Freewheeler "Chopper" Project

wheelerza said:

Congrats Jeff, beautiful, one of a kind, machine. I followed this thread from the beginning, you must be delighted with what you’ve achieved! You’re still going with the springer front end?

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Yes.... but next year. I want to ride it for a while. I went for a 75 mile ride around Franklin County Sunday dodging light rain but had a straight up blast! The new shocks ride like a dream compared to the OEM air units. The response that I get from the Woods cam is great too. Reliable acceleration is nice! The bars are tall but very comfortable. Bottom line: The upgrades are awesome!

So the springer will wait while I enjoy some miles. It does go to the saddlemaker today to get a king and queen seat.... but other than that... it is ride time (finally)

Good to hear Free Bird. You deserve some ride time. When I return from my trip, maybe we can get a ride in.

Well.... I had my first operational design issue. Since I put the fenders on I have not been above 65 MPH (just realized that when this event occurred) as I have been riding the quieter blacktop two lane roads and not the super slab.

I was driving the bike to the saddle shop on a freeway and within a mile or two broke free of rush hour congestion and opened her up. When I hit 70 the fenders started a hard oscillation banging into and off of the tire. The sound scared the hell out of me at first as I thought the calipers had come loose or???? Then I saw it. The LH fender was trying to flap like a wing. I pulled over and inspected things. No breaks, cracks etc.... So I pulled off at the next exit. No problems. Got back on the highway and cranked it up. 50 MPH NP, 60 ..same... 65...same... 70? BANG BANG BANG.... :gah:

So, It appears as if airflow and/or nodal vibrations (harmonics) in the structural elements have an issue at speeds above 70.

Good News - I can pull the fenders off and keep riding

Bad news - Engineering a modification/repair likely means a re-paint for the fenders (Damn)

One of my theories is the gap between the tire and fender (~0.250") is too tight and the fender is lifting off the tire. Think about how those tires shed water from the tread pattern... air is a fluid too... so at speed they could be creating an air flow that lifts the fender. The solution for that fix could be swapping the MT 29x18 R15 tires for 28x12 R15 tires. That would give me 0.500" vs 0.250 clearance and perhaps provide an exit for the airflow. I lose width but save the paint.

It is just a theory though

The other fix would be to increase the stiffness of support structure by moving from 1/2" to 1" round bar in the fender frame. Essentially rebuilding the fender. I would also have to thicken the bracket and beef up the attach points as I would move that bending load someplace else by stiffening the uprights. But I could also add the clearance of the smaller tire at the same time and retain the tire width I like ...

So gotta make a choice

First thing is to remove the fenders.... I will be able to think better when I am riding orag:

I'm thinking it could get ugly if your tires picked up a rock, roadkill, bolt off a truck, or what have you at speed with that little clearance between the fender and tire, too! Something else to take into consideration...

RedOregon said:

I'm thinking it could get ugly if your tires picked up a rock, roadkill, bolt off a truck, or what have you at speed with that little clearance between the fender and tire, too! Something else to take into consideration...

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You are right. I have thought that for a while. I actually had already planned on slotting the holes to give it a little more clearance, but this event makes it more mandatory that I make a permanent change.

Free Bird said:

You are right. I have thought that for a while. I actually had already planned on slotting the holes to give it a little more clearance, but this event makes it more mandatory that I make a permanent change.

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Yeah, and with luck, the extra gap *might* reduce the airflow sucking on the fenders. DAMN sharp looking machine, saw it featured somewhere the other day... Instagram maybe?

(edit) Yeah, on the Ginzchoppers feed! Perfect sissy bar!

I had a t bucket with fenders. My fenders were rigidly mounted. They didn't move.They had 1" clearance,not enough. As the tires would grow the faster you went. At 70 you would start to hear them, at 80 it was like a siren. Its possible the tires are hitting and it's not an airflow problem? Just check the bottom of the fenders you should see the evidence.

Sidecarbill said:

I had a t bucket with fenders. My fenders were rigidly mounted. They didn't move.They had 1" clearance,not enough. As the tires would grow the faster you went. At 70 you would start to hear them, at 80 it was like a siren. Its possible the tires are hitting and it's not an airflow problem? Just check the bottom of the fenders you should see the evidence.

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THANKS! Great thought... This is why I like this forum!

They only have 25 lbs in them and they are big and relatively soft so that is definitely something to evaluate. Where did you end up on clearance for the T Bucket?

I ended up with about an inch and a half. It wasn't what I wanted but it's what I ended up with. Those fenders were like the flat chopper fenders and had a little lip on the side. Helped to hide the issue. I know we don't use dragster tires. But it's an ideal example of how tires grow at speed.

Sidecarbill said:

I ended up with about an inch and a half. It wasn't what I wanted but it's what I ended up with. Those fenders were like the flat chopper fenders and had a little lip on the side. Helped to hide the issue. I know we don't use dragster tires. But it's an ideal example of how tires grow at speed.

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Yep. Sure is. I had not given that consideration.

Is it possible dropping psi to 24-23 would help?

MDO said:

Is it possible dropping psi to 24-23 would help?

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Not sure. When they get the saddle on next week I am going to do some experiments.

Replacement wheels and tires are the most expensive option. I have my engineers in my plant volunteering some time on a potential repair scheme that includes raising the fender 1.5" (min) and stiffening the verticals and extending the support structure across the trailing edge of the fender... of course that means a repaint (Crying)

But it rides great without them... So I have that as a consolationorag:

Back online, met MDO and Freebird at Doc’s. Beautiful trike, I too will copy something from his build. I was happy to meet them, looking forward to a few rides with two nice guys.

My saddle is finished!!

Here is a different view of it

Very 70's chopper ... nice.

I know wheels and tires would be expensive....but would just a lower profile tire be enough?

Very cool old school look:clapping:

jc1300 said:

I know wheels and tires would be expensive....but would just a lower profile tire be enough?

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Yep, could be. I am exploring that option after I get the bike back in my possession. It has spent all of its time in the saddle makers house since I discovered the issue. I was actually riding it out to his place when the problem showed up. Thanks!

Free Bird said:

Here is a different view of it

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WOWOW!!! Fantastic!

Congrats on your win at the show!

Curious to know if the tires growing is what is starting the oscillation.

Kevin