Variable Head Tube Angle Frame

Variable Head Tube Angle Frame

I have mostly selected the head tube angle on my frames based on what I have picked up as being the norm for the intended purpose of the bike. Usually this is within a very narrow range, and sometimes influenced by the angles of available lugs. I have to admit I have not been able to discern much difference in handling between any of the bikes I have ridden and I assume one simply quickly adapts to any differences in handling.
In my wisdom I decided that it might be a good idea to build a frame whose head angle (and hence trail) I can adjust, and I have chosen, taking in design constraints, 55 to 83 degrees, which should take me either side of ludicrous. Furthermore I want the frame to fit wheel sizes of 20 inches, 26 inches and 700c and accommodate up to 57mm tyres so I can test handling of most wheel sizes. The rear dropout spacing will have to be variable from 120 to 135mm and the bottom bracket height will have to be adjustable. Of course it may not work!

The Variable Head Tube

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 Pieces of 5mm mild steel drilled out then slotted by hand, two sections 40mm square section 2mm thick, 36mm head tube, section of steel tube cut into three and a couple of 12mm bolts.

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Tube brazed in 3 sections and reinforcing tube for second bolt.

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Steel plate hinges brazed to sides then head tube silver soldered into front box section.
                                                                   The Forks
Using 28.6mm standard tubing with fitting crown and dropouts.

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Given the size of the components, the forks were brazed in 3 stages

 

 

 

 

 

 

Having now made the forks and head tube from a provisional drawing I measured the forks and head tube accurately and made a final drawing with these dimensions.

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Front triangle section completeIMG_1569

Sliding bottom bracket tube added
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4 Comments

Charlie Merivale

about 3 years ago

Hi Stephen, I hope you had a merry Christmas. I was wondering if you had finished your trail-test bike. If you have I am also wondering what results you have had. Kind regards, Charlie.

Reply

Stephen Hilton

about 3 years ago

Dear Charlie, No I haven't finished yet. I have done the front triangle and now need to do the rear end and brake bosses etc. I have put it on hold whilst I concentrate on an Audax bike I am doing for the Bespoke show in April, so I want to make sure that is ready first. Merry Christmas to you too. Stephen

Reply

Morty

about 2 years ago

Hi Stephen, Any news on the build?

Reply

Stephen Hilton

about 2 years ago

Sorry the post needs updating. The frame is essentially complete apart from brake and disc bosses I still have to add, been preoccupied with other things

Reply

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