Dark side – gear ratio question

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  • Dark side – gear ratio question
  • orange_c
    Member

    Thinking of buying a road bike, where I live is quite hilly (some 1 in 5 hills). I can twiddle up these in a fashion in the granny gear on my mountain bike but would a bike with 48/34 at the front and 11-36 casette at the back be suitable for this kind of terrain? Completely clueless about gear ratios.

    thanks

    Completely clueless

    Calling it the “Darkside” would clearly indicate this. πŸ™„

    Premier Icon njee20
    Subscriber

    Personal, as on the MTB.

    That’s not standard gearing though, are you sure about those ratios? I’d stick with the 50/34 chainset, rather than fitting a 48, a bit pointless.

    If you’re absolutely in bottom gear on an MTB then I’d suggest you’ll struggle on a road bike, unless your MTB is a Giant Glory. If it’s a case that you drop to the granny because you’re a bit lazy, and you’re prepared to MTFU a bit then you’ll likely be fine with an 11-28 cassette, which will avoid you needing to fit an MTB mech/cassette.

    To be fair, you’re unlikely to need a 36 at the rear. as njee says if you stick to 11-28 then you can use a std road rear mech, any bigger and you’d have to use an MTB mech.

    Regarding front chainset you’ll be wanting a compact I’d think, 34or36/50 is a usual ratio, 48’s can be had but not std fit so you’d have to buy one additionally. I actually have a 39/48 on my training bike as it’s not that hilly here and the 48 allows me to stay on the big ring most of the time, that and the fact it was in the spares box when the old one wore out!

    orange_c
    Member

    Thanks for the replies – well apart from Teetosugars who need to get out of his own backside.

    Having checked the spec on a few different websites, it consistently says that it is 48/34 although they do another version with 50/34 and 11/25 but costs more and comes with discbrakes. I am guessing that would be better for where I live? Sorry for dumb questions.

    I drop to the granny because I am (whispers) a girl. And I don’t want to get all sweaty as this would make my make up run :mrgreen:

    Premier Icon njee20
    Subscriber

    What is the specific bike?

    Is it more of a cross bike?

    titusrider
    Member

    My wife is running a ‘compact’ ie 34/50 and an 11/28

    She is fine on almost anything for normal rides but when she had panniers on some hills were walks πŸ™‚

    ID try and find a triple if you plan to ever put some luggage on otherwise compact is fine. (imo)

    Premier Icon Dickyboy
    Subscriber

    cover all bases & get a triple, compacts are only made for those not man enough for std gearing & won’t admit to needing a triple

    orange_c
    Member

    It’s a specialised sirrus comp – find drop handlebars scary

    http://www.specializedconceptstore.co.uk/Detail/13sirrus/sirrus/Sirrus%20Comp

    Do plan to use it for lightweight touring and also for commuting but the commute has about 500m of ascent.

    Premier Icon Dickyboy
    Subscriber

    It’s a specialised sirrus comp

    34t chainring & 36t cassette is gonna be pretty darn low to get you up anything I would say & you won’t find a road based bike with much lower ratios.

    I do find that a triple gives you less of a jump between ratios though & might be worth considering the sirrus elite?

    Premier Icon rOcKeTdOg
    Subscriber

    There’s a tiagra cassette that’s 12-30 which’ll get you up anything with a 50/34 compact

    Ignore the bike snobs btw, they might have flash bikes but the’re probably left in the shed most of the year

    Premier Icon GrahamS
    Subscriber

    I went for the new SRAM WiFLi dΓ©railleur on my new cx/road bike.

    That lets you run a proper wide 11-32 cassette, paired with a compact 50/34 front.

    My roadie mates gave me a bit of teasing for the “dinner plate” but soon saw the advantages when I was still spinning on steep hills where they were grinding.

    cover all bases & get a triple, compacts are only made for those not man enough for std gearing & won’t admit to needing a triple

    My compact set up gives me more range than a triple. Just means there are bigger jumps between the gears.

    titusrider
    Member

    Ps everyone is nervous about drop bars when they first use them but they are easy to get used to after a while feeling wobbly! Worth it for the extra hand positions and ability to get out of the wind

    Premier Icon Dickyboy
    Subscriber

    My compact set up gives me more range than a triple

    Love to know how a 50/34 compact gives you more range than a 53/39/30 triple, defying the laws of physics perhaps?

    Premier Icon GrahamS
    Subscriber

    As usual Sheldon Brown* explains gear ratios well and has a handy calculator which is useful for comparing them:

    http://sheldonbrown.com/gears/

    Or Gear Seer is quite good if you are more graphically minded:

    http://www.andrusia.com/gearseer/#

    .

    (* RIP πŸ™ your wisdom is missed as always Sheldon)

    Premier Icon GrahamS
    Subscriber

    Love to know how a 50/34 compact gives you more range than a 53/39/30 triple, defying the laws of physics perhaps?

    Because the road triples are more limited on the cassette range.
    What’s the max size rear you can run on your triple?

    AFAIK Most Shimano set ups are limited to 27t at the back.

    So my 50/34 x 11-32t compact gives me 122.7 to 28.7 gear inches
    Whilst my mate on his 50/39/30 x 12-27t only gets 112.5 to 30.0 gear inches.

    Premier Icon Dickyboy
    Subscriber

    Because the road triples are more limited on the cassette range.
    What’s the max size rear you can run on your triple?

    No, the restricting factor is the capacity of the rear mech.

    I generally run an 11-25 cassette, but chuck on an 11-28 on when touring, could go to an 11-32 if I wanted. All this with ultegra triple & XTR rear mech.

    globalti
    Member

    Love to know how a 50/34 compact gives you more range than a 53/39/30 triple, defying the laws of physics perhaps?

    It gives you roughly the same range as with a compact double, the difference is the lower first gear for hill-climbing and the fact that your cassette can be closer ratio, giving you a much nicer progression through the gears as you speed up. On a compact, the cahnge from the 50 to the 34 is worth about three gears on the cassette so if you don’t want to slow down dramatically as you tackle a hill you’ll need to change from 50 to 34 and, say, two or three gears taller on the cassette. Hope that makes sense.

    There’s a lot of snobbery over triples on road bikes, purists say they shouldn’t be used but unless you’re a hardcore roadie they are very good, especially if you live somewhere hilly. With a compact you are supposed to attack short hills and get up them by momentum rather than by sitting and spinning.

    Premier Icon Dickyboy
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    There’s a lot of snobbery over triples on road bikes

    ^^^^ this & the number of friends who have been advised to buy compacts when non competitive riding in the Chilterns would be more suited to riding a triple.

    Premier Icon GrahamS
    Subscriber

    All this with ultegra triple & XTR rear mech.

    So not actually a road mech then?

    Yes obviously if you start bodging in mountain bike parts then you can run bigger ranges.

    Likewise you can damp down any handlebar vibration on a road bike by simply running 2.1 tyres and a some big travel Bombers πŸ˜€

    glenh
    Member

    orange_c – Member
    Thinking of buying a road bike, where I live is quite hilly (some 1 in 5 hills). I can twiddle up these in a fashion in the granny gear on my mountain bike but would a bike with 48/34 at the front and 11-36 casette at the back be suitable for this kind of terrain

    With a 36 tooth cassette you should be able to ride up a a wall!
    For reference, when I went for a ride at the weekend on fairly hilly terrain with sections up to that sort of steepness, I didn’t go lower than 50/25. That said, I would ride smaller gears than that if I wanted to go faster (which may seem odd, but you need to spin faster the higher your power output).

    Premier Icon Dickyboy
    Subscriber

    So not actually a road mech then?

    so which std road mech does manage a 32t cassette then?

    PS – you call it bodging, I call it mixing & matching – its rapid rise too πŸ˜†

    Premier Icon FuzzyWuzzy
    Subscriber

    48/34 and 11/36 is a decent spread of gears and suited to a hybrid that you could do light touring on as well. If you just want to use it to get fit and start doing longer rides and then maybe join up with other road riders it’s going to be overkill and the big jumps between the gears could end up being annoying. That said you could always change it to say a an 11-30 later and fit a 50 up front if you wanted once you got fitter.

    Premier Icon GrahamS
    Subscriber

    so which std road mech does manage a 32t cassette then?

    The one I linked to earlier, the SRAM WiFLi:

    http://www.sram.com/sram/road/products/sram-force-wifli-rear-derailleur

    Runs up to 11-32, which is what I have, and can be specced off-the-shelf on a new bike (as I did)

    PS – you call it bodging, I call it mixing & matching – its rapid rise too

    πŸ˜€ Don’t you have any issues with it? A quick google suggests problems with pull-ratios and the like when you mix them.

    I’d be interested to know as my mates now want some wider gears for their triples πŸ˜€

    orange_c
    Member

    Glenh – thanks for putting it simply. The hill at the start of my commute does feel like a wall at 7am!

    I think I am getting it – a 50/34 and an 11-32 or 36 would be good but would mean large jumps bewteen gears. Except that the bike does not come in this combination and I just want to get on with riding it not faffing around swapping stuff around (not that I like to get my hands dirty, ruins the nails). So if I get it with the standard 48/34 I will be spinning on the flat? Could I subsequently fit a 50/34 combo with the 11-36 at the back to get a bigger range? Or would this not work?

    Premier Icon Dickyboy
    Subscriber

    Don’t you have any issues with it? A quick google suggests problems with pull-ratios and the like when you mix them.

    Pull ratio differences are only relevant for the front mechs, so you have to run a road bike front mech & chainset, originally I ran it with the road bike flat bar shifters (r440 by memory) now fitted drop bars & tiagra 3×9 shifters, it is fantastic for fast alps touring πŸ™‚ & no problems to date.

    All shimano stuff btw – not familiar with sram myself

    trail_rat
    Member

    id sooner have a triple than a compact again.

    compact are the work of the devil… the jump is horrible.

    Premier Icon GrahamS
    Subscriber

    So if I get it with the standard 48/34 I will be spinning on the flat?

    Nah probably not (unless you’re pretty damn fast!) but you will max out your gears on a downhill a bit faster.

    jonba
    Member

    I’ll wade in with my opinion but without really reading everything above, even the OP πŸ˜‰

    Gears are personal. There are people who will swear they can ride up Alp duez with only a 53 at the front and an 11:23 at the back. This is fine. However, if you can’t that gear mix is useless. The glory is not in pushing a massive gear up the hill but getting to the top first! I consider myself a good climber, I have my name on some hill climbing trophies to prove it. I run a compact chainset and an 11:28 on the back as I prefer to spin. Some people may mock me but they are normally breathing out their arse disappearing off the back of the bunch so I don’t hear them.

    So my advice is not to go with fashion but to get what suits you be that a 36 at the back or a triple at the front.

    It is easy to change a casette compared to a chainset.

    Road bikes climb better than mountain bikes, grip is seldom an issue so standing up and cranking it for a short sharp climb not a problem. This may be the approach you’ll need for short sharp hills. Longer shallower hills are better tackled (by me) sitting and spinning.

    My cross bike has a 46 on the front and 11:28 on the back. I put 32mm slicks on it and ride it on the road occasionally. The gearing is fine for most riding. I can hit 40mph without worrying too much about cadence (See above, I prefer to spin). At 40mph I tend to stop pedaling as the hills round here aren’t that long so there will be a corner or junction coming up.

    For the 3pks I ran a 32 on the back. A long gage ultegra managed that with a bit of fettling. You need to find a longer B screw to stop it hitting the larger sprocket. I had a tiagra 9spd that happily switched between road and mtb gearing.

    You should be able to switch casettes easily enough. if it takes a 36 it will probably take everything smaller.

    You might also be able to get a big ring easily enough for the front. What type of crank is it. Shimano stuff is pretty easy to find replacements. Cross riders often use standard road chainsets and swap rings. You need to know the BCD (spaces between the holes and the number of holes). Spa cycles and sjs cycles has a wealth of chainrings for all wierd and wonderful sizes. Common ones are much cheaper.

    scotroutes
    Member

    GrahamS – I run a 9-speed XT mech and 10-speed Ultegra STIs with a triple crankset on my tourer. Never had any problems, and we are talking thousands of miles.

    antigee
    Member

    So if I get it with the standard 48/34 I will be spinning on the flat?

    possibly i run a 48 front and spin out at about 30mph with a cadence of about 95 – if you spin now your cadence might be higher

    can you borrow a road bike with a compact double and give it go on local hills and see how it feels you might be surprised i very much prefer a triple but some roadies do stuff on a double no problem

    Premier Icon GrahamS
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    Never had any problems, and we are talking thousands of miles.

    Cool. Sounds like that might be a good option for my mates then. Cheers.

    Premier Icon ac282
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    48/34 sounds like a good set up to me.

    48/11 is between 52/12 and 53/12 so your not loosing anything at the top end really.

    traildog
    Member

    OP. You’ll be fine with the gearing the bike comes with. I commute with a 46 chainring and can follow traffic at 30mph with a 12 as the smallest cassette sproket so a 48-11 will seem a huge gear, especially if you’re used to mountain bikes.

    As for the others discussing matching mountain bike and road gears. In terms of Shimano, cable pull does play a part when you start putting 10 speed mountain bike deraillieur on – the pull is different. If you get a 9speed then it all works fine.

    traildog
    Member

    Also for the OP, here is a valuable lesson. Never ask a roadie a simple question about gear ratios… πŸ˜€

    Premier Icon scaredypants
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    9sp mtb mech here, with 9sp stis and it’s lovely

    mine is RR too – more intuitive IMO, though it only takes half an hour to learn any new shifters and then that becomes “natural” too

    I run a triple on both my current road bikes 52/39/30 with 12-25 I live in the Dales am a fat old Bstard and managing 98% of the hills only ones to stop me in the last year have been Park Rash which is 25% for a bit of its 5 miles of climbing and the infamous killer mile of Mow Cop.
    If I was going double I would get a 52/39 with a 12-30 or for closer ratios a 50/36 with a 12-30

    ransos
    Member

    I’d stick with the 50/34 chainset, rather than fitting a 48, a bit pointless.

    50/34 makes for a really horrible jump, you have to change a couple of gears at the back to maintain cadence. 48/11 is about the same as a 53/ 12, which is more than enough unless you’re Cav.

    Newer road rear mechs now take a 30T cassette, which opens up the options for a compact. But ultimately, if you want a wide range and close ratios, it has to be a triple.

    Premier Icon swavis
    Subscriber

    Similar to Colin above, I run a 9speed XT mech with a 10 speed 105 shifter on my Gryphon without problems. I’m using a 34T chainring and 11-36 cassette.

    crikey
    Member

    I’m laughing at all the earnest gear ratio advice; if the OP hadn’t said she was a girl, this thread would have been so much shorter.

    MTFU would have been the gist..

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