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Educate me - gravel bike drivetrain and disc brake choices...
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Maybe this info is out there, but I've searched and can't find it in one thread.
And I'm starting pretty low on the knowledge curve.....

Me: old roadie. I like Campy. 8-speed! Woo-hoo.

Interested in building up a gravel bike.. new frame with thru-axle.
I "get" the idea of disc brakes... tire width clearance ++

So what are my options in terms of drivetrain...
SRAM? what is there product line-up? I looked at their website... info overload over there.
Shimano?

And disc brakes.. mechanical vs. hydraulic?
I a DIY wrencher. Looking at the service manual for SRAM hydraulic, it looks like a nightmare.

Thoughts, opinions, product recommendations?
All welcome. Thanks!
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Re: Educate me - gravel bike drivetrain and disc brake choices... [spookini] [ In reply to ]
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First questions will be whether you want to run 1x and/or flat bars. It is really personal preference for both decisions. For 1x it will depend on the terrain where you ride (i.e. pitch and length of hills), your climbing ability, whether you mind larger gaps in gearing, and whether you will be racing. For drop vs. flat bars it is just a personal preference on comfort for the terrain where you will ride. Mountain bikers tend to prefer flat bars and roadies tend to prefer drop bars but there is overlap and it can depend on whether you will be riding more singletrack or more open gravel.

If you want to run 1x with drop bars I recommend SRAM because of their clutch RD and ability to run a 42t cassette. If you want to run 2x or flat bars then there are fewer differences. In general the SRAM road RD's can handle a larger cassette so that may also be a deciding factor.
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Re: Educate me - gravel bike drivetrain and disc brake choices... [spookini] [ In reply to ]
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Have you ever bled the brakes on a car? If so, hydro is no big issue.

Cable discs work nearly as well and will be easier, since you'll not need many (if any) new tools. Additionally, with cable discs, you'd use the same brifters as always, so just choose your level and go.

There are some standards issues to consider:
  • caliper mounts - post mount vs flat mount. There are adapters going both ways, but better to match them from the starts
  • brake disc mounting - not sure what the best is here, but make sure the rotor matches your hubs
  • brake rotor size - check the frame specs for right size
  • probably others that I'm not aware of (building up a cross bike right now and am learning as I go)



(If you want to buy the whole group, always check merlin. Their prices are pretty dang low and ship quick from England. I've had small orders take a week or so, but full groups are within 5 days.)
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Re: Educate me - gravel bike drivetrain and disc brake choices... [spookini] [ In reply to ]
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Agree on the SRAM for drivetrain...especially since staying with 1:1 actuation allows you to run MTB derailleurs with road shifters. For example, I'm running 10sp Red shift levers with a Force FD (I've got a standard road 53/39 crankset on my Fuji) with a 10sp MTB derailleur w/clutch (I forget the model) on the rear. That way I can run a Sunrace 12-42 cassette :-)

For brakes, don't let the "hydro snobs" fool you...to be honest, a quality, well set up mechanical disc work just as well. For example, I'm using TRP Spyres (which move both pads) and have them connected with solid Jagwire Link housings. That combo gives up nothing power or modulation or "light lever feel" as compared to hyrdraulics. There are other mechanical stoppers that work extremely well, such as the Paul's Klampers...that said, the opinion that mechanical actuation isn't as good as hydraulic seems to have originated from early use of the BB7 road calipers, which only push one pad and rely on disc flexing. Obviously, that's not "ideal"...

Speaking of the pads, the only feature of hydro that the mechanicals don't have is automatic pad wear adjustment. Every once in awhile you have to manually turn the barrel adjuster and bring them in. BUT, that also points out something the hydros don't allow...in the case of accidentally bending a rotor and having it out of true, with a hydro it's going to rub...with mechanical, you can just back out the spacing a bit. Also, I've seen where one piston of a hydro will get stuck and rub (usually due to grime). Never seen that with mechanical.

Just my 2 centavos.



http://bikeblather.blogspot.com/
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Re: Educate me - gravel bike drivetrain and disc brake choices... [spookini] [ In reply to ]
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I think it'll help to know what you want out of the bike.

In my humble opinion...
SRAM wins the 1x conversation, but I LOVE my 5800 Shimano 2x w/ a GS RD and 6800 46/36 crank with a 11-32 cassette.
Hydraulic is awesome but mechanical gets you 95% of the way there. HY/RD is great, Spyre is generally regarded as best bang for the buck.
For me, reusing standard shifters or having shifters I can repurpose later is a +1 for Mechanical over Hydraulic.
You can run centerlock to 6 bolt adapters but not 6 bolt to centerlock...I think?
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Re: Educate me - gravel bike drivetrain and disc brake choices... [spookini] [ In reply to ]
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I'll just keep it simple without a lot of run on.....Shimano Ultegra Di2/hydraulic disc.
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Re: Educate me - gravel bike drivetrain and disc brake choices... [zo541] [ In reply to ]
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Definitely drop bars, and no plans to race.. organized gravel fondos might be fun, but those ain't races...
So I'd say 1x.

What the SRAM product hierarchy? (For example, I'm familiar w/ Shimano... 105-->Ultegra-->Dura-ace.)
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Re: Educate me - gravel bike drivetrain and disc brake choices... [Tom A.] [ In reply to ]
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Tom A. wrote:
Agree on the SRAM for drivetrain...especially since staying with 1:1 actuation allows you to run MTB derailleurs with road shifters. For example, I'm running 10sp Red shift levers with a Force FD (I've got a standard road 53/39 crankset on my Fuji) with a 10sp MTB derailleur w/clutch (I forget the model) on the rear.

I'll assume this is all still Red-to-Red, though?
It'll all be new purchases for me.. I have nothing to re-purpose except old Campy parts.

If I'm going budget-ish, what is SRAM's entry-level line? And Shimano's?
(All these names/product line naming conventions are foreign to me.)
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Re: Educate me - gravel bike drivetrain and disc brake choices... [spookini] [ In reply to ]
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spookini wrote:
Tom A. wrote:
Agree on the SRAM for drivetrain...especially since staying with 1:1 actuation allows you to run MTB derailleurs with road shifters. For example, I'm running 10sp Red shift levers with a Force FD (I've got a standard road 53/39 crankset on my Fuji) with a 10sp MTB derailleur w/clutch (I forget the model) on the rear.


I'll assume this is all still Red-to-Red, though?


Nope. The shifters happen to be Red, but the front derailleur is Force and the rear is (I just looked) MTB GX 10 speed...like this:





spookini wrote:
If I'm going budget-ish, what is SRAM's entry-level line?
(All these names/product line naming conventions are foreign to me.)


For SRAM, any of the road levels (Red, Force, Rival, Apex) all work with each other...and are all what SRAM terms "exact actuation", or 1:1 cable pull ratio. So, if you find a MTB derailleur with the same number of gears, and it's also "exact actuation" (like what you see above...not all SRAM MTB derailleurs are), then "Voila!", it'll work with the SRAM road shifter.

Shimano used to be that way also a long time ago...I'm pretty sure it's not the case any longer, and I have no idea...



http://bikeblather.blogspot.com/
Last edited by: Tom A.: Nov 14, 17 12:53
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Re: Educate me - gravel bike drivetrain and disc brake choices... [spookini] [ In reply to ]
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spookini wrote:
What the SRAM product hierarchy? (For example, I'm familiar w/ Shimano... 105-->Ultegra-->Dura-ace.)

Entry level is Apex although I don't see it spec'd much. More typically I see entry level gravel and cross bikes spec'd with Rival.
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Re: Educate me - gravel bike drivetrain and disc brake choices... [zo541] [ In reply to ]
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Ok, next question...

I live in a pretty flat/coastal part of the world.
If I go 1x, it's going to be a pretty small chainring up front, anyways..

Is there any need to go w/ massive 36t or 42t (or even 2t) cassette?
If I don't need more than 39x26t on a roadbike, why would I need a pancake cassette?
And if not, then can I just run a mid-range road rear derailleur?
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Re: Educate me - gravel bike drivetrain and disc brake choices... [Tom A.] [ In reply to ]
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Tom A. wrote:
Agree on the SRAM for drivetrain...especially since staying with 1:1 actuation allows you to run MTB derailleurs with road shifters.

I am running Shimano (electronic) MTB derailleurs with road shifters on two different bikes now. So there's that option.

The new Shimano 80xx Ultegra Di2 hydro levers are reasonably priced ($350 retail), and you can get them cheaper from the UK as always. An XT Di2 rear derailleur can be had for under $200. Add $200 for e tubes/junctions and $100 for a battery...okay, it's not the most affordable option, but for a 1x setup it's not outrageous compared to the top- or even mid-shelf mechanical options.
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Re: Educate me - gravel bike drivetrain and disc brake choices... [spookini] [ In reply to ]
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I live in the Cascade foothills of Washington, and do a lot of gravel riding in the logging/access roads near Mt Rainier Nat'l Park and Capital Forest. Think long, steep hills. I currently use a 2x10 system of 105 shifters, 8-speed Ultegra FD, and 9-speed XT RD, with a Gossamer crank running 46/34 rings. The cassette I use most off-pavement is a 11-32, and there are times I'd really like another gear. But again, the gravel can get steep for a long time. You might be able to get by with less, but having the option to get near a 1:1 ratio could be a good idea when going to other areas. Just my situation/thoughts.

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Re: Educate me - gravel bike drivetrain and disc brake choices... [spookini] [ In reply to ]
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You might look in to Gevenalle. I'm running their 1X setup with a Shimano XT derailleur (with clutch), 11-36 cassette and a 42t wolftooth components chainring up front on my cross bike this season. I'm using avid bb7 cable actuated disc brakes because I already had them. These brakes are ok, not great, not awful, just ok. You can get a Gevenalle setup with hydraulic disc brakes too - that would be sweet.

I've really liked this setup for racing cross. Being able to quickly sweep up and down the cassette is awesome! Key features - its simple, light, tough and a lot less $ than sram force 1X.
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Re: Educate me - gravel bike drivetrain and disc brake choices... [tri_curious] [ In reply to ]
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Genevalle. .interesting concept but sort of retro in terms of exposing the shift cable for all the world to see. Think I prefer a cleaner look..
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Re: Educate me - gravel bike drivetrain and disc brake choices... [spookini] [ In reply to ]
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spookini wrote:
Ok, next question...

I live in a pretty flat/coastal part of the world.
If I go 1x, it's going to be a pretty small chainring up front, anyways..

Is there any need to go w/ massive 36t or 42t (or even 2t) cassette?
If I don't need more than 39x26t on a roadbike, why would I need a pancake cassette?
And if not, then can I just run a mid-range road rear derailleur?

Off-road - gravel or MTB - gets a whole lot steeper than paved roads. Even in nominally flat areas. You're better off with that little bit of extra reserve, and a 1:1 ratio off-road isn't outrageous at all.

ZONE3 - We Last Longer
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