while saving for a v20 I made .....

[Don1]

couldn't take it any longer... I wanna try one of these things, see what all the fuzzibout. Only way I was going to try one is to make one.

Went to the local tip shop (I don't have a yanky translation, sorry) got a coupla bikes, a few bits of junk scrapped up around the farm a few special bits from ebay, a few kind donations from the lbs, a welder and angle ginder. this is what I've come up with. 700c x 32 tyres, disc hubs relaced onto some old mavics from the 1990's, low end 3x7 MTB gears and levers.

I don't have close access to a carpark but I have a gravel road that snakes through our property (unfortuneatly ripped up by the flood here, northern NSW) and its been a challenge. just doing slow repeats of the road (about 600m) can't really do figure 8's but once I can handle this slow gravel i'll take it into town for some figure 8 on tarmac somewhere. Second time out I could recline successfully but still a lot of wobbling about. went down a coupla times on my back until I realized I could just put my feet down....lol it's been funny. enjoying the frustration of learning.

 

[RojoRacing]

I'd be very worried about you rear wheel stays breaking when you hit a big enough bump because it doesn't have any triangulated bracing. Other than that it's a very impressive custom build

 

[LarryOz]

I'd be very worried about you rear wheel stays breaking when you hit a big enough bump because it doesn't have any triangulated bracing. Other than that it's a very impressive custom build

I agree - very impressive.
You could make the rear much stronger by bring a stay from the rear drop-out to the frame location under the seat.

 

[Scott Haggenmiller]

I like your seat angle! I agree that adding rear stays to make a triangle for the rear wheel would add a lot of strength, most bike forks are made to flex for suspension. I had a straight bar on my first build, switching to a drop bar gave me a more ergonomic grip on the handlebar (less of a T-rex grip). Great work!

 

[telephd]

Very impressive indeed. I agree with the triangulation suggestion. That is quite the curve in that seat. What brand and model is it?

 

[Don1]

the seat is from flevobike. i will convert from straight bars to drop bars like a midge or gary with sora3000 brifters or something but i used what i had for the moment. i was going to do another stay at the rear but with so many examples just using a fork, i left it. it has quite a thick gusset of welding and i will check for cracks as we go. anyways, thanks for the kind words!

 

[Don1]

oh about the seat angle. it seems everyone has gone from higher seat angles to lower. so i went lower and will put up with the longer learning curve. i might have another go at a frame sometime, with cro mo and carbon tubes but this will do for now.

 

[Bentas]

Have to chime in ,nice simple frame design , what is your head angle ,trail etc, it looks like it's in the predictable handling ballpark!
Good to see the Aussie creative juices are still flowing ,long live the Tollhurst spirit!

 

[bazzawill]

Awesome bike Don. I am curious what it weighs? I to am concerned about the rear stays.
Where did you purchase the seat from? Was it somewhere local? Wondering if it will suit a V (would love the new vendetta seat but as it cost just as much in shipping it's not an option)

 

[trapdoor2]

i was going to do another stay at the rear but with so many examples just using a fork, i left it. it has quite a thick gusset of welding and i will check for cracks as we go. anyways, thanks for the kind words!

It does look lovely. However, it isn't the weld that will fracture, it is the margins of the weld and the head-tube (from the fork) which very likely will not survive. The head tube was never designed for that kind of loading...it is too thin in wall thickness. There's just too much lever arm...that's a huge amount of shock-bending delivered to that joint. Adding a set of stays beneath will convert a large percentage of that bending load into compression/bending (at that joint)...and better distribute the shock load into the rest of the frame.

Otherwise, nicely done!

 

[Jerrye]

It does look lovely. However, it isn't the weld that will fracture, it is the margins of the weld and the head-tube (from the fork) which very likely will not survive. The head tube was never designed for that kind of loading...it is too thin in wall thickness. There's just too much lever arm...that's a huge amount of shock-bending delivered to that joint. Adding a set of stays beneath will convert a large percentage of that bending load into compression/bending (at that joint)...and better distribute the shock load into the rest of the frame.

Otherwise, nicely done!

Would gusseting that triangle work as well as stays? My thought is that gusseting would take vertical as well as horizontal stresses, whereas stays may only take vertical stresses.

 

[Don1]

there is room for a huge gusset behind the rear fork. so i will do that and keep the integrity of the design. hopefully appeasing the concerns of the brains trust... mind you the frame will probably be trashed onnce the v20 is bought since this thing only really cost me time. but i understand safety is of high concern and concur.....



the flevobike seat was ebay for bout$180au weights 1100g... from eu....

 

[keithkling]

Wow Don1 you did a great job. You make it sound like you cobbled it together, but it looks really nice. I can see what may be an issue other than what the others have pointed out. The front of the seat seems kinda high. It looks like it would cut into the back of your leg as you peddle down. That might make it a bit awkward to ride. If you look at the Cruzbike seats the bottom seat pan approximately points toward the bottom bracket or just a little higher so you don't slide forward, but your seat points up toward the handle bars. Just what I observed as I looked at it. I'm not sure what you can do about it, but with your skills I'll bet you can think of something. Good luck to you.

 

[Don1]

yes keith you are right. it was my first mistake by not measuring twice.. seat should have been 75mm lower. its just a little too high and seat a liitle to wide to flintstone successfully. once riding its ok. later the solution instead of cutting the seat will be to make a longer chain stay to rise the bb and use a proper boom. at the mo, Im the only one who can"ride" it since the front triangle cant move. my 14yo son is dying to give it a go.

 

[ak-tux]

Great work! "If you can't afford to buy it, build it!"

 

[Don1]

finally weighed it... 15kg. considering what materials and componemts used .. thats not bad

 

[DavidCH]

It looks pretty aero so it's going to be fast. It only takes half a second to go 10 feet on a Vendetta.

Best not go that fast unless you really sure that frame can take the load.

You have to have cat like reaction (and the nine lives)

 

[trapdoor2]

While I'm not a stress analyst (I do engineer for food though), gusseting will simply xfer the loads on the fork to the end of the gusset. So, what you would want is to gusset far enough to get to where the steel of the fork is strong enough to react the load. This means shortening the lever arm (distance from dropout to end of gusset). What happens is that the fork hasn't been designed for loads in the new direction and the gusset will probably need to run down to within 6" (guessing) of the dropout. Now you have a big, honkin' gusset that weighs a ton. Safer...but ugly and heavy.
Better would be to run two stays from the main seat-tube back underneath the fork...say, to within a few inches of the dropouts. This type of stay now takes a tension load and reduces the bending load on the fork and weld...making it more of a compression load as the new triangle better distributes the loads. And...then the rear end would look very Vendettaish. Hmmm!

 

[super slim]

A 0.8 mm thick steel sheet, as the gusset will work, if there is a 40 mm long fold on the open part of the triangle near the rear wheel to stop the gusset buckling!

 

[Don1]

was gunna use some 3mm flat.... so that'll do. I have no fear of using as is, since the fork is welded in both sides of the 'seat' tube and has less load on it compared to a df ... but i will cut the gusset in so that it supports the fork thru both sides of 'seat' tube