Polar Power sensor with triple chainring

Discussion in 'Power Training' started by kneighbour, Apr 30, 2003.

  1. kneighbour

    kneighbour New Member

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    I have fitted a Polar S720i with the Power Output sensor to my Softride Solo road bike.

    I also have triple chainrings fitted, and all components are standard 105 or equivalent.

    I have a problem with the Power sensor. It sits on the chainstay bar underneath the chain. As the chain passes over it, it measures chain speed and vibration, somehow or other working out the Power at the pedals from that. This seems to work ok.

    The problem is when I drop down to the third chainring (the smallest one, 30 teeth, I think), the chain gets very close to the Power sensor. If I drop the chain down about halfway on the rear cassette, the chain actually gets dragged onto the sensor, and gets dragged across it.

    The problem is that the sensor is a very strong magnet, and this drags the metal chain down onto it. So the chain is dragged across the sensor while you are pedalling - doing all sorts of damage I have no doubt.

    There is no way to make the gap any bigger, which is my problem.

    Does any one else have this problem?? Can anyone suggest a solution?
     
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  2. clever_guy

    clever_guy New Member

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    kneighbour;

    Can't help you on the Polar/Power Output sensor, but...

    Great choice in bikes! I have a Softride Solo with 105 as well.

    :)

    -CG
     
  3. kneighbour

    kneighbour New Member

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    Good stuff! Softrides are VERY rare here in Brisbane. I know of only two other here in Brisbane at all.

    I have been trying to get an answer to this for some time, but as I do not know any other Softride owners, it is difficult.

    I have fitted flat bars to my Solo - mainly on the advice of the bike shop owner. Much better comfort, etc. Since I am 51 and I got the Softride for comfort in the first place, this seemed the way to go.

    I recently rode a "normal" road bike for the first time ever - and it had dropdown bars on it as most road bikes do. The difference between that bike and the Softride was remarkable. It was so much easier climbing hills it startled me. It was even faster on the flat. And this was a fairly cheap Raceline with a Tiagra groupset - nothing special at all. I had a sore back at the end of the day - but at the time I frankly did not care at all!

    I am now wondering what to do with the Softride to get the same sort of performance as the Raceline. The weight of the Raceline was about 10kg, and the Softride is around 14kg.

    My first thought is to replace the flat bars with dropdowns. But as this is a fairly expensive thing to do, I am not convinced. (around AUD$700 for Tiagra - no idea what 105 stuff would cost, I hate to think).

    In your experience with the Softride, does dropdowns make all that much difference? Should I go to dropdowns at all?

    I am even thinking of buying an entry level "normal" road bike - just for the hillier and faster rides I go on. I do not race - I am doing it mainly to get fit.

    Any thoughts?
     
  4. rek

    rek New Member

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    I find drop handlebars much more comfortable than flat bars -- mainly due to the fact there are multiple hand positions. My hands go numb after about half an hour riding a bike with flat bars, even when wearing padded gloves.

    I don't know what sort of frame Softride bikes have, but it sounds as though it is more a touring-oriented road bike than one designed for speed and high speed agility. Dropping 4kg off the bike weight is going to be very expensive! You'd probably find it cheaper to buy something like that Raceline, and keep your Softride for the more recreational rides where speed and such isn't that much of a concern. Horses for courses, and all that.

    Road bikes, when properly set up, are very comfortable for long rides. If you had some back pain, I think the bike might not have exactly been right for you (in terms of frame size, saddle and handlebar height, etc.)

    (I don't race either, but the razor sharp precision and sheer acceleration of a proper road frame is addictive! :) )
     
  5. rek

    rek New Member

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    Oh, and about the power sensor .. I don't have one myself (when I have some spare money for one I definitely will though!) but I have heard that a number of people put a layer of sacrificial electrical tape over the top of the unit to protect the cover of the sensor.
     
  6. clever_guy

    clever_guy New Member

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    kneighbour - I use drop bars, Profile Design AirStryke Aero bars, Profile Design RC fork, Syncros neck, full Shimano 105 flight deck, and Ambrosio wheelset. So it's a pretty light setup. If you are going to spend the money anyway why not upgrade the Solo? It is a great frame set.

    Rek - The Softride Solo (http://www.softride.com/) is an entry level race bike. Unfortunately the UCI and UTI have deemed the frame design to have an competitive advantage over "standard" frame designs and as such illegal in competition. So you see Softrides more on the Triathalon side. The Solo is the older design used by the Coors Light team in the early 90's, Ryan Bolton the 2002 Ironman USA Champion rode a new Softride design. I would compare the Softride solo to mid-range Cannondales, Treks, and Lemonde's I tried. It is a different feel but when you get used to it, it corners fantastically.

    -CG
     
  7. kneighbour

    kneighbour New Member

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    That is what I am deliberating over. The problem I am having is that there are no Solo riders around here for me to talk to. Your feedback is very useful to me, and I am ecouraged by what you are saying.

    When you say "ugrade", what do you mean exactly?

    My vague intentions are to put on dropbars, plus 105 gear shifters. The rest of the drive train is 105, so that seems ok.

    This will cost me around AUD$850 - plus I suppose I will "need" a Flight Deck computer (another $250 or so, I think).

    The standard Solo frame actually comes with carbon forks now, so that is ok.

    I am also using a Softride cro-mo Powerstem. This looks fairly heavy, and I guess it is more for MTB than road bikes. But it does a great job of taking out road vibrations. I would hate to lose it...

    Does this sound like what I should do to you?
     
  8. clever_guy

    clever_guy New Member

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    kneighbour;

    Upgrade = upgrade components around the frame set (Solo).

    The solo frame itself is a little heavy (being aluminum with sturdy welds), but it is stiff and really puts the power to the rear wheel. It wasn't designed initially to be a MTB frame, it was designed as a stiff road frame, but as the design is aging I think Softride is trying to get as much out of it as possible. I ride over some pretty broken roads and paths, and I really appriciate the carbon beam suspension. The only thing I have debated changing on mine is the groupo. I think I would rather have the Ultegra, its a little smoother and wears better - but that's a good amount of $$$ to upgrade.

    I don't think a few kg's makes a big difference, but I am not a competative racer. I'm not likely to drop $8k on a an all-carbon frame/dura-ace(campy)/carbon-wheelset, to loose a few lbs - cheaper to drop a few kgs off the rider..

    ;)

    The Softride stem is more for MTB, but it works for road. It is a little heavy (over-built) for road. I went with a much lighter stem. But if you like it keep it, it does eat road vibes well.

    If you like the feel of the Solo then by all means do the upgrade. I don't think you will be disappointed. I know my next bike is going to be another Softride!

    Hope it helps,

    -CG
     
  9. chuy

    chuy New Member

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    I just got the power kit today for my kona kapu road bike and am having the same problem as kneighbour. I will try the electrical tape and see how it goes, as well as calling polar and seeing what solutions they offer if any.
     
  10. kneighbour

    kneighbour New Member

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    Polar did not seem to understand my problem - simply quoting almost verbatim the mounting instructions yet again.

    But I did seem to find a solution - at least a partial one.

    I went to the LBS and bought a chainstay protector. This particular one is a very thick, clear plastic film about 6 inches long by 3 inches wide that I stuck on top of the power sensor. I then trimmed off the excess bits of plastic, and it seems to work ok.

    The thing is so thick it seems to do the job. And being plastic it does not interfere with the sensor operation.

    Until we get a real answer from Polar, this seems a good tempory solution.
     
  11. ART

    ART New Member

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    Read my response to Bikemerry above. I have this problem with my very standard double chainring/cassette setup 52/39;12-23. This is unacceptable from a company like Polar. There is no solution for your problem other than not using the gear combinations that cause this problem.

    Art
     
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