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Mountain bike wheels + Road frame?

Started by Jim Rogers · · Last activity · 7 posts · 494 views

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01 / Original postMountain bike wheels + Road frame?Jim Rogers · 24 Feb 2005 02 / This pagePosts 1–7Page 1 of 1 · chronological order 03 / Latest replyPost #7Tom Sherman · 26 Feb 2005

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Original section
Cycling Equipment
Published
24 February 2005
Last activity
26 February 2005
Original author
Jim Rogers
Posts
7
Discussion status
Public discussion
Total views
494
Views / 30 days
0
Topics
Mountain bikingTouringCrank arm lengthFrame geometryRim brakesTitanium frames

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  1. Original post
    Jim Rogers
    Archived post
    #1

    I was looking into setting up a touring bike for my wife. I have an old
    Bridgestone road frame that is just slightly too big for her, but I
    also have an excellent set of 26" mountain wheels that I don't use
    much. So I was thinking about running the mountain wheels in the road
    frame.

    Taking the diameters of each wheelset + tires, the switch to mountain
    wheels will lower the bike by about 0.9 inches, which would make the
    stand-over height perfect for her. Harris Cyclery sells extra-long
    reach brake calipers that would fit.

    The BB height on the bike with the 700c wheels (700x23 tires, 672mm
    diameter) is about 10.4 inches. Thus, the switch to mountain wheels
    (26x1.25 tires, 624mm diameter) would put it at about 9.5 inches. (BB
    drop is about 7cm) There would also be some affect on the trail.

    I know a 9.5" BB height is far below standard acceptable height, but
    is it crazy low? My wife is never a speedster, and this bike would be
    used for low-speed, loaded touring, leading me to think it would not be
    a problem. On the other hand, she's not particularly bike-savvy, so I
    don't know if she would be careful about keeping the low-side pedal up
    during (rare) high-speed turns. Since the point of this conversion is
    low cost, I'd rather avoid getting new (shorter) cranks.

    If the BB height is not a killer, are there any other reasons to not do
    this conversion? If this is a dumb idea, I would consider getting a
    Surly Long-Haul Trucker frame. Her size in that frame would take the
    26" wheels I want to use. However, I'd love to get some life out of
    the Bridgestone frame I have, so I'm studying this option first.

    Any advice?

    Thanks,

    Jim Rogers

    Report
  2. Mark Hickey
    Archived post
    #2
    Jim Rogers said:

    If the BB height is not a killer, are there any other reasons to not do
    this conversion? If this is a dumb idea, I would consider getting a
    Surly Long-Haul Trucker frame. Her size in that frame would take the
    26" wheels I want to use. However, I'd love to get some life out of
    the Bridgestone frame I have, so I'm studying this option first.

    A couple things to think about...

    1) if she does manage to put a pedal down going around a corner, your
    life will become hell in lots of different ways... ;-)

    2) whatcha gonna do for brakes? You'd need some VERY long caliper
    brakes to reach those itty bitty little rims (they're 31.5mm futher
    away from the brake bridge). You MIGHT be able to get by with a pair
    of the Tektro 78mm calipers... but it'll be close (and they're not
    that great, but they ARE cheap).

    Mark Hickey
    Habanero Cycles
    http://www.habcycles.com
    Home of the $695 ti frame

    Report
  3. Jim Rogers
    Archived post
    #3
    Mark Hickey said:
    Jim Rogers said:

    If the BB height is not a killer, are there any other reasons to not


    do

    Quoted message said:
    Quoted message said:

    this conversion? If this is a dumb idea, I would consider getting a
    Surly Long-Haul Trucker frame. Her size in that frame would take the
    26" wheels I want to use. However, I'd love to get some life out of
    the Bridgestone frame I have, so I'm studying this option first.

    A couple things to think about...

    1) if she does manage to put a pedal down going around a corner, your
    life will become hell in lots of different ways... ;-)

    2) whatcha gonna do for brakes? You'd need some VERY long caliper
    brakes to reach those itty bitty little rims (they're 31.5mm futher
    away from the brake bridge). You MIGHT be able to get by with a pair
    of the Tektro 78mm calipers... but it'll be close (and they're not
    that great, but they ARE cheap).

    Mark Hickey
    Habanero Cycles
    http://www.habcycles.com
    Home of the $695 ti frame

    Report
  4. Jim Rogers
    Archived post
    #4


    Quoted message said:

    1) if she does manage to put a pedal down going around a corner, your
    life will become hell in lots of different ways... ;-)

    That is exactly what I'm worried about!

    Quoted message said:


    2) whatcha gonna do for brakes? You'd need some VERY long caliper
    brakes to reach those itty bitty little rims (they're 31.5mm futher
    away from the brake bridge). You MIGHT be able to get by with a pair
    of the Tektro 78mm calipers... but it'll be close (and they're not
    that great, but they ARE cheap).

    I already measured, the 78mm will just work, otherwise I would not even
    have considered the conversion.

    Are these brakes not good? I don't need brake issues on top of the BB
    height issue.

    --Jim

    Report
  5. Mark Hickey
    Archived post
    #5
    Jim Rogers said:
    Quoted message said:

    1) if she does manage to put a pedal down going around a corner, your
    life will become hell in lots of different ways... ;-)

    That is exactly what I'm worried about!

    Quoted message said:

    2) whatcha gonna do for brakes? You'd need some VERY long caliper
    brakes to reach those itty bitty little rims (they're 31.5mm futher
    away from the brake bridge). You MIGHT be able to get by with a pair
    of the Tektro 78mm calipers... but it'll be close (and they're not
    that great, but they ARE cheap).

    I already measured, the 78mm will just work, otherwise I would not even
    have considered the conversion.

    Are these brakes not good? I don't need brake issues on top of the BB
    height issue.

    They're not "bad" per se, but they do wholesale for about 10% or what
    a pair of 105 calipers go for (!), so you can't expect too much. I
    tossed one of 'em on the back of my 'cross bike to see how it would
    work... I can pull the brake lever to the bar without locking the rear
    wheel. I suspect most of that is due to the cheap pads, and am going
    to try again with better pads - but I just wouldn't count on the brake
    "doing the job" for anyone who relies on their rear brake for most of
    their slowing/stopping.

    Mark Hickey
    Habanero Cycles
    http://www.habcycles.com
    Home of the $695 ti frame

    Report
  6. JeffWills
    Archived post
    #6
    Jim Rogers said:
    Quoted message said:

    1) if she does manage to put a pedal down going around a corner,


    your

    Quoted message said:
    Quoted message said:

    life will become hell in lots of different ways... ;-)

    That is exactly what I'm worried about!

    Long, long ago, I built a bike around 26 x 1.5" mountain bike wheels
    and tires, a frame built for a 27" rear wheel, and a fork built for a
    24 (yup, twenty-four) x 1 3/8" wheel. The front tire barely fit, and I
    had a framebuilder move the brake bridge down about 1 1/4". Because the
    fork was so short, the head angle leaned forward to roughly 78 degrees.
    I have no freakin' clue as to what the trail was on the bike. I found
    that it would shimmy at about 30 mph... so I never rode it that fast
    again.

    The cranks were about 9 inches off the ground, and I had to be very
    careful to coast through turns. I grounded the inside pedal a couple of
    times, causing the rear wheel to hop up and sideways a few inches.
    Fortunately, I never went down because of this- dumb luck, I suppose.

    The bike eventually got stolen- I wonder how far the thief got.

    Jeff

    Report
  7. Tom Sherman
    Archived post
    #7
    JeffWills said:

    Long, long ago, I built a bike around 26 x 1.5" mountain bike wheels
    and tires, a frame built for a 27" rear wheel, and a fork built for a
    24 (yup, twenty-four) x 1 3/8" wheel. The front tire barely fit, and I
    had a framebuilder move the brake bridge down about 1 1/4". Because the
    fork was so short, the head angle leaned forward to roughly 78 degrees.
    I have no freakin' clue as to what the trail was on the bike. I found
    that it would shimmy at about 30 mph... so I never rode it that fast
    again.

    The cranks were about 9 inches off the ground, and I had to be very
    careful to coast through turns. I grounded the inside pedal a couple of
    times, causing the rear wheel to hop up and sideways a few inches.
    Fortunately, I never went down because of this- dumb luck, I suppose.

    The bike eventually got stolen- I wonder how far the thief got.

    That sounds worse than these tube socks!
    < http://home.pacifier.com/~jwills/Gallery/Aerorivr.jpg>.

    Sorry. 😉

    --
    Tom Sherman - Earth

    Report

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