# what i learned about klunker forks.....



## surly357 (Jan 19, 2006)

one thing to keep in mind when choosing a fork for a prewar schwinn klunker is the difference between the geometry of the early bikes that came with the more elaborate truss rod fork with the crown supports and the later 40-41 dx bikes that had the 'ashtabula' looking forged fork. the later bikes have a much shorter axle-to-crown length so often running a modern mx style cruiser fork is like putting a shock on a non-suspension corrected mtb. combine that with barely half the offset in some cases and your long anticipated klunker project becomes a wobbly, floppy bike that shouldn't even leave the driveway! if you check alan's site you'll see the 40-41 dx's (joes, gary's, etc) run original style forks and the mx cruiser style forks are on bikes in the 35-39 era. it took me a while to figure this out on my 40, since i had always run 'pyramid' mx forks on my previous projects. of course i'm unusually dim, so it took a lot of staring at alan's site and an email from joe breeze (who kindly went the extra mile sending me a scan of one of his original sketches) to confirm my suspicions. maybe this will save someone a little time and frustration. apologies to aemmer, who has probably seen these pictures too many times already

flopping death trap  









sweet riding bike


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## Fillet-brazed (Jan 13, 2004)

Thanks for sharing. I'll have to post mine and you can tell me what I have. I'm pretty clueless on these old bikes.

I don't know if it's cause you already told me or what, but the first rendition doesn't look right.


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## scooderdude (Sep 27, 2004)

I suppose it depends on the purpose you intend for the bike. The postwar bikes had lower BB shell and steeper head angles, the precise reason the '38-'41 Schwinns were the frame of choice, as they are both slacker and with higher BB shell. This is how it's been explained to me.

But I believe the a-c lengths on the years you mentioned didn't change from ~15.5". After market BMX/cruiser forks were a similar length. My old school Tange TX1200 is 15.5", for example. AB mentions a BMX fork on one of his bikes to be 16.5", yet he isn't sure how that is, or why that is, as he recalls it's also a Tange TX1200. 

The forks you see on different bikes are essentially snapshots in the course of the evolution of the burgeoning sport. AB's bikes appear to have evolved in ways that Joe's and Gary's bikes didn't. I think the bikes you mention were the end of the klunker line for those two guys. The BMX forks, and alloy rims from Ukai/Araya, were just starting to appear on the klunkers built by AB about the time Joe was building the first purpose-built custom frames that ended up underneath both he and Gary. I suspect that if they didn't head in that direction, you'd have seen BMX forks on their bikes, too, eventually.

I would say that if you plan to climb steep hills on a hybrid klunker, then the taller/slacker bike would be a floppy handful, just like any mtb with slack angles, long fork and high BB would be. Headman in Fairfax prefers the postwar bikes for townie duties because they're so much more nimble (lower/steeper). On the other hand, if speed is your thing (it is MY thing, for sure), then that nimble little townie bike will become a handful, while the slacker bike will just start to find its legs.

Here's my '40/41 DX Larkspur-gang inspired bomber, now about 98% complete. I'm just waiting for a chain and headset, and to get the darn brake bosses brazed to the fork. This one's built for speed, and will be used for speed, yet I'll still tootle to the cafe on it, too.


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## surly357 (Jan 19, 2006)

*cool bike scooterdude*

keep in mind i'm not saying it's only the (3/8 to my eyes) change in a-c length. it's when that is combined with a severe reduction in the offset of the fork. my 40 dx just doesn't seem (to me) as able to absorb that change as easily as others. i can run a pyramid mx fork on an older motorbike frame and it feels ok, and on my rollfast (w/a longer-than-schwinn tt) it feels great, almost like a modern rigid ss! i'll have to pick up a tange fork sometime. like you said, it depends on the ride you're after. it sure is fun to experiment, that's for sure :thumbsup:


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## scooderdude (Sep 27, 2004)

surly357 said:


> keep in mind i'm not saying it's only the (3/8 to my eyes) change in a-c length. it's when that is combined with a severe reduction in the offset of the fork. my 40 dx just doesn't seem (to me) as able to absorb that change as easily as others. i can run a pyramid mx fork on an older motorbike frame and it feels ok, and on my rollfast (w/a longer-than-schwinn tt) it feels great, almost like a modern rigid ss! i'll have to pick up a tange fork sometime. like you said, it depends on the ride you're after. it sure is fun to experiment, that's for sure :thumbsup:


Yep, the slacker the head angle, the more offset needed if you want to retain a similar handling characteristic to one with a steeper head angle. Slack angle with less offset (or longer fork w/ no increase offset) will produce more trail (READ: straight line stability).

What fork is on the bike you show at the top of this thread? It definately looks longer than my Tange - seems there's a bunch more material between the unicrown and lower bearing perch than on mine.


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## surly357 (Jan 19, 2006)

scooderdude said:


> Yep, the slacker the head angle, the more offset needed if you want to retain a similar handling characteristic to one with a steeper head angle. Slack angle with less offset (or longer fork w/ no increase offset) will produce more trail (READ: straight line stability).
> 
> What fork is on the bike you show at the top of this thread? It definately looks longer than my Tange - seems there's a bunch more material between the unicrown and lower bearing perch than on mine.


it's one of the cheapo 'pyramid' brand forks from j&b. 15 1/2" a-c, only about 1" of offset. i figure it's the one most clunker builders will encounter if they go to their local lbs- that's pretty much why i raised the topic. i have a bad one that makes a 'snapping' noise at the dropout when it's loaded/unloaded. pulled it out of the bike and put it in the park fork jig, got out the old fork 'straightening' tool and played with differing amounts of 'rake'. it was fun to feel the changes with each test ride, being in almost immediate succession. time to ebay that fork i guess. it's funny 'cause it's true. no, wait, i'm kidding- honest......


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## scooderdude (Sep 27, 2004)

surly357 said:


> it's one of the cheapo 'pyramid' brand forks from j&b. 15 1/2" a-c, only about 1" of offset. i figure it's the one most clunker builders will encounter if they go to their local lbs- that's pretty much why i raised the topic. i have a bad one that makes a 'snapping' noise at the dropout when it's loaded/unloaded. pulled it out of the bike and put it in the park fork jig, got out the old fork 'straightening' tool and played with differing amounts of 'rake'. it was fun to feel the changes with each test ride, being in almost immediate succession. time to ebay that fork i guess. it's funny 'cause it's true. no, wait, i'm kidding- honest......


Hmmm..... Me thinks your fork is a good inch longer than 15.5". Take a look at the 3/4 view of my DX, and then look at yours. Notice how the headset baseplate perch of mine is immediately on top of the junction where the curved upper legs meet the steerer, while yours has ~1" more material between that same point and the base plate.

And my fork has just 1" of offset, too.


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## surly357 (Jan 19, 2006)

*weird, huh?*



scooderdude said:


> Hmmm..... Me thinks your fork is a good inch longer than 15.5". Take a look at the 3/4 view of my DX, and then look at yours. Notice how the headset baseplate perch of mine is immediately on top of the junction where the curved upper legs meet the steerer, while yours has ~1" more material between that same point and the base plate.
> 
> And my fork has just 1" of offset, too.


made me look! just ran out to the garage and measured one not on a bike. 15 5/8 from the bottom of where the crown race would be to the center of where the axle would be. can't explain the optical effect between the 2 forks. at least not after 2 beers and an episode of 'family guy'.....


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## ScottyMTB (Oct 26, 2005)

*Tange 1200 champion*

I think the Tange 1200 Champion forks have a total offset similiar to the blade forks because the legs come off of the steer tube at an angle, and you have the drop out offset. The chrome Tange on the black bicycle seem to come down more straight, similar to the Pyramid you are running so I guess it depends on the fork.


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## scooderdude (Sep 27, 2004)

ScottyMTB said:


> I think the Tange 1200 Champion forks have a total offset similiar to the blade forks because the legs come off of the steer tube at an angle, and you have the drop out offset. The chrome Tange on the black bicycle seem to come down more straight, similar to the Pyramid you are running so I guess it depends on the fork.


Hmmm.... Could be.


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## scooderdude (Sep 27, 2004)

I took off my TX1200 Tange to whack on the headset race, and noticed it has offset worked into the crown, too. So I measured the overall offset to be ~1.5". Looks like the red one when I lay it flat.


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