45 tooth rear sprocket evaluation on pavement
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Thread: 45 tooth rear sprocket evaluation on pavement

  1. #1
    Senior Member old w/??'s Avatar
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    45 tooth rear sprocket evaluation on pavement

    I may not do anything more off-pavement soon, other than dirt/gravel roads; so thought I'd test a 45 tooth. Only required: switch sprocket and shorten chain one set of links. No new chain required until I try a 55 tooth rear.

    2014 TW, no performance mods, 2,300 elev, 185 lb rider, 87 octane NON-ethanol. Not to compare mine to yours, just 50 tooth vs 45 tooth.

    Test #1: 60 miles, mostly flat with a few short hills, paved back country roads, 10 stop signs, steady 45 mph.
    50 tooth held 5th gear throughout.
    45 tooth had to use 4th gear once or twice for 5 seconds to maintain 45 mph on hills.
    Result: Smoother more comfortable ride due to less buzz/vibration and fuel mileage improved 6 mpg over 50 tooth.

    Test #2: 60 highway miles (30 each way), some slight grades, steady 60 mph.
    50 tooth held 5th gear throughout.
    45 tooth had to use 4th gear quite a bit to hold 60 mph on the grades, especially into the wind.
    Result: 4th gear 45 tooth had a little more buzz/vibration than 5th gear 50 tooth -but-
    45 tooth 5th gear was a MUCH smoother and more comfortable ride than 50 tooth.
    Even using 4th gear on the grades; fuel mileage improved 5 mpg over 50 tooth.

    Test #3: 2 miles, 6% grade, full throttle test.
    50 tooth 5th gear - 58 mph at bottom - 55 mph through middle - 58 mph at top.
    50 tooth 4th gear - 56 mph at bottom - 57 mph through middle - 58 mph at top.

    45 tooth 5th gear - 52 mph at bottom - 42 mph throughout most - 40 mph at top.
    45 tooth 4th gear - 57 to 59 mph with almost no fluctuation off 58 mph.
    45 tooth 3rd gear - 55 mph bottom to top.

    Test #4: Maybe 1/2 mile, steeper grade, full throttle test.
    50 tooth 5th gear - low of 46 mph - high of 48 mph.
    50 tooth 4th gear - low of 48 mph - high of 54 mph.

    45 tooth 5th gear - USELESS at steady 31 mph.
    45 tooth 4th gear - steady 50 mph.
    45 tooth 3rd gear - steady 52 mph.

    My opinion: For "street only bikes" or "those whose off-pavement riding may only be hard packed dirt, gravel, fire-roads etc.", a 45 tooth is a winning improvement. With a simple down-shift to 4th you pretty much give up nothing to a 50 tooth (even in 4th), and gain a much smoother, more comfortable bike with improved fuel economy.

    A lot of non hard-core off-road situations (and some hard) you may find 2nd gear a little too high and 1st gear a little too low. This might make 1st a sweet spot; like gearing lower and 2nd becoming perfect.

    The biggest drawback to the 45t would be on off-road downhills. On those; I want the lowest gearing/most engine braking possible, if needed!

    -----------------------------------------------------------------------------------------------------------------------------
    ADDENDUM 102614: 55 tooth rear on hill tests (no 60 mph test done):

    2 miles 6% grade full throttle
    55 tooth 5th gear - 53mph bottom - 56mph through middle - 53mph top

    1/2 mile steeper grade full throttle test:
    55 tooth 5th gear - 52mph bottom - 56mph top
    ---------------------------------------------------------------------------------------------------------------------------
    Update: February 2017: (my testing above had been done in calm weather) Have had a 65 tooth on for quite awhile. Tested a 35 tooth and then put the 45 tooth back on. Went out in strong winds and could barely hold 55 on a flat road into the wind and could barely hold 45 up a slight but long rise by shifting to 4th. So I am amending my opinion to: the 14-45 is lacking in very windy conditions. I put the 50 tooth on and got to 60 on the flats. In the future, I hope to try 14-47 or the equivalent 15-50.

    Update: March 2017: Tested 14-45, 15-50 and 15-45 (equivalents of 14-47 and 14-42) on the freeway. No gearing setup higher than stock would hold 60 mph in the wind in some sections regardless of being in 4th or 5th gear.

    So I just ordered a 42 tooth rear. The 15-42 is equal to a 14-39 setup.

    Update April 2017: Tested 15-42 which is equal to 14-39. My motor is totally stock - unlike some who have gone to this gearing set-up. I do not recommend these gear set-ups with a stock motor, as I felt there was too much lag (bogging taking off from a stop) for everyday use. I switched to 15-45 and had no problem - and was holding 60+ on sections I had problems before.

    Update June 2017. Admiral loaned me his 44 tooth and I tested it today 15-44 which is equal to a 14-41. It did not have the bogging problems taking off from a stop like the 15-42 did; and was able to hold 65 with a shift to 4th if necessary (where the 42 tooth wouldn't hold 60 in 5th or 4th).

    So: 15-44 / 14-41 is the highest gearing I can recommend for a stock motor - unless I get a 43 tooth to test with my 15 front (equal to 14-40 "within 15rpm").

    So, knowing 15-44 or 14-41 is good - and 15-42 or 14-39 fails with my stock motor:

    Anybody have a loose 43 tooth sitting around that I could borrow to complete this test. I would pay shipping both ways.
    Last edited by old w/??; 06-16-2017 at 02:35 PM.

  2. #2
    Senior Member dogonit's Avatar
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    Hi old w/2 many guns and bikes: Quite interesting data. What about the torque you are forgoing? Does that ever seem a problem in initial acceleration or when going slow and having to go up a steep road?

  3. #3
    Senior Member old w/??'s Avatar
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    Quote Originally Posted by dogonit View Post
    What about the torque you are forgoing? Does that ever seem a problem in initial acceleration or when going slow and having to go up a steep road?
    Just did the 45 tooth test yesterday, and was not focusing on that. Had not noticed anything unusual. Actually thought it felt about like my KLX 250s 1st gear rev around town. But after reading your post, ran out now to see what its like from dead stop on flat - no hill close by. Took about 3 feet before really accelerating - though this may not mean much because I didn't test this with the 50 tooth. A little longer usable 1st gear means not having to shift to cross an intersection (one lane each way with a turn lane).
    When testing on the 6% and steeper grade section, there was just a slight uphill start area, but I didn't notice anything that made me even think about that - although of course it would take longer to get up to speed. But since I just made the change, I'll post if I find anything different.

    Addendum 102614: testing a 55 tooth and still had about 3 feet before really accelerating-so no real difference.
    Last edited by old w/??; 10-26-2014 at 03:34 PM.
    Smitty Blackstone likes this.

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  5. #4
    Senior Member old white truck's Avatar
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    OW2MG&B,

    Congratulations to you! It is great that you took time to do testing and then posted your detailed quantitative results for all of us. Questions about 45 and 47 tooth changes come up all the time. Now you can point them to some to real data.

    Very useful.

    I look forward to hearing your real world feedback after you have had a chance to use this for a couple of months.

    Thanks again.

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