UKH

Changing Cassette

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 AndyMusgrove 15 Jan 2021

Hi 

I currently ride a stock Giant Defy 1 (2015) but having moved from the flatlands of the south up to hilly Yorkshire am considering changing the rear cassette to an 11-34. This is only based on reading a few articles that suggest it may help, my questions are:

- Is this just a simple case of changing the cassette, or do i need to consider the rear derailleur, chain, etc. 

- Is this going to be the most cost effective way of making the hills a little easier (excluding a diet or just 'getting better at hills'). 

Thanks

Andy

In reply to AndyMusgrove:

Done it now on two different bikes. On the first I needed to get a longer cage back mech, but it was only Sora and I found one cheap in local shop so it wasn't costly. On my newer gravel bike the Tiagra mech worked going from 11-32 to a 11-36 back block without any problems at all. A tiny bit of fiddling with the wire tension was all that was required.

Haven't tried on a 1x system and a MTB back mech though so don't know if they are more or less tolerant that road groupsets.

In reply to AndyMusgrove:

Always change your chain when you change cassette.   I would be surprised f your mech couldn't accommodate a 34. unless you have a very short cage it should be fine.

1
 GrahamD 15 Jan 2021
In reply to balmybaldwin:

> Always change your chain when you change cassette.   I would be surprised f your mech couldn't accommodate a 34. unless you have a very short cage it should be fine.

I wouldn't be that confident on a 2015 vintage bike.  It would be useful to know what the existing groupset is.

 GrahamD 15 Jan 2021
In reply to AndyMusgrove:

What is the existing set up ?  I'm guessing a 2015 Defy has 50/34 at the front, but what groupset ?

 webbo 15 Jan 2021
In reply to balmybaldwin:

> Always change your chain when you change cassette.   I would be surprised f your mech couldn't accommodate a 34. unless you have a very short cage it should be fine.

Why. I reckon I get at least 4 or 5 chains to a cassette.

2
 nniff 15 Jan 2021
In reply to AndyMusgrove:

Have a look at this 
https://productinfo.shimano.com/download/pdf/com/2.6/en

Sadly, it isn't exactly straightforward

It helps if you know exactly which rear derailleur you have, but this will let you know the range of large sprockets each derailleur will accommodate.

You will need a new chain - wise for a new cassette anyway - 3 chains to one cassette is usual.  Besides which, the old chain will be too short

 Richard Horn 15 Jan 2021
In reply to AndyMusgrove:

Hi Andy, I would be surprised if you need a 34 on the back - my gravel bike has a 34/34 lowest gear and I only use that on insane steep off-road sections.

Generally for equipment from 2015 - I would assume if you have a medium rear cage that would accommodate a 32 max (or if a short cage 28). Newer rear derailleurs (R7000 etc onwards) can have a max 34 on the back. 34/32 should still be fine for any road.

With regards to changing cassette, as someone has said would be good idea to change the chain as well. Good test is try to pinch the chain at the front of the chainring and pull it forwards, if it feels taught its ok but if its relatively easy to pull away a small gap (a few mm) then the chain will be stretched. A stretched chain will make mincemeat of a new cassette and will not run well (as its likely your existing cassette will have had its teeth "modified" by the stretched chain). Generally I go through ~3 chains before cassette replacement, front chainrings should last a lot longer.

 steveb2006 15 Jan 2021
In reply to webbo:

> Why. I reckon I get at least 4 or 5 chains to a cassette.

Yes so start a new 4-5 chain cycle with a new cassette. A worn chain on a new cassette can cause it to slip/jump the teeth. Not good and cause greater wear on new cassette. Chain is relatively inexpensive so always a good idea to get a new one with a new cassette

 webbo 15 Jan 2021
In reply to steveb2006:

> Yes so start a new 4-5 chain cycle with a new cassette. A worn chain on a new cassette can cause it to slip/jump the teeth. Not good and cause greater wear on new cassette. Chain is relatively inexpensive so always a good idea to get a new one with a new cassette

I didn’t say use an worn chain on a new cassette. If I put a new chain and it slipped, I would replace the cassette. Which would mean new chain and new cassette.

In reply to webbo:

> Why. I reckon I get at least 4 or 5 chains to a cassette.

Because if you put an old chain on a new cassette you will get maybe 2-3 chains of wear out of your cassette and chains are cheap

 AndyMusgrove 15 Jan 2021
In reply to AndyMusgrove:

Thanks all for the advice, I suspected it might not be as straight forward as some websites would have me believe. Having had a closer look it appears it has an FSA Gossamer 50/34 Crank at the front and 11-32 Cassette on a Shimano 105 derailleur.

I guess the best option is possibly just to find a good local shop and go have a word...once we can!

In reply to AndyMusgrove:

I've just changed to a 11-34 on my stock giant defy 1 (2015). It needed a bit of retuning on the rear derallleur but nothing much. Cable tension and the b-tension screw, the limits remained as they were, and it rides fine.

I'm not so sure if having the 34 has made much difference on the hills yet, will maybe change back again in a few weeks as a little experiment to see.

Post edited at 17:11
 AndyMusgrove 15 Jan 2021
In reply to kedvenc72:

What a coincidence keep me updated, and yes that was my other thought. I'd get it done and expect some sort of miracle that isn't going to happen. 

In reply to AndyMusgrove:

sorry, made a mistake! I have a 2014 model which has a 12-32, ten speed cassette, not the eleven speed 11-32. So, I changed to a ten speed 11-34.

 webbo 15 Jan 2021
In reply to balmybaldwin:

> Because if you put an old chain on a new cassette you will get maybe 2-3 chains of wear out of your cassette and chains are cheap

I may have misread your post higher but you said change the cassette change the chain. But now your saying you get 2 or 3 chains per cassette. So I puzzled to what you are trying to say.

 GrahamD 15 Jan 2021
In reply to AndyMusgrove:

If you already have 34 front 32 rear you are already pretty much at the limit of what you will achieve on a standard road bike.  Much more gearing it's hard to retain traction and balance.

1
 RobAJones 15 Jan 2021
In reply to GrahamD:

I'll use the excuse that I live in Lakes, but you can call me wimp if you want. On my winter bike I have got a mountain bike cassette 11-42 (I think). Needed to buy a cheap version of a Wolf Tooth Roadlink to extend the medium cage 105 rear mech.

This might be another option for the OP.

 top cat 15 Jan 2021
In reply to RobAJones:

If you are a wimp, what am I with my 26 upfront and 11-46 cassette.  And I still have to get off and walk from time to time.  All off road though .......

 GrahamD 15 Jan 2021
In reply to RobAJones:

I don't think I could pedal fast enough to stay upright!

In reply to GrahamD:

> If you already have 34 front 32 rear you are already pretty much at the limit of what you will achieve on a standard road bike.  Much more gearing it's hard to retain traction and balance.

Are road bikes lower in grip and harder to balance than mountain bikes? I only have an old mountain bike. The lowest gear is 22 on front , 34 on cassette and it only has  26inch wheels (told you it was old). I couldn't imagine it running out of grip or being hard to balance on a road although on our local (West Cheshire) roads I only use the two bigger chainrings.

Post edited at 21:03
In reply to RobAJones:

Me too, i’m running a 40-11 on a compact chain set.

For the conversion I used a shimano MTB cassette, new chain and a road-link extender. This is for a 105 group set with the medium cage rear mech.

No issues whatsoever and climbing no longer feels like a grind, I’m helping my knees and hips no end.


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