Bike Advice

[Slave]

Hi fellow cyclists and forumites.

 

I am new to this forum and I joined it 'cause I am looking for advice.

 

I am not a mega competitive cyclist, but enjoy fair weather cycling as a way to keep fit. I do not cycle when it is too cold, too wet or too windy. (Yeah, a REAL sissy.)

 

I am 1.9m tall wiegh in around 100 kg and currently ride an old Peugot Rapport road bike.

 

The thing has a real crappy centre of gravity and feels like it will fall over if "leaned" in a corner. The gearing is also somewhat out of date even though a 12 speed. (Chain ring has 53 teeth and the smallest gear on the casette has 13 teeth. So I get to spin at lowish speeds and find I'm running out of gears even on a flat stretch of road.

 

I want to buy a new bike (or second hand) and need advcie on size of frame, gearing and that sort of stuff that I know little about. I am also just the other fella so carbon fibre and all this new fangled hi-tech, hi-expense stuff is not in the budget and not required.

 

Appreciate any help I can get.

[Spinnekop]

Hello Slave2Love.

Welcome!!!

We all started like you.  I still have fond memories of my Peugot with 12 speed!!!  Simple yet elegant!!

 

Rule #1.

SIZE MATTERS!!

Get yourself to any bike shop and ask the to measure you.  Then you know.

 

Rule#2.

If you are going to buy second hand, get a "in the know" friend that will be able to help you find a bargain.

 

Enjoy this....buying the bike is 50% of the experience!!!

 

[Canaris]

rule #3 shop around

some brands are expensive because it is an image thing..........

[Slave]

Thanks guys.

 

I have been to a few bike shops around the area (Alberton) and those that seem to know have huge price tags, and those that have no idea have big price tags on the goods.

 

Simply put, the indian lady that owns one local shop has fair prices on some stuff but cannot tell me a thing about what size frame I should be using. (My current fram is 61 cm from centre Crank to saddle post, but the length of the fram from saddle post to steering post is on about 57 cm. Way off square and probably the reason it is such an uncomfortable ride with such poor handling dynamics.

 

The cycle hub (I think thats what they called themselves. were also pretty out if info and mainly wanted me to look at anything with a new price tag, the cheapest bike being 38 grand. Man that's more than my car is worth and the way cyclists get jacked these days, I'm more than a little scared to be spending bug bucks on my summer toy.

 

I have heard that Raleigh and Scott have middle of he road prices, but I still need to come up with a size of bike frame.

 

For the rest of it, I can fix almost anything, derailers, chains, bearings etc. So, long as I can get a decent size frame that can handle well, I can get a better time on my best 3.5 hours cycle challenge time.

[Spinnekop]

Get your size and we'll help you shop around on the Hub......

[Slave]

I will do that Spinnekop and thanks for your interest.

 

Part of the reason I posted here was that I have found getting "sized" to be somewhat more difficult than actually doing the Highveld challenge.

 

If I wanted to do it myself, what measurements would I need?

[AndreZA]

I'm 1.88 ans rides a 56cm (old school sizing) or M (compact sizing). You should be about a 57/58 (M/L, L) but all depends inseem length. Anything you get will be better then what you have and they pop up every now and again here from anything from R3000. Like this one  https://www.bikehub.co.za/forum_posts.asp?TID=34149

 

 

 

 

Mampara2008-10-06 06:54:22

[Spinnekop]

Sizing is a lot of factors.

 

The best online tool I know of can be found here:

http://www.competitivecyclist.com/za/CCY?PAGE=FIT_CALCULATOR_INTRO

 

 

[Johan Bornman]

 

Cut cut cut cut

 

The thing has a real crappy centre of gravity and feels like it will fall over if "leaned" in a corner. The gearing is also somewhat out of date even though a 12 speed. (Chain ring has 53 teeth and the smallest gear on the casette has 13 teeth. So I get to spin at lowish speeds and find I'm running out of gears even on a flat stretch of road.

 

 

Slave, welcome to The Hub. Take your vitamins before posting, it can be a tough place, especially the tech forum here.

 

Your bike's centre of gravity (coG) is not as crappy as you think. It's CoG rins exactly down the middle of you. If you sit on your bike and you draw a line that bisects your body front to back, through your nose, laryncs, spine, sternum, belly button, totti and exactly between your legs, through the bike's top tube and BB, exactly through the front and back wheel, you would have cut through your CoG.

 

No matter how much money you spend, whether you go for a mountain bike, unicycle, tandem, racer or tourer, your CoG will still be in that plane.

 

As for the gearing, you'll find that it is average. You may be able to go down to an 11 smallest at the back, but that's it. You'll be surprised how quickly you tire in that gear though.

 

Go ride a bit more, hang with the guys on bikes and then decide why you actually want a new bike. You're doing it for all the wrong reasons right now.

 

 

 

[Captain Fastbastard Mayhem]

 

 

Cut cut cut cut

 

The thing has a real crappy centre of gravity and feels like it will fall over if "leaned" in a corner. The gearing is also somewhat out of date even though a 12 speed. (Chain ring has 53 teeth and the smallest gear on the casette has 13 teeth. So I get to spin at lowish speeds and find I'm running out of gears even on a flat stretch of road.

 

 

Slave' date=' welcome to The Hub. Take your vitamins before posting, it can be a tough place, especially the tech forum here.

 

Your bike's centre of gravity (coG) is not as crappy as you think. It's CoG rins exactly down the middle of you. If you sit on your bike and you draw a line that bisects your body front to back, through your nose, laryncs, spine, sternum, belly button, totti and exactly between your legs, through the bike's top tube and BB, exactly through the front and back wheel, you would have cut through your CoG.

 

No matter how much money you spend, whether you go for a mountain bike, unicycle, tandem, racer or tourer, your CoG will still be in that plane.

 

As for the gearing, you'll find that it is average. You may be able to go down to an 11 smallest at the back, but that's it. You'll be surprised how quickly you tire in that gear though.

 

Go ride a bit more, hang with the guys on bikes and then decide why you actually want a new bike. You're doing it for all the wrong reasons right now.

 

 

 

[/quote']

 

I don't think you're talking about that COG (centre of G) - rather the centre of where all the weight is, and how far above the ground that point is. For example, if you are on a compact frame, chances are the COG would be alot lower, as you are sitting closer to the ground. Also, alot of the weight is currently high up because of the waythe frame makes him sit on the bike.

 

Unfortunately, taller ppl generally have worse times with balance than shorter, because of this very reason.

 

Oh, and feel free to shoot me down for this. Seems to be the latest "thing" to confront people giving advice that differs from other ppl's views...

 

[Johan Bornman]

I don't think you're talking about that COG (centre of G) - rather the centre of where all the weight is' date=' and how far above the ground that point is. For example, if you are on a compact frame, chances are the COG would be alot lower, as you are sitting closer to the ground. Also, alot of the weight is currently high up because of the waythe frame makes him sit on the bike.

Unfortunately, taller ppl generally have worse times with balance than shorter, because of this very reason.

Oh, and feel free to shoot me down for this. Seems to be the latest "thing" to confront people giving advice that differs from other ppl's views...
[/quote']

 

Yes I am. And I purposefully kept it simple and in one place because the OP described a problem to do with cornering, which suggests that the CoG is high up and that the bike is at fault. The fore/aft point of the COG is irrelevant in this scenario.

 

CoG doesn't work like you describe, since all the weight is not in one point, but distributed over a wide plane. CoG refers to a point where the weight either side of it, in all three dimensions, is equal.

 

A bike weighs 15 kilos, a rider 80 kilos. Bikes are more or less all the same height off the ground and therefore their position on the CoG is pretty constant. A Peugeot Rapport and a Cinelli Ferrari will all have a similar effect on the rider/bike's CoG.

 

Further, a compact frame doesn't alter your CoG over that of a standard frame. The BB heigh is the same (slightly higher for a MTB though) and thefore the position of the CoG in the fore-aft plane doesn't change for a compact or standard frame.

 

Taller people don't have any more difficulty of balancing. You don't see tall people stagger around or zig-zag all over the road unless inebriated.

 

I stand by my initial statements.

 

What is this pre-emptive bullsh*t of "shoot me down if you dare 'cause it seems to be the done thing."?

 

If you present fallacy as fact, you may well get corrected. It has nothing to do with opinion or views. It has to do with understanding of scientific fact.

 

 

[Captain Fastbastard Mayhem]

Ha. Ha.

 

Centre of gravity.

 

The point at which the whole object's weight can be centred, within a 3 dimensional plane.

 

Correct. The CENTRE, where all weight, can be pinPOINTED, and is said to reside in a particular body.

 

Centre of gravity runs down a person's mid-line, head to toe, straight through the middle, and is not in one point, but distributed over a wide plane.

 

Incorrect.

 

A person's COG lies at a singular point in the human body. For some, it can be in the pelvis, for others, as high as the belly button.

 

This is purely because, as different people have differenct body compositions, their weight distribution varies accordingly. You can't tell me a person coming in at 5ft dead has the same COG as someone who is 6'9". Neither can you say that your centre of gravity is the same as mine.

 

What you are referring to is the median line. The line that you can draw, as you so eloquently put it, from your head to your Tottie. That has no bearing on a person's centre of gravity, as my left side could be less muscular than my right, i could have lost an arm or a leg, etc etc.

 

In addition, when i get onto a bike, the overall centre of gravity shifts. I am now a bit higher off the ground, and thus gravity is trying to pull me down that much more (physics 101) Add to that the fact that i have something beneath me which weighs in at between 6 and 20kg (and before you shout me down about this, and ask how my bike can vary that much - Pinarello prince vs old Peugeot steel mountain bike - quite a weight difference, I think you'd agree) and my COG is suddenly higher off the ground (or lower, for that matter) than i am used to.

 

For a heavier guy (weightlifter, for example) he would have a helluva time balancing on a large-framed bike. This is because all his weight is in his torso, making him more unstable than, say, a cyclist, who's weight is centred in the lower part of his body.

 

Centre of gravity explained.

 

Oh, and as for taller people not staggering. What have they done for their whole lives? Baby steps... learning to adjust to their bodies, which, in turn encapsulates the activity of BALANCING. They've had years to perfect it.

 

Here's a case study for you, demonstrating height and centre of gravity rather well, if simply - place 2 poles, each weighing 20kg or so, on a flat surface. One is 1m tall, the other 2m. Now, which one is easier to topple?

 

As for the pre-emptive bullsh*t - who said it was aimed at you?

 

Did I strike a nerve? Or are you just being, I dunno. Mugabe-ish.

 

Mugabe-ish:- Noun. Quick to accuse. Defensive and totalitarian. Eager to declare ones-self as the only option. Even if one is a bit "cracked in the head"

 

[Slave]

OK. Let's all take a deep breath and stop the brick throwing.

 

I love lively debate because I learn from it so let's keep it civil. Others will hopefully learn from this topic as well.

 

As a teenager, I had a SUN Snipe Plus road racer and I used to be able to corner at almost any speed and really low to the ground without suffering the feeling that the bike would fall over. Diffierent tyre sizes (27 X 1 & 1/4) probably had something to do with it. The current 700 by 23 tyres are really skinny and were a new experience for me.

 

The problem,as I see it has very much to do with my height above the ground, combined with tyre shape and size and probably, the frame design and geometrics.

 

My saddle post is out of the current frame by the max disatance it can be, so my position on the bike is very high. My ass end is far higher than my head and almost feel like I am riding in an inverted position.

 

Not a comfortable position to ride in for a long period of time, so I tend to have my hands "resting" on the top of the brake levers while riding. In the "Drop" position, I get this crazy inverted feeling and a mean crick in the neck just to see where I'm going. Not a safe riding position as I often look down at my feet to "rest" my neck. 

 

As for the gearing, I have more endurance than speed and rather power my way up a hill than spin. The smaller chain ring on the bike has never been used by me and the two to three larger gears on the rear casette very rarely get used. As I get fitter, I use less and less gear changes until I use only the last two "smaller" gears.

 

Thus I find it frustrating to be doing 45 when I know I could be doing 10km/h faster on the same strecth of road.

 

I have tried mountain biking and I just cannot do the spinning thing so have opted for road biking if that helps.

 

In the past 18 hours, I have learned several things. The sizing I got at Just cycles only took my crotch height which told them I need a 60cm or large frame. They did not measure anything else. (thanks for the calculator,I will make use of it.)

 

Given the gearing problem, I need to run the biggest chain / pull ring up front and an 11 tooth gear at the back. I now also know what they mean when the tell you the spec is 11/ 23.

 

Problem is, I have been told by all the bike shops, that I cannot get an 11 for the back and the smallest available gear for my bike is a 14. Strange, I managed to get a 13 from a mate of mine.

 

Because the bike is old and parts are becoming a problem (had this with the crank bearing cups a while back) and because it handles so badly, I am reluctant to spend money on it. I feel I need to get a newer bike. The simple logic is that despite my age, the more I enjoy cycling, the more I will do it and probably enter more races.

 

I just don't want to have to rob a bank to get a reasonable ride.

 

Thanks for the replies so far and the debate. Let's keep it going.

[gungi]

sounds like you guys need to start mountain biking...

[Johan Bornman]

 

As a teenager' date=' I had a SUN Snipe Plus road racer and I used to be able to corner at almost any speed and really low to the ground without suffering the feeling that the bike would fall over. Diffierent tyre sizes (27 X 1 & 1/4) probably had something to do with it. The current 700 by 23 tyres are really skinny and were a new experience for me.

 

The problem,as I see it has very much to do with my height above the ground, combined with tyre shape and size and probably, the frame design and geometrics.

 

[/quote']

 

When you are younger you take bigger risks and risky maneuvres are best learnt at a young age.

 

However, I don't understand your feeling of the bike falling over, hence my explanation of the plane in which youre CoG lies. At first I thought you perceived the bike to be unbalanced left to right. Now it starts to sound like a fear of leaning. If that's the case, still, a different bike wont make a difference. It cannot move your CoG so much that it would.

 

The tyre size does not come into the equation at all. Those old tyres probably had a lower coefficient of friction than modern tyres and hence a steeper slip-out angle. It sounds more and more like a confidence thing.

 

 

My saddle post is out of the current frame by the max disatance it can be' date=' so my position on the bike is very high. My ass end is far higher than my head and almost feel like I am riding in an inverted position.

 

Not a comfortable position to ride in for a long period of time, so I tend to have my hands "resting" on the top of the brake levers while riding. In the "Drop" position, I get this crazy inverted feeling and a mean crick in the neck just to see where I'm going. Not a safe riding position as I often look down at my feet to "rest" my neck. 

 

[/quote']

 

The drops are not the most comfortable position possible. Stay out of them until you regain flexibility and confidence. A new bike will create the same effect. Stay on the hoods for now.

 

A seatpost gets extended to the position dictated by your body dimensions. The same will go for a new bike. Don't expect a dramatic different feel on the new bike.

 

Given the gearing problem' date=' I need to run the biggest chain / pull ring up front and an 11 tooth gear at the back. I now also know what they mean when the tell you the spec is 11/ 23.

 

Problem is, I have been told by all the bike shops, that I cannot get an 11 for the back and the smallest available gear for my bike is a 14. Strange, I managed to get a 13 from a mate of mine.

 

[/quote']

 

It sounds to me like you have a screw-on cluster or freewheel rear wheel. Typically the smallest sprocket you can fit on these is 14 for modern versions of these clusters. Older ones with 13-tooth sprockets are extinct and the 13 you got for yours is an old one. Bike shops are right, they cannot get smaller ones for freewheel hubs. You'll have to convert to a freehub system.

 

 

Because the bike is old and parts are becoming a problem (had this with the crank bearing cups a while back) and because it handles so badly' date=' I am reluctant to spend money on it. I feel I need to get a newer bike. The simple logic is that despite my age, the more I enjoy cycling, the more I will do it and probably enter more races.

 

[/quote']

 

I still don't understand the bad handling, especially with respect to the feeling of toppling over but lets leave it at that.

 

Handling is also a function of fork angles but I also doubt that is the problem. There was nothing funny about a Rapport's fork angles.

 

I agree that it is time for a bike with modern, obtainable parts and suggest you look at the second hand market. Lots of good 8-speed bikes are going for a song. Second hand bikes have less value than 2nd hand Alfa Romeos so there's lots of bargains to be had.

 

You mention sizing and the fact that bike shops only take your crotch height into consideration. That's right, because frames only come in different vertical sizes and you have no horizontal choice nowadays. You have to fix the horizontal discrepancies at the stem.

 

I don't think you're getting bad advice from the bike shops.

 

 

[VincentBikes]

Hi Slave

 

Sizing is a big thing so be very carefull - According to my inseam I must ride a 58 but when I get on it it feals really cramped because I have short legs and a long upper body so I have to go for a 60. It actually cost me having to buy a new bike. Fortunately I could give the other one to my son.....