Mtb and road bike efficiency

Discussion in 'Bike buying advice' started by Andy Jennings, Dec 12, 2016.

  1. Andy Jennings

    Andy Jennings Member

    Joined:
    Nov 3, 2016
    Messages:
    58
    Likes Received:
    7
    Given that the bike is a very small amount of the riders speed and efficiency, many years ago I seem to remember reading the the rider was something like 85% and the bike was only 15% of ability (could be incorrect numbers this IS 30 years ago) can anyone give me an indication of the difference a road bike will make over a MTB with near slick tires when ridden on black top roads?

    Aerodynamics, contact resistance and position will, I know, play a part, But will it be all that much more efficient?
     
    Tags:


  2. dabac

    dabac Well-Known Member

    Joined:
    Sep 16, 2003
    Messages:
    1,958
    Likes Received:
    77
    On my XC MTB I can do about 17-18 MPH during an extended effort on good surfaces.
    Same effort - as close I can tell - on my road bike brings me into the low 20s.

    But the road bike feels a lot faster. Wheels are lighter. Tires are firmer. Bike is overall lighter. Steering is more direct.
    There's simply more payoff from pushing some extra power into the pedals.
    On a shorter ride, for as long as I'm able to hold onto that feeling of "this is fun", the road bike has a bigger speed advantage.

    For rides long enough to settle into a steady grind, it drops into some +10%.

    Notes:
    - This is for me. Other may have different experiences
    - My MTB is newer and runs better tires than my road bike.
    - course specifics, a strong headwind, long sweeping descents etc might favor the road bike.
    - I've got a limited range of motion in my lower back, making it difficult to get much aero advantage from a drop bar bike.
     
    Andy Jennings likes this.
  3. CAMPYBOB

    CAMPYBOB Well-Known Member

    Joined:
    Sep 12, 2005
    Messages:
    10,535
    Likes Received:
    773
    Yes.

    It will be more efficient on the flats. It will be more efficient climbing. It will be more efficient descending. It will be more efficient cornering. It will be more efficient when accelerating.

    The longer you ride and the faster you ride the more the efficiency advantage becomes apparent. Every detail of a road bike is designed with energy efficiency foremost.

    Turn off the pavement and...the mountain bike is King Of The Hill for equally obvious reasons.
     
    Andy Jennings likes this.
  4. Andy Jennings

    Andy Jennings Member

    Joined:
    Nov 3, 2016
    Messages:
    58
    Likes Received:
    7
    Thanks dabac and Campybob for the replies. main reason I am asking is I am looking for my next bike and I am doing more road work than off road. More dust road tbh than off road. This is playing havoc with my bike ad the dust is getting every where in to the bike, including the Bottom Bracket. I have had to take it apart, clean and re lube twice in the last 3 months to get rid of terrible knocking in the BB. Not to mention thoroughly cleaning and lubing the drive chain every other day to stop wear and tear.

    My biggest problem in making a decision is my weight. At 265Lbs, even on a MTB, I can't really get a cadence I want as much higher than 90 rpm my legs are bouncing me out of the saddle making contact with my bloody gut. lol.

    I really don't want to have a road bike and not be able to use it much as I am working hard to get my fitness and strength back after a long, 15 year, period of ill health resulting in total inactivity. Losing weight is harder for me than getting fit again with cycling so I want to get a good background there and then add the weight loss after I am in a good place fitness wise. I know this is a bit ass about face methodology, but it works for me.

    I have seen an improvement in speed and times, for set courses, of a little over 35% in 3 months at around the same perceived effort and % MHR (I do realise that this kind of improvement will not continue as the fitter I get the harder it is to improve that fitness. For now however those are the results I am looking at) and really want to get up to my first metric century by the end of February, but the MTB is a touch uncomfortable for the required time frame to do 100k on it and so the consideration of a road bike.

    Anyway, thanks again for the feed back. Always gratefully accepted and taken on board.
     
  5. CAMPYBOB

    CAMPYBOB Well-Known Member

    Joined:
    Sep 12, 2005
    Messages:
    10,535
    Likes Received:
    773
    You can replace most cartridge bearings with versions that have contact seats, labyrinth seals and/or double seals depending on size and application. Contact seals have slightly more drag than the traditional non-contact seals used in many bike bearings, but offer beer protection.

    You can also make you own disposable seals by wrapping greased up pipe cleaners cotton strips or rubber tubing around the bearing in some cases. Not elegant, but it works to keep dust and water infiltration down.

    Simply packing the exposed area with grease or silicone is also an option.
     
    Andy Jennings likes this.
  6. Andy Jennings

    Andy Jennings Member

    Joined:
    Nov 3, 2016
    Messages:
    58
    Likes Received:
    7
    Unfortunately very hard to get stuff out here, Thailand, But now I know what I am looking for I will start looking around the better shops. I'm sure the main guy I go to can order something for me if not in stock. Don't care about the drag fi it's going to save the potential wear and tear. Problem is language barrier and distance, so a phone call wont do the job unfortunately. lol. But i'm out there next week so I will pop on and have a chat with him then.

    many thanks again Campy Bob.
     
  7. dabac

    dabac Well-Known Member

    Joined:
    Sep 16, 2003
    Messages:
    1,958
    Likes Received:
    77
    If you have pedals with a foot-retention system, work on one-legged riding. That's an efficient way to practice a smooth pedalling stroke.
    Simply slip one foot off the pedal at at a time, park it somewhere out of the way and pedal with the other.
    If all you manage are 30 second intervals, that's fine.

    You'll probably want to shift to an easier gear.

    Don't try to pull as hard up as you're pushing down, that's not what it is about.
    (almost) all useful power comes from the downstroke anyhow.
    What you're trying to do is to teach your leg to get out of the way by its own accord rather than being shoved upwards by the pedal, which is why you're getting bounced off the saddle.
    In theory, having zero force on the upward bound pedal would probably do the trick, but a slight upward pull is an easier training goal.
     
  8. CAMPYBOB

    CAMPYBOB Well-Known Member

    Joined:
    Sep 12, 2005
    Messages:
    10,535
    Likes Received:
    773
    Andy Jennings likes this.
  9. CAMPYBOB

    CAMPYBOB Well-Known Member

    Joined:
    Sep 12, 2005
    Messages:
    10,535
    Likes Received:
    773
  10. CAMPYBOB

    CAMPYBOB Well-Known Member

    Joined:
    Sep 12, 2005
    Messages:
    10,535
    Likes Received:
    773
    And like I said...don't be afraid of experimenting with making your own ersatz 'seals'. Decades ago, when 1" headset bearings wear loose ball designs, guys used to cut up old inner tubes to make slip-over 'jacket' seals to keep crap out of the headsets. I also used to silicon seal a plastic bar-end plug into the bottom of the steerer tube/fork crown.

    Now, we can buy Velcro installed versions...progress!
    http://www.jensonusa.com/!0IYla6CFj...&pt_keyword=&gclid=CKvXy9zZ89ACFd61wAoddRYCPA
     
    Andy Jennings likes this.
  11. Andy Jennings

    Andy Jennings Member

    Joined:
    Nov 3, 2016
    Messages:
    58
    Likes Received:
    7
    Thanks for the advice. You actually passed it on to me in another thread as well. lol I have started doing the one leg pedaling based on that. Only problem I am having is that even putting a small amount of positive pressure on the up stroke I have the same problem. Not sure if it's the trailing leg being pushed up or literally my gut getting in the way and being hit by the trailing leg. I will keep working on the pedaling technique though as I need to get a smother action going and hopefully things will improve. If not I am making a concerted weight loss effort now that I am fitter and stronger on the bike so if technique is not the problem I should hopefully get rid of the gut.

    Many thanks for both links and iformation. I am off to my better stocked LBS later this week, long drive unfortunately, so I will have a chat with them to see if they have anything in stock or can order locally first. If not I will get on it myself.

    I must admit I am only having this problem on my wife's bike, with lower quality components. I'm doing more Dirt Km than she is with no BB hassle. If necessary I will research if changing her BB for a higher quality one will make a difference.
     
  12. Froze

    Froze Well-Known Member

    Joined:
    Jul 13, 2004
    Messages:
    3,314
    Likes Received:
    161
    Not sure why no one has addressed this but the OP stated he weighs 265 pounds, most road bikes are designed for riders under 225 pounds. I would recommend going with a cross bike with large diameter tubing, but even with those bikes you need a strong wheelset because most wheelsets are only made for 225 pounds or less which you'll find on cross bikes.

    This means you will probably need to have special wheels made like a 36 hole Mavic A319 that can handle 28 to 47 mm tires, built with Dt Alpine III, which may sound like an overkill but the wheels will stay true for a very long time which means it will be very reliable, or maybe the DT Super Comp but I personally would use the Alpines III's because I like things over engineered to reduce reliability issues.

    My tightwad innerself say that I would continue to use the bike you have now and simply find some slick MTB tires for, that bike has been holding up well for you so there no sense in trying to go to road bike for speed. Good slick tires like the Specialized Fat Boy
     
  13. Froze

    Froze Well-Known Member

    Joined:
    Jul 13, 2004
    Messages:
    3,314
    Likes Received:
    161
    ,
    My computer jumped on me and posted before I was done.

    Schwalbe Kojak Slick, and the Maxxis Xenith slick are all good slick tires make for road use only.
     
  14. Andy Jennings

    Andy Jennings Member

    Joined:
    Nov 3, 2016
    Messages:
    58
    Likes Received:
    7
    Thanks for the reply Froze.

    I knew weight would be an issue for this but wasn't as yet aware of the limit, so good info for me thanks.

    Because of the weight issue, this is a plan ahead bit of research, probably too far ahead admittedly, as I have such a limited amount of knowledge and limited amount of resources available to me in Thailand. The main reason I started looking at things so early is that I may have to either import a bike, big tax though here, or a frame, substantially lower tax, and build it myself. That's if I can't find the bike I want in one of the few good LBS in thailand. I am already looking 750Km away from home just for a professional fitting. lol

    I have a set of more road friendly tyres one the MTB atm, not slick though, that I can use on the compacted dirt roads surrounding my area as well as the blacktop. I may well invest in a set of slicks to use for longer road rides though.

    Many thanks for your input here Froze, Very much appreciated.
     
  15. Froze

    Froze Well-Known Member

    Joined:
    Jul 13, 2004
    Messages:
    3,314
    Likes Received:
    161
    No prob, that's what we're all here to do.

    Not sure what kind of tires you have but if you do hard pack dirt there are tires for that too like the Schwalbe Sammy Slick, not a slick like the 3 tires I mentioned earlier but it has a middle section designed for pavement and hard packed dirt with slightly deeper lugs on the sides for traction when turning, or the Michelin Country Rock tire that uses a consistent tread design that is also again good for street and hard pack dirt. But having said that, I've ridden hard pack dirt on slick narrow 700 x 23c road tires and never had an issue with traction even riding at 18 mph or so, so I doubt you would have an issue on hard pack dirt with a much wider 26 size mtb tire. But those things are a judgement call you have to make depending on your comfort level of how you feel you can handle your bike. I've even ridden 23 C tires in gravel, not fast mind you probably around 5 to 10 mph depending on how loose the gravel got, but I was able to ride a gravel road for several miles on narrow slick road tires.
     
Loading...

Share This Page

Loading...