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 Post subject: Moving the freehub
PostPosted: Mon Feb 18, 2013 7:22 pm 
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bad kitty!
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Hey, I think I just got a fun idea.

I've spent a lot of time around trial bikes lately.
They have the freewheel up on the crank, rather than in the rear hub.

I have a hard time getting rid of the thought of making a XX1 style setup, with a 9 or even 8 tooth as the smallest in the rear, and a 24 or 26 in the front.

Besides being real nice on the ground clearance, it could be real light as well, and offer some neat possibilities for shifting when not pedaling.

What do you think guys and girls?


Magura :)

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 Post subject: Re: Moving the freehub
PostPosted: Mon Feb 18, 2013 7:31 pm 
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friendly kitty

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I didn't know that about trials bikes. The thought had occurred to me, but I never went any further.

I like the idea, do you think there would be a way to utilize one way bearings for instant engagement and run silent?


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 Post subject: Re: Moving the freehub
PostPosted: Mon Feb 18, 2013 7:50 pm 
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bad kitty!
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I spent some time, years ago, on one way bearing engineering, for rear hubs.
It always came back to being too heavy for what they are offering.
Moving them up to the crank, only makes matters worse, as there is less space, and potentially higher load.

Trials bikes are a funny breed. It's much like they are in a world, completely isolated from the rest of the MTB scene.
In some aspects, that has brought inventive engineering, in other cases, they make you slap your forehead, like the lack of development of frames...
Trials frames are cracking left and right, when ridden by top riders, yet they are still fighting to make the first carbon frames.
As late as yesterday, I made a partly carbon frame, for competition use. The guy who is going to ride it, usually cracks a frame every 2 months.


Magura :)

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 Post subject: Re: Moving the freehub
PostPosted: Mon Feb 18, 2013 8:17 pm 
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friendly kitty

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That's interesting that there seems a sort of partition between trials and the rest of bicycle development.

It's to bad about the weight issue of one way bearings, I keep looking for an application for bikes and it just isn't there.

The idea I keep wanting to pursue is that of a two speed gearbox, but it always comes down to weight. If Hammerschmidt with its planetaries are to heavy I don't know that a gearbox could be lighter.

Have fun with that carbon trials frame project, it sounds like a fun challenge.


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 Post subject: Re: Moving the freehub
PostPosted: Mon Feb 18, 2013 8:31 pm 
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bad kitty!
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The partly carbon frame is already made. As I type this, it is being assembled, and will be used in a show next weekend.

I am though in the process of making a full carbon trial frame, as that simply can't be that big a problem to do.
The company that sponsors my trial habit, is more than interested in such a frame, and sponsors some of the top riders in Europe, so why not? ;)


Magura :)

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 Post subject: Re: Moving the freehub
PostPosted: Mon Feb 18, 2013 8:43 pm 
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friendly kitty

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Pics perhaps?


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 Post subject: Re: Moving the freehub
PostPosted: Mon Feb 18, 2013 8:49 pm 
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bad kitty!
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It was picked up by the sponsor yesterday, and I was too lazy to make pics then.
I would guess that the sponsor will post pics galore real soon though.
I'll post a link to some pics ASAP.
I think he is going to bring me some brake seals tomorrow, then I'll ask where he has posted the pics.


Magura :)

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 Post subject: Re: Moving the freehub
PostPosted: Mon Feb 18, 2013 8:52 pm 
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friendly kitty

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Very cool. Between this and the carbon rotors on there way to you it seems your days are currently pretty interesting.


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 Post subject: Re: Moving the freehub
PostPosted: Mon Feb 18, 2013 9:03 pm 
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bad kitty!
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Naah, I made the trial frame together with a friend, the day before yesterday, it was pretty much just another day at the office, so to speak.
Truth be told, I'm pretty bored at the moment.
I guess the most interesting thing that has happened lately, was that I got a brand new kick a$$ trial bike last week, that I've built up the last couple of evenings.
That thing is just smothered in titanium bits, machined stuff, forged and CNC machined 7075T6 cranks, titanium BB, titanium cogs, the works.
That thing is just real neat....and the best part: it was sponsored!


Magura :)

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 Post subject: Re: Moving the freehub
PostPosted: Mon Feb 18, 2013 9:51 pm 
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stealth kitty
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Them one way bearings don't hold much torque before they slip...

Maggie... we want to see pics of the stickered up sponsor bike. LOL

-S

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 Post subject: Re: Moving the freehub
PostPosted: Mon Feb 18, 2013 10:03 pm 
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Shibiwan wrote:
Them one way bearings don't hold much torque before they slip...

Maggie... we want to see pics of the stickered up sponsor bike. LOL

-S


That is only partly true in my experience. The biggest issue I've had when testing, is that they tend to explode the housing, if it's not real massive. Thus the weight problem.

I'll see if I can make a couple of pics of the new bike tomorrow.
I still haven't mounted the brakes and the chain. The build has been a bit slow, as first thing was to mount a carbon gusset on the down tube, or I'd be 100% sure to not have it for long. That little detail took 2 days, due to the cure time for the adhesive and poor planning on my part.

The bike is pretty much a souped up 20" Echo MK2 ti, or Lite SL as they seem to call them now.
http://www.tartybikes.co.uk/20_inch_tri ... 11616.html

The more I look at it, the more I think I want to make something to fit those cranks to my carbon MTB project.
http://www.tartybikes.co.uk/isis_splined_bbs/echo_urban_isis/c2p11117.html
http://www.tartybikes.co.uk/cranks_pair/echo_sl_2013/c514p12016.html

Magura :)

EDIT: Just realized that nice people use the sponsors website for linking :D
http://www.trialaction-shop.dk/cykeltrial/echo-bike-2013-model-20-mk-ll-ti.html

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 Post subject: Re: Moving the freehub
PostPosted: Mon Feb 18, 2013 10:59 pm 
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stealth kitty
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Magura wrote:
Shibiwan wrote:
Them one way bearings don't hold much torque before they slip...

Maggie... we want to see pics of the stickered up sponsor bike. LOL

-S


That is only partly true in my experience. The biggest issue I've had when testing, is that they tend to explode the housing, if it's not real massive. Thus the weight problem.

Magura :)

EDIT: Just realized that nice people use the sponsors website for linking :D
http://www.trialaction-shop.dk/cykeltrial/echo-bike-2013-model-20-mk-ll-ti.html


That's because the one way bearings "ramp outwards" radially and cause thin/soft (i.e. aluminum) housings to deform. Once they push outwards, everything starts to go... then you have the kaboom! LOL Only good solution is to use a thicker (and more massive) housing...

Nice... I wanna see videos of you riding on top of some fences soon..... er wait someone forgot the seat tube/seatpost/seat. LOL

-S

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 Post subject: Re: Moving the freehub
PostPosted: Mon Feb 18, 2013 11:14 pm 
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bad kitty!
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Shibiwan wrote:
Magura wrote:
Shibiwan wrote:
Them one way bearings don't hold much torque before they slip...

Maggie... we want to see pics of the stickered up sponsor bike. LOL

-S


That is only partly true in my experience. The biggest issue I've had when testing, is that they tend to explode the housing, if it's not real massive. Thus the weight problem.

Magura :)

EDIT: Just realized that nice people use the sponsors website for linking :D
http://www.trialaction-shop.dk/cykeltrial/echo-bike-2013-model-20-mk-ll-ti.html


That's because the one way bearings "ramp outwards" radially and cause thin/soft (i.e. aluminum) housings to deform. Once they push outwards, everything starts to go... then you have the kaboom! LOL Only good solution is to use a thicker (and more massive) housing...

Nice... I wanna see videos of you riding on top of some fences soon..... er wait someone forgot the seat tube/seatpost/seat. LOL

-S


Yeah, the problem is the "thicker" part, as thicker in this case, pretty much means steel, and loads of it.

Seat and seat post was not included in the deal, so I decided against it. Seats are pretty expensive these days you know.
The video part, I think I'll leave to others, I don't get paid for killing myself. ;)


Magura :)

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 Post subject: Re: Moving the freehub
PostPosted: Mon Feb 18, 2013 11:40 pm 
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Tell me more about the free BB.


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 Post subject: Re: Moving the freehub
PostPosted: Tue Feb 19, 2013 3:04 am 
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Magura wrote:
I have a hard time getting rid of the thought of making a XX1 style setup, with a 9 or even 8 tooth as the smallest in the rear, and a 24 or 26 in the front.

Besides being real nice on the ground clearance, it could be real light as well, and offer some neat possibilities for shifting when not pedaling.

What do you think guys and girls?
Being able to shift without pedaling could be kind of cool. I'd be concerned for myself that I would wear out an 8-tooth sprocket very quickly, or put too much tension on the chain and wear it out too quickly. But those issues are probably easily handled.


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 Post subject: Re: Moving the freehub
PostPosted: Tue Feb 19, 2013 3:41 am 
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revolting kitty
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I, for one, LOVE, this idea!


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 Post subject: Re: Moving the freehub
PostPosted: Tue Feb 19, 2013 3:42 am 
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Will the always-moving-chain be more prone to jumping off the chain ring when going down rough descents?


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 Post subject: Re: Moving the freehub
PostPosted: Tue Feb 19, 2013 4:12 am 
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stealth kitty
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Sti wrote:
Will the always-moving-chain be more prone to jumping off the chain ring when going down rough descents?



How about "more mechanical drag" ?

-S

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 Post subject: Re: Moving the freehub
PostPosted: Tue Feb 19, 2013 10:58 am 
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bad kitty!
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Bill in Houston wrote:
Magura wrote:
I have a hard time getting rid of the thought of making a XX1 style setup, with a 9 or even 8 tooth as the smallest in the rear, and a 24 or 26 in the front.

Besides being real nice on the ground clearance, it could be real light as well, and offer some neat possibilities for shifting when not pedaling.

What do you think guys and girls?
Being able to shift without pedaling could be kind of cool. I'd be concerned for myself that I would wear out an 8-tooth sprocket very quickly, or put too much tension on the chain and wear it out too quickly. But those issues are probably easily handled.


I too think 8 is maybe to go overboard, but I'd like to try.


Magura :)

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 Post subject: Re: Moving the freehub
PostPosted: Tue Feb 19, 2013 11:00 am 
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bad kitty!
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Sti wrote:
Will the always-moving-chain be more prone to jumping off the chain ring when going down rough descents?


As the chain ring gets smaller, this should diminish. How much? Time will tell.
Coupled with a XX1 style ring, it just might work out.


Magura :)

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 Post subject: Re: Moving the freehub
PostPosted: Tue Feb 19, 2013 11:01 am 
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bad kitty!
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Shibiwan wrote:
Sti wrote:
Will the always-moving-chain be more prone to jumping off the chain ring when going down rough descents?



How about "more mechanical drag" ?

-S


That will be in situations, where it won't matter much, so I'm not too worried about that.


Magura :)

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 Post subject: Re: Moving the freehub
PostPosted: Tue Feb 19, 2013 11:03 am 
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bad kitty!
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Wmac wrote:
Tell me more about the free BB.


Take a look at the pics here:

http://www.tartybikes.co.uk/20_inch_tri ... 11616.html

One of the pics shows the BB freewheel.

Magura :)

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 Post subject: Re: Moving the freehub
PostPosted: Tue Feb 19, 2013 3:01 pm 
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Would an 8t cog have enough surface area to distribute the load of the chain to minimize the mechanical drag Shibi is talking about?


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 Post subject: Re: Moving the freehub
PostPosted: Tue Feb 19, 2013 3:35 pm 
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bad kitty!
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Wmac wrote:
Would an 8t cog have enough surface area to distribute the load of the chain to minimize the mechanical drag Shibi is talking about?


AFAIK S. was talking about the drag of a constantly moving drive train ;)

I guess that if the teeth are not ripped of at the bottom, it's all good.
Time may tell, as the jury is still out on the smallest cog being 8 or 9.


Magura :)

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 Post subject: Re: Moving the freehub
PostPosted: Tue Feb 19, 2013 3:39 pm 
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revolting kitty
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Yeah, I got that, but I'm not coasting much when I ride, so that mechanical drag isn't a concern. I'm thinking about the meshing of the chain surface and internally on an 8t cog. That would be some serious force concentrated two links.


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 Post subject: Re: Moving the freehub
PostPosted: Tue Feb 19, 2013 4:23 pm 
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Wmac wrote:
Yeah, I got that, but I'm not coasting much when I ride, so that mechanical drag isn't a concern. I'm thinking about the meshing of the chain surface and internally on an 8t cog. That would be some serious force concentrated two links.


In that case we are in agreement. Hence the jury is still out on that.


Magura :)

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 Post subject: Re: Moving the freehub
PostPosted: Tue Feb 19, 2013 4:31 pm 
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Please think of us owners of 135x12 and 142x12 rear axles when designing the skinny cassette! :lol:


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 Post subject: Re: Moving the freehub
PostPosted: Tue Feb 19, 2013 5:10 pm 
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bad kitty!
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Oh, you mean the ones running vintage hubs?

Well, it happens to be limited by the RD, so you can keep on running prehistoric hubs to your hearts contend ;)


Magura :)

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 Post subject: Re: Moving the freehub
PostPosted: Wed Feb 20, 2013 3:52 am 
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Vintage hubs, you are cracking me up man! 142x12 frames are pretty much cutting edge for trail bikes on this side of the pond. :lol:
Anywho, how about this? http://www.pinkbike.com/video/77069/
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 Post subject: Re: Moving the freehub
PostPosted: Wed Feb 20, 2013 10:08 am 
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bad kitty!
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Oh, so it's old news to move the freewheel up front, talk about vintage goods.
Any idea how the ride was with the Shimano FF?

At some point, 160x14 will trickle down to even the most conservative riders ;)

Magura :)

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