First riding impressions

[Vargas]

I finally built my converted bike and want to share my experience.

alt="Vargas Bike"

The conversion kit is a very high quality product. I assembled it in less than one hour. Of course it took much more than that to have the bike finished with all the cabling and bottom bracket installation.
I rode it so far for about two hours this weekend, Saturday and Sunday. Beginning was quite difficult. Then I released the pressure on the handlebar and manage to ride it.
The place I was riding isn't flat, but also not hilly, just ups and downs. In one of the stronger downs, feeling more confident, I was riding a little bit too fast. When I applied the brakes to make the turn at the end of the descent, the rear wheel locked. Most of the weight was concentrated at the front and the rear wheel wasn't helping braking. I must say it scared me a lot. I couldn't make the turn but managed to stop before hitting the opposite sidewalk. Luckily no car was coming. I feel learning to properly stop the bike will be more challenging then riding it.
After the two hours on Sunday I started feeling a strange vibration coming up my upper body, and concentrating in my face. Suddenly I realized it was just a big smile...

 

[ak-tux]

Congratulations! Looks nice.

Congratulations! Looks nice. With these bikes(and generally any bike) the majority of the stopping power in on front brake. On a dry clean paved surface (i.e. without sand grit e.t.c) you can apply huge power to the front break without loosing traction or skidding. The rear wheel cannot give the same power without fish-tailing especially when descending a slope. You have to practice applying asymetrical braking with more power to the front and controlled power to the rear wheel.

According to John Tolhurst, as long as the angle betwen the COG(centre of gravity) and the front brake from the horizontal is not more than 60 deg you will not go over the bars under normal circumstances.

 

[John Tolhurst]

To clarify, if  you get that

To clarify, if you get that 60 degrees, you can deaccelerate at half a g-force without lifting the rear wheel, and 0.5g is the rate of
deacceleration that you discover if you apply calculus to the braking distances cited in the EU regulations for bicycles.

 

[Tarmac Terrorist]

I am surprised that more

I am surprised that more people are not having "endo" issues, John keeps saying "the seat is to high". The question I have is what happens if you don't reverse the front fork and extend the wheelbase to the maximum?

 

[ak-tux]

@Tarmac Terrorist; Your

@Tarmac Terrorist; Your question is about the fundamentals of bicycle kinetics which requires some good mathematics to explain. But basically, if you dont reverse the fork, the conversion kit will increase the rake and reduce the trail of the front wheel significantly enough to affect the stability of the bicycle.

If you like to have a look at all the mathematics: Check here http://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics

Trust John Tolhurst, he has done his homework and after all, he is the inventor on the conversion kit! However I believe we are all free to experiment.

 

[John Tolhurst]

Bicycles require trail, to

Bicycles require trail, to create a self centering effect on the front wheel. There about 50 bicycles in the world at the moment that don't have positive trail. These are called pythons and are not commercially available. They self centre by a different mechanism.

There is nothing about trail that a good google won't sort out.

Its possible to ride a bike quite well, if it doesn't have any positive trail, even a little negative trail. The bicycle can work fine until in one unexpected moment, just when you wished the wheel wouldn't have flicked sideways on you, it does. And down you go - I've built and ridden front wheel drive bikes with very little trail so you don't have to.

Obviouly no one is responsible for what you build but yourself. Word of caution though, the best approach for most of us is to accept the rules of thumb, explore them, understand them, and then consider variations. Seat height, trail requirements, frame integrity, the best approach is to be conservative, accept advise and gather experience. Cycling is a dangerous activity, that we manage by taking a whole range of precautions, from frame design, to what route to take and what clothes to wear.

 

[The Blue Iris]

Ok I had the same question,

Ok I had the same question, curious because we all know that the rake angle effects stability but I have never heard of trail on a bike so off to Google I go.

 

[The Blue Iris]

Super, I learned much and

Super, I learned much and understand now how the rake angle creats trail. I suffer from fork flop on my road bikes and understand why now but is there a riding technique to reduce the effect? When I'm riding fast I often "fall" into the apex of the corner. My Merida is better than the Apollo I had but both have minimal trail, why would that be?

 

[Tarmac Terrorist]

Hey thanks guys I googled it

Hey thanks guys I googled it too, with a bit of luck I will be able to lower my rear suspension far enough to get enough steering axis angle to accomodate forks forward. If I can find a shorter spring I will be cruizing.

i009899 you may want to try lowering your rear suspension, at least you Centre of Gravity will be lower and help with the braking, I think the seat could go back a bit too by the look of it.

Those handle bars are unique did they come with the bike? They would be very cool on a normal bike. I would love some for my beach cruizer.

 

[Vargas]

Adjustments

Hi TT,
About moving the seat back. I read the weight distribution should be 55% front and 45% back. I didn't weight the bike with me on it yet. Will do it and then find if I should move the seat further back or not. Anyway thanks for the suggestion.
The handlebar is a regular "beach cruiser" handlebar I bought in a bike shop and installed upsidedown and turned the other way around. It is very confortable but when I open my legs - more about opening legs to follow - my knee hits the shifter lever. Thus I changed it to the flat one which came with the bike.
There is a tendency, at least with me, to open my legs (move the knees apart without taking the feet out of the pedals) when trying to balance the bike. This is wrong. Now that I got more used to the bike I am no longer opening my legs and would not have the problem with the shifters. I'll install this handlebar back again. Glad you liked it.
BRs

 

[John Tolhurst]

"I will be able to lower my

"I will be able to lower my rear suspension far enough to get enough steering axis angle to accomodate forks forward"

okay, so, new issues: fork flop, difficult low speed handling, difficult to hit the apex of a corner. Head tube angles matter.

 

[Tarmac Terrorist]

"I will be able to lower my

"I will be able to lower my rear suspension far enough to get enough steering axis angle to accommodate forks forward"

Also looks like there would be problems with the brake mounting on a standard MTB sprung forks in Forks Forward (FF) position. If you go FF it looks like you would foul the tyre especially on compression. I will mess around with it anyway, tinkering is half the fun. Currently working on changing the high head stem to something closer to the boom extension on the Silvo and Vendetta. The aluminium tubing and flat bar section in Bunnings (like Lowes)is a fun place to hang out!

John, when it is built up I will appreciate your assessment of the geometry

 

[John Tolhurst]

head tube angle too

"I suffer from fork flop on my road bikes and understand why now but is there a riding technique to reduce the effect? When I'm riding fast I often "fall" into the apex of the corner. My Merida is better than the Apollo I had but both have minimal trail, why would that be?"

As well as trail, head tube angle affects the handling and might be the cause of the different feeling you have with those two bikes. On a DF I believe it would be possible to add the effect of trail by using a longer stem. If I am right, there would be more forward force being applied to the handlebar by your arms and this can have a centering effect also. A DF frame expert might have additional insight here.

 

[Tarmac Terrorist]

Blue Iris, "Falling onto the

Blue Iris, "Falling onto the apex" check this site http://www.bikesplit.com/bsa7.htm they talk about shifting your weight to the outside pedal if you are coasting through the turn. If you are pedalling through the turn, vary your cadence so that your outside pedal is down when you hit that apex. One technique I learned is to look at where you want to go. You will naturally go where you are looking, you need to look at the apex of the corner to hit it but you need to move your focus to the exit point of the corner before you hit the apex. If you are still looking at the apex when you arrive there you tend to fall into it.

 

[GeneO]

What Donor

What donor bike is this is makes a great looking Cruzbike.

 

[Vargas]

It is a cheap one I got in

It is a cheap one I got in Brazil:
http://www.trackbikes.com.br/produtos/destaque/tb-100-xs-18-v/
Components were of very poor quality and I exchanged everything. At the end only the frame was original.
I enjoyed riding it so much that later I bought a V2K frame.
The original frame is still here with me. I can give it to you if you pay the freight costs to USA...propably won't be worthwhile.