Swap out ratios on 12-25 10 speed Ultegra

gettyalex

New Member
Location
United Kingdom
Hi, I have a 2006 Trek Madone 5.2 with Shimano Ultegra 10 speed groupset. It currently has a 39/53 up front and a 12-25 in the rear. I live is a very hilly area and find that I run out of climbing gears on my rides. Is it possible to simply swap out the cassette (and maybe chain) for a wider ratio of gears, or would I need to do more?
 

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Sharky

Guru
Location
Kent
Pretty much as you describe.
A few teeth extra on the big sprocket (28t) and wouldn't be any problem at all. Your current chain if not worn may be OK without needing to lengthen it.

If you want to drastically reduce your gears, then going to a much bigger cassette, may require a longer RD cage and a longer chain.
The other option you have is to get a smaller chain ring at the front. A compact 50/34 would reduce the gearing.
Don't be too attached to the idea that you need a 12t top gear. A 13t or 14t even with a 50t chain wheel should be more than adequate and would avoid big jumps in the middle ranges.

Good luck
 

si_c

Veteran
Location
Wirral
Hi, I have a 2006 Trek Madone 5.2 with Shimano Ultegra 10 speed groupset. It currently has a 39/53 up front and a 12-25 in the rear. I live is a very hilly area and find that I run out of climbing gears on my rides. Is it possible to simply swap out the cassette (and maybe chain) for a wider ratio of gears, or would I need to do more?
Should be easy enough - I'm assuming with your current setup that you have a short cage rear derailleur (SS variant) so you'll be limited to swapping to something like an 11-28 cassette at the back. Should make a bit of a difference.

Unfortunately I don't think you'd be able to change the chainrings to smaller ones - from the photo it looks as though that chainset is 130mm BCD so limited to 53/39 - you might be able replace the entire crankset but you'd lose the aesthetics of the matching silver which personally I'd not want to do.
 

rogerzilla

Legendary Member
Squillions of Boardman Team Carbons have 12-28 10-speed on the back. I changed mine to 12-23 as I found 12-28 had gaps where I wanted a cog.
 
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