BIKE COMPUTER

Questions about purchasing bicycles and parts

Postby europa » Thu Jan 25, 2007 11:36 am

I've been out for quite a bit and missed the last stream of posts.

Commi, the bloke who programmed your computer is probably so used to putting in the value for a 25mm tyre, which is more common than your 28, that he just typed in the figure without checking. He might even have been under the misunderstanding that your tyres were 25 and hence thought he was putting in the right figure anyway. Yes, it's a lack of attention to detail but it's one of those human things that happens. I think that when you balance that with the rest of the service you've received, yoiu've got yourself a darned good lbs and I wouldn't hesitate to help keep them profitable (by spending money there).

When it comes to measuring the distance laid out by one revolution of your wheel, the Polar manual says to measure as described above, then take off 4mm to allow for tyre deformation.

Richard
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by BNA » Thu Jan 25, 2007 11:46 am

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Postby commi » Thu Jan 25, 2007 11:46 am

my reply on bicycle victoria forum titled "what's your bicycle store like?"

http://www.bv.com.au/forums/viewtopic.php?p=66639#66639

(which is essentially what I've already said in this thread, but I've actually used names)

So, yes understand it was human error. God know I make them all the time!! I'm more than happy with my LBS (The Freedom Machine, Prahran).

I'll be back there to get some lights soon. I also need a pump, puncture kit, rack........
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Postby stryker84 » Thu Jan 25, 2007 1:11 pm

heh, mine's The Freedom Machine, Port Melb, also excellent service =)

only bike shop I've visited where they actually appraoched me to ask what i wanted, immediately after walking in, considered my riding, gave me the options of all their bikes, and not try to influence me, instead of the "you're a commuter, so this is the best for you" which I'd gotten used to.
even measured the sizing properly, and when they didn't have my size, said so, unlike another nameless shop which tried to sell me a obviously oversized bike.
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bike computer

Postby fabs » Sun Jan 28, 2007 5:27 pm

How do you guys feel about cadence function with your computer. Do you use it?
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Postby commi » Sun Jan 28, 2007 7:58 pm

Definately. I did a little reading up about cadence.

Now I try to keep it between 70 and 80. Everyone will probably have a different range, depending on type of bike, skill level, type of training you're doing etc
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Re: bike computer

Postby europa » Sun Jan 28, 2007 9:19 pm

fabs wrote:How do you guys feel about cadence function with your computer. Do you use it?


As close to essential as you can get while talking about an electronic gizmo on your bike (that's to avoid the 'do you need it at all' question :roll: ).

You can work out your cadence by counting and using a clock, but that's just hard work, so a cadence meter itself is a good idea.

The faster your legs are turning, the more efficiently they are using the power ... up to a point. That point is personal and appears to be around the 90 mark, and it does seem to go backwards as you get older. That's not to say you can't sprint at higher speeds and my max for a session is typically around 110 (unless on the track where I hit 140's and more :eek: )

Personally, while it was initially difficult to maintain a cadence of 90, that's what I aim for and can now spin in the eighties and nineties without drama. My natural cadence seems to be in the high eighties and I can run for hours at that speed with my heart rate popping along at around 130.

If climbing a big hill, while I can keep the cadence at 90 or above, I am producing real power and can power up that hill. When the cadence drops below that, I start to struggle even if I still have power in my legs.

The only time I've suffered knee pain in recent times was on a day when I decided to ignore the cadence meter and ride by feel, also allowing my cadence to drop as I became tired (which is the natural tendancy). My average cadence that day was 71 and it killed my knees (okay, the big climb at the end did the damage but I've climbed that hill before without knee troubles). However, on rides just as long and demanding, if I work on keeping my cadence in the eighties or higher, I have no knee pain and I actually ride further and faster.

When you are fit and feeling fresh, you can judge your cadence nicely but, as you get tired, you will want to pedal more slowly and once you start dropping below the 70 mark, you are applying more pressure to the pedals (ie, working harder) without realising it because you are pedalling slower (ie, it feels like you're taking it easy) - it's seductive and tiring.

When on a ride where I'm working on my endurance, or just trying to keep on going (because some stupid distance has rolled under my tyres and I'm stuffed), I keep an eye on that cadence. If I find I'm working to keep it in the eighties, or it's dropping out of them, I change down a gear. This does mean that you can find yourself going slower, in a lower gear than you might otherwise, but the payoff is that you go longer and further ... and I've been close enough to the bonk often enough in recent months to appreciate just how this allows you to extend your effort.

So yes, a cadence meter is an essential part of your kit - you'll be able to use your body more effectively if you have one and refer to it.

Richard
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Re: bike computer

Postby tuco » Mon Jan 29, 2007 9:52 am

fabs wrote:How do you guys feel about cadence function with your computer. Do you use it?


Bloody oath!

I have two things displayed on my computer, speed and cadence. The rest of the functions are superfluous.

I stick to about 95.
Now I've learnt about cadence I laugh when I see riders busting a foofer valve pedaling in the wrong gear. It's like driving your car around in 1st gear.

Since we're on the subject, is there such a device which only counts and displays cadence?
My daughter was given an el cheapo Aldi branded computer but it lacks cadence. Instead it has unwanted stuff like temperature and calories burnt. Calories burnt can be useful but not for a 13 year old.
Unlike me who had to break old habits to get a good cadence, she's just starting out so I'd like her to learn about it early.
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Postby commi » Mon Jan 29, 2007 10:22 am

What is the best way to go about improving my cadence? I'm sitting between 75-80, though for short periods it goes to the high 80s.

I'm just comfortable at this rate at the moment. Mind you, when I get back from my week end Mordialloc ride (50km) my legs (mostly in the thighs) are sore until the next day. I don't do any stretching or anything.

Will changing down a gear help?

P.S. I've only done 4 of these "big" rides. Only ever did < 10km for communting purposes.
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Postby europa » Mon Jan 29, 2007 10:29 am

This suggestion is probably going a bit up market Tuco, but if she's going to be in the game for a while, it's worth considering.

The various bits of the wireless Polars can be bought individually. Get her the computer and the cadence sensor, then if she wants to add heart rate later on, she can just buy the heart rate sensor. It's still a tad pricey but it might be a better route than buying a unit that has to be replaced if she wants more (sort a 'buy the best bike you can afford' theory). I said Polar because they're good and I know you can get the bits seperately - there may be other brands that can make the same claim and which aren't as pricey.

Counting cadence needn't be hard. Before I had a cadence meter, I'd leave my computer showing the time. I knew what cadence I wanted and what 'pedal count' I needed over ten seconds to give me that - 15 to give a cadence of 90. In practice, I'd start the count when the clock showed an even ten seconds (ie, 10, 20, 30, etc), watch the road as I counted, only dropping my eyes again when I neared the appropriate 'count'. By only counting for ten seconds, I didn't have to remember start or finish times, just looked for a time with a zeron on the end. By knowing what answer I was looking for, it was easy to tell if I needed to speed up or slow down, even though I actually rarely knew what my cadence actually was.

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Postby europa » Mon Jan 29, 2007 10:42 am

commi wrote:What is the best way to go about improving my cadence? I'm sitting between 75-80, though for short periods it goes to the high 80s.


I used to have that trouble. I made the break through when I started going riding with my girlfriend. She's still very new and nervous on the bike so the trips were straight, flat and slow. I'd sit behind her in a very low gear and spin up to my 90 cadence - yep, bottom gear and fingers resting on the brakes and all. But it worked and I got used to spinning those speeds. While you possibly aren't tempted to get yourself a girlfriend and to teach her how to ride (not a problem if you are :D), I'm sure you can extrapolate from that experience :roll:

Once your legs get the feel for the high cadence, it's easy to find it and maintain it.

If I find my cadence is too low, I go down a gear, or two. That's all it takes. You'll find you'll speed up. It can very very hard to read the effort you're putting in sometimes (especially if you're tired) - you think you know what you're feeling but it's only when you have something monitoring you that you realise the times you've got it very wrong.

If the gear gets too low, you can find that you're not pedalling smoothly (you'll find you get behind the freewheel, then catch it up with a bump on the pedals). This is just technique and a simple solution is to go up one gear then work a tad harder to get the cadence right.

But cadence does have to be monitored and thought about until your body get's the 'feel' for it.

Richard :D
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Postby commi » Mon Jan 29, 2007 11:42 am

That's the other thing about the gears on my flat bar.

I never change the 3 gears on the left (don't know what they are called, the front crank things). I always have it on 3 (highest?) and just change the right hand side gears from 1 to 8 as needed. I'm usually between 4 and 6. And 3 on hills (where cadence goes down to the 60s or less)

On the weekend I tried to change to 2 on the left gear, then change up one on the right hand side to compensate. I couldn't really tell the difference.

Now that I know a little about cadence I try to see what other people are doing on the road and I can tell their cadence is higher, maybe around 90.

I'll try and change down a gear from my usual.

I can't wait to get shoes and clips (not that that will help my cadence)
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Postby tuco » Mon Jan 29, 2007 11:51 am

commi wrote:That's the other thing about the gears on my flat bar.

I never change the 3 gears on the left (don't know what they are called, the front crank things). I always have it on 3 (highest?) and just change the right hand side gears from 1 to 8 as needed. I'm usually between 4 and 6. And 3 on hills (where cadence goes down to the 60s or less)

On the weekend I tried to change to 2 on the left gear, then change up one on the right hand side to compensate. I couldn't really tell the difference.

Now that I know a little about cadence I try to see what other people are doing on the road and I can tell their cadence is higher, maybe around 90.

I'll try and change down a gear from my usual.

I can't wait to get shoes and clips (not that that will help my cadence)


Cadence 60 or less isn't good on hills. That's where you use the gears to keep your cadence at 90ish even going up hills.

The left gear change is for the chain ring (on the pedals)
I don't know which bike you have, but I run on the middle chain ring and use the smaller one for up hills and the larger one for down hills. This keeps my cadence the same up hills, on flat and down hills.
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Postby commi » Mon Jan 29, 2007 11:59 am

tuco wrote:I don't know which bike you have, but I run on the middle chain ring and use the smaller one for up hills and the larger one for down hills. This keeps my cadence the same up hills, on flat and down hills.


OMGosh!! Why didn't I ever think of that!! What a revelation...I'll try this on my way home.

My bike is an Avanti Blade Sport
http://www.avantibikes.com/fitness/team ... spx?bid=15
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Postby europa » Mon Jan 29, 2007 12:04 pm

commi wrote:I can't wait to get shoes and clips (not that that will help my cadence)


They will actually, by giving you a more positive feel for the pedals :D

It would seem to me that you are just riding in too high a gear. :wink: And probably not changing often enough - I'm up and down through the gears all the time (but I'm not riding on dead flat roads either). Even a small change in grade, headwind, traffic conditions, can result in a change of gears, aimed at keeping that cadence and effort just 'right'.

Start of on the middle chainring (them big toothy brutes on the front end of the chain by your feet :D). Work on there and only go up to the largest chainring when your speed is high enough to justify it. Don't think about what gear you are in with regards to numbers or anything, think leg speed (cadence) and effort - the actual gear is immaterial.

Gear systems are set up to provide overlap between the three (or two) chainrings - roughly half the gears on the largest chainring are repeated by roughly half the gears on the middle chainring. This varies depending on the setup and choosing how you set it up is a black art all in itself (so just accept what the factory gave you - it's easier), but at a very basic level, it allows you to move up and down through the gears without having to change chainrings too often.

For example. My Black Beast has three chainrings on the front and 9 freewheels (cogs) on the back. I basically live on the middle chainring, working my way up and down the freewheels. If, however, I'm going downhill or on a flat strip where I want more speed, I'll shift up to the large chainring, work that up and down until I feel the need for that middle range again. Similarly, in hilly country, I work my way down through the freewheels unless I hit a steep bit when I'll go down onto the lowest chainring. In this way, I'm not making many changes at the front at all. I'm also lucky in that the gearing on the Black Beast suits me perfectly - on the Europa, I was on and off the large chainring all the time.

You do have to be aware of chain crossover - using the big cog at the front and the big cog at the back. This has the chain running at an angle across the gears because the bigs are on opposited sides of their appropriate cluster. It's not a good thing because it increases wear on everything and isn't mechanically efficient. On my setup, I can use all the freewheels from my middle chainring (but avoid the two end ones if appropriate) but when on the largest chainring, don't use the two largest freewheels (I go onto the middle chainring) and similarly for the smallest chainring (I don't use the two smallest freewheels).

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Postby commi » Mon Jan 29, 2007 12:19 pm

Thanks for the explanation Europa, that was really helpful :D
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Postby Bnej » Mon Jan 29, 2007 12:46 pm

You just keep turning your legs and use the gears to keep the effort consistent.

Using the lower gears (smallest chainring) is great for hills, and also for taking a breather. You can go longer at slower speeds.

Bear in mind, when you shift with your left hand, the part of the gear that the chain jumps on is under tension when you're pedalling. It will shift easier if you are not pedalling hard. If you are really standing on the pedals, the tension on the chain can hold it on the cog and prevent it from shifting at all. For this reason, you should switch to the small chainring as early as possible on the hill, then change up/down gears with your right hand as you climb.
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Postby LuckyPierre » Mon Jan 29, 2007 2:50 pm

commi wrote:I never change the 3 gears on the left (don't know what they are called, the front crank things). I always have it on 3 (highest?) and just change the right hand side gears from 1 to 8 as needed. I'm usually between 4 and 6. And 3 on hills (where cadence goes down to the 60s or less)

I wish I never needed to change to the small chainring! :wink:
I know one guy who's done the Urriara - Cotter loop on his big (53t) chainring but he's a bit of a freak - and it was only to prove a point ie. it's not the way he'd usually ride.
To my mind, 'no small chainring' probably means 'no real hills' - or am I just being grumpy / jealous? :? .
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Postby mikesbytes » Mon Jan 29, 2007 4:19 pm

peterrjleach wrote:
commi wrote:I never change the 3 gears on the left (don't know what they are called, the front crank things). I always have it on 3 (highest?) and just change the right hand side gears from 1 to 8 as needed. I'm usually between 4 and 6. And 3 on hills (where cadence goes down to the 60s or less)

I wish I never needed to change to the small chainring! :wink:
I know one guy who's done the Urriara - Cotter loop on his big (53t) chainring but he's a bit of a freak - and it was only to prove a point ie. it's not the way he'd usually ride.
To my mind, 'no small chainring' probably means 'no real hills' - or am I just being grumpy / jealous? :? .


I was one of those freaks mid year when I weighed 74kg, I went up the hill from spit bridge going towards the city towards the end of a hill ride using the 53T, just to see how it felt. Not that I'm recommending it, the reason it can be done, is that your body produces more toruqe at lower cadience and a guy with really strong legs, such as a weight lifter can apply large amounts of force for short period of time. However its not the most efficient way to get up a hill. BTW, I'm now 82kg, so I doubt I could do it again.

Commi, how many teeth on the front ring you are using and how many on the biggest and smallest on the rear ?
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Re: bike computer

Postby matagi » Mon Jan 29, 2007 4:52 pm

tuco wrote:
fabs wrote:How do you guys feel about cadence function with your computer. Do you use it?


Bloody oath!

I have two things displayed on my computer, speed and cadence. The rest of the functions are superfluous.

I stick to about 95.
Now I've learnt about cadence I laugh when I see riders busting a foofer valve pedaling in the wrong gear. It's like driving your car around in 1st gear.

Since we're on the subject, is there such a device which only counts and displays cadence?
My daughter was given an el cheapo Aldi branded computer but it lacks cadence. Instead it has unwanted stuff like temperature and calories burnt. Calories burnt can be useful but not for a 13 year old.
Unlike me who had to break old habits to get a good cadence, she's just starting out so I'd like her to learn about it early.

The Sigma B1606 isn't a bad device, although it isn't wireless so I don't know if that's an issue for you. I have the older Sigma B1600 which I got cheap because the 1606 was coming out. It displays speed and cadence as one of its standard displays. I think the only difference between the two computers is that the 1606 will give you average cadence as well.
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Re: bike computer

Postby Hotdog » Mon Jan 29, 2007 5:16 pm

matagi wrote:The Sigma B1606 isn't a bad device, although it isn't wireless so I don't know if that's an issue for you. I have the older Sigma B1600 which I got cheap because the 1606 was coming out. It displays speed and cadence as one of its standard displays. I think the only difference between the two computers is that the 1606 will give you average cadence as well.

There is a wireless version (the BC 1606L DTS), but it's quite a bit more expensive than the wired BC 1606L. The 1606L does add a few features over the older 1600, as you say it has average cadence, but it also has a backlight and a 'programmable trip section counter' whatever that might be.

I've got an old BC 1600 too, and have been extremely pleased with it, especially with the readabilty of the display. Problem is I didn't buy the optional cadence kit when I bought it and now it's been superceded by the BC 1606 it's hard to find the cadence sensor, eBay is about the only option.
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Postby commi » Mon Jan 29, 2007 5:57 pm

mikesbytes wrote:Commi, how many teeth on the front ring you are using and how many on the biggest and smallest on the rear ?


As per advice, I've just started using the middle front wheel and it seems easier somehow. Will be able to tell for sure this weekend on my long ride.

The crankset is Shimano 2200 Triple, 30-42-52T, does that help? Or do I have to actually count the number of teeth?
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Postby Bnej » Mon Jan 29, 2007 9:46 pm

30-42-52t are tooth counts (the "t" = teeth).

The back will probably be about 11-30t. That's typical relaxed road gearing. You can use those numbers and the wheel size to calculate what the actual gear ratios are.

You might not use the smallest chainring if you don't have any hills around, but you should find a hill and try it anyway. Hills are your friend - because every hill you go up is a hill you get to come down!
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Postby mikesbytes » Mon Jan 29, 2007 10:06 pm

So you are riding on a 52 big ring all the time. You must have strong legs.
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Postby commi » Mon Jan 29, 2007 11:06 pm

mikesbytes wrote:So you are riding on a 52 big ring all the time. You must have strong legs.


not particularly. its just what i'm used to:

on my old MTB i used to ride on the big ring and on the highest gear...i couldn't be bothered changing gears and sometimes it wouldn't change back properly so i just left it as is.

the flat bar has more gears so i rode it in the first few days on an equivalent gear and left it as it was...

then i got onto this forum and started researching how to ride properly.

from now i'll ride on the 42 and go from there
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Postby JackHenry » Tue Jan 30, 2007 4:18 pm

If anyone wants to be more confused about tyre size than they already are, take a look at this link

http://www.sheldonbrown.com/tyre-sizing.html
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