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In racing we use 3 different measurements - a sewing tape is used to measure the tire roll out in a circle
different roll outs ( we would check the tires so the top ed the car is not roof walking ) will give you different speeds and gearing its not a lot but its a thing they never looked at - we match the roll out so the car stays straight at hi speed
In racing we use 3 different measurements - a sewing tape is used to measure the tire roll out in a circle
different roll outs ( we would check the tires so the top ed the car is not roof walking ) will give you different speeds and gearing its not a lot but its a thing they never looked at - we match the roll out so the car stays straight at hi speed
Roll out is just tire circumference which can vary from tire to tire regardless of if its a 16 or 18", tire inflation, tread wear. Both having a 26" diameter would be more critical than roll out. Honestly on a bike I cant see a reason why roll out would even be a factor and would have nothing to do with trail and its trail that Harley legend says was the issue. Correct me if Im wrong, Im just trying to understand exactly what the issue is beyond just going with stories from 80 plus years ago and bending the frame to correct the problem. I get the relationship between neck angle and tank slapping but my sport bikes are less than 25 degree necks. Maybe its something like the weight of the 16" front wheel on a springer front end without a shock absorber that sends it into a gyroscopic fit. Stands to reason the wider rim and tire would weigh more than the skinny 18" setup and require something more than a fiber washer under a thumb screw to control suspension movement. Change the angle of the neck and its a bandaid fix for a different issue. Just a thought.
Its not a guess if its going to happen - people crashed bikes as the new machines were delivered in 1940 for the 41
Not disputing people crashed and that bending the frame solved it, doesn't answer the question as to why though when clearly wheel diameter had nothing to do with it. Im leaning to suspension and lack of a shock showed its short comings with a steep neck angle.
Last edited by hellonewman; Feb 1, 2022 at 10:08 PM.
As i know it it was 1 inch of height difference that was the issue and in the writings it said it was not all machines
the end fix was 5 degrees difference in neck angle and an off set springer - so they were at the crash spot and never knew it
that is what i came to believe - but your vast experience it Twinkie colors like your new Lavender FFDODY5EEDBWl4 special edition 39TILL6 - only 26000 ever built in the same color
As i know it it was 1 inch of height difference that was the issue and in the writings it said it was not all machines
the end fix was 5 degrees difference in neck angle and an off set springer - so they were at the crash spot and never knew it
that is what i came to believe - but your vast experience it Twinkie colors like your new Lavender FFDODY5EEDBWl4 special edition 39TILL6 - only 26000 ever built in the same color
Don't get cranky now because a Twinkie owner is using logic to challenge your infinite wisdom and long held beliefs. Without really having an answer you're having to resort to regurgitating what someone else told someone else before WWII who didn't know what they're talking about and that isn't really dispensing wisdom now is it? I like to know things, not blindly believe folk lore so Im digging for an answer and my motivation is real because I dont feel like croaking on this bike. If you had a solid answer that made sense then I wouldn't bother looking into it. The original tires according to Harley are the same diameter so the 1" difference is a myth. Thinking more about it last night, the tire construction itself, not the diameter could be the final nail in the coffin no pun intended. The tire technology at the time, a 16" tire with a taller or soft sidewall vs the 18 or even tread block squirm would add more flex between the front and rear wheel alignment to an already flexible frame and lastly, no shock on the springer combined with a steep neck isn't good. Change one factor in that combo and its either a disaster or a solution.
Last edited by hellonewman; Feb 2, 2022 at 07:25 AM.
This speedo was found in a barn - way before this discussion and the farmer told the young guy who got it for me almost 7 years ago // the farmer when they ran out of gas offered some from the barn and they guys seen bike parts on shelves
he picked up the speedo and asked about it knowing i needed a 1940s unit - farmer said he had bought a new 1941 knucklehead and with in 1200 miles he crashed the **** out of it from a death wobble - so he stripped the bike to fix it and never did but in all the years sold off most of the parts and my guy bought the speedo 100 bucks
john boorish in Texas i sent him the speedo to go through it - he called me to inform me its was the best looking unit from that era he had ever seen - he changed the glass and the chrome ring and / re painted the needle - checked the speed timing oiled it and sent it back - couple hundred bucks
the machine i have is a utility FL the cheapest model that was available and it did not have a trip set in th speedo head - no one knows how many in 1941 they built in the bent frame era of 2600 machines that were affected - and dropped that model before the next series in Mid series 1941 were built - the speedo does not have a trip set - sure your going to find one of those - i put the original mileage that was on the title work from the 1960s i have for it for john to add to the unit
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