating termoil for those that respect the sport and hobbie.
 
Grant,

Choose gearing so as to do at least 20mph full throttle or so that you have enough torque to climb the hills you want. One of my bike's gearing is (f to r) 22 44 32 44. I used a White Ind motor cog -- they last forever.

You will need a chain tensioner.


View attachment 3

A projection Racing spider fit freehub and has 104 bolt pattern.


View attachment 2

The red spider is from Origin 8 and the black plate is from Luna Cycle.


IMG_0186.jpg

IMG_0187.jpg
 
Hillhater,

Any ebike, especially serious off road ebiles , ride so much better wothout the battery fixed to the frame.
A backpack battery is a huge step up from fixed packs, and often much more secure from theft.
Click to expand...

I disagree. I move around one hell a lot while standing on my pedals and lever the bike. The battery pack on my back would add interia to my movement and slow changes to my jockeying the bike around.

If carrying part of the bike- motorcycle weight on one's back helps so much why wouldn't KTM riders carry their gasoline on their backs?

A look at my low profile & out of the way battery pack.

IMG_0190.jpg



Mathematically --- engineering wise the second moment of inertia is somewhat higher when the battery pack is on one's back than when the pack is on the frame as that quantity does vary with the square of the distance from the turning axis.

I wish I could carry the battery under the bottom bracket.
 
DingusMcGee, do you have a build page for your bike?

I have another big hit that would like to go the e motorbike route...and your build treath would be a good help :)
 
Antenor,

No I do not but a lot of these ideas are on the Cyclone 3000 thread.

This thread is a somewhat likely title to carry on such particulars as you might need from my builds with a DH frame.
 
Ianhill,

and the ktm seat backwards is just right up my street good improvisation :

Backwards? I know it has an odd look but it was purchased eBay as a used KTM sx 85 seat. I did google KTM sx85 and from the first picks displayed it looks my mounting of the seat is not backwards. I see however the seats on those bikes have more dip near the middle than mine does. More dip would hold me in better when sitting. I may work on this but standing on the pedals butt just above the seat is the power position for serious maneuvering.
 
Ianhill,

and the ktm seat backwards is just right up my street good improvisation :

Backwards? I know it has an odd look but it was purchased eBay as a used KTM sx 85 seat. I did google KTM sx85 and from the first picks displayed it looks my mounting of the seat is not backwards. I see however the seats on those bikes have more dip near the middle than mine does. More dip would hold me in better when sitting. I may work on this but standing on the pedals butt just above the seat is the power position for serious maneuvering.
 
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