Custom frame production reaserch... (updated on pg 1)

[ls7corvete]

MH, your idea is similar to what i'm working on for an ES member at the moment, though its not a FR or DH frame, just a normal mtb frame.
It holds 6 x 6s 5ah lipo packs in the downtube. Top tube could hold a further 2 or 3 packs if desired.
Downtube dimensions are: 70mm high x 120mm wide:

View attachment 3View attachment 2View attachment 1
*Battery access hole hadn't been cut in the top of the downtube at the time of pictures taken.
*Original frame needs final trimming before welding to the new downtube in these pictures.
*Shock mount yet to be re-welded on either.

Paul

This looks great. Someone needs to start producing a frame like this to sell. I would make the battery space smaller though, its easy enough to add a couple more cells in a pack somewhere on the bike for longer trips.

 

[Hyena]

Thats a slick looking frame timma and indeed it could be made even more stealthy with a single file row of lipo in the top and down tube at the expense of more welding work. But you'd barely notice anything from the side profile of that bike as it rode by. The guy you're making that for sounds pretty switched on and I'm sure he'll be happy with it.

bzhwindtalker, I've been looking into making custom frames too and as above I reckon it's important to keep the frame looking as bicyclish as possible. What you've drawn/proposed is essentially a stealth bomber which sticks out like dogs balls. If you're trying to make an e-motorbike with masses of lithium stoage that's fine but if you're trying to make a good electric mountain bike I think subtlety is the key.

What I'm looking to make is not an electric downhill bruiser with a big battery like the bomber, but more of an electric cross country bike. I think this would appeal to the masses much more as most who ride ebikes offroad aren't downhill champions or riding like they think they are - they just want something to blast around on over the rough stuff with enough suspension to soak up the bumps and take the odd little jumps. I reckon something with 4" or so of travel front and rear is perfect. Or bolt on some hookworms or similar and you've got a comfy commuter / all purpose ebike. If you can build something like this cheaply I'll buy them off you to save the trouble of doing it myself

 

[Phoebus]

What I'm looking to make is not an electric downhill bruiser with a big battery like the bomber, but more of an electric cross country bike. I think this would appeal to the masses much more as most who ride ebikes offroad aren't downhill champions or riding like they think they are - they just want something to blast around on over the rough stuff with enough suspension to soak up the bumps and take the odd little jumps. I reckon something with 4" or so of travel front and rear is perfect. Or bolt on some hookworms or similar and you've got a comfy commuter / all purpose ebike. If you can build something like this cheaply I'll buy them off you to save the trouble of doing it myself

Not to pick nits, but:

What's the downside to 8" travel vs. 4"?

My understanding, limited though it is, is that folks prefer 4" so that they can pedal more efficiently. Without that necessity, why not go for 8" front and back? You can control costs by using solid but cheap components. I use a full DH bike for XC riding all of the time - it's quite nice. People use 14" (?) of travel on moto bikes for XC riding as well.

A few extra pounds and a couple of hundred dollars seem like a bargain when you get a super plush ride.

If you can keep the stealth look and not compromise anything, may be worth a look...

 

[RallySTX]

I'm no expert, but what I read from others here , is that those 8 inch ravel bikes wallow arround on the road too much, the handling is too loose. Now personally, I like the idea of more travel, as I don't intend to hit 50 MPH on the road. However, my first bike will be a hardtail, beggers can't be choosy.
Brian L.

 

[bzhwindtalker]

I am trying to secure a workshop rigth now, I'm not able to do quality work at the moment and I hate spending time working in bad conditions... Keep you up to date

 

[sn0wchyld]

I'm no expert, but what I read from others here , is that those 8 inch ravel bikes wallow arround on the road too much, the handling is too loose. Now personally, I like the idea of more travel, as I don't intend to hit 50 MPH on the road. However, my first bike will be a hardtail, beggers can't be choosy.
Brian L.

yea im pretty sure your right... like driving a bmw m3 or a toyota landcruser. The suspension on one means on road performance is great, but offroad sucks balls... the other makes on road performance pretty wallowy but take it offroad and your in its element... personally I'd prefer more travel, but then again my enjoyment on a ebike involves getting off the tarmac! the more/softer suspension you have the harder jumps and other tricky stuff becomes though (ie that's why DJ frames are typically hard tails w 4" forks or so...)

 

[BATFINK]

Looks very nice that frame, great work! I want to learn to weld

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[MadRhino]

I'm no expert, but what I read from others here , is that those 8 inch ravel bikes wallow arround on the road too much, the handling is too loose. Now personally, I like the idea of more travel, as I don't intend to hit 50 MPH on the road. However, my first bike will be a hardtail, beggers can't be choosy.
Brian L.

A short travel suspension can be very loose, and a long travel very stiff. This has nothing to do with travel. The advantage of a shorter travel suspension on the road is related to aerodynamics, for it makes possible to build a lower bike, with a rider posture that is dragging less wind.

Long travel bicycle suspensions that have a wide tuning range can be set to ride the road with very good handling, even at speed above 100 Mph, yet they require a stiffer frame than a short travel. Some think that adding a DH fork to a Wallbike or extending the rear travel makes it a better ride, but it just emphasize their weakness by adding leverage to the forces applied to the frame. The more suspension travel and wheelbase that you build, the stiffer the frame you need.

 

[BATFINK]

What do you think about this type of frame, the idea could easily be adapted for most types of frames. Also nothing stopping the same method being used for both down tube and top tube. Stromer is the name of the bicycle

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[Phoebus]

the more/softer suspension you have the harder jumps and other tricky stuff becomes though (ie that's why DJ frames are typically hard tails w 4" forks or so...)

I believe that DJ bike are setup that way to maximize pump/pedal efficiency.

For a counter example, look to MX stunt bikes. Huge travel, crazy jumps, excellent control for tricks. It's all in how the suspension is tuned/outfitted/setup.

 

[Phoebus]

What do you think about this type of frame, the idea could easily be adapted for most types of frames. Also nothing stopping the same method being used for both down tube and top tube. Stromer is the name of the bicycle

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The Stromer's low key downtube battery storage is great inspiration, I would think.

I've ridden a Stromer, and their pedal assist software is fantastic. If anyone gets the chance, I highly recommend taking it for a spin around the block; very smooth, high quality bike. Professional is every way, and perfectly suited to the casual rider.

 

[Hyena]

What's the downside to 8" travel vs. 4"?

I guess alot of it is due to geometry as well. I have 100mm travel forks on my hardtail and 170mm triple crowns on my stealth fighter. Aside from limiting the maneuverablity of the bike the bigger forks (and again I guess it's probably more the geometry) make the front end feel quite heavy, which extends to the whole feel of the bike. It feels more like a motor bike and less nimble and agile. The rear suspension is great for soaking up the bumps though.
The other consideration from a production point of view is the cost. While rear suspension is relatively cheap a set of long travel forks will be quite expensive. Semi decent 100mm travel forks can be had for as little as $200 (I just picked up a set of 110mm travel rock shox tora airs new for $180) where as longer travel forks start at around $600 and are closer to a grand for a decent set.

A few extra pounds and a couple of hundred dollars seem like a bargain when you get a super plush ride.

True, but again it depends on your application and also the target audience. Are you trying to replicate a stealth bomber/fighter for offroad use or make an all round ebike ?

 

[ls7corvete]

What do you think about this type of frame, the idea could easily be adapted for most types of frames. Also nothing stopping the same method being used for both down tube and top tube. Stromer is the name of the bicycle

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Or this type.

 

[MadRhino]

What's the downside to 8" travel vs. 4"?

I guess alot of it is due to geometry as well. I have 100mm travel forks on my hardtail and 170mm triple crowns on my stealth fighter. Aside from limiting the maneuverablity of the bike the bigger forks (and again I guess it's probably more the geometry) make the front end feel quite heavy, which extends to the whole feel of the bike. It feels more like a motor bike and less nimble and agile. The rear suspension is great for soaking up the bumps though.
The other consideration from a production point of view is the cost. While rear suspension is relatively cheap a set of long travel forks will be quite expensive. Semi decent 100mm travel forks can be had for as little as $200 (I just picked up a set of 110mm travel rock shox tora airs new for $180) where as longer travel forks start at around $600 and are closer to a grand for a decent set...

Very good description of the differences applied to rider's experience. The geometry is very important, adding a long travel fork to a frame that is designed for shorter, doesn't make a good ride. Yet the opposite is not true, because building shorter travel with a long travel frame usually makes a very good ride.

We build shorter travel for many purposes, mostly weight and agility related. Either we need to pedal them, deal with technical trails, or need to handle at will their position in the air. AM, XC, 4 Cross or slopestyle bikes all have an advantage to be built lightweight with short travel suspension. Short travel bikes are made to be nimble and reactive

Long travel bikes are made to be linear, meaning they are soaking the obstacles with the least disturbance to the trajectory, and corner with stability and predictability. They have a longer wheelbase and slacker steer angle, making them perfectly suited to ride fast on rough terrain. On the street, they feel like a motorcycle as you noticed, and unless you have a frame with variable geometry, they are much better at riding fast, to gain the agility that they lack at lower speed. Fortunately, variable travel and geometry are becoming the norm with DH and Freeride bikes, making them very adaptable to various riding style and terrain. The next step will be variable rear suspension deflection angle, making possible to set a bike to be reactive or linear at will. The racing horse and the show jumper on the same frame. :wink:

 

[geetarboy]

Finding the balance between manuvering and handling like a bike and performing like a motorcycle is a tricky thing. Wheelbase & rake are critical.

 

[bzhwindtalker]

I have been sidetracked by other projects, but now it's time to get this one firing again, and make it mid drive compatible, and apply what I have learned from last bike (jumps and handling)
I am quite sure that for a lower power offroad bike, a mid drive will dominate a wheel hub setup.

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I will try to make the frame work for both hub, non hub and RC drives. I don't now If I will be able to produce some frames, but I will for sure test mine to destruction (either me or the frame :lol: )

This is my idea : double down tube, single top tube, single pivot and straight swingarm, progressive shock leverage, made of round ST37 tubes.

This design will retain more a bike look than a bomber or a fighter but should be plenty strong and rigid.

I am downloading another CAD package and weather sucks so I will work on this one a bit and post more accurate drafts