# Top speed. Chain rings ?????



## Doyleyburger (29 Sep 2013)

Hey guys,
Will changing my front chain rings help with better top end speed???
I have a carrera tdf with a 52/42 chain ring set (if I counted correctly)
Also if I change it, will it effect my climbing, as I find climbing ok with how it is currently


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## Andrew_Culture (29 Sep 2013)

Top speed on flat or downhill.


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## Doyleyburger (29 Sep 2013)

Andrew_Culture said:


> Top speed on flat or downhill.


Down.


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## Doyleyburger (29 Sep 2013)

I feel like I'm aero enough but I seem to run out of pressure in the pedals or resistance even tho iv a lot more to give in terms of energy.


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## Dusty Bin (29 Sep 2013)

Doyleyburger said:


> Will changing my front chain rings help with better top end speed???



In absolute terms, yes it will. But seriously, you are a beginner aren't you? If you think you need a bigger gear than most club racers and some pros ride on, then something isn't right.

Anyway, there comes a point on most descents where it's better just to stop pedalling and tuck in.


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## Rickshaw Phil (29 Sep 2013)

What's your smallest sprocket on the rear? Changing cassette may be an option.


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## Doyleyburger (29 Sep 2013)

Dusty Bin said:


> In absolute terms, yes it will. But seriously, you are a beginner aren't you? If you think you need a bigger gear than most club racers and some pros ride on, then something isn't right.


Yes I am most definitely a beginner, this issue has bugged me from the word go. Can you tell me if this chain ring set up is normal or not? Very new to this lol!
A few newbies are faster than me on the down hills and have the same bike. Not much heavier than me either.


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## Rickshaw Phil (29 Sep 2013)

Doyleyburger said:


> Can you tell me if this chain ring set up is normal or not? Very new to this lol!


Your chain ring set up is what's popularly known as a standard double (as distinct from a compact double, which would be something like 50/34). It's what pro racers generally use but the compact set up is probably more popular for club riders at the moment as it's easier for climbing.


Doyleyburger said:


> A few newbies are faster than me on the down hills and have the same bike. Not much heavier than me either.


If they're faster than you downhill on the same type of bike it's probably down to technique rather than the bike set up. (Don't ask me about that though. Not an expert.)


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## Doyleyburger (29 Sep 2013)

Ok excuse my ignorance here....
I have 8 rings at the back (cassette) the largest ring with 26t and the smallest with 12t


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## smutchin (29 Sep 2013)

What speed are you reaching before you can't pedal any more?

With that gearing, if you're spinning out at anything less than 40mph, you simply aren't pedalling hard enough. You should be able to hit 120rpm - at least for short spells - which will give you a top speed of about [41mph]* with your gearing. 

So you just need to learn to spin your legs faster.

*edit: changed after recalculating based on 52x12 rather than assumed 52x11.


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## Doyleyburger (29 Sep 2013)

Perhaps, there are some big hills here, so some big decents to match. One in particular I can get 44-46mph but then I'm spinning out. Most get 50+ going down it. Only 16 gears on my bike also


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## smutchin (29 Sep 2013)

Doyleyburger said:


> Perhaps, there are some big hills here, so some big decents to match. One in particular I can get 44-46mph but then I'm spinning out. Most get 50+ going down it. Only 16 gears on my bike also



I'd say you're doing ok, in that case. Carry on working on your cadence and the higher speeds will come - you can practise increasing your cadence by riding in a lower gear on the flat.


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## fossala (29 Sep 2013)

Doyleyburger said:


> Perhaps, there are some big hills here, so some big decents to match. One in particular I can get 44-46mph but then I'm spinning out. Most get 50+ going down it. Only 16 gears on my bike also


You are complaning about going 44-46mph? I do over that sometimes but what are you trying to prove? Anyway, once over 40mph, I just tuck in. Maybe invest in some aero bars.


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## Doyleyburger (29 Sep 2013)

Not trying to prove anything to anyone, apart from myself .......
Love the sport and want to improve is all


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## Doyleyburger (29 Sep 2013)

smutchin said:


> I'd say you're doing ok, in that case. Carry on working on your cadence and the higher speeds will come - you can practise increasing your cadence by riding in a lower gear on the flat.


Cheers matey


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## boydj (29 Sep 2013)

How often do you get the chance to reach these speeds and how much time do you actually lose? There's much more time to be gained by improving your speed *up* the hills.


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## Doyleyburger (29 Sep 2013)

Agreed !
But I am finding the hills ok which is something I DO NOT want to sacrifice instead of getting better top speed. If there was an option to change the gearing without sacrificing the climbing then I would be up for doing it. Never mind, was just wondering about it


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## Rob3rt (29 Sep 2013)

Not as aero as the people you are comparing yourself too. At those speeds, aero is everything!


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## Nigelnaturist (29 Sep 2013)

Well you can change the rear to a 11-25, change the inner ring to a 40th this will give you more range.


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## AK9 (29 Sep 2013)

Is there significant difference to be gained by moving from a 12 to an 11?


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## HLaB (29 Sep 2013)

IIRC I fitted a SRAM 8spd 11-26t cassette to my Sirrus, in theory that will make you spin out less but as Rob says at high speeds its more about technique and aerodynamics; FWIW, the fastest I've been this year (45.6mph) was on a cyclocross with only a 48t big ring.


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## Dusty Bin (29 Sep 2013)

Doyleyburger said:


> Agreed !
> But I am finding the hills ok which is something I DO NOT want to sacrifice instead of getting better top speed. If there was an option to change the gearing without sacrificing the climbing then I would be up for doing it. Never mind, was just wondering about it



I'm pretty sure we did this exact same topic a few weeks ago. Did you ever find out what gearing your mates were on? My guess is that it will not be a lot different to yours.


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## guitarpete247 (29 Sep 2013)




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## Rickshaw Phil (29 Sep 2013)

AK9 said:


> Is there significant difference to be gained by moving from a 12 to an 11?


 By my calculations it'll give approximately 11 gear inches extra at the top end.


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## Nigelnaturist (29 Sep 2013)

Rickshaw Phil said:


> By my calculations it'll give approximately 11 gear inches extra at the top end.


120" is a big gear to push even downhill.


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## zizou (29 Sep 2013)

When you get to the mid 40s mph there is more speed to be gained from technique and tucking in rather than continuing to pedal.



AK9 said:


> Is there significant difference to be gained by moving from a 12 to an 11?



It will certainly give you a bigger gear but whether there is anything to be gained from that is debatable. Eddy Merckx and others of his generation were on a max gear of 52x13 it didnt hold them back too much


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## Paulus (29 Sep 2013)

Moving up to a 53 chainring will increase your top speed a little, but, it will make it a bit harder, as would changing the rear sprocket to an 11. If you have the legs to power along in a 53/11 you need to join a club that specialises in racing.


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## Rickshaw Phil (29 Sep 2013)

Nigelnaturist said:


> 120" is a big gear to push even downhill.


 It'll be higher than that. More like 125".


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## Nigelnaturist (29 Sep 2013)

Rickshaw Phil said:


> It'll be higher than that. More like 125".


Sorry I was looking at a 50x11 a 52x11 is 124.33" as you say.


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## Rickshaw Phil (29 Sep 2013)

Nigelnaturist said:


> Sorry I was looking at a 50x11 a 52x11 is 124.33" as you say.


Either way it's a big old gear and not necessarily the answer.

For @Doyleyburger, gear inches explained here so you know what we're on about.


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## Doyleyburger (29 Sep 2013)

Rickshaw Phil said:


> Either way it's a big old gear and not necessarily the answer.
> 
> For @Doyleyburger, gear inches explained here so you know what we're on about.


Ha ha thank you


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## Hacienda71 (29 Sep 2013)

Spin faster. When you hit 40 get into an aero tuck. Elbows in, either on the drops or with your hands close together on the tops, chin an inch or two from the bars. Some people get off the saddle and sit on the top tube. Not for the faint hearted  Another big part of descending is knowing the right line to take, get it wrong and you will scrub loads of speed off and worse may even have an off. Personally I would stick with the gears you have and work on your technique


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## Rob3rt (29 Sep 2013)

Hacienda71 said:


> Spin faster. When you hit 40 get into an aero tuck. Elbows in, either on the drops or with your hands close together on the tops, chin an inch or two from the bars. Some people get off the saddle and sit on the top tube. Not for the faint hearted  Another big Part of descending is knowing the right line to take, get it wrong and you will scrub loads of speed off and worse may even have an off. Personally I would stick with the gears you have and *work on your technique*



My technique is to grab the brakes and drag them all the way down. Then go kaboom up the next hill!


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## User16625 (29 Sep 2013)

Doyleyburger said:


> Hey guys,
> Will changing my front chain rings help with better top end speed???
> I have a carrera tdf with a 52/42 chain ring set (if I counted correctly)
> Also if I change it, will it effect my climbing, as I find climbing ok with how it is currently




My fastest ever speed was 50mph on a serious downhill. The chainring happened to be a 50 and with a 11-28 cassette. Just work on increasing cadence.


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## screenman (30 Sep 2013)

Doyleyburger said:


> Perhaps, there are some big hills here, so some big decents to match. One in particular I can get 44-46mph but then I'm spinning out. Most get 50+ going down it. Only 16 gears on my bike also


Have they got 2 magnets on their wheels or is this just and internet speed?

Either way pedal faster, if you cannot get 180rpm + then you are wimping out.


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## Doyleyburger (30 Sep 2013)

This is according to strava


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## Dusty Bin (30 Sep 2013)

Doyleyburger said:


> This is according to strava



Don't worry about it. Any old chopper can ride downhill quickly. It's going up that really seperates the cyclists from the bike riders.


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## Rob3rt (30 Sep 2013)

Dusty Bin said:


> Don't worry about it. Any old chopper can ride downhill quickly. It's going up that really seperates the cyclists from the bike riders.



Group rides = me waiting at the top for everyone else, them waiting at the bottom for me, lmao! I am a massive pussy coming down hill, I ride faster on the flat on my TT bike than I do on some descents!


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## User6179 (30 Sep 2013)

Doyleyburger said:


> This is according to strava


 
Well my top speed is 86mph!!!


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## Boris Bajic (30 Sep 2013)

Doyleyburger said:


> Hey guys,
> Will changing my front chain rings help with better top end speed???
> I have a carrera tdf with a 52/42 chain ring set (if I counted correctly)
> Also if I change it, will it effect my climbing, as I find climbing ok with how it is currently


 
I think most of the replies here have hit the button.

I'm slightly terrified at the suggestion you use aerobars to increase descending speed, but that may just be me.

My normal road bike runs 35 and 12 as its highest gear. This allows me to pedal up to about 43 or 44 mph on a descent. After that, it's gravity and air resistance.

I think the main thing about fast (ish) descending is confidence and being comfortable on your bike. Confidence comes with experience and with the knowledge that everything is appropriately tight, straight, inflated and lubed (not all the same component).

If you want to descend super-quickly, getting your cadence up will help.

As to only having 8 gears, there was a time when that was a pretty cool number and people descended fast in those days too... often the missing gears on an 8-speed cassette in comparison to a 10-speed are in the middle of the range, not the extremities.

Have fun!


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## Rob3rt (30 Sep 2013)

Boris Bajic said:


> I think most of the replies here have hit the button.
> 
> *I'm slightly terrified at the suggestion you use aerobars to increase descending speed, but that may just be me.*
> 
> ...



Not just you. If the descent has anything more than very gentle curves, then you won't want to be on aero bars really, the level of control is reduced and you won't have access to the brakes!


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## Doyleyburger (30 Sep 2013)

Boris Bajic said:


> I think most of the replies here have hit the button.
> 
> I'm slightly terrified at the suggestion you use aerobars to increase descending speed, but that may just be me.
> 
> ...


Cheers appreciate it


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## Hacienda71 (30 Sep 2013)

Rob3rt said:


> Not just you. If the descent has anything more than very gentle curves, then you won't want to be on aero bars really, the level of control is reduced and you won't have access to the brakes!


Don't think anyone has actually suggested aero bars.  I think he is getting confused with an aero tuck.


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## Rob3rt (30 Sep 2013)

Hacienda71 said:


> Don't think anyone has actually suggested aero bars.  I think he is getting confused with an aero tuck.



Someone did, somewhere back there....


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## on the road (30 Sep 2013)

Doyleyburger said:


> This is according to strava


Don't rely on Strava, they estimate speeds down. A bike computer would be more accurate.


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## HLaB (30 Sep 2013)

on the road said:


> Don't rely on Strava, they estimate speeds down. A bike computer would be more accurate.


OT, I find Strava is consistently lower than that recorded by my computer (Garmin with speed sensor) RWGPS is close or identical to bike computer but GC sometimes gives me rediculousy high figures.


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## Dusty Bin (30 Sep 2013)

on the road said:


> Don't rely on Strava, they estimate speeds down. A bike computer would be more accurate.



Strava doesn't estimate the speed - it simply takes the data recorded from the GPS unit. In any case, I don't find that my GPS times are any different than from when I used to use a bike computer.


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## mattobrien (30 Sep 2013)

Dusty Bin said:


> Strava doesn't estimate the speed - it simply takes the data recorded from the GPS unit. In any case, I don't find that my GPS times are any different than from when I used to use a bike computer.


As an average in a ride Strava is fine, it measures distance and time and comes up with an average. As for finding an individual top speed, it is utterly hopeless and very inaccurate. For individual top speeds a bike computer is much more accurate. Some of the Strava estimates are frankly laughable. Either that or I am faster than many cars.


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## on the road (30 Sep 2013)

on the road said:


> Don't rely on Strava, they estimate speeds down. A bike computer would be more accurate.





Dusty Bin said:


> Strava doesn't estimate the speed - it simply takes the data recorded from the GPS unit. In any case, I don't find that my GPS times are any different than from when I used to use a bike computer.


I was really talking about maximum speeds. I find that my maximum speed on Strava tends to be lower then what my bike computer records, although I'm using a mobile.


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## Dusty Bin (30 Sep 2013)

mattobrien said:


> As an average in a ride Strava is fine, it measures distance and time and comes up with an average. As for finding an individual top speed, it is utterly hopeless and very inaccurate. For individual top speeds a bike computer is much more accurate. Some of the Strava estimates are frankly laughable. Either that or I am faster than many cars.





on the road said:


> I was really talking about maximum speeds. I find that my maximum speed on Strava tends to be lower then what my bike computer records, although I'm using a mobile.



Guys - Strava doesn't do any of that. It only computes the numbers it is given by whichever GPS unit you use to record and upload the ride. You should be blaming Garmin, or Bryton, or maybe even the US Government's original 1973 Navstar programme - but it ain't Strava's fault.


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## Shut Up Legs (1 Oct 2013)

Dusty Bin said:


> In absolute terms, yes it will. But seriously, you are a beginner aren't you? If you think you need a bigger gear than most club racers and some pros ride on, then something isn't right.
> 
> Anyway, there comes a point on most descents where it's better just to stop pedalling and tuck in.


Yes, sometimes, moving to a more aerodynamic position is more effective than pedalling harder.


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## puffinbilly (1 Oct 2013)

Boris Bajic said:


> My normal road bike runs 35 and 12 as its highest gear. This allows me to pedal up to about 43 or 44 mph on a descent. After that, it's gravity and air resistance.



Is that correct? Or is it a 53/12 combination? I'm new to all this gearing and trying to learn what I need to know for my bikes set up.

At present I seem to run out of gears at 50/12 when I hit 35mph going uphill.


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## Linford (1 Oct 2013)

Doyleyburger said:


> Perhaps, there are some big hills here, so some big decents to match. One in particular I can get 44-46mph but then I'm spinning out. Most get 50+ going down it. Only 16 gears on my bike also



It begs the question why you aren't wearing motorbike clothing as if it goes wrong at that speed, you are going to need some serious skin grafting.
As a beginner, you should focus on improving your ascent ability. I'm fairly pants, but have noticed an improvement in this with time.


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## Rob3rt (1 Oct 2013)

Dusty Bin said:


> Guys - Strava doesn't do any of that. It only computes the numbers it is given by whichever GPS unit you use to record and upload the ride. You should be blaming Garmin, or Bryton, or maybe even the US Government's original 1973 Navstar programme - *but it ain't Strava's fault.*



Actually to some degree it is.


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## Dusty Bin (1 Oct 2013)

Well, I don't really see how Strava can be blamed, unless someone can explain...


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## on the road (1 Oct 2013)

puffinbilly said:


> Is that correct? Or is it a 53/12 combination? I'm new to all this gearing and trying to learn what I need to know for my bikes set up.
> 
> At present I seem to run out of gears at 50/12 when I hit 35mph going uphill.


On a motorbike?


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## Doyleyburger (2 Oct 2013)

As a beginner I AM focussing on my ascent abilities ( I never said I wasn't) 
As I said before, I am generally happy with my climbing (still improving all the time)..... But I still want to improve this area of my cycling....... ' I Cant help the fact that I get a rush out of going fast down a hill'


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## lukesdad (2 Oct 2013)

Rob3rt said:


> Not as aero as the people you are comparing yourself too. At those speeds, aero is everything!


 Not quite, weight has quite a large bearing on the matter to.


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## Mr Haematocrit (2 Oct 2013)

lukesdad said:


> Not quite, weight has quite a large bearing on the matter to.



Not in reality from my own experience, weight only has a large bearing on acceleration, so you benefit in situations where the pace changes such as when climbing.
On the flats, where aerodynamics can be up to 90% of your resistance, saving drag is the answer for increased performance.

My Tarmac is substantially lighter than my Venge, yet on the routes I ride regularly I am consistently unable to match the speeds and times I can do on the Venge when using the Tarmac. 
Im with @Rob3rt on this one,


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## Rob3rt (2 Oct 2013)

Dusty Bin said:


> Well, I don't really see how Strava can be blamed, unless someone can explain...



Without knowing their algorithms one couldn't give specifics, however, it is all in the data processing and you can do a lot with GPS data to correct for various artifacts.


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## Dusty Bin (2 Oct 2013)

Rob3rt said:


> Without knowing their algorithms one couldn't give specifics, however, it is all in the data processing and you can do a lot with GPS data to correct for various artifacts.



Why would Strava want to routinely and pre-emptively alter the raw data given to it by a third party's input device?


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## Rob3rt (2 Oct 2013)

Dusty Bin said:


> Why would Strava want to routinely and pre-emptively alter the raw data given to it by a third party's input device?



In order to extract the most accurate metrics they could from a "noisy" data set.


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## HLaB (2 Oct 2013)

lukesdad said:


> Not quite, weight has quite a large bearing on the matter to.


 Not too much, some of the best descenders I know are compact units it's more to do with aero, skills and courage. I also know that I lack the latter two but when I adopt an aero position on a non technical descent, I shoot by folk heavier than me.


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## Dusty Bin (2 Oct 2013)

Rob3rt said:


> In order to extract the most accurate metrics they could from a "noisy" data set.



Who says it is 'noisy' ? And who says this 'noise' is materially affecting the integrity of the raw data?


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## Rob3rt (2 Oct 2013)

Dusty Bin said:


> Who says it is 'noisy' ? And who says this 'noise' is materially affecting the integrity of the raw data?



The scientific community, that is mathematicians, engineers etc.


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## Dusty Bin (2 Oct 2013)

Rob3rt said:


> The scientific community, that is mathematicians, engineers etc.



Noise implies a random distortion, which is not something you can economically address on what is effectively a free web app. If people are seriously worrying about losing a few nanoseconds off their top speed, then they obviously don't have enough to worry about...


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## Rob3rt (2 Oct 2013)

Dusty Bin said:


> Noise implies a random distortion, which is not something you can economically address on what is effectively a free web app. If people are seriously worrying about losing a few nanoseconds off their top speed, then they obviously don't have enough to worry about...



I can't help but feel you don't really know what you are talking about.


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## lukesdad (2 Oct 2013)

HLaB said:


> Not too much, some of the best descenders I know are compact units it's more to do with aero, skills and courage. I also know that I lack the latter two but when I adopt an aero position on a non technical descent, I shoot by folk heavier than me.


..and probably some of the best descenders you know are heavyweights too ?


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## Rob3rt (2 Oct 2013)

With regards weight, it does have an impact and assuming all else equal a heavier rider will have a higher terminal velocity. However a heavier rider will also generally be larger and thus have a higher (generally speaking, not always true as drag is not solely dependant on presented area) CdA, which will counteract the increase in mass.

It would be interesting to see how much effect it has at various levels of rider though because for competitive riders, heavier and lighter riders won't necessarily have that much difference in their presented frontal area as positions are dialled and physiques converge, whereas at lower levels, where you get all shapes and sizes and loads of weird and wonderful bike fits, the chances are a heavier rider is bigger, which is reflected in their ride position and a generally larger frontal area such that the CdA vs weight is not so clear cut.

Having said all of this, terminal velocity is not the end of the story either.


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## fossyant (2 Oct 2013)

Rob3rt said:


> Not as aero as the people you are comparing yourself too. At those speeds, aero is everything!



This.

You dont need a bigger gear. I have 53x13 which is like 50x12 and don't need any more. I can pedal till about 40 to 45 but its not as efficient as an aero tuck which you will go faster. 

Being able to ride up hills faster is key. Down fast is technique, skill, positioning and being able to spin.

I also think you are probably grinding the gears too much (low cadence)


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## HLaB (2 Oct 2013)

lukesdad said:


> ..and probably some of the best descenders you know are heavyweights too ?


Nope as said they are compact units, lighter than me.


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## Dusty Bin (2 Oct 2013)

Rob3rt said:


> I can't help but feel you don't really know what you are talking about.



Why - because you have no credible response? 

I'm saying it doesn't matter. Your turn now - what are _you_ talking about?


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## Rob3rt (2 Oct 2013)

Dusty Bin said:


> Why - because you have no credible response?
> 
> I'm saying it doesn't matter. Your turn now - what are _you_ talking about?



What do you want by way of credible response?

You have questioned the fact that GPS data is noisy, something that is accepted by the scientific community, as I have informed you. A quick Google search on your part should confirm that this is the case.

You have then assumed that the effect of this noise is minimal, which is not strictly true. The error introduced can be substantial!

Further you have made the statement that it is not economic to reduce the effects of such issues, which again is not true and some basic statistical methods could be implemented reduce the impact of such noise. I suggest you look up a few methods employed in GPS data interpretation. The Extended Kalman Filter might be a good place to start. To help you understand this, start with some basic Bayesian Estimation!


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## Dusty Bin (2 Oct 2013)

Rob3rt said:


> What do you want by way of credible response?



Ideally, something which doesn't involve you running off to google every time you need to answer a question. I work in the microwave industry (no, not the ovens, ffs! ), so if you want to get technical, you will need to step away from wikipedia.



Rob3rt said:


> You have questioned the fact that GPS data is noisy, something that is accepted by the scientific community, as I have informed you. A quick Google search on your part should confirm that this is the case.



Multipath noise and other interference is inevitable in radio signals - no argument there.



Rob3rt said:


> You have then assumed that the effect of this noise is minimal, which is not strictly true. The error introduced can be substantial!



Neither of us knows the precise noise levels involved here, so your comment is irrelevant.



Rob3rt said:


> Further you have made the statement that it is not economic to reduce the effects of such issues,



You need to go back and read what I said. I said it was probably not economical for Strava (a free web app) to do this. Why should they - and how much more accuracy could they provide? For that matter, how much more accuracy is needed for people who want to casually race each other on the internet? If you need high precision GPS data, then you won't using Strava anyway.



Rob3rt said:


> I suggest you look up a few methods employed in GPS data interpretation. The Extended Kalman Filter might be a good place to start. To help you understand this, start with some basic Bayesian Estimation!



ho hum...


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## Rob3rt (2 Oct 2013)

Dusty Bin said:


> Ideally, something which doesn't involve you running off to google every time you need to answer a question. I work in the microwave industry (no, not the ovens, ffs!), so if you want to get technical, you will need to step away from wikipedia.
> 
> 
> 
> ...



I did not run away to Wikipedia, this subject being discussed employs many of the techniques used in my own area of research.

Further, I didn't initially comment on the extent of the noise, I simply said the data is noisy, you questioned this fact, then you further stated, in a roundabout way, that the effect was minimal. I simply said this is not strictly the case and that the effect of the noise CAN be substantial. So my comment is no more irrelevant than your own.

Not economic for a free web app? 1st, Strava is not wholly a free app! As for why should they do it? Well it would help with segment matching for starters which would save them time manually matching segments where the GPS data has not registered a segment and the user emails in asking for it to be matched (they tell you to do this on their website). How much more accuracy would it lend? Well, that depends on many factors, not least the desired metric you are extracting from the data.


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## Dusty Bin (2 Oct 2013)

Rob3rt said:


> Further, I didn't initially comment on the extent of the noise, I simply said the data is noisy, you questioned this fact, then you further stated, in a roundabout way, that the effect was minimal. I simply said this is not strictly the case and that the effect of the noise CAN be substantial. So my comment is no more irrelevant than your own.



Again, you need to go back and read what I said. I asked _who_ said it was noisy and whether the noise materially affected the data's integrity.



Rob3rt said:


> Not economic for a free web app? 1st error here, Strava is not wholly a free app!



Strava does indeed have a premium option - with 'option' being the operative word. So it is a free app, to all intents and purposes. Are you seriously trying to score a point there?


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## lukesdad (2 Oct 2013)

HLaB said:


> Nope as said they are compact units, lighter than me.


Interesting.


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## Doyleyburger (6 Oct 2013)

Hacienda71 said:


> Spin faster. When you hit 40 get into an aero tuck. Elbows in, either on the drops or with your hands close together on the tops, chin an inch or two from the bars. Some people get off the saddle and sit on the top tube. Not for the faint hearted  Another big part of descending is knowing the right line to take, get it wrong and you will scrub loads of speed off and worse may even have an off. Personally I would stick with the gears you have and work on your technique


Tried this morning...... HUGE help. Thank you. I managed to break the 50mph barrier (51). Just by tucking in more than peddling. (basically free wheeling)
Thanks for the advice guys


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## sreten (7 Oct 2013)

Hi,

Heavier fit people do go down hills faster (and up hills slower). The CdA of a rider
twice as heavy as another if you assume all dimensions are increased by the
cube root of 2 increases by (cube root of 2)squared, i.e. ~ 1.6. Ergo the big
riders terminal velocity will be higher due to weight versus drag issues.

Going from a 12 to an 11 minimum on the back would mean if you currently
spin out at 40mph you would spin out at 43.5mph, i.e. going 9% faster.

As a beginner I'd say its safe to assume you can improve your top cadence
by quite a bit more than 9% in the long run. As said past a certain point a
good tuck is lot faster than pedalling :


View: http://www.youtube.com/watch?v=0tFpNsZXWgc

" I seem to run out of pressure in the pedals or resistance even tho iv a lot more to give in terms of energy."

That is running out of cadence I reckon rather than gearing. Applying power
pedaling fast takes time, fitness and practice. Only after a while will you
know how useful a minimum 11 would be compared to a 12 for you.

(Racers of course change all the gearing to suit each stage of a race.)

52/12 is a big enough big gear for most, 34 mph @ 100 rpm, 25mm tyres.
At 50+ I live with 52/14 max, 30mph @ 100 rpm, 32mm tyres, which I
can push to about 36 mph downhill before coasting makes more sense.
My top speed downhill is a bit limp, with my non-aero bull horns.

rgds, sreten.


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