theronin

TLDR: How much of the non-drive crank spindle needs to be inserted into the left crank to be secure? Would taking approx 2-3mm away be a problem?

I've been going crazy converting my and my wife's hybrids into wanna-be gravel bikes by adding drop bars and now upgrading the frankensteined groupsets that came on them from the shop. And, yes, I'm relatively new to this and still learning. And I just learned that road cranksets are narrower than MTB cranks to accommodate the wider rear braces for wider wheels.

So specifically, I'm wanting to migrate the Claris groupset that came on my roadbike (real one, not one I "transformed") to my wife's Giant hybrid that came with square taper secured cranks. I always hated the gap left by square taper but now I see why. When I put on the Claris crankset, I was left with maybe 5mm of clearance to the rear braces!! I'm not comfortable with that since either the rear brake or deurallier housing passes right by it and likely to rub against the chain. (Otherwise, I do think the chain is clear.)

So what I plan to do is add some spacers to both sides of the crank. Yes, I've read the 2 on drive side, 1 on non-drive side for MTBs but I need spacing on both sides. I get that this may mess up my chainline. But what I'm more concerned about is that I'll be taking maybe 2-3mm of spindle away from the non-drive side crank. Is this going to be safety issue?

Thanks for any feedback and bearing with yet another I-wanna-turn-this-hybrid-into-anything-other-than-a-hybrid post.

DorkDisk

There are many things to digest here but overall, road hollowtech II cranks do not use any spacers. The NDS has soft aluminium splines and require to be completely seated or they might strip. Another issue to look for in hybrid to road crank is to make sure that the BB shell is 68mm in width, many MTB derived Al framed hybrids will use 73mm shells.

But 5mm clearance from crank arm/rings to chainstay is not bad.

theronin

Thanks DD. I'm happy to report everything worked out!! Now if you are a hardcore gravel biker out to cross country ride or something, I would def just get a legit gravel bike. But if you've got a hybrid you are itching to make 100x better for some local riding, then this is worthwhile.

With that said, using road cranks on hybrids and its pedal clearance is just one of the issues evidently lol.

Another issue I ran into is that it would seem to me at least that most gravel wheels use thru axles rather than the quick release axles typical on road wheels. And oddly there isn't as many adapters out there than one would think. While many wheel makers (like DT Swiss) provide conversion kits specific to their wheels, I found out about that only after settling on some Amazon adapters with good reviews. So far so good though!