More gears - compatibility help

milese

I've just got my hands on a very nice BMC Team Machine with full Sram Red.

Its got a 39/53 crankset and 11-26 cassette, which bluntly is too much for my ability and terrain (Cornish lanes and a week and the Alps coming up!).

I see my options as:

1. Fit compact chainset
2. Fit 11-28 cassette
3. Fit smaller inside chainring

So, on reflection.

1. 34/50 will defo give me the gears I need. Will I need a new rear mech? I fitted a compact to my old Tarmac with the same rear mech and chain it worked ok so I guess it will be the same? New Sram Red chainsets are expensive. I also quite like the Rotor stuff, but they look equally expensive and a bit heavier?

2. That only gives me an extra 2 teeth on the back, which probably still wont be enough. 39 / 28 is still a lot bigger than 34 / 26. I had a 27 tooth on my Tarmac cassette and still fitted a compact. Sram Red cassettes arent cheap either.

3. Is it possible to fit a 36 tooth inside chainring and run 36 / 53 up front? This seems like it might be the best combination of gears / £s if it’s technically possible.

Any thoughts appreciated!

Thanks.

sloppyschleckonds

Surely the shop you bought it from gave you the option of a compact or standard double?

milese

SloppySchleckonds wrote:

Surely the shop you bought it from gave you the option of a compact or standard double?

Bought used.

andyk19

I would recommend the compact option, all you'll need is the chainset as a short cage rear mech will work with a compact and any normal cassette; you will need to shorten the chain a little and drop the front mech a couple of mm but that's it.

A new cassette wont make a lot of difference, and as you say it's not cheap anyway.

36 tooth could be an option but there may be compatibility issues, the front difference (the difference in the number of teeth on the small and large rings) will be very large at 17 and as such the derailleur may not shift properly. Looking on SRAMs website older Red can only manage a front difference of 16 and they don't provide the information for new Red. The rear mech may also struggle to take up the considerable variation in chain slack meaning the chain could fall off.
Some chainsets offer a 52/36 combination but I don't remember a 53/36.

If you go down the compact option you could always try eBay for an as new replacement as it'll be a bit cheaper. You could then sell your double on the bay and most likely make most of your money back - as a side note I switched from 50/34 to 53/39 by buying and selling on the bay and made £8...

sloppyschleckonds

Just get a compact, sell the double and it shouldn't cost you anything.

Assuming 2nd hand also.

milese

Thanks for the replies.

I'll plump for the chainset. Eyes out for a Sram Red Compact in 170 or 172.5.

Everything for good money seems to be either 175mm or std double.