Right to go Compact???

too_sleepy

Hi.
Been reading a bit about compact/ triple and standard chain sets. I have a standart set up, cassette 12-25 with a *53x39.

This seems to be very highly geared for me. Even descending a steep hill I dont get near to using my top gears.*
Ascending even a moderate hill I find I'm in my granny gear very early. I know fitness plays a part but I'm starting to think I need slightly lower gearing.
*
So it's a compact I'm now after. Specifically an SRAM Force.*
There's two choices 50/36 and 50/34, any recommendations *on these two. Also, how do I know it will fit without changing the bottom bracket? I'm assuming because Im replacing like for like, just different size, all will be dandy. Is there something I'm missing?
*
Thanks*

SurferDude41

too_sleepy wrote: »

Hi.
Been reading a bit about compact/ triple and standard chain sets. I have a standart set up, cassette 12-25 with a *53x39.

This seems to be very highly geared for me. Even descending a steep hill I dont get near to using my top gears.*
Ascending even a moderate hill I find I'm in my granny gear very early. I know fitness plays a part but I'm starting to think I need slightly lower gearing.
*
So it's a compact I'm now after. Specifically an SRAM Force.*
There's two choices 50/36 and 50/34, any recommendations *on these two. Also, how do I know it will fit without changing the bottom bracket? I'm assuming because Im replacing like for like, just different size, all will be dandy. Is there something I'm missing?
*
Thanks*

Hi There.
I would go for the 50/34. most of us who don't race, would really benefit from a compact chainset.
It is a straight swop, from your 53/39 chainset. You will however, have to remove one pair of links, from your chain.
Also your front derailleur, needs to be lowered so the outer cage plate sits 1-2mm above the 50 tooth outside chainring. The shift cable, would need to be shortened and readjusted.

I hope this helps, let me know how you get on.

Happy cycling:)

Lumen

Are you saying you have SRAM Force standard and you want to change to SRAM Force compact?

If so it's very easy to change, just off with the old crank and on with the new, then maybe tweak the derailleur height.

Regarding 50/34 vs 50/36, if you need more gears you really have to decide if you want it gappy at the front or gappy at the rear. 12-25 is a nice close cassette, so perhaps start out with the 34 - you can always buy a new chainring if it annoys you.

I have a SRAM Red compact with 50/34 rings lying spare if you want to swap with your standard.

IM0

the 36-50 will be better at shifting, a smoother shift than a 34-50 as the 34-50 (16 tooth difference) is right at the edge of front der capacity and is starting to trade off a more clunky/possibility of dropping chain.

I have a 34-50 for marmotte training (long climb intervals) but when I put the standard 53-39 back on it shifts like glass! . Id get the 36 if I was you, and if THAT isnt enough, then go for a 34t.

blorg

If you are not racing certainly go compact, 50/34. The shift is a bit abrubt but you get used to it, you just have to shift at the back simultaneously. Compact is a fantastic idea frankly.

oflahero

Did exactly this last Saturday with the aid of Mr Skeffington (105 double -> 105 compact 50-34). Too early to judge, but I was definitely glad of the extra spinnage when out suffering the next day.

Was also pleasantly surprised by the still-high gearing on it for the descents, I really didn't miss the 53x11 like I feared I might've.

souter

definitely. I don't race, struggle to manage 100km yet due to monumental hubris insisted on swapping the compact the bike came with for a standard double just because I was a single speed before and thought I had reasonably strong legs.

So I'm running 53/39 - 12-25 and getting killed on hills, yet am too embarassed to change it. Can I post this anonymously?

ROK ON

FWIW. I have a compact and a triple.

In a recent training run up a steep climb over 3.6km @8,3% my time using gearing of 30/27 was 4 mins faster than my time when using a compact with 34/25.
Similarly on another climb that is 7km at 3% my time on 34/21 was 2m30s than when using 39/21.

Spinning on climbs works. Choose gear ratios that leave you spinning freely. This may be a compact but could be standard with an 11/28 or 29.
Have a look at Sheldon Browns gear calculator to figure your easiest gear in terms of inches per revolution. Then decide how much easier you would like it to be on the climbs in order to spin more.
Then go for that gear combo.

Turbulent Bill

I also have a standard double with 12-25 on the back, which doesn't help my rubbish climbing (though I can't really blame the gears). It's also difficult to improve your cadence, as there's a limited range of usable gears at normal commuting speeds. I'd spend almost the entire time on the smaller ring, and maybe 6 gears at the back.

Before anyone else says it, yes, I just need to HTFU.

Ryaner

Lumen wrote: »

I have a SRAM Red compact with 50/34 rings lying spare if you want to swap with your standard.

Beat me to it

leftism

Following an embarrassing experience up the Sally Gap (involving me climbing off the bike twice at steeper sections), I took the advice of some of the learned gentlemen on this forum and switched to a compact crankset about 3 months ago.

I cannot recommend them highly enough! I got a SRAM rival 50/34 and i love it. I tried a 12/27 rear block instead of my 11/25 but i didn't like the gaps between some of the gears. I'm very happy with my compact and 11/25 set up now...

DirkVoodoo

I got to try out a regular 53/39 for racing last week. It was great, perfect for the speeds and the changes in speed. The shifting at the front (yes, I used 39 at one point) was so smooth and nothing like the "have I dropped a chain?" feeling you get from shifting down on a compact.

But I wouldn't take it out to Wicklow.

Outside of racing, I am more than happy with my compact. All the gears I need to get around and while the shifting at the front is a bit rougher, I'm not racing on boards spins or on sportives so quick, smooth changes aren't necessary. The wider range of gears is perfect and I can't understand how anyone wants a regular double outside of racing except for looks or ego.

You could swap around cassettes, but even a 12-27 becomes somewhat gappy for climbing (19-21-24-27) and I wouldn't go more than 12 teeth up front really.

too_sleepy

Hi. Thanks for the great advice. Decided on a compact 50/34, planned a few days in the Wicklow hills next month and an event there in the summer has made my mind up.
Thanks for the offer of a swop, might want to hang on to the standard for a trip to Holland in the summer. Anyone wanting to sell an SRAM compact I'd be very interested.
Thanks again.

IM0

also with a 25/11 and 50t you get to feel what a professional feels like when he rides a 53/39 w 23t, you spend most of the time in the middle of the cassette, with the minority of time in the 25/23 and 11. Also you spend the vast majority of time in the big ring as you can get down to 19km/hr in the 50-23 on hills around 70 rpm. the only place wou will miss a 53 is in a sprint over 70km/hr, a 50/11 will get you to 69km/hr at 120rpm! :eek::eek:

if nayone is wondering where these numbers come from its like this:

50/11 =4.545 (can use any numbers, basically the front chainring size your on divided by the back cog size)
4.545 X 2.121 (a 700c wheel) =9.6409
9.6409 x 60 (dont ask! but it's always 60) =578.454
578.454 x 120 (or ANY other cadence you want)
=69.4km/hr

CheGuedara

DirkVoodoo wrote: »

The wider range of gears is perfect and I can't understand how anyone wants a regular double outside of racing except for looks or ego.

You could swap around cassettes, but even a 12-27 becomes somewhat gappy for climbing (19-21-24-27) and I wouldn't go more than 12 teeth up front really.

me@ucd wrote: »

also with a 25/11 and 50t you get to feel what a professional feels like when he rides a 53/39 w 23t, you spend most of the time in the middle of the cassette, with the minority of time in the 25/23 and 11.

I'm surprised at this frankly appalling abandonment of Euroness

OREC wrote:

31. Gearing shall be restricted to a titanium Campy Record 11-23 cassette with a ABSOLUTE MINIMUM of 42-53 up front....The use of 25-toothed cog is acceptable for severely mountainous training situations.

I think most will accept that the 42t is hard to come by as standard so we'll let that fly but to so flagrantly abandon the rest is tantamount to heresy...

Repolho

I don't race, only leisure cycling. I plan to do all the An Post events this summer but I'm a bit aprehencive about the climbing involved in some of them. From reading this I think a compact is exactly what I need. I rarely use the top gears and often find myself looking for a lower gear going uphill!

Pardon my ignorance, but are they compatible with all setups? I have a Trek 1000. Its got Shimano Sora (Double) up front and Tiagra on the back with Sora shifters.

Finally, roughly how much would a local bike shop would charge to supply & fit?

Thanks.

Lumen

Repolho wrote: »

Pardon my ignorance, but are they compatible with all setups? I have a Trek 1000. Its got Shimano Sora (Double) up front and Tiagra on the back with Sora shifters.

Finally, roughly how much would a local bike shop would charge to supply & fit?

A new Sora compact chainset is less than €60, and it's a five minute job to fit.

blorg

Lumen wrote: »

A new Sora compact chainset is less than €60, and it's a five minute job to fit.

Sora only went to an external bearing BB very recently, I think when it went 9 speed- so just be careful you get the right one. You may have to get a new BB for that chainset.

leftism

DirkVoodoo wrote: »

the "have I dropped a chain?" feeling you get from shifting down on a compact.

In my case the answer is almost always "Yes, i have indeed dropped a chain! Again....." :mad:

Not for long though! My super-deluxe chain catcher is hopefully on the way soon.

leftism

blorg wrote: »

Sora only went to an external bearing BB very recently, I think when it went 9 speed- so just be careful you get the right one. You may have to get a new BB for that chainset.

The Sora compact crankset does require an external bottom bracket! Just a warning, coz i can't fit the bloody thing on my brothers bike...

How do you remove internal BB's??? I suppose i'm gonna have to buy another stupid tool for that am i???

blorg

leftism wrote: »

How do you remove internal BB's??? I suppose i'm gonna have to buy another stupid tool for that am i???

Yes, it's a tool like a cassette removal tool, this for Shimano square taper/octalink ones. You would also need a crank puller to get them off I think- and the Hollowtech BB tool to get the new one on.

Repolho

Think I'll just get the guy in the local shop to do it for me!

Thanks for the input!