compact or triple

the playing mantis

Currently im hacking around on a mountain bike. i tend to climb the steeper hills on the lower end of the lowest of the 3 gear option whilst sitting in the saddle. i can climb moderate hills on the lowest gear of the middle ring whilst still in the saddle. my question is what will the lowest gear be equivalent of on a compact set on a road bike?

would it be low end of the 2nd ring of my mtb?

i guess the lack of a 3rd ring will be compensated by the offsets in weight of having a carbon frame somewhat compared with a heavy alu mtb, but how much?

my concern is i buy a road bike and struggle on the hills. would a triple be worth getting, or should i be able to cope witha carbon framed compact.

arthur_scrimshaw

as a generalisation there's not much difference between the lowest gear on a compact or a triple, if you really want a low gear on a compact, SRAM Apex group set has a WiFli option which goes up to a 32 tooth rear cassette (may be higher) You would be able to climb just about anything with that.

the playing mantis

o ok, i was under the impression a triple would give me the much derided granny gears?!, so here is not much benefit in a triple over a compact?

any ideas on what the lowest gear on atriple would be in mtb terms, and how much thw eight saving from a carbon road bike makes it easier than a heavy old mtb?

lc1981

It's not quite as simple as triple versus compact. What really matters is the number of teeth on the smallest chainring (and the biggest sprocket on the cassette). Count these on your mountain bike and then compare to the figures for the road bikes you're looking at, and you'll have a better idea.

Ride hard

This should help http://philsroadbikingblog.blogspot.co. ... sette.html

arthur_scrimshaw

that's a hard question, on the road it's much easier climbing on a road bike due to the lower inertia of lighter wheels which take less effort to accelerate. This means higher gearing on the road bike isn't such an issue. As an example, I've got a carbon road bike with a compact chainset and a 12 -25 rear cassette. I've also got a cx which is also a compact but with a 12 - 32 cassette. On a steep hill (15% for about 500m) near me I'm faster on the road bike by some margin. The CX is a bit heavier (quite a bit!) but the biggest difference is the lower effort needed to spin up the wheels on the road bike.
This opinion is from my own experiences and may have no scientific basis!

Bordersroadie

I've just posted this in the other thread on triples but as it's actually more relevant to your question I've pasted it below.

As a long time compact chainset rider, and more recently triple rider, the advantages of a triple over a compact I've found are

# No more seeming to always be wanting "small/small" or "big/big" and thus no more needing to constantly be skipping from one front chainring to the other to avoid cross-chaining. A compact makes the temptation to cross-chain very high and I notice a lot of compact riders doing so.

# A set of gears on the 39 ring (11-28 out back) that mean, in the real world, that I make far far fewer front ring changes than with a compact. On rolling terrain I can seem to stay in the 39 for a lot of the time.

# Much smoother front ring changes due to not having the big leap from 50 to 34 and back. 50 to 39 to 30 is significantly easier and less mechanically stressful on the chain/chainring teeth.

# A much bigger and closer-ratio set of climbing gears for long steep climbs. The lowest may be similar to a compact in many cases but the gaps tend to be closer. And whatever big sprocket you can put on a compact (eg 30 or 32) you cans also put on a triple so ultimately you can go really low if you want.

# A chainring (the 39) that allows all 10 rear sprockets to be used without cross-chaining or chainrub on an adjacent chainring is a big plus over a compact.

The much-derided "granny ring" thing I find hilarious especially as a compact small ring is just 4 teeth bigger and in any case there are plenty of hardmen who live in places like the Swiss Alps that use triples because they just make sense.

At the end of the day it all depends on (a) your power level (b) what you expect to be climbing as far as hills go and (c) whether you give a toss about the advantages a triple gives. If you're heading out to places like Hardknott pass (which I do) then triple is a natural choice. If you are self-conscious about riding with three chainrings then get a compact and accept the disavantages.

People will mention the weight and the complexity of a triple. The latter is a red herring and the former, a few grammes, is irrelevant.

the playing mantis

thanks very useful info from all. no stigma from me about a triple, too new to the road to give a sh*t, just repeating what some have said from what i have read in the past. didnt wiggo use one in the alps? if its good wnough for the pros its good wnough for anyone. clmb wise im taliking herts essex and suffolk, so very few hills, but all relative to what we are used to. i think a compact would be more thn suitable for me but was slightly concerned i would find it a struggle if im using the lowest of 3 on my mtb on some hills.

i will count the teeth and compare them. if i lived in an area with pwopa hills i think i wold plump for a triple for sure.

Timmers

things to take in account, as to wether siting or stamping (standing) and MTB vs Road Vs Ratios vs restance (alas I knew him well)
Easy peesssey,
Ratios = turn of peddle to cover distance = Front gear / rear gear x circumference of wheel/tyre outer diameter + Coefficient resistance(maybe squared or added=tyre roll/restistance, wind, incline ect) = enjoy ya ridding until someone passes you at twice your speed

Don't bother going carbon unless ya racing or ya on some kind of personal time/speed challenge, there are some great frames/bikes out there that will get you form A to B just as quick, i have 3 bikes (hack town, Focus Varadio and a TCR carbon) and there is little differance in my rides unless I'm racing.
So weigh up ya ratios and terrain, do you want to be stuck to smooth surfaces?, can you have both? are there lots of inclines (hills), what are the incline surfaces like? once ya worked out ya road surface choose ya wepon, then ya level of fitness and stength which will give ya ratios (see above)

StillGoing

Arthur Scrimshaw wrote:

as a generalisation there's not much difference between the lowest gear on a compact or a triple, if you really want a low gear on a compact, SRAM Apex group set has a WiFli option which goes up to a 32 tooth rear cassette (may be higher) You would be able to climb just about anything with that.

Sorry but surely there is. If a compact is 34/50 with an 11-26 cassette, the lowest range the rider has is a 34/26. A triple is going to be 52/42/30 and with the same size cassette will give a lowest range of 30/26. You can fit a long cage rear derailleur to allow you to put a larger cassette (11-32 or bigger) on a compact or a double chainset and give a lower ratio.

John.T

To answer the OP. Roughly the bottom gear on a compact is around the same as the 3rd from bottom on the middle ring. Without knowing what gears your mtb has I can not be closer than this. As said earlier a road bike rides 'easier'.
A 'standard' triple on a road bike will be something like 50/39/30 which for the same cassette will only give 1 lower gear. It is possible to fit granny rings as small as 26 to a triple which does increase the climbing possibilities.

StillGoing

If I apply the same logic I used when racing motorcycles around and having to alter the gearing for different tracks, down one tooth on the front was the equivalent of up 2.5 on the rear. If a triple is running an inner ring of 30 teeth as opposed to a compacts inner ring of 34 teeth, that's the equivalent of an extra 10 teeth on the same size sprocket on the rear cassette for the triple. That's a massive difference even if you round it down to an advantage of 2:1 for each tooth less on the front. There can't be anything different in the physics of chain driven gearing; the bigger the sprocket on the front the greater the top speed, the smaller the greater the acceleration, match it with the opposite on the rear and the results are magnified.

John.T

philthy3 wrote:

If I apply the same logic I used when racing motorcycles around and having to alter the gearing for different tracks, down one tooth on the front was the equivalent of up 2.5 on the rear. If a triple is running an inner ring of 30 teeth as opposed to a compacts inner ring of 34 teeth, that's the equivalent of an extra 10 teeth on the same size sprocket on the rear cassette for the triple.

I think not. The logic has got lost somewhere in translation. Your motor bike has something like the equivalent of a 15 driving a 46 so your figures are about right for that. If you assume a 30 tooth sprocket at the rear then going from a 30 tooth front to a 34 tooth one will raise the gear by 34/30 or from 1:1 to 1: 1.13 which is not a great deal (except if you are on knackered).

nickel

I came from mtbing and bought a road bike with a 50/34 compact and a 12-25 cassette. I found because my road bike was about 10lb lighter and a hell of a lot stiffer than my mtb I could climb hills in 34x25 just fine when I'd have to be on the 22t chainring on my mtb. As others have said, if you get a sram groupo you've always got the option of putting a 32t cassette and wifli rear mech on. But tbh 34x28 should be low enough to see you over all but the most extreme climbs in the UK.

SPOC

I spin even when going uphill, and I have a compact with a 12-28 cassette and have only felt like I have run out of gears when in 34x28(for me that's when I feel like I am grinding under about 70rpm) on gradients above about 15% which is not where 99.9% of my riding takes place.

I did consider putting a 30 on the back but considering most of my riding is on the flat I didn't want to compromise my middle range gears but having too big jumps on the cassette.

the playing mantis

my crappy old hardtail mtb is 48-38-28 14/28 im i correct in thinking, having done a rudimentary look at the chart on

http://philsroadbikingblog.blogspot.co. ... sette.html

the lowest gear on the compact 50-34 12/25 i have been looking at would be pretty much similar to the lowest gear on my middle chainset of my old mtb, or am i way off?

if im correct then i think as mentioned above by others the lightness and stiffness of the road bike should make it easier in that lowest gear than it is on the mtb.

please corect me if ive got this completely wrong.

thanks

StillGoing

Your 38/28 would be slightly harder than the compact ratio of 34/25.

Secteur

the playing mantis wrote:

no stigma from me about a triple... ...didnt wiggo use one in the alps? if its good wnough for the pros its good wnough for anyone.

No.

Pro's dont use triples or compacts, they use doubles. However, by way of some concession, I have heard of even Contador using a SRAM Apex rear mech to give him a 32 tooth cassette for really steep hills. Wiggins prefers osymmetric (?sp) chain rings, which I believe give him higher gears even on the hills, which he believes is traded off by the biomechanical benefits of osymmetric rings (supposedly why he struggled up the Angliru (?sp) in last years Vuelta)

StillGoing

Secteur wrote:

the playing mantis wrote:

no stigma from me about a triple... ...didnt wiggo use one in the alps? if its good wnough for the pros its good wnough for anyone.

No.

Pro's dont use triples or compacts, they use doubles. However, by way of some concession, I have heard of even Contador using a SRAM Apex rear mech to give him a 32 tooth cassette for really steep hills. Wiggins prefers osymmetric (?sp) chain rings, which I believe give him higher gears even on the hills, which he believes is traded off by the biomechanical benefits of osymmetric rings (supposedly why he struggled up the Angliru (?sp) in last years Vuelta)

If you look, you'll see that some of the pro peloton do in fact use compacts on occasions and Contador used a long rear derailleur to give him the bigger cassette at the back. Why would they choose not to if it gives them an advantage? There's a thread on here somewhere that shows of the front runners in the TdF who used what during one of the climbs. From memory I think only Wiggins and Froome stuck to a double combination (53/48) with the others in compact with either a 36 or 34 inner ring. If I can find it I will post the link.

Secteur

I'd believe that, but just havent read it. As you say, I am aware of using bigger cassettes, though I read in (I think) CycleSport that as Wiggins prefers he Osymmetric chain rings, he has to use a standard cassette for some reason...

John.T

Secteur wrote:

the playing mantis wrote:

no stigma from me about a triple... ...didnt wiggo use one in the alps? if its good wnough for the pros its good wnough for anyone.

Pro's dont use triples or compacts, they use doubles. However, by way of some concession, I have heard of even Contador using a SRAM Apex rear mech to give him a 32 tooth cassette for really steep hills. Wiggins prefers osymmetric (?sp) chain rings, which I believe give him higher gears even on the hills, which he believes is traded off by the biomechanical benefits of osymmetric rings (supposedly why he struggled up the Angliru (?sp) in last years Vuelta)

Smallest Osymetric ring is 38. Not sure what rear sprocket Wiggins used but Millar has used an MTB cassette and mech on the back of his bike for some stages.

StillGoing

Again I read that Wiggins uses the 48 inner ring because the changes between rings with osymetrics is awful if there's too much difference in size.

John.T

philthy3 wrote:

Again I read that Wiggins uses the 48 inner ring because the changes between rings with osymetrics is awful if there's too much difference in size.

As far as I know they do not make a 48. See http://www.trainsharpcyclecoaching.co.uk/products/chainrings.html
I use 52/38 on my TT bike and the change is fine. I have 50/38 on the Madone and it is fair. It would be better if I had a braze-on mech and could use the spacer block but it is not bad enough to spend money changing it.

Chris James

the playing mantis wrote:

o ok, i was under the impression a triple would give me the much derided granny gears?!, so here is not much benefit in a triple over a compact?

any ideas on what the lowest gear on atriple would be in mtb terms, and how much thw eight saving from a carbon road bike makes it easier than a heavy old mtb?

If you buy a compact you already have a 'granny' gear - the 34 tooth chainset. What you lose is teh (quite useful) middle chainring.

Be aware that mountain bike triples are much lower geared than road triples. To compare gears simply divide the chainring size in teeth by the sprocket size to get the 'gain ratio' - these can then be compared

. - e.g. a triple with a 25 sprocket would be 30/25=1.2 and a compact might be 34/28=1.21.

But a MTB triple might be a 26 tooth chainring and a 32 tooth sprocket! = 26/32=0.81!

Chris James

Sorry, I missed the bit saying what your current gearing is. But the principle is still the same.

I wouldn't worry about the overall range (i.e. top and bottom) of gearing too much. It is much the same for triples and compact setups - most triple users run fairly closely matched cassets like 12-23 or 12-25 whereas most compact users have a 12-27 or even 11-28 cassette. The difference is really in how the gears are distributed.

greasedscotsman

Chris James wrote:

the playing mantis wrote:

o ok, i was under the impression a triple would give me the much derided granny gears?!, so here is not much benefit in a triple over a compact?

any ideas on what the lowest gear on atriple would be in mtb terms, and how much thw eight saving from a carbon road bike makes it easier than a heavy old mtb?

If you buy a compact you already have a 'granny' gear - the 34 tooth chainset. What you lose is teh (quite useful) middle chainring.

Be aware that mountain bike triples are much lower geared than road triples. To compare gears simply divide the chainring size in teeth by the sprocket size to get the 'gain ratio' - these can then be compared

. - e.g. a triple with a 25 sprocket would be 30/25=1.2 and a compact might be 34/28=1.21.

But a MTB triple might be a 26 tooth chainring and a 32 tooth sprocket! = 26/32=0.81!

Nice, but don't mountain bikes and road bikes have different sized wheels?

John.T

greasedscotsman wrote:

Nice, but don't mountain bikes and road bikes have different sized wheels?

26" wheel with a 2" tyre is very close to a 700c. Differences are negligible.
If you use a decent gear calculator like Sheldon's set to 'gear inches' you can compare any gears on any size of wheel.
http://sheldonbrown.com/gears/

Secteur

John.T wrote:

Secteur wrote:

the playing mantis wrote:

no stigma from me about a triple... ...didnt wiggo use one in the alps? if its good wnough for the pros its good wnough for anyone.

Pro's dont use triples or compacts, they use doubles. However, by way of some concession, I have heard of even Contador using a SRAM Apex rear mech to give him a 32 tooth cassette for really steep hills. Wiggins prefers osymmetric (?sp) chain rings, which I believe give him higher gears even on the hills, which he believes is traded off by the biomechanical benefits of osymmetric rings (supposedly why he struggled up the Angliru (?sp) in last years Vuelta)

Smallest Osymetric ring is 38. Not sure what rear sprocket Wiggins used but Millar has used an MTB cassette and mech on the back of his bike for some stages.

Sorry - that's what I read - the larger small chainring with the osymmetric

John.T

Secteur wrote:

John.T wrote:

Secteur wrote:

the playing mantis wrote:

no stigma from me about a triple... ...didnt wiggo use one in the alps? if its good wnough for the pros its good wnough for anyone.

Pro's dont use triples or compacts, they use doubles. However, by way of some concession, I have heard of even Contador using a SRAM Apex rear mech to give him a 32 tooth cassette for really steep hills. Wiggins prefers osymmetric (?sp) chain rings, which I believe give him higher gears even on the hills, which he believes is traded off by the biomechanical benefits of osymmetric rings (supposedly why he struggled up the Angliru (?sp) in last years Vuelta)

Smallest Osymetric ring is 38. Not sure what rear sprocket Wiggins used but Millar has used an MTB cassette and mech on the back of his bike for some stages.

Sorry - that's what I read - the larger small chainring with the osymmetric

Smallest ring with 130 BCD is 42 and with 110 BCD is 38. The 38 varies between a 34 and a 42 so can not be any smaller. The 42 goes from 38 to 46.