Frame type

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t_tberg   100 W

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Frame type

Post by t_tberg » Dec 09 2016 1:32pm

I've really enjoyed the simplicity of my latest build; its a cr-mo ridged frame, single speed with widish tires with a ebay DD hub that I run at 2.5kw.
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I'd like to build another similar bike but perhaps with an air fork. My questions is about frame types; I'd like to find one with horizontal dropouts as I've found most sliding dropouts are alluminum. Are dirt jump frames a good candidate for a strong steel frame? I like downhill frames but they seem to be a lot more expensive and almost exclusively alluminum, I would image that a heavy DD hub would put extra stress on all of the pivot points on the rear triangle. Also the additional moving parts and components necessitate additional maintenance. For those reasons I think I might stick with a hard tail. Can anyone suggest a good heavy duty steel frame that would support a single speed drivetrain? I've been looking on craigslist and such and I want to keep the price down-- strong simple cheap. Any suggestions?

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Chalo   100 GW

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Re: Frame type

Post by Chalo » Dec 09 2016 11:28pm

Don't be afraid of aluminum. Weight for weight, it makes stiffer and stronger frames than steel. You just have to be scrupulous about having strong, tight-fitting torque arms (if you use a hub motor), because aluminum dropouts are not hard and strong enough to do that job.
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dogman dan   100 GW

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Re: Frame type

Post by dogman dan » Dec 10 2016 7:31am

just make or buy some good torque arms for your dirt jumper, aluminum, frame.

Or get this. and weld what you need onto it.
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That's not entirely a joke,, if you are into steel, get a welder and start building the kind of frame you like. It's so easy I could do it.

Take half a steel frame,, in this case it was a fine old school cromoly MTB, and start building the rear end you want onto it.
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2old   100 kW

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Re: Frame type

Post by 2old » Dec 10 2016 9:49am

Or locate a Kona Honzo.

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EVTodd   10 kW

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Re: Frame type

Post by EVTodd » Dec 10 2016 6:19pm

Dirt jump frames from a few years ago can be very nice for a build. I've been using a KHS dj-200 for a few years now and love it. Started off with friction drive on it now it's powered by a rear hub at 2000 watts. Not super high powered but a very nice all around bike. I will say with the hub it might be nice to have a full suspension bike. Not a huge issue but some bumps while street riding scream for a rear shock. That's actually my next project. Unfortunately that one will be aluminum since it's almost impossible to find steel full suspension frames.

It seems to me that the geometry has drastically changed on the new dj frames though, way more BMX bike than mountain bike at this point. I've always had my eyes open for the steel version of the dj-200 and the azonic steelhead frames. I believe the steehead has horizontal dropouts too.

My current ride: Well, that picture is almost current. Wires are hidden better now and I'm using a larger controller.
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New Tidalforce friction drive build: http://endless-sphere.com/forums/viewto ... 28&t=28029

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dogman dan   100 GW

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Re: Frame type

Post by dogman dan » Dec 11 2016 7:46am

That does look nice. I was just meaning that if you can't find it,, build it. If it's steel, then you can put whatever rear drops on it you like. they are easy to fabricate from some plate steel.

I'd snap up that bike if I found it,, for the prices I'll pay.

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EVTodd   10 kW

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Re: Frame type

Post by EVTodd » Dec 11 2016 10:36am

dogman dan wrote:That does look nice. I was just meaning that if you can't find it,, build it. If it's steel, then you can put whatever rear drops on it you like. they are easy to fabricate from some plate steel.

I'd snap up that bike if I found it,, for the prices I'll pay.
I hear ya. That's the nice thing about steel.

I got the frame in that picture for around $30 brand new. Love cheap! Lol
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MikeSSS   100 W

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Re: Frame type

Post by MikeSSS » Dec 11 2016 11:37am

my 2 cents, or perhaps nonsense.

From observing those with a lot of experience, no one bike or frame type fits well all situations. Grocery getter and rough trail bike are different, unless you limit the quantity of groceries to fit in a messenger bag, then the rough trail bike can be used for groceries.

Hard tail has the advantage of no pivot point bushings, compared to full suspension. The dirt jump style frame is hard tail, but uses a long seatpost, this allows the use of something like a Thudbuster LT, the long travel model. I'm leaning in this direction, dirt jump frame, rear hub motor, Thudbuster LT, suspension seat, etc.

I find the ebike used by Ozzzz, for his Great Divide ride (Continental Divide in US terms?) to be particularly appealing. The trick is to get close to the same function, at a lot lower price point.
https://endless-sphere.com/forums/viewt ... z#p1235326
His frame is not the dirt jump style and he uses the Thudbuster ST rather than the LT, but the fat tires probably add a lot of suspension effect. The frame is aluminum, so really good torque arms are a must.

Full suspension is another option, rear hub motor, instead of mid drive, reduces chain pull forces to only those provided by the riders pedal torque. On the other hand, if the rider is content with slow trail riding, then the mid drive is viable. A factor is the availability of suspension bushings and the difficulty level to replace them. Cheap full suspension is probably better using a rear hub motor.

t_tberg   100 W

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Re: Frame type

Post by t_tberg » Dec 11 2016 4:00pm

I certainly would like to learn to weld, I have a friend who just went to school for it.. I've always been a little leery of learning and building myself a homemade frame due to how slight variations in geometry create different stress points or how it would affect handling or a multitude of other factors. But the more I look into it, it seems more feasible. Im actually consider welding two clamping torque arms to make horizontal drpouts on my current frame.
MikeSSS wrote: Hard tail has the advantage of no pivot point bushings, compared to full suspension. The dirt jump style frame is hard tail, but uses a long seatpost, this allows the use of something like a Thudbuster LT, the long travel model. I'm leaning in this direction, dirt jump frame, rear hub motor, Thudbuster LT, suspension seat, etc.
Right now I actually have a thudbuster LT (although the seatpost was all gobbled up by the long seattube on my old mountain bike). I like the solidness of a hardtail, I've never ridden full suspension with a hub motor but it seems like you'd run into some issues over time..

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Re: Frame type

Post by MikeSSS » Dec 11 2016 4:24pm

Yep, probably bushing problems. Specialized makes full suspension, mid drive bikes. Saw one on the trailhead the other day. It looked excellent. Price is high though, 5,500 to 9,500 USD.

I've pedaled a few thousand miles on hardtails with suspension seatposts. That combination works very well. Add the weight of a geared hub motor to the hardtail rear and a Thudbuster LT looks very attractive.

I'd like to try a mid drive or rear geared hub motor on my FS bike but am reluctant to screw up the bushings, especially when replacements are probably not available. Another FS option is to get a cheap FS bike at Wally World and put a rear hub motor on it. For small bumps on the street or bike path, it might do OK. Life of the pivots and fork may be short but it would give experience with the concept. One of the very experienced members here on ES, rides a FS bike with rear geared hub motor. He reports that it works well for his offroad use. To me that indicates that it works well, he has the experience to know.

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EVTodd   10 kW

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Re: Frame type

Post by EVTodd » Dec 11 2016 6:28pm

MikeSSS wrote:Yep, probably bushing problems. Specialized makes full suspension, mid drive bikes. Saw one on the trailhead the other day. It looked excellent. Price is high though, 5,500 to 9,500 USD.

I've pedaled a few thousand miles on hardtails with suspension seatposts. That combination works very well. Add the weight of a geared hub motor to the hardtail rear and a Thudbuster LT looks very attractive.

I'd like to try a mid drive or rear geared hub motor on my FS bike but am reluctant to screw up the bushings, especially when replacements are probably not available. Another FS option is to get a cheap FS bike at Wally World and put a rear hub motor on it. For small bumps on the street or bike path, it might do OK. Life of the pivots and fork may be short but it would give experience with the concept. One of the very experienced members here on ES, rides a FS bike with rear geared hub motor. He reports that it works well for his offroad use. To me that indicates that it works well, he has the experience to know.
I admit I haven't been on ES that much lately but I don't recall seeing people talking about problems with suspension bushings running a hub motor. I'm interested to find out now that I'm building a full suspension bike.
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MikeSSS   100 W

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Re: Frame type

Post by MikeSSS » Dec 11 2016 9:05pm

I don't recall discussion on ES about bushing problems, either. But, our son bought a new full suspension bike and wore out the bushings in a year and a half, he did this with pedal power alone. Don't remember the brand of bike but it was quite expensive, much more than I can afford. He used it in Houston, there are no mountains there, just bayous and trails with roots to cross. After the FS bike, he tried going back to hardtail and found it to be pretty harsh. That said, he is very strong and is an offroad motorcycle racer, so his riding style uses a lot more power than my ebike riding ever will.

Reason I'm thinking rear hub motor on a FS bike, or a hardtail with Thudbuster, is for simplicity, reliability, and low maintenance.

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EVTodd   10 kW

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Re: Frame type

Post by EVTodd » Dec 11 2016 10:03pm

MikeSSS wrote:I don't recall discussion on ES about bushing problems, either. But, our son bought a new full suspension bike and wore out the bushings in a year and a half, he did this with pedal power alone. Don't remember the brand of bike but it was quite expensive, much more than I can afford. He used it in Houston, there are no mountains there, just bayous and trails with roots to cross. After the FS bike, he tried going back to hardtail and found it to be pretty harsh. That said, he is very strong and is an offroad motorcycle racer, so his riding style uses a lot more power than my ebike riding ever will.

Reason I'm thinking rear hub motor on a FS bike, or a hardtail with Thudbuster, is for simplicity, reliability, and low maintenance.
I hear ya. That's why I've always liked hardtail bikes myself. I'm old old school BMX guy so I'm always drawn to that style of bike anyway.

I'm interested to see if anyone else comments about the bushings. My thinking is the hub motor wouldn't really change anything for the same amount of miles of non-ebike riding when it comes to that. Seems to me the suspension would just work as usual. Maybe it would compress a bit more over a bump when the weight of the motor rebounds. I don't know... Interesting. I guess I'll find out in the spring.
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MikeSSS   100 W

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Re: Frame type

Post by MikeSSS » Dec 11 2016 11:52pm

When you try a rear hub motor on an FS bike, please let us know how it works for you.

My present bike is rigid, both front and rear. It uses a front, direct drive hub motor and a Cloud 9, Cruiser Cruiser suspension seat. Most of the road shock is noticed through the handlebars and through the pedals. Sketchers Go Walk 2 shoes take care of the pedal shock and vibration. I have a couple of suspension stems, but have not installed one. The seatpost is 25.4mm, I don't want to spend money on a suspension seatpost in this size.

It doesn't take a lot of suspension to smooth things out over small bumps, as in street and path riding...as long as you don't hit something big. Still, more suspension is better.

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dogman dan   100 GW

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Re: Frame type

Post by dogman dan » Dec 12 2016 8:02am

Honest,, I weld about as good as a monkey on LSD. I'm as good as blind while I do it, so if I can, you can learn. the wire feed welder makes it pretty easy. you may not weld correctly, but you can grind a bit, weld a bit, and eventually get a strong enough weld. But start with small projects, like a rack. I just doodled around with thin steel to learn how to not burn through first, then let er rip on the Schwinn cruiser. Before I had done a longtail with a stick welder, but the welding on that bike was really minimal. like one weld.

Re the bushings,, there is dirt riding, and there is dirt riding. If you buy an FS bike from the wrong guy,, yer screwed, but few MTB riders really do ride like that. Just don't buy the bike from a real racer.

I ride FS bikes with rear hub motors fairly hard. I'm old, don't jump, but the trails did not get easy in my area. I would not call my riding easy on the bike. I had one old cheap ass FS bike get funky because of tail wag, but it was less the bushing than metal fatigue on the steel parts of the rear suspension flexing. Mild steel will limber up, not sure why, I've just seen it a few times on hard ridden, cheap fs bikes. I've never seen chromo steel limber up.

Anyway,, my 25 pound rear hub is not trashing my swing arm pivot on the giant yet.

Re the right bike for the job at hand,, well, this is why I have a lot of bikes. Bike plus one, always. This just shows what I can throw a leg over right now, not including the bikes that don't have motors.
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2old   100 kW

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Re: Frame type

Post by 2old » Dec 12 2016 11:31am

Obviously, bushing life on FS frames is somewhat proportional to how agressively they're ridden. However, my son and I have had excellent service from Santa Cruz Heckler (his) and Superlight (mine) frames used under moderately severe conditions for years. Possibly (probably) the single pivot with a large bushing (or bearing) wears well. We're not lightweight; me 6'1' (180) him 6'1' (200). BTW, no maintenance during that period except to wipe the dirt off the "stantions" or whatever they're called.

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Re: Frame type

Post by t_tberg » Dec 13 2016 3:49pm

Dogman, it looks like all of your FS bikes have geared hubs and not direct drive, which one has a 25lb hub? I have always looked for CrMo in a bike and currently both of my bikes are chromo (albeit my kona has sliding alluminum dropouts). It'd really love to find a CrMo FS bike but it seems like theres a polarized market of high end alluminum downhill bikes and crusty ass mild steel walmart bikes.

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