Single V Double Crank - upgrade question? Boone 7 Disc

lhinchliffe

Hi All

First time posting - I ride a Boone 7 disc and have recently moved back to my home town which is a little hilly :P

I'm not too grand on bikes/technology and the spec :P But my simple question is - its a standard 11 gear bike ;

SRAM Force CX1, 40T Crank
and
SRAM Force CX1

Is it possible to have a double crank installed? to allow me a granny gear?:P I won't be able to do it myself - but I don't want to walk in the local bike shop and be laughed at:P Would anyone have a rough idea of stuff needed to convert and cost?
I know I could go simply for a larger single crank but just wondering on the possibility of doubling the amount of gears

Cheers

trek_dan

You'll need a new left hand shifter (about £120), front derailleur (£15) and double chainset (£160). Plus a new brake cable and some new bar tape if they can't rewrap what you already have.
The left hand shifter will be more expensive if your using hydraulic brakes (not sure you can buy seperate from the brake caliper.)
Sounds expensive but you'll get a decent amount back for the brake lever and chainset you no longer need on Ebay or in classifieds.

Jterrier

Would be way better and cheaper and neater to just go down a size of chainring to a 38t, and fit a wider cassette at the back if poss; you dont say what size yours is but sram do an 11-36 for example. I think you can go even bigger now with a standard 11 speed hub.

Jterrier

I just googled your bike and it looks like it comes standard with an 11-28 at back. Not surprised you are struggling. Thats some narrow gearing for a cx bike. Get a wider cassette; a shimano 105 11-32 will work fine and is about 30quid. Easy.

oxoman

Just looked at the spec for your bike and I believe it's currently got an 11 / 28 rear cassette. Not sure of max capacity for sram force cx1 but suspect you could fit 38 front with 11 / 32 rear cassette. You may be able to go even bigger but not sure. I had similar issue with my TCX with similar gearing as yours.

lhinchliffe

Many thanks - Reckon I will try a 38 front and a 11/32 rear and see how I go!

oxoman

Just make sure the rear mech will handle it ok first.

lhinchliffe

Cheers - I'll go and speak to the guy in the shop - and use all your knowledge and pretend I know what I'm talking about :P

superlightweight

I'd be very interested in any 1x bits you don't want if you end up changing to a double....

Jterrier

I dont think you will get an 11-38 rear cassette but to be honest if you go to an 11-32 you will notice a massive difference immediately without changing anything else, and your rear mech and current chain will definitely work ok straight off. Trust me. I did exactly the same. Its a no brainer. Just bear in mind sram cassettes are more expensive and much crapper than shimano ones, and that it doesnt matter what brand you use as all 11speed stuff works with everything.

Dont make too many changes either at the same time. Leave the chainring for now, and see if the wider cassette sorts it.

lhinchliffe

Jterrier wrote:

I dont think you will get an 11-38 rear cassette but to be honest if you go to an 11-32 you will notice a massive difference immediately without changing anything else, and your rear mech and current chain will definitely work ok straight off. Trust me. I did exactly the same. Its a no brainer. Just bear in mind sram cassettes are more expensive and much crapper than shimano ones, and that it doesnt matter what brand you use as all 11speed stuff works with everything.

Dont make too many changes either at the same time. Leave the chainring for now, and see if the wider cassette sorts it.

Hi

Thanks for the advice - sorry meant 11/32 not 11/38 that was a typing error!


I'll go with the idea of getting Shimano then! Many thanks

tgotb

I don't know the spec for CX1, but I do know (because I've done it) that you can run an 11-36 cassette with a short-cage Sram X9 MTB mech. I'd be very surprised if CX1 doesn't do the same.

I was doing this with a 34T single ring, but you can choose whatever gives you the range you need.

tgotb

Just looked it up:
https://www.sram.com/sram/road/products ... derailleur
CX1 short cage will handle 11-28; medium cage 11-36; long cage 10-42(!!)

My guess is that you have a short cage mech, in which case any change other than switching to a smaller chainring is going to require a new mech. Switching from short to medium cage is a straightforward 10-minute job, you don't have to change the shifter or cable.

When you swap chainring and cassette, you'll probably need a longer chain (though it turns out that my 34x11-36 setup uses the same chain length as 38x12-32, so you might get away with keeping the same one...)

lhinchliffe

tgotb wrote:

Just looked it up:
https://www.sram.com/sram/road/products ... derailleur
CX1 short cage will handle 11-28; medium cage 11-36; long cage 10-42(!!)

My guess is that you have a short cage mech, in which case any change other than switching to a smaller chainring is going to require a new mech. Switching from short to medium cage is a straightforward 10-minute job, you don't have to change the shifter or cable.

When you swap chainring and cassette, you'll probably need a longer chain (though it turns out that my 34x11-36 setup uses the same chain length as 38x12-32, so you might get away with keeping the same one...)

Hi,

Many thanks for looking into this! And to the others too! (Too kind of you).
Thank you for your advice - it all seems to make sense (well explained) - I'll take it the bike shop and hopefully he will confirm what you and others have said!

Many thanks

lhinchliffe

Thought I would update and say thank you

Booked it in for yesterday - he put on a 32 - said he had no trouble and that I should take it out for a quick ride - if it feels ok then leave it or could put a bigger rear cassette on - £50 cost including fitting - so all good!

Haven't taken it out and won't be able to ride it till Monday but hopefully these hills will be a little easier!:P