As wonderful as my triple chainset is, with the 30/39/50 combo there are still occasions when I run out of gears on descents. Is there a reason triples stop at a 50 ring – I’m assuming it is to do with the range of the mech? Otherwise a 53 would make much more sense, surely?

Some triples have a 52 plaque but consider that 53/12 is a lower GI than 50/11 the differences aren’t that big… And then if you are on a triple then you are less likely to worry about Needing the 53

think “capacity” is the issue – if shimano mechs then you can find the max capacity on the technical pages of the shimano website but some people choose to ignore them and get away with it sometimes

the late great Sheldon Brown explains it all

http://sheldonbrown.com/gloss_ca-g.html scroll down a bit

My Alfine 8 tourer spins out at about 55kmh downhill. I’ve hit 90kmh with a good tuck. Big gears are overrated.

(9 speed) 53/40/30 coupled with 11/34. XT long cage rear mech. Ultegra shifters. Works fine. Even flight deck is happy with this combination.

As said – if you don’t have an 11-up cassette change that first.

I thought 52 was more ‘normal’…it’s what I had anyhow (like this

I switched to a 50 only because that is what was being offered for a ‘bargain’ price …I have an 11 cog at the rear and can’t say I’ve missed the 52 much…for the few times I might use the extra on a downhill I think it has made the large front a slightly more useful gear on the flat / undulating roads.

change your cassette to an 11-25….simples! 🙂

I think I have 12-26 on the back currently….maybe (going by memory). So I will give an 11 a shot.

…for the few times I might use the extra on a downhill I think it has made the large front a slightly more useful gear on the flat / undulating roads

Never really thought of it that way. You could be right… Doesn’t stop the child in me wanting it on the long descents though 🙂

I run a campag 53,42,30 with a 12-29 and veloce medium cage.

On proper descents I’m faster not pedalling over 26mph. The big ring is of use on those lovely very slightly descending smooth roads.

I’d not want to sacrifice the 29 on the rear. It’s only barely low enough to go seated up long 15% climbs without having to put too much work in for loooong rides.

How fast do you pedal?

50×12 at 95 rpm is 31mph
50×11 at 95 rpm is almost 34mph
50×12 at 105 rpm is over 34mph

If you pedal slower than 90, it migh be worth practicing to spin a gear rather than mash along.

I run a campag 53,42,30 with a 12-29 and veloce medium cage…… The big ring is of use on those lovely very slightly descending smooth roads.

I’d not want to sacrifice the 29 on the rear. It’s only barely low enough to go seated up long 15% climbs without having to put too much work in for loooong rides.

+1

think “capacity” is the issue …….

but some people choose to ignore them and get away with it sometimes

I’m running a Veloce medium cage mech with 53/39/28 front and 13-28 rear which covers all the terrain I might cover on a typical South Devon road excursion without spinning out. (1 in 3s to nice long flat stretches)

^ my exact set up. Do you run a standard left lever or a triple specific one? Mines a 2010 standard veloce which is OK but the trim on the middle ring is a little finicky.

How fast do you pedal?

50×12 at 95 rpm is 31mph
50×11 at 95 rpm is almost 34mph
50×12 at 105 rpm is over 34mph

My record thus far is 52mph but my legs were going like roadrunner that day, and despite this, due to favourable weather conditions and someone having a bigger chainset (or faster legs), I was beaten on Strava within the hour 😡

Seriously, I know it’s not too often you need it. Most rides you do well to get over 35mph really. But there are some super good, long flowing descents (think 5 miles) in my local area, which when you get a good tailwind really make you smile. There’s always a hint of disappointment though when you run out of gears and can’t reach the full potential.

I used to run a 48×12 set up and was never dropped through lack of gears. Worry less and pedal faster.

52 mph on 50×12 would be about 160rpm! But then on 53×11 you would still have to be doing about 140rpm

I would imagine that speeds over 50mph on downhills are more about good aerodynamics and smooth cornering rather than high gearing. Trying to pedal at that speed might just slow you down because of the increased turbulence.

Maybe time to work on that nice aero tuck?

Also you need to look up rule 5 and ditch the 30 🙂

Duplicate 😳

My record thus far is 52mph but my legs were going like roadrunner that day, and despite this, due to favourable weather conditions and someone having a bigger chainset (or faster legs), I was beaten on Strava within the hour

You might have been beaten by someone who didn’t pedal at all. Apparently pedalling at high speeds causes more turbulence than just keeping the pedals level and coasting. You can also tuck more if you coast. I have a short steep hill here that I can hit 40mph on pretty reliably, if I pedal to 30mph at the top then tuck very low and coast, I’ve hit 43mph, if I pedal like mad, even on the drops I can just about hit 43mph. I think once you’re over 40mph there’s got to be no point pedalling on many descents.

Even if you ignore the difference in aerodynamics, assume it’s the same when you pedal as when you don’t, and just look at the power, on a 5% hill, 245W of effort gets you just under 6mph advantage at 40mph. If you can get an even slightly better position without pedalling surely you’d make that difference up.

http://www.endurancecorner.com/Alan_Couzens/optimal_pacing

And maybe I’m a bit of a spinner*, but 50×12 will surely get you up to 40mph no problems – that’s only 120 rpm, and 50mph is only 160, which isn’t too insane if you’ve got no resistance. I’ve got 52×12 and that is a ridiculously high gear.

*I’ve ridden an hour at 160 rpm on fixed a few times, so I guess I am

I would imagine that speeds over 50mph on downhills are more about good aerodynamics and smooth cornering rather than high gearing. Trying to pedal at that speed might just slow you down because of the increased turbulence.

on my local long, steep hill, on a calm day i can hit about 52mph rolling off the top and tucking. my skinny mate will roll straight past me about halfway down and hit about 55mph. with a tailwind 60mph is achievable.

butcher – Member
Is there a reason triples stop at a 50 ring

The whole world has gone GAY – see 34T middle rings also.

I think once you’re over 40mph there’s got to be no point pedalling on many descents.

The steeper the descent, the less point in pedalling. I’d agree that over about 40mph on just about any descent, there’s little point in pedalling anyway (unless you’re Mark Cavendish or Andre Greipl) as the average person is likely to go faster getting into a good aero tuck. I can spin a pretty reasonable cadence when required, certainly enough to be knocking on around 45mph on a 50/11 gear, but when you see the guy in front of you pull away from you just because he’s got into a good aero tuck, it kind’ve defeats the object!

The whole velominati “you will not stop pedalling until you have spun out your 53/11” thing is (like all the velominati rules) to be taken with a pinch of salt.

Also you need to look up rule 5 and ditch the 30 🙂

If I did this I wouldn’t be descending any hills because I’d never make it to the top in the first place 🙂

Interesting about aerodynamics and turbulence. For the record, these are rarely mega steep hills. Usually long mellow ones with strong tailwinds where going aero seems (at least to me) to have less impact, and pedalling provides a lot of power. I’m a bit of a wuss on the really big ones and usually on the brakes!

mboy – Member
The whole velominati “you will not stop pedalling until you have spun out your 53/11” thing is (like all the velominati rules) to be taken with a pinch of salt. only to considered/quoted by nobs or noobs

FTFY!

Recent TT slightly down hill pedaling and up at 41 MPH 120 revs, only thing higher was HR @ 180