Need help raising Frankenbike from the grave

[Jesse Groves]

I recently bought from the Parkers the prototype frame that Thom Ollinger built. Most of you should be familiar with it because the rear part of the frame was used for Larry Oslund’s Frankenbike that he did his track records on. I love the FWD of the Cruzbikes but have problems with fitting the frames, so I wanted to try mating my S40 front end to the prototype rear so I could have my own Frankenbike and be able to use my Railgun seat on it.

However, as soon as the front end was attached, it became apparent that the handlebars are WAY to high; when seated on the bike, my view is UNDER the bars. I believe I can cut the steer tube and replace the straight slider with curved to get better visibility, but before I commit to that I wanted to get everyone’s thoughts on whether I should expect any other problems using the S40 front end, as opposed to the V front end like Larry used.

I looked on the CB website to see what the different specs were for the forks; the website has the rake, trail and head tube angle for the S40, but not for the V. Does anyone know the specs for the V20 fork for comparison to the S40?

Does anyone see any other problems I might have using the S40 front end rather than the V20?

Any thoughts are appreciated.

 

[Doug Burton]

I've built a lot of Frankenbikes. If you could post a photo, it would help.
(I realize that's not too easy on this board...)

 

[Jesse Groves]

Here is a pic

 

[LarryOz]

Jesse,
From what I understand the S40 and V20 front ends are the same.
In my opinion, you will need the curved slider and it should work just fine. That is what I used.
From what I remembered, I had to elevate the from part of my railgun seat quit a bit so I could get a nearly flat position of the center of the seat. So hard to make power that flat though I would come to find out 3 hours into the ride
Looking at your build - You can also swivel the handlebars toward you buy getting a longer chainstay - Measure yours and then see what they have. I think they make 3 different sizes: 19, 21, & 23. I suggest getting one 2" longer and based on your photo that 2" longer chainstay should drop your handlebars a good 3+".
Good Luck with the build!
Larry


Here are a couple of pictures I pulled from the WUCA record I did on this my build of this bike in Aug, 2017 - These shows pretty well how it was built.


This link has a couple more pics and a good description of the bike too: https://worldultracycling.com/record/larry-oslund-100-mile-outdoor-track-record/

 

[bladderhead]

What Larry said. In his pictures you can see the boom is almost horizontal. Yours is a lot steeper. Your BB must be really low. Long chainstay will cure this.

 

[CruzLike]

One other item I noticed. You have an extension just above the headset. Get rid of the 2" extension. Go straight from the coupling that connects to the boom to the fork.

 

[Jesse Groves]

One other item I noticed. You have an extension just above the headset. Get rid of the 2" extension. Go straight from the coupling that connects to the boom to the fork.

View attachment 8511

Definitley those are gone, just included in the pic of “before I make a final decision” stage.

D

One other item I noticed. You have an extension just above the headset. Get rid of the 2" extension. Go straight from the coupling that connects to the boom to the fork.

View attachment 8511

 

[Jesse Groves]

Jesse,
From what I understand the S40 and V20 front ends are the same.
In my opinion, you will need the curved slider and it should work just fine. That is what I used.
From what I remembered, I had to elevate the from part of my railgun seat quit a bit so I could get a nearly flat position of the center of the seat. So hard to make power that flat though I would come to find out 3 hours into the ride
Looking at your build - You can also swivel the handlebars toward you buy getting a longer chainstay - Measure yours and then see what they have. I think they make 3 different sizes: 19, 21, & 23. I suggest getting one 2" longer and based on your photo that 2" longer chainstay should drop your handlebars a good 3+".
Good Luck with the build!
Larry


Here are a couple of pictures I pulled from the WUCA record I did on this my build of this bike in Aug, 2017 - These shows pretty well how it was built.
View attachment 8508
View attachment 8509
This link has a couple more pics and a good description of the bike too: https://worldultracycling.com/record/larry-oslund-100-mile-outdoor-track-record/

Thanks Larry, I was thinking the same as you, just wondering if the the fork geometrey is slightly different between the s40 and v20.

 

[Jesse Groves]

Jesse,
From what I understand the S40 and V20 front ends are the same.
In my opinion, you will need the curved slider and it should work just fine. That is what I used.
From what I remembered, I had to elevate the from part of my railgun seat quit a bit so I could get a nearly flat position of the center of the seat. So hard to make power that flat though I would come to find out 3 hours into the ride
Looking at your build - You can also swivel the handlebars toward you buy getting a longer chainstay - Measure yours and then see what they have. I think they make 3 different sizes: 19, 21, & 23. I suggest getting one 2" longer and based on your photo that 2" longer chainstay should drop your handlebars a good 3+".
Good Luck with the build!
Larry


Here are a couple of pictures I pulled from the WUCA record I did on this my build of this bike in Aug, 2017 - These shows pretty well how it was built.
View attachment 8508
View attachment 8509
This link has a couple more pics and a good description of the bike too: https://worldultracycling.com/record/larry-oslund-100-mile-outdoor-track-record/

What is the white stuff that you used under the seat? Did you put anything in to fill the gaps between frame and seat?

 

[jond]

Thanks Larry, I was thinking the same as you, just wondering if the the fork geometrey is slightly different between the s40 and v20.

it may well be as s40 is definitely wider to fit plus tyres. Check with Robert holler he would know straight away .

 

[LarryOz]

What is the white stuff that you used under the seat? Did you put anything in to fill the gaps between frame and seat?

This was just some thin plastic from a for-sale sign and taped up with duct-tape. It was a "sorry" late minute attempt at making the frame little more aero. I was still pretty aero -but I think it could have been better.
If I look back at my data from that 100 Mile record attempt at the Northbrook outdoor track, it is quite amazing (not me, just the data ) : https://www.strava.com/activities/1120688099/laps

Started out averaging a tad over 200 watts, and was able to keep my average speed at around 27mph for the first 80 miles on an average of 188 watts. The last 20 miles I just died. I could only hole 25.4mph on 158watts. I remember I was in agony at the end. I had hoped to continue to set the 6 hour record too, but my legs hurt so much it was all I could do to finish the 100 miles.
I have to admit I did not ride this bike very much, and could easily hold 200+ watts for 4 hours on my V20. I did not account for how much harder it was to make power laying almost flat.
All power is not the same is my takeaway - You might be more aero, but power is just harder to make. Maybe you can acclimate to it somewhat with a lot of seat time, but inherently I think it is just way harder on your heart and lungs the flatter you are
......
Good Luck with the continued build Jesse! Can't wait to see what you come up with and how fast you are!

 

[Jesse Groves]

This was just some thin plastic from a for-sale sign and taped up with duct-tape. It was a "sorry" late minute attempt at making the frame little more aero. I was still pretty aero -but I think it could have been better.
If I look back at my data from that 100 Mile record attempt at the Northbrook outdoor track, it is quite amazing (not me, just the data ) : https://www.strava.com/activities/1120688099/laps

Started out averaging a tad over 200 watts, and was able to keep my average speed at around 27mph for the first 80 miles on an average of 188 watts. The last 20 miles I just died. I could only hole 25.4mph on 158watts. I remember I was in agony at the end. I had hoped to continue to set the 6 hour record too, but my legs hurt so much it was all I could do to finish the 100 miles.
I have to admit I did not ride this bike very much, and could easily hold 200+ watts for 4 hours on my V20. I did not account for how much harder it was to make power laying almost flat.
All power is not the same is my takeaway - You might be more aero, but power is just harder to make. Maybe you can acclimate to it somewhat with a lot of seat time, but inherently I think it is just way harder on your heart and lungs the flatter you are
......
Good Luck with the continued build Jesse! Can't wait to see what you come up with and how fast you are!
View attachment 8512

Thanks Larry! I also lose power the more I recline. The difference in power between riding my M5 at 10 degrees and my s40 at 50 degrees is about 50 watts for equal heart rate and perceived effort. Looking back on it, I should have rode the s40 when I did 6 gap, but I hadn’t bought it yet. Oh well, hind sight is 20-20.

BTW, using a cut up for sale sign and duct tape, is that a hack or a bodge? Lol!

 

[Alain]

I've also tried to become faster by lowering the seat angle, but for me it doesn't work (contrary to Matthias König). The aerodynamic gain is smaller than the power loss. Furthermore, I did not feel comfortable with the zero visibility to the front. My favourite angle is between 17 and 23 degree, that's my best compromise between power output and aerodynamic.

 

[Rampa]

You could use a tether to pull against.

 

[jond]

I've also tried to become faster by lowering the seat angle, but for me it doesn't work (contrary to Matthias König). The aerodynamic gain is smaller than the power loss. Furthermore, I did not feel comfortable with the zero visibility to the front. My favourite angle is between 17 and 23 degree, that's my best compromise between power output and aerodynamic.

My favourite angle is Cruzbike twenty degrees.

 

[bladderhead]

You could use a tether to pull against.

I did not know it was that kind of forum. I have had a sheltered life.

 

[Alain]

I built a seat with support at pelvis and shoulders. The pelvis was completely at the back and both sides. That was a minor improvement but not enough to compensate the power loss due to the flat position.

 

[Balor]

As I understand from browsing pubmed sport medicine articles, *most* people experience no difficulties in power production at reclines up to 30deg, and in fully supine position most people do experience them.
Where will you find yourself on that spectrum (and how much adaptation can make up for that) depends on your personal circulatory system and it's quirks.
An often neglected nuance is BB height. Too high a BB combined with low recline may lead to foot numbness because your feet will not get enough blood to fully oxygenate nerves... and likely calf muscles. I suspect this is why midfoot position works so well on a bent - it 'turns off' a muscle group that does not really contribute anything to power except foot stabilisation with conventional cleat location (and during sprints) and is located highest up.

 

[Jesse Groves]

it may well be as s40 is definitely wider to fit plus tyres. Check with Robert holler he would know straight away .

I checked with Robert Holler, he said that the differences between V20 and S40 forks are very subtle (other than width). The fork for the V20 is slightly taller and straight as opposed to slightly curved like the S40.