So wait, I've just seen a snippet of a Scott SRAM mentioning that riders with more power tend to rider bigger chainrings, and lower power riders are better with smaller chainrings and higher cadence.
Does this ring true, because I'm a lower power rider racing with a 36 up front, am I compromising myself?
36 front?
#Bragging or #FensRider
I'd say that as a bigger rider, I'm often happier pushing a bigger ring on the flat than others.
Equally, those others tend to make it up the hills ling before me, and I don't find myself wishing for a bigger ring as I try to keep up.
Do they not simply mean that pro riders might push a 36t chainring with the same RPE as a weekend warrior pushes a 30t? And everyone else is on a scale inbetween the two.
In the same way the average rider can't possibly keep up with Nibbali on a climb, so when Nibbali choses a 38/52 chainset and 11-25 cassette, in the real world you should just pick a 34/50 with a 11-32 and try and match his cadence whilst finishing many minutes behind him.
In fact if you just scaled off W/kg (i.e. what you're actually able to climb at), where a weekend warrior is probably managing ~2.5, and Nico Scurter is at >5.5 (based on a claimed normalised power of 370W at Albstadt and a weight of 67kg). Then if his bike has a 36t chainring we should probably be down at more like 18t on the climbs 😮. On the flats (where power matters, not weight) it might be closer if Joe average can perhapse muster perhapse 3/4 the power (and aero drag goes up with the square of speed so it's not linear) you might justify a 30.
Do they not simply mean that pro riders
No, the comment was quite specific to the fact that Nino rides a 36, because he is more powerful than Lars, who defers to a 34.
Ok not much in it, but I'm wondering whether for me specific "overgearing" could cause muscular fatigue e.g. lower power rider generating bigger torque on a bigger ring.
Albeit having said that my 36 is an oval on a GX 50-10, so it could be a very moot point 😀
Albeit having said that my 36 is an oval on a GX 50-10, so it could be a very moot point
Is that on a 29 or 27?
Albeit having said that my 36 is an oval on a GX 50-10, so it could be a very moot point 😀
I'd argue it's moot unless you find yourself grinding up hills in too high a gear.
There's a good bit in the Hunter Allen Power Meter training book about looking back at the data for races you do badly in, but shouldn't have. In the examples they show the rider struggled because each lap had a steep climb that forced their cadence down even though they were riding ~FTP. Solution - stick a lower gear on to avoid that fatigue and ride it consistently lap after lap.
I'm nowhere near as quick as you but I can get around Swinley without going below ~3rd on the 10-50 cassette, but I'm fairly sure I'm quicker and can ride longer if I conciously use the 50t chainring. Especially as Jobber hill is followed by deerstalker-labrynth so it feels quicker to take a breather on the climb then make up those seconds on the way down again as it's a rare case of the descent (which is really lots of short climbs) being longer than the climb.
No, the comment was quite specific to the fact that Nino rides a 36, because he is more powerful than Lars, who defers to a 34.
Could simply be that Nino is 6% more powerful, so rides a gear 6% higher?
The only alternative explanation is on raw power rather than power/weight, but that's the opposite, heavier, more powerful riders tend to be slower on hills so ride lower gears look at the gearing on a GT (or one day) rather than a climbing specialist on a hilly day.
Do they have a lot of large chainrings in stock?
I used to use a 36t chainring back in the day. Down to 32t now...definitely weaker now, so probably be some truth to it.
Whether or not that’s adaptation or preference is another matter
Discalimer, im certainly no top tier athlete or even mid tier
ive been into MTB for 2 years now, to start with i was struggling on hills, ended up on 30x50+ ring/cassettes and spinning...
Over christmas i bought a gravel bike of sorts, and commuted to work.. i found myself out of the seat and pushing rather than spinning.
Now.. my out of the seat pushing hard is my go to, i sit and spin for a minute breather then try to get back on it.
My point is, perhaps there is something in it, i find pushing slow and hard better for me that spin spin spin. when im seated spinning, i dont feel i can put much power into the pedals.
im now on a 34t ring on my HT, and i'll probably jump to a 34 from 32 on my FS when the ring needs replacing. And then maybe next time i'll go for 36.
As above, if you have higher power-to-weight ratio, you will generally run a bigger chainring. If you have longer legs and run longer cranks, then you have more leverage so would probably be able to run a slightly larger chainring. However, you just have to find what works for you. If you're not spinning out on descents, then the bigger ring won't give you any benefit apart from preventing you from being lazy and running too easy a gear on steep climbs.
If it's anything like chaingrings for road bikes, isn't this all about fitting a chainring that keeps you around the middle of the cassette for drivetrain efficiency, while putting out power comfortable for you at your preferred cadence?
Before he wrecked his knee(s) a couple of years back, Tom Dumoulin was using something like a 58/60T for TT stages.
i wouldnt say it was like road bikes at all. I can be in a very low gear trying to clear a climb at not much more than walking pace, then o nthe way down again i can fly through the gears, or find myself briefly in a gear for a few turns of the crank.
THats for climb and descent
im guessing for xc it may well be different, but i still think you spend more time going up and down gears than you would a road bike?
From my own experience, I am faster on steeper climbs >maybe 8% on my gravel bike which has a 32/40 ratio vs my normal road 34/32. I am 95kg and I find above this kind of gradient or even below it when more fatigued my cadence gets so low I am really pushing far too much through my anterior muscles and properly straining vs being able to keep a cadence of 80-90 RPM on the gravel bike for the same gradient. I think the rule should be if you can't get an adequate cadence on the climbs you want to do then going to a lower ratio will definitely benefit you.
I have a theory. The bigger your legs, the more energy is wasted moving them up and down instead of powering the bike. I'm sure people will jump in and start reasoning that the energy required to move your leg up is provided by the other leg coming down, but why not try riding as fast as you can in bottom gear on your MTB. You'll go maybe 15mph and be knackered within a minute or two, whereas riding at 15mph in a normal gear is but dawdling and can be continued for many hours.
If this is true it'd be more efficient for lighter riders to use lower gears, at least on the flat, because they can pedal less hard and therefore put less strain on their muscles; but waste less energy moving their legs up and down.
Hmmm,
Chainring tooth count is one variable in a system full of variables focussed on mechanical advantage.
The ultimate point is achieving appropriate mechanical advantage betwixt the point of application (riders foot) and final output (tyre's contact patch), and of course what is "appropriate" varies depending on lots of other factors like rider strength (and fatigue) as well as terrain and traction, wheel size, tyre size, etc, etc...
So does it really matter?
Maybe a bit, not as much as people think, the ratios on a modern drivetrain are of course selectable with the mere click of a thumb, you just need to have them in about the right range...
If it’s anything like chaingrings for road bikes, isn’t this all about fitting a chainring that keeps you around the middle of the cassette for drivetrain efficiency, while putting out power comfortable for you at your preferred cadence?
Basically this, adapt the bike to suit the rider, not the rider to suit the bike...
Kryton57 - you are a fit bloke and if you aren't running out of gear at either end of the cassette then 36t is fine. Mrs Yak has a 36t as well. Me, well 32t is just fine :-), but I have given up on racing intentions.
i find pushing slow and hard better for me that spin spin spin. when im seated spinning, i dont feel i can put much power into the pedals.
I used to think the same, but the power meter on my road bike tells a very different story.
You're not putting power into the pedals. Power is simply a measure of work rate. You're applying a force to the pedals which imparts a torque on the crank and power is a function of torque and cadence.
Spinning faster and lighter definitely produces more power, to a point...there comes a point where to increase cadence you physically can't move your legs fast enough. Everyone is different, whatever works for you.
What is more important is what cogs are on the cassette. The difference between 34 and 36 on the chainring is minor and unless they are running out of gears from their 12 speed? cassette at either the very top or very bottom the chainring size is irrelevant.
I find that on some courses (certainly towards the last few laps) having a larger chain ring can be telling on the fatigue. Here's some race data from Saturdays CX race at Broughton Hall, I don't know how many others run a PM at cross races but I do it because I like numbers.
I found myself grinding a bit too much in places, which caused me to fatigue. Depending on the conditions I'll run different chainrings (smaller if it's muddier, the casette will stay the same however 11 -36.) This was running a 40T but I'll sometimes run a 36t or 42t. Conditions were very dry but it's also a very hilly course for a CX race. I never found myself spinning out. I did manage to find a new max HR that I've not seen for a few years though!)
To add:
Spinning faster and lighter definitely produces more power, to a point…there comes a point where to increase cadence you physically can’t move your legs fast enough. Everyone is different, whatever works for you.
This sums it up for me.
For riders of similar ability. (Chris Hoy can still spin faster than me, and Cav probably puts out more power per revolution)
Bigger legs means more muscle mass to stop and start on each pedal revolution. Fast spinning cadences lose a lot of energy, but you have the muscle bulk to drive a big gear at low cadence.
Small legs lose less energy to the stop and start and can therefore spin faster other load being equal. But they don’t have the muscle bulk to drive a big gear. Lower gearing allows them to spin faster.
Now is a good time to confuse force, power, energy and torque. 😉
For what it’s worth, I found climbing on the road got easier when I moved from an 11-34 cassette to an 11-30. The tendency I had to say this is hard I need a lower gear left me putting too much energy into stopping and starting my legs and not enough into the back wheel.
Surely this is as simple as for each person there is an optimal cadence. We choose gear ratios that allow us to maintain this cadence along as much of the route as possible.
A fitter rider will go faster and need a larger chain ring, all other factors being equal.
However it does feel that the cycling industry, particularly in the world of road and gravel, has no interest in acknowledging this and providing the range of gears that people might need. They are backed up by an internet contingent who will say it's faster to get off and walk. It essential that is you are in that camp you have no knowledge of likely walking pace or cadence
Pro xcers are going to be spending most of their time in the middle (middle 8 out of 12?) of their cassesttes, maybe one or two times they will use the bottom gear (climbing while fatigued, or caught in a bit of traffic on an up) and similarly the top gear is only really getting used in a sprint.
whether someone prefers a 34 or 36 when they can easily select from one of 8 usable rear ratios at the twitch of a thumb is a bit academeic really.
Now the weekend warrior who needs to gently winch up a climb and also has a little road section to get to the trails, might have a different calcualtion to make.
I spent the winter on my turbo trainer doing a Sufferfest training plan which included regular cadence workouts, my spin out increased from 130rpm to 190rpm. The Sufferfest coaches say that training at high cadences improves neuromuscular control and the efficiency of your pedal stroke. Novices prefer low cadences because they haven’t taught their muscles to turn off and on fast enough to pedal efficiently at high cadences yet. I’m now happy to pedal for sustained periods at any cadence between 50-110rpm for long periods when out on my mtb. I do notice a higher cadence is more tiring when I’m wearing winter boots rather than my summer XC shoes, I suppose this is giving me a feel for what having even heavier legs would be like.
I run 34t, the max my frame allows and don't think I'll go smaller any time soon, I love a good sprint and have always had good quads so it works for me with 165mm crank arms, I still manage to climb stuff until my rear tyre loses all grip or the front end keeps lifting.
“You’re not putting power into the pedals.”
Well, to be pedantic, you are. If the pedals aren’t moving then you’re only applying force, but as soon as the pedal moves you have force multiplied by distance divided by time, or from the perspective of the crank axle, torque x rpm. That’s power.
Strong legs can generate more force so won’t need such low gearing to get up a climb and I suspect the reciprocating weight argument is true - cars with short stroke engines (ie short cranks) and light pistons and conrods (ie light legs) are better at high revs than the reverse. Long stroke (ie long cranks), big bore (high force) engines have the torque to work well at low revs and are disadvantaged by their moving mass abs peak piston speeds.
cars with short stroke engines (ie short cranks) and light pistons and conrods (ie light legs) are better at high revs than the reverse. Long stroke (ie long cranks), big bore (high force) engines have the torque to work well at low revs and are disadvantaged by their moving mass abs peak piston speeds
It's far more complicated than that. A limiting factor on revs is airflow, which is limited by the size of the inlet valves. With a larger bore, you can fit larger inlet valves so you get better volumetric efficiency at high revs.
Another limiting factor is the ratio of conrod length to stroke. The shorter the conrod, the higher the piston acceleration in the first half of the piston stroke after top dead center. To get a good conrod length for high revs with a longer stroke engine, you need to increase the deck height, which makes it hard to fit under the bonnet. However, a short conrod will give good torque at lower revs because the high piston acceleration gives high intake charge velocity at lower revs, which gives better fuel atomization. For low-rv torque, smaller intake valves and ports also give better air-fuel mixing, so the smaller bore size doesn't matter.
Four cylinder engines are inherently unbalanced and a longer stroke makes that worse, so four cylinder engines tend to be shorter stroke with a larger bore, except when they are fitted with balance shafts. Straight six engines are perfectly balanced, but a large bore and short stroke will make the engine too long so they tend to be narrower bore and longer stroke. They are usually fitted to larger, heavier, more expensive cars so a smooth engine with lots of low-down torque is desirable. A long-stroke with shorter conrods and smaller valves is better than high-revs for heavier vehicles because it gives excellent low-end torque.
So, the analogy of cyclists legs and car engines is really no use at all, there are some quite complicated decisions made in selecting the bore/stroke ratio of car engines and they have no analogue in cycling.
the analogy of cyclists legs and car engines is really no use at all
I actually think it's a reasonable reference for 'laypersons' you're perhaps cursed by an excess of knowledge, but if you want to talk to people about turning reciprocating motion into torque, then a car engine is an accessible analogy for most...
****el?
There is also the economic consideration with the cost of cassettes, smaller chainring keeps you in the smaller sprockets longer which are more durable!
I've gone from 34 to 32 recently simply due to lack of availability. I can't say I noticed a difference.
Thread has gone way OT 😀
This is a bit of a cadence question really and then an understanding gearing question
In theory lower cadence stresses the NM system more and higher cadence stresses the CV system more.
TRAININGPEAKS.COM So basically if your lowest gear is too hard you muscles are going to be your limiter not your CV system (massive over simplification but more or less right).
If your gears are too "easy" you risk not being able to go fast enough on flatter sections.
Your other question was; is a 36t chainring and a 50t largest sprocket inappropriate for a non-Pro ? Not at all!
36-50 is still "easier" than 32-42 which is what most people were more than happy cranking heavy ol' enduro bikes up before the dinner plate cassettes got extended further. In fact your 36t ring with a 50t sprocket is more like 30-42 which was considered really spinny not too long ago. Funny how our perceptions change 😉
Oval makes it a bit different but in simple terms I reckon an average fitness rider should be able to get up anything with your gearing and not have to go too deep
****el?
Mumsnet has plenty of advice for dealing with perversions like that.
Oval makes it a bit different but in simple terms I reckon an average fitness rider should be able to get up anything with your gearing and not have to go too deep
Perfect then, as I use a 36 Oval.
So, GX AXS.... any good? 😀
“It’s far more complicated than that”
Yes, that’s how analogies work. You’re trying to find similarities to help explain things, not trying to prove how two completely different things aren’t exactly identical... 🙄
36-50 is still “easier” than 32-42 which is what most people were more than happy cranking heavy ol’ enduro bikes up before the dinner plate cassettes got extended further. In fact your 36t ring with a 50t sprocket is more like 30-42 which was considered really spinny not too long ago. Funny how our perceptions change
Excellent point, I've still got a 30/40 bottom gear on my MTB so I suppose I'm technically more manly then?
Or just too cheap to buy a new drivetrain.
30-40 soundz well pro 😀
It always amuses me that you can talk to one group of MTBers and they can see 36-50 as potentially too hard a gear to climb in for crazy powerful pros only, whilst if you talk to a SS group of MTBers about 32-20 (pretty much 36-22) you are a weakling 😀
@kryton57 you definitely need SRAM AXS.... then you would be able to choose your chainring by analysing the time spent in each sprocket and maximizing your time in the middle of the block for full pro points 😀
@kryton57 you definitely need SRAM AXS…. then you would be able to choose your chainring by analysing the time spent in each sprocket and maximizing your time in the middle of the block for full pro points 😀
Lol! Although the way my brain works - I forgot about the mobile app - having that available would drive me much madder than trying to replace the cables...
I know you like a good rabbit hole to dive down 😀
If you are trying to replace the cables on the AXS then you have properly gone mad 😀 😀
It's all about those gear inches for SS innit?
52 (32-16 on a 27er/32-18 on a 29er) is the baseline, you might go taller if you need to assert your alpha status, but lower? I don't think that's an approved option is it? Not without a doctor's note...
What none of this considers is that tyre grip on climbs often becomes a limiting factor - I fail more often due to lack of grip than lack of 'legs'. That said, I do have a 26 chainring on my fat bike with a 42 max sprocket and in really soft (snow) or steep conditions it sometimes wasn't enough when laden with gear.
If you are trying to replace the cables on the AXS then you have properly gone mad
I meant on the mechanical setup, even I'm not that mad...
I fail more often due to lack of grip than lack of ‘legs’
I don't suffer from this problem very often.
whilst if you talk to a SS group of MTBers about 32-20 (pretty much 36-22) you are a weakling
Probably because 32-20 is very low (46 GI) and would just be a chore on anything flat or even gentle uphill. Obviously you don't have a choice with SS so you are pretty much always going to be climbing in a higher gear than someone with gears
All depends what you are used to. I had a geared bike for 2 month a few years ago (first in 18 years) and could believe people would actually use the cogs over 36 teeth.
But the size of the front ring only matters when in perspective to the cassette and I don't think many people will not be able to get up a hill on 34 - 50 but can on a 32 - 50 (1 GI)
36-50 is still “easier” than 32-42 which is what most people were more than happy cranking heavy ol’ enduro bikes up before the dinner plate cassettes got extended further. In fact your 36t ring with a 50t sprocket is more like 30-42 which was considered really spinny not too long ago. Funny how our perceptions change 😉
But then you are forgetting the 22 32 or even 22 34 of the 3x9 era. These were often on 26 inch wheels
I'm currently on 30 50 on 29er. I'm very feeble add very happy to have missed the era of bikes without really low gears.
