Track gear ratios questions

dru

Hi people,

Attended a Track Session last night at the Newport velodrome and was surprised to see so many differences in cadence for a specific speed. Up until now I thought that all track bikes pretty much had all the same ring setup but clearly not.

The bike I'm using has 48 up front and 16/20 on the back (currently running the 16)

Is this a normal setup - should I be looking at bigger front ring and smaller rear?

Did some calculations based on last nights times etc and appears that the 24 second laps which seemed 'ok' were 23.3 mph and 96 cadence
My best lap was 21.5 sec laps which was 26 mph but 108 cadence

e999sam

I imagine it would depend at what level you are racing at but 48x16 does seem a bit low. 48 or 49x15 maybe.

Eddy S

Dru wrote:

Hi people,
The bike I'm using has 48 up front and 16/20 on the back (currently running the 16)

Is this a normal setup - should I be looking at bigger front ring and smaller rear?

You should be looking for the gears that work you! 8) You will need to experiment a bit.

The 81" that you used is probably a bit small - a good sprinter's warn up gear though.

For general training you should find something in the 84" - 88" range that works for you and if you progress to racing, you'll need chainrings and sprockets to also cover 88" - 92" depending on your discipline.

I would have ridden a general session like that on 84" (47/15) - keep it light on your legs and develop good cadence.

Your current collection of 16T - 20T sprockets is at the wrong end of the range really. For track you need 13T - 15T and maybe 47, 48 and 49 chainrings and add a 50/51 if you race.

There's a gearing calculator/spreadsheet here on Fixed Gear Fever if it helps.

acidstrato

48x16 was ok for me at beginners but after I soon found myself spinning my bollocks off!

now I've got a 50 up front and a 15t cog on my bike, got a 14t spare as well. think 50/15 is about 90"

dru

Thanks for the replies guys.

Will have a look at what options I've got, oh BTW, the rear rings are 16 or 20 only.

Presumeably a track specific chainset will take all the different chain rings you mention ok?

Regarding the cadence thing, I was far more comfortable in the 90-95 range, with 85-90 feeling too low, even thou the 85-90 is the range Im in when I'm tt'ing out on the road with a 53 front ring.

Regarding racing, I've very new to the track, but I've just done the begineers course and part way through the intermeadites course, then comes the acceditation part.

AlanW

Good session Saturday night wasn't it?

That 10 miler was bloody hard thou, not withstanding the fact that I didn't hear him say what we were doing at the start. :oops:

dru

AlanW wrote:

Good session Saturday night wasn't it?

That 10 miler was bloody hard thou, not withstanding the fact that I didn't hear him say what we were doing at the start. :oops:

It was fantastic - just interested i what gears I should be running - becasue over 100rpm for that long is not somethnig my body is used too!

dru

Attended another track session last night (last on my intermediates course) and we managed to get a flying lap time in.

Managed a 17.10 which with the 48x16 combination meant a cadence of 135 rpm

Definately going to look to get some larger gears for when I get accredited and maybe start track racing.

trickydisco

Hi Dru (Gav here)

Last nights session was amazing. Really loved the team pursuit. What a buzz! Now i see why people rave about it. At speed around those bankings it was awesome.

Oh.. and the flying 250 was great as well

I was wondering what cadence/speed i was hitting. iI think i was running a 48x15.. felt I could have done with more (the guy's bike it was think runs around a 92)

dru

trickydisco wrote:

Hi Dru (Gav here)

Last nights session was amazing. Really loved the team pursuit. What a buzz! Now i see why people rave about it. At speed around those bankings it was awesome.

Oh.. and the flying 250 was great as well

I was wondering what cadence/speed i was hitting. iI think i was running a 48x15.. felt I could have done with more (the guy's bike it was think runs around a 92)

Your 16.1 second time means 34.7 mph
With a gearing of 48/15 thats a cadence of 135 so the same as mine (!) any higher - I'm sure our legs legs would have fallen off

oldwelshman

give it a few weeks, then go for 86", then once your used to cadence probably 88 or 91.8 thats what most use, some use higher for pursuit but not your age and thats when they start goin really fast

trickydisco

With a gearing of 48/15 thats a cadence of 135 so the same as mine (!) any higher - I'm sure our legs legs would have fallen off

<big head mode> I'm Bristol's rollapaluza champion

Although that's with hardly any resistance

dru

trickydisco wrote:

With a gearing of 48/15 thats a cadence of 135 so the same as mine (!) any higher - I'm sure our legs legs would have fallen off

<big head mode> I'm Bristol's rollapaluza champion

Although that's with hardly any resistance

good man! its all about good pedal stroke and high cadence.... who cares about resistance

AlanW

Eddy S wrote:

I would have ridden a general session like that on 84" (47/15) - keep it light on your legs and develop good cadence.

Up until a few moments ago I would have agreed with the fact that 84" was the result of having 47/15, in fact I have always gone via this gear chart - HERE

Now comes the but.........the formula for working out the ratio in inches is as follows:-

The wheel diameter multiplied by the number of teeth on the front chain ring divided by the number of teeth on the rear sprocket.

So the outside diameter of a wheel fitted with a 23mm tub is 26.4", (I know this coz I have just measured mine!)

Using the ratio above as an example then, 26.4" x 47 / 15 = 82.72" ??

Now I have to admit to being very confused because I have always looked on 47/15 as being 84" as being correct, and please tell me that I have missed something and that 84" is correct.

But before you do, I had a search around and found this site HERE Okay it doesn't show this exact ratio, but using other ratios as an example:-

48/15 = I always thought it was 86", but doing the sums it equals 84.18", and according to the above site 84.4"

Which one is right then...... :?:

dru

AlanW wrote:

Eddy S wrote:

I would have ridden a general session like that on 84" (47/15) - keep it light on your legs and develop good cadence.

Up until a few moments ago I would have agreed with the fact that 84" was the result of having 47/15, in fact I have always gone via this gear chart - HERE

Now comes the but.........the formula for working out the ratio in inches is as follows:-

The wheel diameter multiplied by the number of teeth on the front chain ring divided by the number of teeth on the rear sprocket.

So the outside diameter of a wheel fitted with a 23mm tub is 26.4", (I know this coz I have just measured mine!)

Using the ratio above as an example then, 26.4" x 47 / 15 = 82.72" ??

Now I have to admit to being very confused because I have always looked on 47/15 as being 84" as being correct, and please tell me that I have missed something and that 84" is correct.

But before you do, I had a search around and found this site HERE Okay it doesn't show this exact ratio, but using other ratios as an example:-

48/15 = I always thought it was 86", but doing the sums it equals 84.18", and according to the above site 84.4"

Which one is right then...... :?:

Alan - you are geting competative I'm sure

I've been riding a 48/15 for the last month or so and I think that my decreasing lap times is due to the weight I'm losing and the coaching program I'm following

AlanW

Dru wrote:

Alan - you are geting competative I'm sure

I've been riding a 48/15 for the last month or so and I think that my decreasing lap times is due to the weight I'm losing and the coaching program I'm following

No not really, just messing about looking at ratios really and up until this evening I would have said that you were riding a 86.4" gear, but it actually works out to 84.4"?

On the flip side, I ride a 50/16 which I always took as being 84.4", but it actually works out to 82.5"?

Eddy S

AlanW wrote:

Which one is right then...... :?:

They're both right but nobody talks in terms of their exact gear measurement otherwise they would be relatively meaningless conversations because as soon as you fit a different tub or tyre or use a rim with a different profile it changes again. Only important if you're concerned with meeting a (youth) gear restriction measurement or you're looking for the nth degree of accuracy for yourself.

Everybody discusses track gearing in terms of the standard imperial gear table i.e. 47x14=90.6 which is based on a notional 27" diameter wheel.

Eddy S

...double post...

Pokerface

AlanW wrote:

Dru wrote:

Alan - you are geting competative I'm sure

I've been riding a 48/15 for the last month or so and I think that my decreasing lap times is due to the weight I'm losing and the coaching program I'm following

No not really, just messing about looking at ratios really and up until this evening I would have said that you were riding a 86.4" gear, but it actually works out to 84.4"?

On the flip side, I ride a 50/16 which I always took as being 84.4", but it actually works out to 82.5"?

50/16 is 84.4
47/15 is 84.6

AlanW

Pokerface wrote:

50/16 is 84.4
47/15 is 84.6

Wheel diameter x chain ring divided by sprocket would suggest otherwise?

26.4 x 50 / 16 = 82.5"

26.4 x 47 / 15 = 82.7"

But as we have already established we all know it when it used to be measured with a 27" wheel, therefore:-

27 x 50 / 16 = 84.37"

Like everyone else no doubt, I will always know them as the ones that you have shown. However, my point was more of confusion on my part as when I worked out the calculation using today's wheel diameter (ie 700c with a 23mm tub), the measurement is different.

If you open up this LINK and then download the Gear Tables .xls chart. Then change the calcs from 27" to 700c, you see what I mean.

oldwelshman

You can use any method you like as long as your happy but if you talk to any track riders they all use 27" calculation.
13 14 15 16 17
51 105.9 98.4 91.8 86.1 81.0
50 103.8 96.4 90.0 84.4 79.4
49 101.8 94.5 88.2 82.7 77.8
48 99.7 92.6 86.4 81.0 76.2

This could be iportant if you are going to ride many events on different tracks as most riders talk to each other during warm ups and races tosee what gearing to use so if you use your own calculation they would not understand your gears and you would get mixed up and end up riding under or overgeard
I am useless with gearing and have to look at the teeth to check as I cannot go by feel, some ridersnotice very small changes.
I have raced with 91.8and 94.5 but recently used 96.4.
The only gear I noticed to struggle to turn over was 103.8 but I might perservere with higher gear for pursuit.

dru

Silly question - how do you remove a track cog from a rear wheel? I presumed you could remove the rear track cog with a chain whip - but what else do I need?

Eddy S

Dru wrote:

I presumed you could remove the rear track cog with a chain whip...

Exactly that but make sure you get a 1/8" one.

Dru wrote:

...but what else do I need?

A lock ring tool. And if a lock ring isn't fitted, fit one!

AlanW

IMHO this is the best tool is get - HERE and its £29 from HubJub, or HERE for £49??

SteveR_100Milers

I was using the sheldon brown chart, which is for road bikes! I thought I was riidng 92", it's been 88 all along. Time to get a 50 and 52 front ring.

oldwelshman

Eddy S wrote:

Dru wrote:

I presumed you could remove the rear track cog with a chain whip...

Exactly that but make sure you get a 1/8" one.

Dru wrote:

...but what else do I need?

A lock ring tool. And if a lock ring isn't fitted, fit one!

They dont like you to use a lock ring at newport, I had to take mine off when I rode the track league.

oldwelshman

Dru wrote:

Silly question - how do you remove a track cog from a rear wheel? I presumed you could remove the rear track cog with a chain whip - but what else do I need?

Ask anyone down the track, or maybe courtney or chris to give you bit of old track chain and you can drill hole in your chainwhip and use chain removal tool to fit it so you have one chain whipo with road and track chain on it, thats what I use.

oldwelshman

SteveR_100Milers wrote:

I was using the sheldon brown chart, which is for road bikes! I thought I was riidng 92", it's been 88 all along. Time to get a 50 and 52 front ring.

So you been using a 49 x 15 ?
To be hionest thats perfect for Newport training and just go to 91.8 or 94 for races.