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I'm a believer in having just one bike that i can use for anything I do, mostly club rides and light touring. I currently have a Giant Defy 1 with 28c tires, but am intrigued by the new gravel grinder bikes such as the GT Grade, which have road bike components but accept broad tires. I'd like to make a few changes to a GT Grade, and would appreciate any guidance on a few questions I have:

  1. I'd like to replace the road bike transmission (Shimano 105) with a mountain bike transmission Shimano XT), both 11 speed.

    1. Is it possible to make the change? Will an XT crankshaft fit on a road bike?
    2. Can i use the 11 speed 105 shifters to shift the XT front and rear derailleurs?
  2. I'd also like to replace the wheels (Stan's No Tubes Grail Disc) with XT wheels, which i expect would be more robust when touring. The XT wheels have an internal width of 24 mm. I believe they will fit the bike, but will they work with 32c tyres (Conti Gatorskins or Schwalbe Marathon Supremes)?

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    'Gravel Grinders' are just glorified, marked up cross bikes. Get a cross bike and you'll be able to take it most anywhere. – Scott Hillson Jun 29 '15 at 1:22
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    Why do you want XT drive train? What functional benefit do you expect it will give you over 105? – mattnz Jun 29 '15 at 2:14
  • If the inner width is 24mm you can definitely go 32. Are you doing gravel rides? You don't say so... Do you just want wider tires? Whatever - I recommend 35 for gravel. But ymmv. Get some panaracer ribmos- they're so choice. – jqning Jun 29 '15 at 3:13
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    24mm Internal width is too overkill. The rims on my bike have 18mm inner width and I still can put 45mm tires on them. – azer89 Jun 29 '15 at 23:53
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    Additionally, one of the best wheels for touring is Mavic A719. They are not light but really strong. – azer89 Jun 29 '15 at 23:57
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To me, gravel bikes seem mostly like cross bikes with a bit more money they can take from your wallet.

1) Road and mountain shifters and derailleurs don't play nice with each other at 11 speed, so this question is moot. If you want to check a particular crankset on the bike, look at the width and the type of BB setup. I don't see why you'd want to switch to a mountain drivetrain in the first place.

2) If a wheel is 700c, you can technically mount any tire on it thats 700c (though you'll have problems if too narrow or too wide). If you look at the width compatibility chart from Sheldon Brown, you'd want a rim with a smaller width. Since you're upgrading, may as well buy the right width. By running this, you increase the risk of pinch flats/rim damage over a more well matched width.

  • I appreciate your cynicism, except the CX bikes are race bikes and typically can't run bigger tires (I.e. > 32c) because they are designed with UCI regulations in mind. That said, they seem to be slowly reinventing is the 1940's randonneur bikes. Taller frame stack and wider tires are a good change in my opinion. – Rider_X Jun 29 '15 at 1:53
  • Theres a good amount of CX bikes which are suitable for commuting as well as racing (obviously not on the top end). Kona's Jake ships with 32c tires and can easily clear 35's, for example. – Batman Jun 29 '15 at 11:57
  • The UCI tire limit is 35 mm, typical cyclocross race bikes have room for that and lots of mud. But then again, many bikes marketed as cross bikes have the eyelets for fenders and racks. – ojs Jun 29 '15 at 15:04
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    A lot of cross bikes also have water bottle mounts even though water bottles are banned in cyclocross. Keep in mind cyclocross bikes are a lot like road racing bikes: 99% of them never actually get used in competition. – ChrisL Jun 30 '15 at 17:30
  • @ChrisL - Which in a strange round about way is why "all-road" bikes may actually be more appropriate for most riders. Taller frame stack (many cx bikes have too short of a stack), ability to run tires larger than 35 c with fenders, lower BB and a few other bits. I used to use CX bikes to fill this gap, it is nice to see something more tailored. Maybe the industry is finally realizing most don't want to race. – Rider_X Jul 1 '15 at 14:48
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Any bike can go anywhere. I've taken a road bike down an off-road course, and an electric assist road bike up a steep gravel path (not fun)

My weekend ride these days is a non-suspension steel mountain bike with knobbly tyres but a smooth strip on the face of the tread for road comfort.

As long as the parts work together and fit your body and style of riding, then why not? Cost would be the main preventative.

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    "Any bike can go anywhere" That is absolutely true. I ride my rigid BSO on downhill courses. As long as you go slow you won't break anything. – BSO rider Jun 29 '15 at 16:32
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    True but not helpful – brendan Jul 1 '15 at 1:46
  • 1. I'd like XT instead of 105 because I don't use the high gears much, but low gears are useful when going up steep hills. Shimano stopped making the 105 triple, which would have been perfect. 2. I think I could get much of what I need by having a 11-40 cassette with an XT rear derailleur, but it appears the 11 speed 105 shifter won't shift the 11 speed XT rear derailleur. 3. Some gravel bikes (e.g GT Grade) are exceptionally comfortable while still being quite fast, especially when equipped with reasonably big tires (32c-35c). I'm not looking to be hunched over a stiff, punishing frame. – Thomas Philips Jul 2 '15 at 1:46

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