rosefarts

More hypothetical since I'm only shopping.

Let's say I found a bike I liked but I wanted a different 1X gear set up. Said bike would probably have GRX.

If I switched to a XDR freehub and tossed a 10-42 cassette on, would it work? I know they are published as 11 tooth minimum but has anyone tried it.

Like I said, this is hypothetical. I'd probably opt for Force 1 on a new bike but there's quite a bit I like better with the mostly Shimano setup.

davidad

Get a Capreo hub and go down to 9t.

bldegle2

There is a possible slight problem, it your bike was designed for an 11 as the smallest, which most are, the 10 may not work, the chain might rub the frame back by the axle.

DrIsotope

From a September post in the 3T bike blog, Gerard Vroomen says they used the SRAM 10-42 cassette, and it worked just fine, though shifting was a bit better when paired with a SRAM chain. It's mostly down in the QnA at the bottom.

onsay99

The Shimano GRX should be able to handle the 10t cog mechanically. The main challenges are to use the appropriate chain and to
make sure the frame handles the cassette space with proper chain clearance.

Moulton bikes were Shimano ultegra equipped back in the late 90's and early 2000's and they had no mechanical drivetrain problems
using a 63t big ring and a 9t smallest cassette cog for top gear. Ultegra at that time was listed in the compatibility charts for 11t and 12t.

Retro Grouch 

Cogs with fewer teeth have a smaller diameter. The free hub outer diameter will determine the smallest size cog that will fit.

rosefarts

Reading comprehension fail

Andrew R Stewart 

For further chance of reading comprehension challenge check out 2.2.1 Chordal Action

This is one reason why I dislike the trend to tiny rear cogs. I like a smooth and long lasting drivetrain. Andy

rosefarts

I've always assumed this was the case. I thought that was the reason that 11 remained the minimum for so long. The idea of redesigning and destandardizing has never bothered manufacturers before. I'm sure it makes a far bigger difference on high speed and high torque motors. Humans riding down hills, I'm unconvinced.

For me it's really a matter of simplicity to achieve a better low end. Currently running 11-42 x 40 on a gravel bike is a 90% solution. I do encounter steep enough hills that I'd like to go a smidge lower or higher on, depending on up vs down.

Options are 11-46 x 42, a double, or 10-42 x 38. You know as well as I do that when I'm in the 10 that I'll be half tucked and alternating between coast and pedaling. I think my losses or inconsistency at this point will be minimal. I'm not a machine.

DrIsotope

As someone with a lot (A LOT) of miles on a 10-42, I can say that going from the 11-42 to the 10-42 is huge-- with a 38T in the front, going from an 11 to a 10 in the back is almost 10GI. It's absolutely worth it. And I use the cheapest SRAM 10-42 I can get. xD all the way.

rosefarts

That's kinda my thought. 1x for gravel doesn't quite seem dialed until you get a 10 toother. After that, by the numbers, it seems better than any other setup.

HaileSelassie

Im looking into doing the same with a 36..... But im really considering the ETHIRTEEN which is like 240-320$ and goes to 9T... i think the top speed would increase a lot

CHAT gpt says it increases like 50%+ But i really dont know... what you think?

Andrew R Stewart 

The issue with assuming a smaller tooth count, besides wear rate increase and that chordal effect I mentioned 4 years ago (post #8), will lead to more bike speed is that one also needs to be able to apply more power. I don't see where increase the drag (mostly aero but a little mechanical friction as well) with increased speed can happen without more power. I'd love to be shown this is wrong

So the next aspect is can the rider with a set amount of power not be able to apply it to the bike if the cog wasn't smaller. This does speak to the rider's ability to pedal effectively for the ratio they are in or want to have. And this is trainable without spending any $. Andy

HaileSelassie

My friend. I coudnt not understand anything and chordal link was not working a few days ago or today.
Basically im consistently always riding at my 11T while on flats. Maybe not at incredibly high cadence but i only use the last 2 Cogs for any kind of ride for that bike (gravel&road hybrid)
I have a top speed problem with my drivetrain currently from my point of view, im considering going to 10t or 9t.
Do you think this increased wear is VERY big? is there any information on that? Thanks for the response

Andrew R Stewart 

After 4 years no surprise that links evolve, have you tried to google the word?

Your stated cadence and gearing use is exactly what I was thinking it is. Which is why I mentioned training your body to achieve faster cadence, which has a number of advantages IMO.

But I have dealt with too many fellow riders and customers who, like you, feel that they need a higher ratio gearing to believe that you would consider my opinion as having merit. Enjoy your ride. Andy

Dan Burkhart 

Here is a gear inch comparison between 10/42 and 11/42. Both with 38 tooth chain ring and 40/622 tires. The 10 tooth will gain about 10 gear inches at the top end.