29er Gear ratios

Anything specific to off-road riding.
gharrison
Posts: 1
Joined: 17 Apr 2017, 11:20pm

29er Gear ratios

Postby gharrison » 17 Apr 2017, 11:28pm

I'm looking at buying a 29er mountain bike to replace a 26" mountain bike. I loved my 26er with a 48 teeth granny ring. But all the 29er's seem to come with really small chain rings! Does the 29" wheels mean you can run a smaller chain ring without loss of speed? Or will I just be pedalling like mad to make a bit of speed?

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Tigerbiten
Posts: 1410
Joined: 29 Jun 2009, 6:49am

Re: 29er Gear ratios

Postby Tigerbiten » 18 Apr 2017, 4:00am

Some simple the maths.
29/26 is very roughly around 1.1.
Or the new wheel is about 10% bigger.
As long as the back block is the same, you need to drop your chainrings by the same amount to keep the same gears.
So 48 tooth ring drops to around a 44 tooth one.

You can see the same result if you plug in both the new sizes in a gear calculator

hoppy58
Posts: 148
Joined: 9 Mar 2011, 3:07pm

Re: 29er Gear ratios

Postby hoppy58 » 18 Apr 2017, 4:51pm

I loved my 26er with a 48 teeth granny ring

- yikes, what size was your big ring?

..seriously ..my 29er has a double chainring 40/28, coupled with an 11-36 cassette and I find this adequate for most situations..the only time I might need a higher gear is very occasionally going down hill very fast when I sometimes spin out..then I think perhaps a 42 or 44 big ring would be better, however I would normally be free-wheeling by then anyway...also I'm not sure that the front mech would work with a 44/28 combination ?

I find that the 28/36 front/rear combo gets me up just about anything (and I'm not the world's greatest climber) and for 95% of the time, the 40/11 front/rear combo is plenty for the flat/most descents.

MikeDee
Posts: 338
Joined: 11 Dec 2014, 8:36pm

Re: 29er Gear ratios

Postby MikeDee » 25 Apr 2017, 4:17pm

If anything, 29ers are over geared. No need for 11 tooth cogs. I have a 36 tooth cog on the back.