50T to 52T big rings

slowbike

Imposter wrote:

Andycar82 wrote:

People are saying not a huge difference, but it's not a big change to the bike and for the improvement it seems a no brainer, I've got a Wilier GTR which I've been racing this year, bike leg is my weakest, but I'm not crap! So strengthening with bigger chain rings would benefit hugely I'm starting to believe, and anyone who is in awe of pros doing the speeds they do should perhaps look at there 50t/34ts and stop wondering, I have never looked into this before, and may well just get a BMC time machine next spring!

Not really sure what you are saying there, tbh. If you can't already push 50/12 at 35mph (which very few can sustain on their own), then switching to a 52 will not make it any easier to go faster. All else being equal, if you switch to a 52 now, you will just end up using a sprocket a little bit further up the block and the same/similar gear inches that you were using on the 50t anyway...

But it's not all equal is it - a couple of sprockets up usually gives a better chain line and can save (a fraction of) watts.

The compacts benefits are in the lower gears where there is a more pronounced difference between the 34 and 39 rings found on a standard - maintaining a 75rpm with a 27 tooth rear sprocket sees a difference between 7.4 to 8.5mph - actually on a 27-12 cassette you can be in the next sprocket down (24) and still be easier than the lowest combination with a 39 chainring. With such significant differences in the lower end and very little at the top end it's hardly surprising that a lot of people are using compacts.

imposter2.0

Slowbike wrote:

But it's not all equal is it - a couple of sprockets up usually gives a better chain line and can save (a fraction of) watts.

Without knowing what he's using now, you can't really say whether it would be a better chainline - or a worse chainline. You are right though - fractions of watts will make no practical difference.

Slowbike wrote:

The compacts benefits are in the lower gears where there is a more pronounced difference between the 34 and 39 rings found on a standard - maintaining a 75rpm with a 27 tooth rear sprocket sees a difference between 7.4 to 8.5mph - actually on a 27-12 cassette you can be in the next sprocket down (24) and still be easier than the lowest combination with a 39 chainring. With such significant differences in the lower end and very little at the top end it's hardly surprising that a lot of people are using compacts.

None of that matters. We're talking about the difference between a 50t and a 52t - not a 34t and 39t...

bernithebiker

Imposter wrote:

Andycar82 wrote:

People are saying not a huge difference, but it's not a big change to the bike and for the improvement it seems a no brainer, I've got a Wilier GTR which I've been racing this year, bike leg is my weakest, but I'm not crap! So strengthening with bigger chain rings would benefit hugely I'm starting to believe, and anyone who is in awe of pros doing the speeds they do should perhaps look at there 50t/34ts and stop wondering, I have never looked into this before, and may well just get a BMC time machine next spring!

Not really sure what you are saying there, tbh. If you can't already push 50/12 at 35mph (which very few can sustain on their own), then switching to a 52 will not make it any easier to go faster. All else being equal, if you switch to a 52 now, you will just end up using a sprocket a little bit further up the block and the same/similar gear inches that you were using on the 50t anyway...

^^This, totally.

I am in awe of the pros, but I can be pretty damn sure that by changing my 50/34 for a 53/39, I will not suddenly be headhunted by Saxo Tinkoff........

slowbike

Imposter wrote:

None of that matters. We're talking about the difference between a 50t and a 52t - not a 34t and 39t...

We were - but the OP started on about compacts ....

Pokerface wrote:

Andycar82 wrote:

just wondering why so many bike have 50/34s

Because they are good introductory gears to use. They suit most novice riders (and even some experienced ones!)

There is a small issue with trying to run a 34-52 chain set. The jump from small to big chainring is very big and will cause shifting problems. You normally see either 34-50 or 36-52.

then

Andycar82 wrote:

and anyone who is in awe of pros doing the speeds they do should perhaps look at there 50t/34ts and stop wondering, I have never looked into this before, and may well just get a BMC time machine next spring!

Perhaps Andycar should stop looking at chainrings as the answer to all his problems and start working on his speed ...
We have a rider at our club who features at the top of the results each outing - he only recently changed his crankset to 42/52 having done most of the season on ..... a compact ....

Pokerface

Imposter wrote:

Slowbike wrote:

the 50 ring is still good for ~20mph average on the flat too, but with a 27-12 cassette I just don't bother spinning down any steeper descents ..

50/12 is good for 35+mph on the flat..

It's fairly irrelevant how fast you can 'make' a gear go if you infinitely crank up the RPM and are capable of maintaining power at that RPM.

I couldn't hold 110rpm (isn't this what you'd need to push 50-12 to 35mph?), but could push my 53-11 at 93rpm which would give you the same speed, all things being equal.***

Pick a gear (or gearing) that suits how you want to ride, don't try and force yourself to ride way out of your comfort zone just to accommodate your equipment.

From my very basic calculations, going from a 50 to 52T would give you an extra 2kph at the same cadence.


***Apologies if my figures are off. I used my track gearing calculator app which gives speed at rpm for any gearing. The real world might be slightly different with uneven road surfaces, wind, etc - but the principle should remain the same, as would the relative differences in cadence for speeds.

iron-clover

You might well see a benefit from a 52t chainring in TTs. I had a good chance for a comparison when my stock bottom bracket failed on my Trek 1.1 which took the chainset with it. I borrowed a chainset from a friend to tide me over until I could fit a replacement and it happened to be a standard 52/39.
The next week (and last weekly TT of the season) I completely smashed my course best and came relatively close to my overall 10mile pb, which was unusual. The course was a couple of laps of the Wallingford bypass, which has a very slight downwards slope heading North, and a definite false flat heading South. I think the larger gears helped me to push up to a higher speed without a high cadence, but the lower gears weren't too high to deal with the incline comfortably.

I now have another standard on my more recent dedicated TT bike, and have since learned I tend to stick to a lower cadence in TTs than general riding or road racing for some reason, so the larger gears help me a fair bit.

Standards aren't so great for hills though- I was coming towards the end of a 110mile ride that crossed two sets of Downs and came to a short section of 20% incline that almost stopped me dead in my tracks and I could only just keep the pedals turning over so I don't use them for general riding anymore.

Andycar82

Slowbike, cheers for that, I'm sure he will see the benefits of changing fairly quickly and be super fast, I feel too comfortable on the compact during races and can see that other riders on TT bikes are riding bigger rings. Obviously pro riders are on another level due to many different factors. 50T/34T seems a bit pointless for triathlons and pushing yourself to the next level.

imposter2.0

Pokerface wrote:

From my very basic calculations, going from a 50 to 52T would give you an extra 2kph at the same cadence.

Assuming you could sustain the higher power required to maintain the additional effort at that cadence - which is a fitness issue, not a gearing issue. If it was as easy as that, we would all do it.

Andycar82

Yeah Imposter, that's sort of the point of the post, I am confident that I now have the fitness and spin around in a 50T a fair bit on the flat, you really can't push 50T downhill very often at all, thanks to those who have been helpful, I will be changing the set up or getting a TT bike for next year

imposter2.0

Andycar82 wrote:

Yeah Imposter, that's sort of the point of the post, I am confident that I now have the fitness and spin around in a 50T a fair bit on the flat, you really can't push 50T downhill very often at all, thanks to those who have been helpful, I will be changing the set up or getting a TT bike for next year

If this is just about spinning out down hills, then you will never be happy - as there will always be a bigger hill where you will spin out the 52 as well.

But as I said, unless you are already spinning out in 50/12 on the flat, then simply fitting a 52 is not going to make you faster.

Andycar82

What will then as I am spinning out on flat? It seems that racing set ups have bigger rings to allow people to give the power they have, what should I do to go faster? As I really am not getting much out of spinning around in high cadences.

Grill

Imposter wrote:

Andycar82 wrote:

Yeah Imposter, that's sort of the point of the post, I am confident that I now have the fitness and spin around in a 50T a fair bit on the flat, you really can't push 50T downhill very often at all, thanks to those who have been helpful, I will be changing the set up or getting a TT bike for next year

If this is just about spinning out down hills, then you will never be happy - as there will always be a bigger hill where you will spin out the 52 as well.

But as I said, unless you are already spinning out in 50/12 on the flat, then simply fitting a 52 is not going to make you faster.

This just isn't true. First you assume that everyone makes peak power at a high cadence. I know testers who ride at 60rpm. Second, there is still a parasitic loss from running a big-little chainline. Lost watts = less speed.

I ride a compact most of the time, but I would never use one on a TT unless it was mountainous. Even 11.5hrs into my last 12hr TT I was moving pretty far up the cassette (12-25).

imposter2.0

Grill wrote:

This just isn't true. First you assume that everyone makes peak power at a high cadence. I know testers who ride at 60rpm. Second, there is still a parasitic loss from running a big-little chainline. Lost watts = less speed.

I ride a compact most of the time, but I would never use one on a TT unless it was mountainous. Even 11.5hrs into my last 12hr TT I was moving pretty far up the cassette (12-25).

I know all that. The guy has never actually specified at what cadence and what speed he is 'spinning out' - if indeed he is even doing that in any practical sense. I'm just challenging the misconception that people will go faster by fitting a 52 - which they won't, outside of a few specific circumstances.

Andycar82

I would say I'm spinning out at around 53 ish kph on flat or certainly not feeling like I'm getting as much out of the bike as I do on my old bike with 52T, I'm going to go with the bigger ring, if you don't have the smaller rings you don't use them and will ultimately get stronger with it through practice and riding. Thanks for your help

Andycar82

One thing which I've asked once already Imposter, if I feel I can ride a bigger set and go faster than I do now, your saying I won't go faster, how do I go faster if my legs are going as fast as they can on a 50T??

Pokerface

Andycar82 wrote:

One thing which I've asked once already Imposter, if I feel I can ride a bigger set and go faster than I do now, your saying I won't go faster, how do I go faster if my legs are going as fast as they can on a 50T??

There are only 2 ways you can go faster: either spin the gear faster, or use a bigger gear.

If YOU can't spin the gear any faster, then the only logical way to go faster is to ride a bigger gear.


Many will argue that if you improve your fitness, this will allow you to spin your current gear faster or at the same current top RPM, but for longer.

I (personally) feel that what you are describing is a scenario that would suit a larger gear.

bernithebiker

Andycar82 wrote:

I would say I'm spinning out at around 53 ish kph on flat or certainly not feeling like I'm getting as much out of the bike as I do on my old bike with 52T, I'm going to go with the bigger ring, if you don't have the smaller rings you don't use them and will ultimately get stronger with it through practice and riding. Thanks for your help

How long can you hold 53kph on the flat for?

(personally, i may be able to get to 53kph on the flat, but I sure as hell can't hold that for very long (at all)).

imposter2.0

33mph is good for an 18min 10m TT, or a 45min 25....

Grill

Imposter wrote:

33mph is good for an 18min 10m TT, or a 45min 25....

Botty territory!

Andycar82

bernithebiker wrote:

Andycar82 wrote:

I would say I'm spinning out at around 53 ish kph on flat or certainly not feeling like I'm getting as much out of the bike as I do on my old bike with 52T, I'm going to go with the bigger ring, if you don't have the smaller rings you don't use them and will ultimately get stronger with it through practice and riding. Thanks for your help

How long can you hold 53kph on the flat for?

(personally, i may be able to get to 53kph on the flat, but I sure as hell can't hold that for very long (at all)).

I don't know Bernie, not long perhaps, I do know that a 52T would be worth ago and as I have no desire to ride the Alps in the next couple of years a 50T seems like an over cautious waste. I have 52T/36 on my old bike and always felt it had more oomph, while the 50T is very nice it often feels like a keep fit spin class and going nowhere fast

ben@31

Is the OP saying they want a bigger chainring because they are out spinning a 50 front and 11 rear? Maintaining a cadence over 100rpm ?

If YOU can't spin the gear any faster, then the only logical way to go faster is to ride a bigger gear.

Many will argue that if you improve your fitness, this will allow you to spin your current gear faster or at the same current top RPM, but for longer.

Wouldn't a bigger gear require more leg strength and be hard to sustain? Over a long ride you might be better keeping the lower gear higher cadence, to save your legs. Would an improvement in cardio fitness only help low gear spinning and you'll need increased leg strength for grinding a higher gear?

If the OP is a triathlete why would you want to grind a high gear when you've got a run to do afterwards?

Andycar82

Because I can, many of the competitors at the top end will have TT bikes WITH BIGGER BIG RINGS, they are not professional. Some will blow out on the run to have a better bike split as the bike is key. Anyway I said I would stick to shorter Tri which are only 20ish kms of fairly flat routes, in the shorter races, a minute or two in time difference is big

bernithebiker

There's me busting my ass with training, Zone 1, Zone 6 sessions you name it, aero helmets, position, Majorca thrash sessions, lighter, stiffer shoes, cranks, wheels, etc. , all to shave a few seconds off my PB's, when in actual fact, all I needed to do was go from a 50 to a 53!

What a numpty!

And yet, the answer was always staring me in the face, 'cos that's what the pros use. Duh!

Andycar82

And like I said, many amateurs, im sure what you say your doing will help, bigger rings may also help a little, nice day outside, im off for a ride, cheers for your help.

Grill

Seriously, y'all's need to stop trying to impose your specific programs. Fact: the OP feels as though he is spinning out and wants a bigger gear. Just because some people here swear by compacts doesn't mean that it's the best choice for the OP and his chosen program.

Berni- all that and you never considered using a bigger gear? Strange considering you probably have a higher FTP than me.

imposter2.0

ben@31 wrote:

Wouldn't a bigger gear require more leg strength and be hard to sustain?

Just to be clear - turning a bigger gear does not require more 'leg strength' - but it does require more sustainable power.

Pokerface

ben@31 wrote:

Is the OP saying they want a bigger chainring because they are out spinning a 50 front and 11 rear? Maintaining a cadence over 100rpm ?

If YOU can't spin the gear any faster, then the only logical way to go faster is to ride a bigger gear.

Many will argue that if you improve your fitness, this will allow you to spin your current gear faster or at the same current top RPM, but for longer.

Wouldn't a bigger gear require more leg strength and be hard to sustain? Over a long ride you might be better keeping the lower gear higher cadence, to save your legs. Would an improvement in cardio fitness only help low gear spinning and you'll need increased leg strength for grinding a higher gear?

If the OP is a triathlete why would you want to grind a high gear when you've got a run to do afterwards?

Going from a 50 to a 52 is hardly going to all of a sudden cause someone to 'grind the gear'. The OP already stated that he feels he's spinning the 50 past the point of being able to get enough speed/power out. So a bigger gear will help with this.

If he was to jump to a 56t ring and try to maintain the same cadence, then yes, it would require an increase in strength and fitness to push it.

A bigger gear won't necessarily make you go faster, but the right gearing will.

bernithebiker

Grill wrote:

Berni- all that and you never considered using a bigger gear? Strange considering you probably have a higher FTP than me.

I've never tested FTP, I don't have a power meter and I don't make huge amounts of power, but I am light (62kg) and climb well. High speed riding on the flat is not my forte.

It is very rare that I spin out a 50-11. This is about 70km/h (downhill of course) and only once or twice have 53 riders pulled away from me on this type of descent.

A typical fast race round our way is quite lumpy (e.g.. 1000m for 100km) and would average 38km/h ish. I would say that 90% is in the big ring, and that 90% of that time, I will be using 19-18-17-16-14-13 (using a 23-11 cassette).

Therefore I don't see what I would gain going to a 53.

If I did TT's on a TT bike, then I can see that the higher speeds MIGHT make a 53 a better bet, if only to save a teeny bit of power on chain line.

(I would say I tend towards a higher cadence than most, especially when climbing).

Bordersroadie

I have bikes with both 50 and 52, and the main advantage (to me) of a 52 vs a 50 is that it allows effectively a closer ratio cassette, say 12-25 vs 11-25, assuming that 25 is your preferred low gear, with an almost identical equivalent top gear. I think 52-12 is actually a bit lower than 50-11 from memory but inconsequential.

StillGoing

Surely the OP is not spinning out though is he. He might feel he's not putting out his best power above a certain cadence, but unless he's spinning and the chainline can't keep up with his leg speed, he isn't spinning out. I've yet to read him actually state what cadence he's doing.