Hi,

Im kitting out a bike with a new 105 groupset but I'm not sure of best ratios to suit me.

I ride 50 mile rides at the weekend but use my bike for commuting 5 miles to work each day.

I was considering a compact crank setup 53/39 and 12-25 cassette.

I am 6ft tall so will go for 175mm cranks.

My local area is about 50% hills and 50% flat!

My overall fitness is pretty good.

Would this set up be ok for what im looking for? If not, anyone sot another suggestion i might try?

Thanks in advance.

53/39 is not a compact.
You don't say how steep the hills are. I've commuted with those ratios, with some moderate hills and found it good, but I only carried myself and lunch.
Doing a 30km each commute everyday keeps you at a pretty good level of fitness.

53/39 is a standard crank. a compact crank is typically 50/34 or 50/36. As for answering if that is a good setup for you, that is a lot more difficult. Are you currently on a standard or compact crank? Do you find the hills difficult on what you're riding? If so, then a compact crank might be a better choice. If you're already on a compact and still find the hills difficult, there is always the option for a triple.

I meant 50/34! (You see, i told you i was confused!!!)

Not sure how steep the hills are but im cycling around Yorkshire, UK

I am 6'1" and noticed a much higher comfort level with 172.5 or even 170mm cranks. I know it doesn't sound like much, and I was a skeptic, but the shorter arms at our height makes a big difference to your knees.

6 Ft and love 175mm crank arms.

^^^It really does depend on your riding style. Here in the Rockies, I am a spinner, where shorter cranks feel better.

With a 50/34 crank and a 12-25 cassette you'll have all the gears you could want. If the hills are steep, go compact and 12-27 cassette.

I have 105 , 5700 with 50/34 crank ( 172.5) and 11/25 in the back and my town is FULL of hills, I'm 5f11 and 145-150 pounds and I have had no problems with this group so far.

OK, im pretty much sold on the 50/34 crank

I really cant decide between the 11/25, 12-25 or 12-27 cassette - how much difference is there?

Also cant decide between 175mm or 172.5mm cranks (realistically I'm a couple of mm under 6ft).

All your opinions so far are greatly appreciated

ALSO - im reading that the 12-25 cassette will offer the smoothest shifting, from anyone's experience is that true?(could be a deal breaker!)

Well, all the cassettes are 10-speed, so it makes sense that the more closely spaced the cogs, the more uniform and smoother the shifting. Whether it is noticeable with a properly turned derailleur? I doubt it. If it was a serious problem, you'd hear more about it.

I wouldn't let that sway your decision. Buy the cassette with the range you need, but don't obsess too much -- they are relatively cheap and you can always swap as needed.

Thanks, Yes i guess that's true!

On that note though, I guess that makes crank length a more critical decision based on cost.

Any advice on 175mm vs 172.5mm?

I'm a spinner and climber at 6ft-ish (187cm) tall. I've tried anything from 155mm (yes, seriously) to 175mm cranks, and there's no beating that freedom of movement the 175mm gives. The 155mm was fitted to a fixed-gear as a test (trying to make up for the low bottom bracket), but I quickly reverted to 170mm after a bried stint on 165mm. The foot felt restricted - I had this annoying feeling of power building up without a way to vent it, and often felt like I had to stop and stretch my legs for a second. Never got it on the 170mms, nor do I get it on the 175mm cranks my roadbike has. I can spin happily all day and my legs never feel cramped for space.

I have the compact (50/34) and both 11-28 and 12-25. I used the 12-25 on a hilly race a few weeks back. The 28 would have been extremely useful on those hills 20%+ grades.
Next year I will switch to the 11-28 for that race and probably use the 12-25 for pretty much everything else. The 12 vs 11 isn't an issue since I never needed that gearing. On the descent I was able to reach 43mph without even pedaling.

https://www.nettally.com/palmk/crankset.html

Thanks for the help everyone, in the end i went for 50/34 with a 12-25 cassette, 172.5mm cranks and FWIW in silver!

Cheers folks!

Pics or it didn't happen

Nice. Sounds like what we specced for our coming Sportives except we are getting 165 mm cranks.

I like to run 50/34 and 12/25 for most stuff here in Minnesota (river bluff country) and find that works ok up to about 11% grades of not long duration. When we go out west to the mountains, then we shift to 12/27's or 12/28's. It's nice to have that nice granny gear for long uphills to rest the legs with easy spinning. It's easy to change a cassette yourself. I have several and do that frequently.

J.

This is excellent advice. I live in city with hills that rival San Francisco. Also literally across the river, a 5 minute ride, it is dead flat and about 3m above sea level. I run a 172.5mm cranks with 50/34 and 12-27. Occasionally I drive out of town and into the mountains where this setup works perfect as well.

In the future, I [i]could]/i] see myself upgrading to an Ultegra 12-25 over the 105. The 105 groupset if you indeed ar ready to purchase is the cheapest bought from the UK at Ribble. Ridiculously cheap. I live in Canada and even with shipping the price annihilates anything a bike shop can offer.

+1. Shiny Bikes also has very good prices. today I bought a compact Ultegra (6750) crankset+BB, a 5700 12-25 cassette and a KMC DX10.93 chain from them. All in all it was $15-20 less than Ribble's prices. Ribble also had a couple of demo 5600 105 compact cranksets for $75 over the weekend, but were quickly sold out in a couple of days.

According to that I should be riding 186mm cranks