Discussion in 'BUILT FROM SCRATCH' started by tjwilson, Oct 15, 2019.
Names for your drop-out design:
...and my favorite....
Ya know, that’s one of those things I never saw and now that’s all I see! Too funny.
I vote for Hare Extensions! I may not be able to refer to drop-outs as anything else but from now on.
Once the tube was fit and tacked I put everything back into the fixture to double check the crank arm and chain-ring clearance.
Crank arm clearance looks good. The right chain-stay is going to need a little more work to get the back of the chain-ring bolts to clear... so close.
It's nice to see the frame taking shape. I can't wait to see those wheels and tires on it.
Thanks, can’t wait either. Just got the spokes ordered and should be able to get the wheels laced up soon. Waiting till I can get the rear tire on before bending up the cantilever tubes. Hoping to keep those nice and tight to the tire.
Thank you very much. Same to you and yours!
Seat Tube Connection
I've been a little unsure of exactly how this was going to work out. When designing the frame I liked the look of the seat tube curving back and then hugging the rear tire. This meant that the bottom of the seat tube wouldn't attach directly to the bottom bracket. I ended up creating a flat plate that attaches to the bottom of the tube as well as bridges the chain stays. Should add additional strength plus, this created a potential mounting point for a kickstand.
I really like the additional bracing. I wasn't really sold on the chain stays (before) because of how much the tube was flattened, but I decided to keep my opinions to myself and wait to see your next move. Glad I did, looks great!
Glad you like it, thanks. I do see what you're saying. Especially in the area near the chainring. And I think I'm going to have to thin that up even more before I'm done! Those poor chain-stays have literally been put through the ringer. Been a challenge and learning experience getting them past that fat tire.
And keep those opinions coming! Your observations and input are always appreciated.
I changed things up a bit in an attempt to get some better looking welds. More of a stitching / series of paused tacks rather than a continuous bead. I cranked the welder settings up to try to help eliminate some of the cold laps between "stitches". Looks like I got good penetration. A bit too good at the joint between the chain-stays and the bottom bracket though. In hindsight it may have helped if I'd screwed in a sacrificial spindle to dissipate the heat. I ended up having to grind a few areas were the weld bled into the threads. After grinding I was able to get the spindle installed. Just hope that doesn't come back to haunt me.
Here's the seat tube plate and chain-stay / bottom bracket weld up.
First image shows the weld bleed through into the threads. Second shows the same area after a little careful grinding.
And throwing caution to the wind, here's the frame weld up. Waiting to get the wheels laced so I can use the rear tire as reference for creating the cantilever tubes.
Probably a good thing that you didn't have a "sacrificial spindle" in there. It might have been welded in permanently!
Back to the chain stays, my first thought before you went further was to suggest notching out the tube for the chain ring clearance but I don't think there would have been enough tube left after seeing how far in you had to go.
I had to do that on the Blackbird chain stays and seat stays for tire clearance. I cut out a notch and then welded in some flat sheet metal to box it in.
That would have been just a slight set back!
That might have worked and would have been a nice detail. I’m leaving the option open to go with shorter crank arms but not a larger chain-ring. I can imagine a boxed in area behind the ring with a curved edge tight to the outside ring radius. Almost like the chain-ring itself cut clearance into the chain-stay. Will have to file that idea away for the next time.
This is the second time I've laced my own wheels and the first 3x pattern. Referenced Sheldon Brown for the overall how-to and a couple different sites for spoke length, ebikes.com and kstoerz.com. The sites gave differing values using identical hub and rim dimensions. To be safe I decided to use the longer lengths from each. Figured it was better to be a little too long than short. Had to grind a couple mm off some of the spokes once everything was tightened but overall seems to have worked out.
Spoke calculation results from ebikes.com and kstoerz.com
Pieces parts for the rear wheel and initial lacing.
Finished and trued rear and front wheels.
These were a bit more of a challenge then the first wheel I laced for a previous build. That wheel had the same dishing side to side. Both of these wheels were different side to side. The rear only slightly but the front quite a bit. I used a spare fork as a truing stand for the front with a zip tie attached to one side. The end of the zip tie helped me judge how straight the wheel was running. Flipping the wheel in the forks left to right helped me get the rim centered to the hub. Really taught me how nice it would be to have an actual truing stand. Can't say how many times I accidentally hit the zip tie when flipping the wheel and then had to re-set it.
The rear wheel didn't vary side to side as much but the flipping process was the same. I didn't have a frame handy that would accommodate a 170mm rear hub to use as a truing stand so I built one from a donor rear triangle and scrap tube.
Lacing and truing wheels is very satisfying. Looks good.
Thanks. It really is satisfying. To me it feels like pulling off some kind of magic trick that you're not too sure is actually going to work when you start.
The front hub I'm using has a lock nut to lock nut dimension of 100mm. A little wide for the Schwinn fork I'm using. The axle diameter is also a little larger than what the fork accommodates. Got everything to fit together by opening the fork holes a little, stretching the forks a little wider, and grinding small flats onto the axle. Tried to do the minimum at each step to keep things as strong as possible.
Fork ends before, during, and after.
Spreading the fork.
The axle fit at this point but the wheel was nearly impossible to get in past the narrower fork slots.
Before and after grinding axle flats.
Had to throw the wheels onto the in-process frame for a quick look!
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