Fat SWB started at last

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Oct 19, 2012
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Made a first effort this weekend to start my SWB fat tyred two wheeler. The donor was secondhand but can't have covered more than a few hundred yards. All the flashing is still on the tyres and at least these tyres are not knobblies. I don't ride off road and hate using off road tyres - it's like riding over a cattle grate. I got the rear done. The wheel needed a multispeed freewheel as it came with just the one and this involved a longer axle. I'll cut it down later. The swing arm needed slicing in half, a bit of bending and some cut and shut to sort it. It came off a 26" wheel hence it's longer than needed for this 20" wheel but that was always the plan anyway as I like the longer look and it adds some wheelbase back into the twitchy nature of a SWB design. Can anyone spot the failure at the factory? Some kid was probably lucky they didn't ride this much!



The frame became easier than expected as the top tube of the donor is exactly the right length and angle so I kept it and added a brace. It didn't have the room for any triangulation so I made a parallel one. Next job joining the two.

 

SirJoey

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My cozy little nook in the corner!
Ok, I see it now. And yeah, I'd say you're right!
That's just asking for a high-speed blowout! :eek:
***
 
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Joined the two halves and added the boom. Lining up the front and rear consisted of using cable ties to strap a couple of planks to each wheel holding them in alignment whilst the pivot was welded. I'll turn the shock the right way up later!



Seat awaiting fitting. This is the second seat I've had off these people. Good quality and cheap too. I'll need another one from them soon for my next project.

 
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Very cool! It looks like it's coming together nicely :) Are you concerned about the lack of triangulation between the two tubes? A steel plate between them might help a lot in that way if you are. It would form an I-beam of sorts that would out a lot of strength and perhaps not a lot of weight.
 
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Seat awaiting fitting. This is the second seat I've had off these people. Good quality and cheap too. I'll need another one from them soon for my next project.

Hi there

As you say cheap , what's postage to UK ?
Is that some sort of breathable cover ?

regards Paul
 
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That cover is breathable and padded and goes around the fibreglass shell. On the trike seat it velcros to the shell as a pad rather than a cover. Price was £105 delivered for the seat and cover of which £32 of that was postage. The trike seat with the side support is an extra £4 over the flatter seat.
 
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Joined
Oct 19, 2012
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Very cool! It looks like it's coming together nicely :) Are you concerned about the lack of triangulation between the two tubes? A steel plate between them might help a lot in that way if you are. It would form an I-beam of sorts that would out a lot of strength and perhaps not a lot of weight.

Most of this design just use a single tube, usually a little larger than the tubing I have but a single nonetheless. I think doubling up on it ought to suffice and the suspension ought to take some of the shock loading from it too.
 
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I found a 26" fat bike for parts the other day and whilst dismantling it I came across this rather spiffing bracket / derailleur combination. It saves having a tube poking up for the mount which would have to be off centre to allow for the extra wide bottom bracket I'm using to help avoid heel/wheel interface issues. A much neater solution I think though needs some de-rusting due to a (low) quality Chinese finnish.

 
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Hmmm

Shimano I think did one they called an ' E-type Derailleur ' ?

Some like this ?



However my understanding was the Shimano one only did 2 rings and small tooth count ?

From the Web for a 10 Speed SLX FD-M675-E-Type front derailleur

• For large chainring: 38-40 teeth
• Designed for mountain bike frames (26"/27,5"/29")
• Capacity: 14 teeth
• Weight: approx. 129 g
• For Shimano 10-speed HG-X chains

The one you have looks more interesting is there a makers name or ID on it ?
 
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That cover is breathable and padded and goes around the fibreglass shell. On the trike seat it velcros to the shell as a pad rather than a cover. Price was £105 delivered for the seat and cover of which £32 of that was postage. The trike seat with the side support is an extra £4 over the flatter seat.
Love the seat! That is a very keen price too!
 
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No marks or ID bar what's in the picture. It wouldn't be hard to make one out of plate but I've yet to see that type of derailleur for sale anywhere.
 
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Just my opinion but a piece of tube adding some triangulation from the steerer tube to the boom just shy of where it is adjustable would greatly strengthen the front boom
 
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chain management.

What are these ?

If they are from a derailleur they will not stand the force of the drive side chain ...

The drive side needs to run in 1 or better still 2 bearings and needs to be bigger diameter.
 
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I'm not convinced the front boom needs any strengthening. Almost every similar design uses an unstrengthened boom. There's no force on the boom, bar what I can generate via pedalling and a large portion of that goes straight down the tube anyway. I can see it may appeal from an aesthetic view to "pass" the lower tube through the steerer tube to join the boom and will consider doing so. It'd be an awful fishmouth to grind out though at such an angle.

Seat measurements:-
The flater seat is 758mm end to end measured directly. Across the widest part at the bottom - 275mm. At it's thinnest waist point - 212mm. At the widest part of the top 264mm.
The trike seat in the XL size (option 4) on the English version of their site! End to end - 780mm measured directly. Bottom at the widest part 370mm. At the lateral support - 370mm. Across the name at the top 230mm.
No idea what the std size trike seat measures as I'm too fat to consider buying one! The flatter ones are less popular than their trike ones and appear to be made to order only. Mine was just over a month from order to getting.

The guides are intended for a derailleur but have their own bearing unlike any other derailleur I've ever pulled apart. Maybe the better derailleurs have them?



I'll admit I hadn't considered the swap from return to drive side of the chain with the resultant extra forces. I have seen these incorporated into other people's builds on the drive side but that doesn't mean they didn't make a mistake too.
 
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