TRiple chainset

dave_s
dave_s Posts: 4,362
edited August 2007 in Road beginners
I've just bought a Specialized Allez Elite 30
http://www.cyclestore.co.uk/productDeta ... uctID=8385

I need some advice on chainrings for this bike, it's early days yet but I think I might want to go for a 52 or 53 outer chainring rather than the 50t one on the bike now.
Firstly, would that be ok for the derailleur to handle that range of gears and if so, what type of chainring would I have to order.
According to the Spesh site, my bike has a slightly longer derailer than the Elite 20 so I'm hoping this means it will cope with the gears range.
I'm from an MTB background so I know what to order in MTB chainrings but I'm a bit lost with racer chainrings.

The chainset on the bike is a silver FSA Gossamer Megaexo.
I realise I'll have to get a new chain if I go up to a 52/53 outer chainring too.

Very happy with the bike though
Dave S

Comments

  • Fab Foodie
    Fab Foodie Posts: 5,155
    Yep derailiuer will be fine, no need for a new chain either...if you can spin-out a 50T chainring with an 12T on the back then....respect! That's a lot of MPH.

    Stick with it a while, there's not much to be gained to go to 52 unless you have mega-monster sprinter thighs.

    The pessimists of this world are rarely disappointed....
    Fab's TCR1
  • With wheels of 2.1-metre circumference and a cadence of 90 RPM (and most people can go to at least 120 RPM, but I guess it would be better to have gearing to avoid that), 50 x 12 works out to 29.4 mph or 47.2 km/hr. So very fast indeed but perhaps possible in a sprint on the flat, and easy down a sufficiently steep or long hill. A 53T chainring would increase the 90 RPM speed to 31.1 mph or 50.1 km/hr.

    In real life, almost all new cyclists and far too many experience cyclists pedal far too slowly, thereby wasting energy, damaging their knees, and making them think they don't have high enough top gears. But I doubt Dave is pedalling too slowly. More likely going too fast! :D
  • dave_s
    dave_s Posts: 4,362
    I think it's probably a case of testing out the new chainset a bit more.
    Even on my MTBs I'm told that I tend to push a bigger gear than usual by a mate at work who's more into road riding.
    On my MTBs I have a 44t outer and generally cycle in the 3rd from smallest cog on a 11-32 cassette.
    Obviously this hovers me around the 20mph mark which is ok.
    It's a hell of alot easier to get to that speed and stay there on the Allez though

    Even on my short test ride on my Spesh Allez, I found myself creeping towards the end of the available gears but maybe that was excitement at my new ride.
    Got to say, it's a massive improvement on my old Peugeot Virenque Alu bike, the Allez seems a bit more forgiving on the tarmac probably improvements in frame and fork design I suppose.
    Dave S
  • I took a look at the specs of your new bike Dave (very nice, by the way). 700 x 23C tyres have a circumference of about 2096 mm, and your 12-27 cassette goes has sprockets with 12, 13, 14, 15, 16, 17, 19, 21, 24 and 27 teeth.

    So, cruising at 20 mph at 90 RPM in the 50T ring needs a 17.6T rear sprocket, i.e. the 17T sprocket on your bike. That's a decent place to be: middle of the cassette so plenty of flexibility either way. Personally I like my high-speed cruising gears to be in 1-tooth increments so that I can get the exact cadence I like as speed varies a little. (But I've noticed I'm really fussy about cadence compared to my mates.) On your bike, going from the 17T to the 16T is only one tooth, but from 17T to 19T is two. But putting a 53T chainring on would only worsen this situation, moving the chain onto a bigger cog where the differences are at least 2 teeth either way on your cassette.

    All that is meaningless if you cycle with a lower cadence than 90 RPM, which it sounds like you do. Assuming your mountain bike wheels are about 2070 mm in circumference and your third-smallest cog is 14T, doing 20 mph on your mountain bike returns a cadence of 82 RPM. That's not too bad actually. Now, converting that RPM back to your road bike in the 50 x 12 gear, gives you a speed of 26.8 mph or 43.2 km/hr.

    Which is still bloody fast! :D
  • dave_s
    dave_s Posts: 4,362
    Dorian,
    Cheers for the advice on that, I think I'll try out the 50t outer for now based on what you've said. I'm very happy with the bike so far and have been looking for one for a while for longish (50-100mile) road rides and think the Allez will do the job.

    I'm not really well up on road bikes but have looked around at specs and I think the Allez Elite 30 is a decent enough spec for the money I paid for it and I totally trust Specialized as a brand based on nothing but good experiences of MTBs I've had by Spesh.

    The only thing I'm not that pleased with is my choice of pedals in Shimano A520 which I thought were a good idea at first but I actually prefer double sided SPDs really so I've ordered some Time Atac Aliium pedals instead and will only use the A520s as a backup now. The Time pedals are MTB pedals really but I've been riding double sided SPDs for years now and can't get on with having to flip pedals to clip in
    Dave S
  • penugent
    penugent Posts: 913
    dave_s wrote:
    I think it's probably a case of testing out the new chainset a bit more.

    Even on my short test ride on my Spesh Allez, I found myself creeping towards the end of the available gears but maybe that was excitement at my new ride.
    .

    For what it is worth, that is exactly the position I found myself in when I switched from a MTb to my first road bike. I had a 53T chainring and thought I was spinning out. I found it all settled down and I recently took the 53T off and replaced it with a 49T, which I find much more useful in general riding.

    BTW, enjoy your new bike.
  • dave_s
    dave_s Posts: 4,362
    Penugent,
    Thanks, I'm beginning to think it could be that
    It's a long time since I rode a racer (about 5 or 6 yrs) and I think I'll be keeping the 50t for a bit and see how it goes.
    Sounds like it will be enough judging by the advice in this thread
    Dave S
  • richa
    richa Posts: 1,631
    dave_s wrote:
    can't get on with having to flip pedals to clip in
    They should hang so that they never need to be flipped.

    Have you thought about getting a smaller cog on the rear. I expect you have 12-23/25. You could go for an 11.
    Rich
  • jedster
    jedster Posts: 1,717
    dave,

    I've just been messing around with exactly this issue:
    HAd 50/39/30 with a 12:25 cassette

    Rightly or wrongly, I was tending to use the middle ring as my default for rolling/uphills and use the big ring for very flat sections or downhills.

    The whole transmission was due an overhaul and I decided to change the middle (most used) ring as well as the chain and cassette. It seemed to me that despite having a triple, the gear range was relatively limited so I thought I might go for a 42 middle and a 12-27 cassette meaning that I would need to change up to the big ring even less and had an even lower gear in the granny ring.

    Ah, but there's a problem. You can't get the front mech to shift properly between a 42 and a 50 - either it hits the 42 ring when trying to change up or its too high above the 50 to change down properly ( I don't know if you acn run 52/39 on a triple but I rather doubt it). So I've now replaced the 50 for a 52. I thought this might be a bit silly but on the strength of this morning's ride it is useable - I'm very happy in the middle of the cassette with the 52 ring on the flat. I can imagine using 52x12 on long downhills. I do like the extra range in the middle ring.

    Net net - it's fine switching from 50/39/30 to 52/42/30 but I wouldn't be ina hurry to make the switch until you've given the current rings a good hammering.

    J
  • Diogenes
    Diogenes Posts: 1,628
    I have a 53/40/30 with 12 to 25.

    I am happy with this set up as I can get large range on the middle ring but on the flat (and especially with a tailwind) I can cruise along on a big gear.

    Also I find that the lightweight whippets seem to spin with ease whereas the heavy guys like me struggle to spin for more than an hour or so. On long rides I often turn a bigger gear and as long as I m not going uphill I can keep it up for a long ride of 5 -6 hours. When I do go uphill the granny ring comes to life, perhaps if I could spin I would not need it so often!



    D :D
  • dave_s
    dave_s Posts: 4,362
    For the pedals, I'm slightly getting used to the one-sided Shimano ones now but they definitely prefer to hang upside down so I either flip or find that a half rotate of the crank seems to work too.
    I'll prefer it with double sided Time Atacs though I'm sure.

    For the gears, it is a 12-27t cassette but I'm starting to think the 50t chainring will be ok now after a couple more rides.
    If it isn't enough I would deffo look at a 11-23 or 27 cassette as an easier option rather than get a bigger chainring.
    Gear changes are so smooth that I have to check it's in the right gear at the moment.
    On my MTBs there's a clunk when it engages but the road bike just shifts alot smoother
    Dave S