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I've got a ~2007 Specialized Allez double with a Sora/Tiagra drivetrain that's gotten pretty worn from years of use. I'm thinking of upgrading it to the the latest 105 R7000. Would be my first time doing something like this. Any gotchas to look out for here?

I'm aware that I'll need new wheels/hubs as well for the 11spd cassette.

  • You can avoid the new wheels (rear hub) if you opt for an 11-34 cassette – Paul H Aug 20 at 16:33
  • @PaulH how come? Can you elaborate? Thanks! – user44903 Aug 20 at 16:40
  • 11-speed cassette is wider than 8-10 speeds and needs wider freehub body. Except for MTB cassettes, where the largest cog hangs a bit inside freehub body. 11-34 is not everyone's optimal choice for road riding, though. – ojs Aug 20 at 16:43
  • @ojs so then I would need a new hub, as I expected, right? Paul seems to be saying that I won't need a new one. – user44903 Aug 20 at 16:53
  • 11-speed MTB cassettes fit on same hub as all 8-10 speed cassettes. – ojs Aug 20 at 16:54
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You don't necessarily need a new wheel. Some larger 11 speed cassettes can fit on a 10 speed road freehub body, as the larger sprockets allow a wider spider that can overhang the inboard end of the freehub body. A 105 GS derailleur max small sprocket is 34 teeth, but that can very likely be pushed to 36.

There should be no compatibility issues. On a 2007 bike you presumably have a threaded bottom bracket shell and external bearings. R7000 cranks still work with that. You'll have 130mm rear hub spacing, that's not a problem for chainline with R7000 cranks.

Here's the potential gotcha: cost relative to a whole new bike. Add up the cost of a 105 rim brake groupset bundle, new wheels, tires, all the miscellaneous bits you should replace at the same time (cables, housing, bar tape, tubes ...) and the special tools you'll need (BB tool, chain whip ...) and you may find that's a very significant part of the cost of a new 105 equipped, alloy framed bike. Remember with a new bike you get better comfort, modern geometry, ability to run wider tires etc.

That said though, it's worth looking at the used market for wheels. With the switch to disc brakes there are deals to be had on highish end rim brake wheels.

  • Remember with a new bike you get better comfort hmmm. this is a stretch to state so directly. – Paul H Aug 20 at 17:02
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    @PaulH I think it's reasonable given advances in hydroforming alloy frames and the trend to wider tires – Argenti Apparatus Aug 20 at 17:07
  • just check the rear hub. It might take up an 11-speed cassette without trouble. But I'm siding with @ArgentiApparatus the price of the groupset, the tools and the work will probably be higher than a new bike. You'll stay with a relatively old frame and new bits. Keep your bike as #2 and check for a whole new one equipped with 105. The 2020 models will soon be out and you might have a 2019 bargain. – Carel Aug 20 at 17:38
  • Looking at eBay, I can get a complete 105 groupset shipped from within the US for ~$580. Factor in another ~$500 for new wheels and yeah, it won't be cheap. I don't really see many 105-level bikes for <$1500 though. – user44903 Aug 20 at 19:33
  • @user44903 Factor in all the other miscellaneous components and tools and the cost goes up. I did say 'significant part' not 'the same cost as' a new bike. Basically you get to make a choice, there are benefits to a new bike but you do have to pay for them. – Argenti Apparatus Aug 20 at 20:00
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2000s were the great golden age of road bike compatibility, so you are not running into major problems.

  • As already mentioned in question, if you go 11-speed you will need new rear wheel that fits 11-speed cassette. This can be avoided with 10-speed Tiagra or by using an extremely wide range cassette.
  • This should also be obvious, but you will need new shifters and derailleurs
  • Shimano has changed brake actuation ratio in newer road groupsets. Old brakes will work but feel slightly different with new levers.
  • There is a number of new bottom bracket standards, through axles with or without 142mm spacing, direct mount brake calipers and derailleurs and what not. You can ignore all of these and choose the basic BSA/QR/standard version.
  • Worth mentioning that boost spacing applies to MTBs with thru-axles. Not road bikes (QR or otherwise). – Paul H Aug 20 at 17:04
  • True, I confused 142mm and Boost. Editing... – ojs Aug 20 at 17:12

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