msu2001la

Roubaix SL8 Sport 105 (12sp 105 mechanical) = $3500
Roubaix SL8 Comp (12 sp 105 Di2) = $5000
Aside from paint jobs, these two bikes seem like they are otherwise identical: https://www.specialized.com/us/en/co...=355681-218669

If I bought the sport model but wanted to upgrade to Di2, I think I would just need new shifters, front and rear derailleurs. Can I use the same crankset, cassette, chain? What else would I need?
105 FD-R7150 Di2 front derailleur = $112
105 RD-R7150 Di2 rear derailleur = $205
105 R7170 shifters (pair) = $483
That's only $800, plus I could sell off the mechanical 105 stuff. Am I missing something?

PeteHski

A battery pack?

SoSmellyAir

Battery, two proprietary wires, and a charger.

Iride01 

You also need a link to useful information on Di2. https://bettershifting.com/building-...ts-and-wiring/

And it wouldn't hurt to know that information on most every Shimano part or component both old and new can be found here... https://si.shimano.com/#/

Mojo31

The mechanical stuff won't get you much money.

cweb99

Extra price is the future shock

Comp has the FS 3.2
105 has the FS 3.1

Difference I believe is the 3.2 can be adjusted by hand. 3.1 needs springs swapped

I have the 1.5 which is the older model 3.1. It’s perfect, I have the stiffest spring.

I don’t think you need on the fly adjustments for a road bike. A gravel bike for sure depends on terrain.

Steve B.

Specialized Aethos Comp, 105 Di2 is listed at $3999 on the Specialized website, just a thought. I think they sell direct.

msu2001la

This link is super helpful - thanks!

msu2001la

Oh wow - good catch. That info is really buried in the specs but I do see it now.
I have a feeling this will be a "set it and forget it" kind of thing for me, but I can see how on the fly adjustments might make it easier to switch from road to gravel and back.

mstateglfr 

You could reasonably sell new takeoff 12sp 105 shifters, fd, and RD for $200.
That's $200 less to ultimately spend and helps further highlight the pricing gap that the OP points out.

cweb99

I recently debated between Di2 and mechanical. I ended up with mechanical since it was more affordable for me. Also I’m not an electronic kinda guy anyway. I’ve tried it and it’s nice but I don’t want a bike I need to plug in.

to each their own. The Roubaix is a great bike. You can’t go wrong with either model. Warning: You will love the Future and After shock and will probably not ride your other bikes for any distance over 15 miles.

eduskator

Money can be an important reason to not get DI2, but not wanting to ''plug'' a bike, that's far fetched.

msu2001la

OK so this post got me thinking...
I currently ride a Cannondale SuperX as a do-it-all road, gravel and CX bike. I love the way this bike fits me, and with 28-32mm road tires it's plenty fast as a road bike, but it's got a few downsides for that use - mainly that the 1x drivetrain is limited for road, and I know I'm giving up a handful of aero watts.

A Roubaix seems attractive because the geometry is "relaxed road" and there's all the marketing around comfort, etc. It also has aero benefits (though negated by more relaxed riding position?). The fact that it can double as a gravel bike is a nice bonus, but I'll probably keep my SuperX so I don't really need that. My concern about the Roubaix is the fit. In size 54, the reach is the same as my current bike, but the stack height is 30mm higher. I run a few spacers under my stem now, so it looks like if I slammed the stem on the Roubaix it could match my current fit, but with the futureshock it would end up at least 20mm higher, plus the riser bar that comes with it adds even more. This seems like a lot and I'm wondering if it's a dealbreaker - I'd be more aero on my SuperX.

The Aethos looks closer from a geometry perspective. My current stack/reach fit seems to fall right in between the 54 and 56 Aethos numbers. Size 54 would be 11mm lower stack, and 6mm longer reach. Size 56 would be 10mm higher stack, and 17mm longer reach. (Seems weird that the Aethos is longer in both sizes than a SuperX...) I'm assuming I could make either size worth with some adjustments, spacers, stem, etc to get an exact match to my current fit. That said, the Aethos doesn't really do aero and I live in a flat area so the weight weenie advantage is kind of silly. Also I'm in my late 40's and conscious that "aggressive road geometry" is probably not a good idea.

Mojo31

I get that, but you may spend most or all of that $200 paying to have the parts switched. Or, depending on what you do for a living may find you can make more in the time it would take you to make the switch than you can get for the parts.

mstateglfr 

Sure, that is possible.
So assuming a shop is needed to install parts...then the parts are installed, that cost is paid for by the mechanical shift components you sold off, and you still save a bunch of money compared to buying the Di2 bike.


As for your last scenario, yeah maybe you make more in the time it would take you to make the switch than what you can get for the parts. <--I dont you phrased that correctly, but lets roll with it because I think I know what you mean.
- I find it hilarious to see this sort of scenario discussed when it comes to hobby cycling. It could be true for a very select few people, but it isnt at all applicable for most anyone else(this analysis is based on everyone I have met and know). The comedy is based in the false choice that someone must either be working and earning money or 'losing' money by participating in a hobby. Thats just straight goofy. I can list bike parts on ebay or paceline at 9pm and am not giving up the chance to earn more money by working at my job instead. This is true for basically every salaried and hourly person I know. An attorney in private practice could use that time to make more money, but even then, the assumption is absurd since for it to be true it requires someone to always work instead of enjoy hobbies or leisure. Using that absurd view, then everything that person does in life outside of work would be viewed as a financial loss. Watch kids play sports?...financial loss. Go to dinner with spouse?...financial loss(well, double loss). Walk the dogs?...financial loss.
Its just a goofy way to argue if something is, in general, worth spending time on.
Based on how much time people watch TV, read, scroll social media, etc- there is plenty of time for most of us to not waste before we need to genuinely question if spending 10min of free time to post some components that sell for $200 is 'smart' or not.

msu2001la

Now I'm curious if I'm missing something about Di2 instals. I've never done it, but would have no problem installing and setting up mechanical shifters and F/R derailleurs. Is it more complicated than I realize?

I like working on bikes - it's not a burden and I would only go to a shop if it required some special tools that I didn't already own.

Mojo31

It's not more difficult. I enjoy doing my own work, some don't. I know people who pay to have their tires changed.

PeteHski

If I bought the 105 version then I probably wouldn’t be bothered to upgrade the drivetrain to Di2. But it does look cost effective in this case if you can be bothered.

cweb99

what do you want from this new bike?

I have a slammed stem Allez Comp with a bunch of upgrades. I ride it hard and fast. My new Roubaix is slow yet very comfortable.

msu2001la

There is definitely that too. I’ve been quite happy with 105 mechanical for many years, but the electronic stuff is intriguing.

msu2001la

I think I’m mostly after a bike that is better suited for road riding than my current bike. So for me that means more aero, better road gearing but a similar fit. I’d also like it to feel like an upgrade (hence the interest in 12sp Di2 vs my current 11sp mechanical). I race CX and gravel, but my road riding is more training/casual with some occasional faster group riding mixed in - and a rare bike vacation to mountain areas. My SuperX is a bit limited for faster group rides and lacks climbing gears.

Most people I’ve talked to don’t describe the Roubaix as slow. I rode one a few years ago and liked it, but I haven’t been on the SL8 so I’m trying to learn a bit about it.

The other option for me is to just buy a new electronic groupset and drop it on my current bike, but that’s not as fun.

Steve B.

Ive done 2 systems (well, 3, with 2 being Di2), in a road and a mt bike. In each case the thing that made it easy was having a BSA bottom bracket that I had the tools to remove and re-install after installing the e-tube cables. If the bikes had had press fit it would have meant either buying the tools to remove and press the b-bracket, or two shop visits to remove and re-install. Laying cables, installing derailers and shifters was the same as mechanical. One issue I ran into on my Specialized aluminum hard tail was the holes in the top of the downtube were designed for brake housing, not an e-tube connector and needed to be dremeled to open them up. Then some learning curve on different procedures to setup the derailers.

One key factor is once the cables are installed and everything is working correctly, it really never gets touched again, unless I snag a shifter cable and need to replace. I’ve been running my mt bike Di2 for 4 years with no issues or adjustments, 6 years on a road system. The original batteries are still good. I had an XT shifter go bad last fall, replaced it for $95 and maybe 15 minutes of work, as it really was just removing and re-installing grips and the shifter, then a quick OS update via the wireless app off my tablet.

I personally feel that electronic makes best sense on a mt bike as I shift a lot more and electronic is perfect every time. It doesn’t get sloppy from dirt and grit.

choddo

I was about to say “it is more difficult if you have fully internally routed cables” but then I realised actually it’s easier with the disc / semi-wireless shifters.

PeteHski

Oh for sure electronic shifting is worth having. I have one bike with mechanical 105 11-speed and one with SRAM Force AXS. The latter just makes shifting perfect every time without the clunky cable shifters that we all accepted for decades. Once you make that step you won’t want to go back!

Having said all that, the idea of buying a brand new bike and then stripping off a perfectly functional drivetrain is something that I probably wouldn’t bother to do. But I do fully understand your logic. Just make sure you are really motivated to make the effort! Otherwise just buy the Di2 bike so you don’t risk missing out 😂

Kai Winters

To answer your question, you will need the following:
Front Der.
Rear Der.
Shifters
Battery, charging cable, two wires...one from the battery to the front der, the other from the battery to the rear der.
If you want to update the firmware on the shifters the easiest way is to buy another, much longer wire and a connector to connect the shifters...one at a time...to the front der. wire at the front der. The battery is the brain of the system. Another way is to connect the wire from the shifter to the battery directly but you have to pull the seat post and if not careful or if you don't have wires long enough you could disconnect one of the der. wires. It's far easier to use the front der. wire.
The rest of the 105 drivetrain is compatible...crankset, chain, cassette, etc.

Whether you go that route or not is your choice and I have no advice. I changed from 105 11 speed mechanical to 12 speed 105 Di2 and love it. Shifting is so fast and all you need is a light touch of the controls. You can alter the speed of the rear der. shifting speed. The front der. self trims to the gear you're in.
Increased weight is a non issue to me. My Aethos is under 16lbs with cages and pedals and I've done nothing special or spent 'crazy money' on super light weight parts.

Do your homework, think about the differences and maintenance requirements, look carefully at the similarities and differences between the bikes, not just the drivetrains.
Good luck and keep us informed...