Changing to compact?

Discuss light weight issues concerning road bikes & parts.
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Peedee
Posts: 1
Joined: Wed Mar 29, 2017 11:23 am

by Peedee

forgive me - I'm new to all this. This is my first post

I currently ride with Shimano 105 53/39 10speed but I am due to tackle the Alps this summer
I have no mission with those gears

How can upgrade to a compact on the cheap?

I dont need to upgrade to 11 speed, do I?

I don't want to have to start changing everything as realistically I plan a new bike next year at some stage. I just want a cheap fix

Any feedback appreciated and please keep it simple........I'm a rugby player, not a cyclist

by Weenie


jupis
Posts: 27
Joined: Wed Aug 08, 2007 11:27 am
Location: Helsinki, Finland

by jupis

Cheapest way is changing your cassette.
It's size of the cassette sprockets which counts, not 10s, 11s etc.
How many teeth your current cassette has? If e.g. 12-25 you could buy cassette ending 28 teeth (or more if your rear derailleur allows)
If that is not enough you can change to compact cranks (or check if your current cranks allow smaller rings, at least 38 should be OK for standard cranks)

You'll see difference using some gear calculator e.g http://sheldonbrown.com/gear-calc.html
Or play with the hill incline, power etc. http://zhuk.fi/bicycle-power-calculator
Juha H >> Swim > Bike > Run

alcatraz
Posts: 972
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

How many "teeth" does your biggest gear in the back have?

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BRM
Posts: 817
Joined: Sun Mar 16, 2014 3:43 pm

by BRM

In short:

- Look on sites as Ebay for a bargain compact chainset that is compatible with your system.
- Get the right sprockets new
- Take a new chain

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fa63
Posts: 2274
Joined: Mon Feb 19, 2007 7:26 am
Location: Atlanta, GA, US

by fa63

You can find 105 level compact cranksets for under $100 new (I got mine for $80), or around $50 used (you can even use 11 speed cranks; it will work fine). Then get a 11-32 cassette and chain for another $50 or so, and you are ready to climb. If your rear derailleur can't accommodate the 11-32 cassette, you can buy a Wolftooth Roadlink for under $20.

glepore
Posts: 1119
Joined: Thu Mar 28, 2013 4:42 pm
Location: Pa USA

by glepore

11 spd shimano cranks shift just fine with 10 spd. Echo the above, 105 cranks are cheap on ebay.
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FIJIGabe
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Joined: Tue Sep 11, 2012 6:07 pm
Location: The Lone Star State

by FIJIGabe

Seriously, the price of new 105 chainrings is almost equivalent to the price of a new crank. Even if going with 10 speed stuff, you're better off getting a new crank (and the previous generation stuff isn't cross-compatible because of the different BCD - 110 vs. 130, compact vs. full size). The beauty of the new 11-speed stuff is that all the chainrings are compatible, so you can run a compact one day, switch out to a full-size the next, etc.
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grumpus
Posts: 37
Joined: Sat Sep 24, 2016 3:31 am

by grumpus

All good advice so far. Cheapest way to get the easiest gears would be to get a used compact crank and as large a cassette as your bike will fit. Make sure the teeth aren't too warn and you shouldn't have issues. And make sure your chain is long enough.

If you know what power you make, then you can get a better estimate of the gears you need. Look for the steepest section you'll be doing on a map. Say it's 15% and it's going to take you 10 minutes. Input your information here http://bikecalculator.com/, and input a power that you are comfortable with for 10 minutes. The calculator will spit out the speed you will be going. Then head here http://www.bikecalc.com/speed_at_cadence and decide what cadence you want to be able to hold. Play with the gearing until you get it where you want to be.

It might turn out that you can get the cadence you want by just changing the cassette. It's not an exact science though, and it's always better to have a few gears that are too easy than to be stuck pedaling at 20rpms.

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BRM
Posts: 817
Joined: Sun Mar 16, 2014 3:43 pm

by BRM

FIJIGabe wrote:Seriously, the price of new 105 chainrings is almost equivalent to the price of a new crank. Even if going with 10 speed stuff, you're better off getting a new crank (and the previous generation stuff isn't cross-compatible because of the different BCD - 110 vs. 130, compact vs. full size). The beauty of the new 11-speed stuff is that all the chainrings are compatible, so you can run a compact one day, switch out to a full-size the next, etc.


Lol, Not every secondhand chainset is used to dead.
Look back to the startpost, and focus on the Original question.
The TS is asking for a cheap fix and that he has planned to buy a new bike next year.
The focus should be on that.

FIJIGabe
Posts: 1410
Joined: Tue Sep 11, 2012 6:07 pm
Location: The Lone Star State

by FIJIGabe

There is no "on the cheap" when going from an older 53/39 to anything else, because he'll need a new crank spider to go from the 130BCD to 110 to fit the smaller rings. At a minimum, he's going to need new chainrings and a new chain, since the old one will be too long (assuming he will switch back to his 53/39, cutting the chain isn't an option).

Even if he buys a used crank, he's still going to be spending somewhere close to $100 for the two things (and more, if he needs to change the cassette). Maybe another $20 and he'll have a brand new 5800 crank in whatever size he wants, and a new chain.
Madone 9 https://goo.gl/7UwZpV
Crockett https://goo.gl/f5PdCN
Madone 5 https://goo.gl/cMdyFo

Madone 4, Cobia. I own a lot of Treks.

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BRM
Posts: 817
Joined: Sun Mar 16, 2014 3:43 pm

by BRM

I'm glad that you admit, you were just talking in some wild direction not related to the Original question.

Thanks for that . . .

:thumbup:

DJT21
Posts: 186
Joined: Sun Mar 27, 2011 7:35 pm

by DJT21

Buy a second hand compact chainset from Ebay. A Shimano Tiagra 4650 or 105 5750 (there are an abundance of these second hand) will likely be compatible with your current bottom bracket (unless you have a BB30 frame, in which case you need a BB30 chainset).

Avoid any that have "shark finned" teeth, usually on the outer chainring. That means they're badly worn.

It may also be worth getting a 28 or 32 tooth cassette aswell.

Fit a new chain if yours has seen alot of miles.

Adjust your front mech to suit the new chainset.

Job done.

by Weenie


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