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deeper rim rear wheel?

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  • September 7, 2014 at 12:06 am #22324
    lisa76uk

    This might seem daft, and I probably know the answer already, BUT… I’d genuinely appreciate opinions.

    I’ve been making some real gains this year since jumping onto a road bike and actually riding seriously for the first time years. I’m not with a club (yet) and pretty much ride solo. As if it actually counts for anything, I get a few QOMs on Strava when I push myself. I’ve recently started including some decent climbs in my rides and I’m now going to start to incorporate some TT-type training using some clip-on bars on my good bike. There’s some good long straight roads locally. I’m really happy with my bike, have a pretty good riding position and feel comfortable in the drops for longer periods at the moment.

    My current wheels are RS81 C24s which I’m happy with for all the riding I’ve done so far. But I’m wondering if it’s worth swapping out the rear wheel for something with a deeper rim when I’m doing these TT-type training rides. I’m in the North West which always seems to be windy whatever day you go out so I think swapping the front wheel to a deeper rim would just make it twitchy. I realise pros under perfect conditions can make marginal gains over distance, but should I even bother considering swapping out the rear wheel for what I’m aiming to do? Am I likely to see any benefit at all or would it be money down the drain? (I’m looking at the Zipp 60 rear wheel if that makes any difference, about 80g heavier than the RS81 C24 rear wheel).

    Thanks!

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  • September 7, 2014 at 8:15 pm #813299
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    declan bowler 95

    There are far cheaper options
    There are far cheaper options than a zipp wheel. Try planet X, its a lot cheaper (£400-500) for a set of 52mm wheels. Check out their site. Also if you join a club then they should be able to offer some advice.

    September 7, 2014 at 5:55 pm #813297
    0
    lisa76uk

    Blue_Brevatto wrote:You

    Blue_Brevatto wrote:
    You mentioned that you thought you had a pretty good riding position … but is it a perfect riding position ? And is it perfect for time-trialing ?

    Hi. Thanks for our input! I’m sure my riding position is far from perfect, but the fit on my road bike is good. I landed lucky with a good frameset for me and I’ve built it up with parts that suit/fit me. I’m happy with the saddle, stem and handlebar positions (even the cleats feel good) and I’ve dropped the stem down the steerer tube bit-by-bit when I’ve felt ready to. The drop from the saddle to the handlebar is 10cm and I feel comfortable riding in the drops with this set up. I already try to focus on getting a flatter back, dropping my head and tucking my knees and arms in. I’ve ordered a set of Deda Parabolica Due clip-on bars to try out and see if I can improve the bike position further for this type of riding. Obviously I wear (snug) lycra and use overshoes, though I’ve not gone as far as a skinsuit and aero helmet, ha! 😉 I’ve also dropped to a fairly good weight for my build so I’m not carrying ‘too’ much extra body weight.

    Blue_Brevatto wrote:
    If you intend managing with one road bike for all uses then at least you can choose where to compromise and by experimenting you should be able to see what you are losing if you don’t set the bike up purely for TT-ing.

    I’ve been back on a racer since December. I’ve built up a separate commuter from my good bike and it’s not really an issue for me to tweak the set up on the good bike for different types of rides. Ideally I would get a dedicated TT bike, but alas I’ve already built up 2 bikes since December, so I’ll have to tweak the good bike for now.

    Blue_Brevatto wrote:
    So are you measuring your cadence ? Is it optimum for (your) maximum sustainable power output ? Have you compared the cost/benefits of aero rims with that of fitting a power-meter?

    I’m using a Garmin Edge 800 with the speed/cadence sensor and a heart rate monitor. I can’t justify paying out for a power meter, even a relatively ‘cheap’ one like Stages, for now. I’m not in a club yet, not racing and not really sure I will at my age. I just love riding and training hard. I’d love to have power data to use, but, for now, I make do with cadence and heart rate which is useful enough for what I’m currently doing.

    With everything I’m already doing, and hopefully improving with the use of the clip-on bars, if it was of any benefit to me with the training rides I intend to do, the more ‘affordable’ option for me right now would be a rear wheel to swap out for the rides (I’ve seen a Zipp 60 rear wheel for less than £450, whereas a Stages power meter for Ultegra 6800 is around £700). If it’s going to be negligible gains obviously it’s really not worth it and I’d just save the money and use it towards a power meter in the future (or a dedicated TT bike in the more distant future). Thanks!

    September 7, 2014 at 4:34 pm #813295
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    Blue_Brevatto

    I am not a time-triallist so
    I am not a time-triallist so I can’t give you specific advice on kit but from an aerodynamic point of view the vast majority of the drag comes from you and not the bike. I would guess that the part attributable to the rear rim must be less than 1% – possibly a lot less.

    So if you body position is even a few inches out that is likely to cost you much more in wasted effort than a fancy rim will save. You mentioned that you thought you had a pretty good riding position … but is it a perfect riding position ? And is it perfect for time-trialing ? If not then I would suggest getting that sorted first is going to be more beneficial. (either via advice from club-mates – or getting a TT-specific bike-fit).

    My guess (and as I said I’m not a TT’er) would be that the position required for a perfect TT is quite different to that which you would want for normal commuting, leisure riding and climbing. That is probably one reason why TT-ers will often have a dedicated bike (that and it gives them an excuse to buy lots more fancy kit of course – whereas the rest of us just have to invoke the n+1 rule). If you intend managing with one road bike for all uses then at least you can choose where to compromise and by experimenting you should be able to see what you are losing if you don’t set the bike up purely for TT-ing. I would think that any compromise on fit will be much greater than the aero benefit of a deeper rear rim.

    One last observation – you mentioned average speed a lot – and on a flat course that is not a bad measure – it is what ultimately counts in a race. But hills and wind (which you also mentioned) can significantly affect average speed and you never gain from tailwinds what you loose in headwinds. So are you measuring your cadence ? Is it optimum for (your) maximum sustainable power output ? Have you compared the cost/benefits of aero rims with that of fitting a power-meter? I don’t have any of this stuff but then I am not a serious racer. One basic principle I do know however is that if you are serious about improving anything then the first step is to make sure you can measure what you’ve got.

    September 7, 2014 at 7:18 am #813293
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    lisa76uk

    I’m going to be joining a
    I’m going to be joining a club at some point soon, but, even then, I’m still going to be doing solo rides and I’m aiming to be doing this type of training to help me out.

    Just to expand on my qustion, and if any mention of average speeds is relevent to my question, over a 68km (42 miles) loop I regularly do, which is more or less flat except for one ‘bump’ (a drag more than a hill), I average 30-32km/h (19-20mph). On some flatter sections I’m holding 38-40km/h (23-24mph) and hitting higher.

    As I’m going to be doing this TT-type training on long, straight roads where I can currently hold higher (for me) speeds, I’m wondering if I will actually see any of the benefits of a deeper section aero rim, such as the Zipp 60, over the RS81 C24 rear wheel I currently have.

    Thanks.

    September 7, 2014 at 6:19 am #813291
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    CXR94Di2

    Don’t bother, join a club.
    Don’t bother, join a club. I have just joined a club and can just hold onto the pack. If the fastest guys were to put hammer down I would be out of the back in no time. Even the elderly members(65+) are faster than me. 🙁

    I thought I was doing Ok, well 18+ average for 40miles, until I started with the club, but now realise I need more effort on my part.

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