Big cassette.

[gavroche]

I have asked two LBS so far to put a 11-40/42 cassette on my Specialized Roubaix and both refused to it on the grounds that it is not compatible with my Shimano 105 derailleur. I suggested putting a wolf tooth to increase the length but they still won't do it. Yet, when I researched it on YouTube, it seems that a few cyclists have done it with no problems afterwards.
I don't trust myself to do it so why won't a professional bike mechanic give it a go?
The reason why I want to do that is because I would like to take this particular bike when I do the C2C next June as I believe some of the hills are pretty steep.

 

[si_c]

I can't blame them to be honest, it's a liability thing, if they install something outside of manufacturers guidelines and it breaks, then they'll be potentially liable, especially if the derailleur goes into the wheel and causes a crash.

Unlikely scenarios I'll grant, but prudent from their perspective. The good news is that if you really want to do it, it's actually really easy if you have the tools, a 5 minute or so job. I fitted a suntour extender and cassette to my hardtail MTB last year and it worked really well.

Is there anyone local to you who might be able to do it? I'd offer, but I'm probably a touch too far.

 

[roadrash]

Ask them about the price including a compatible derailleur or have a go yourself , it really isnt difficult and plenty of youtube videos to help out

 

[si_c]

Ask them about the price including a compatible derailleur or have a go yourself , it really isnt difficult and plenty of youtube videos to help out

Not a bad idea, a GRX rear derailleur might work.

 

[Cycleops]

Liability or 'elf & Safety.

Not surprised.

It was going to look a bit funny anyway.

 

[Joffey]

I have asked two LBS so far to put a 11-40/42 cassette on my Specialized Roubaix and both refused to it on the grounds that it is not compatible with my Shimano 105 derailleur. I suggested putting a wolf tooth to increase the length but they still won't do it. Yet, when I researched it on YouTube, it seems that a few cyclists have done it with no problems afterwards.
I don't trust myself to do it so why won't a professional bike mechanic give it a go?
The reason why I want to do that is because I would like to take this particular bike when I do the C2C next June as I believe some of the hills are pretty steep.

What chain rings are you using? And why the massive cassette? It seems odd to be using a 42 unless you are running a x1 system? You might be able to faff with your ratios my changing the front?

 

[Dogtrousers]

Not a proper response but you could attack the problem from the other end by installing a subcompact chainset, which may well be compatible with the front mech (I don't know for sure). 105 will handle up to 34T at the rear so you should be able to put together something really low. But it would probably cost more than just replacing the cassette (edit: x-posted with @Joffey)

 

[All uphill]

I understand the reluctance to do this. Any chance of damage when cross-chaining would prevent me from pushing derailleur capacity on someone else's bike.

 

[cyberknight]

Not a proper response but you could attack the problem from the other end by installing a subcompact chainset, which may well be compatible with the front mech (I don't know for sure). 105 will handle up to 34T at the rear so you should be able to put together something really low. But it would probably cost more than just replacing the cassette (edit: x-posted with @Joffey)

Its what i would do as well

 

[gavroche]

What chain rings are you using? And why the massive cassette? It seems odd to be using a 42 unless you are running a x1 system? You might be able to faff with your ratios my changing the front?

The chain ring is 50/34.
I appreciate si-c comment and had not thought about that to be honest so I can now see why they won't do it.
Because my present cassette is 11/32, I don't think 11/34 would make much difference for the extra cost.
If it is too steep, I will just have to walk it, not the end of the world.

 

[Joffey]

The chain ring is 50/34.
I appreciate si-c comment and had not thought about that to be honest so I can now see why they won't do it.
Because my present cassette is 11/32, I don't think 11/34 would make much difference for the extra cost.
If it is too steep, I will just have to walk it, not the end of the world.

You might be able to pop a smaller little chain ring on as a hack / bodge but shift to the big ring might be difficult.

I'm a fat lad who can't climb and I've got over pretty much everything on a 36 front - 34 rear combo which would be similar to your current ratios. Obviously I don't know your specific circumstances so I can't judge but you might surprise yourself.

Going for a 42 on the back might make for horrible shifting with a 50/34 and a wolf tooth but then again it might be fine.

Don't be afraid to try it yourself - you'll need a longer chain though! You can get an 11-42 cassette for about £50 if you are prepared to buy a non branded one.

 

[Peter Salt]

I understand steep climbs but with a 34 at the front and a 42 at the back, assuming you're struggling and doing a low cadence - say 60, your speed will be under 4mph - less than park walkers. At that pace better practice your track stand

What is your typical cadence up a climb? Do you have a target speed?

 

[ColinJ]

I understand steep climbs but with a 34 at the front and a 42 at the back, assuming you're struggling and doing a low cadence - say 60, your speed will be under 4mph - less than park walkers. At that pace better practice your track stand

I do some of the steep climbs round here at under 4 km per hour!

(That takes 230+ watts, so I'm not completely slacking.)

 

[All uphill]

I do some of the steep climbs round here at under 4 km per hour!

(That takes 230+ watts, so I'm not completely slacking.)

I need my 30/40 lowest gear when I head over towards Devon hills! They are still not easy!

 

[craigwend]

You really may surprise yourself - this year a change of bike meant my low gear of 30 [front] & 32 [rear] - was replaced by a 34 [front ] & 32 [rear] which I did a C2C on, I'm really not a climber, even I made it up the 'evil' hill of Settle