32, 34 or 36 cassette for Roux 250?

[LindaW]

Hi, I have a Roux 250 and I'm keen to know if it will really help going up the mountains with 4 panniers if I change the current 32 speed cassette to a 34 or 36.

My bike shop said that the 36 was big for the bike but I want as much help getting up the mountains as possible as we cycle through France! They also said I would need a new chain and that with a 36 I wouldn't be able to use the front big and back big cogs together. Not sure this is a prob as I don't do that now!

I'm female, in my mid 50s so any advice is very gratefully received.

Thanks so much

Linda

[gaz]

A quick google suggests the Roux 250 has an Acera rear mech.

Tech Docs for Acera RD-M360 show it has capacity for a 34T maximum rear sprocket. You might manage 36T but it's not designed to do it.

A new chain would be a good idea. First of all it will need to be longer to accomodate the larger sprocket, secondly new cassettes don't tend to work well with worn chains. The risk of having a chain that is too short to engage big sprocket and big chainring arises from an accidental shift to that combination. At best you'll come to a sudden halt ,most probably with some broken transmission parts. At worst the sudden halt will cause a tumble as well.

If you want lower gears a smaller front chainring may present an easier solution. What do you have currently?

[LindaW]

Thanks Gaz, I have what the bike came with which is 3 front rings. When I searched for reviews, I found a couple of men who had changed to 34 which they said was better but hasn't found anyone who has changed to a 36, probably because of the technical advice you have given!

[gaz]

Do you know what size the smallest chainring is and the BCD (Bolt Centre Diameter) for it's fittings. If you aren't sure then post the model of the chainset. Most Shimano components have code numbers, FC-????.

[LindaW]

On the spec it says Shimano Triple 50/39/30 octalink. Does this help? If not I'll look for part number on bike tomorrow when I'm home.

Thanks for helping!

L

[nirakaro]

Gaz is right that changing the front smallest chainring is a better way to go – it’ll make much more difference to your lower gears. I think front changers tend to have a maximum range of around twenty teeth (difference between biggest and smallest rings), so you may want to change the whole front chainset to, perhaps, 44-34-22. This will give you a lowest gear a good 25% lower than at present. I did this a few years ago, as the years advanced, and found it a huge improvement. As an added bonus, I also became much better acquainted with my large chainring!

[gaz]

The model number will be a big help. In the meantime I've asked the mods to move this thread to the technical board. There are many forum members more knowledgeable than I am in these matters and they are more likely to see it there.

[mercalia]

there comes a point when its better to get off and walk. But as others have said your front chain set is rather high - On my 26" wheeled bike I have a 46/36/26 which is about right and goes up most hills before I want to get off and walk - Yours is more set up for riding on the flat & I take it you have 700c wheels to top it all?

[peterh11]

I agree that moving to a chainset with smaller chainrings would be good as it allows you to manage lower gears without a very large cassette, and also the potential to go even lower with one!

But do take some advice about the compatibility of your front derailleur with smaller rings. Modern triple front derailleurs can be very fussy about which chainrings and chainsets they will work with. If your local bike shop cannot help, I suggest a call to Spa cycles, who stock touring chainsets and will know what the limits are likely to be with the Sora front derailleur (assuming that is what you have - it is what the Roux 250 spec says). You may be fine with say a 46/36/26 but need to adjust it very carefully.

I switched to a Spa touring chainset a couple of years ago and had to try 3 front mechs before I found one that worked. You need to look at the chainline (using a touring or road chainset @45mm, NOT a mountain bike one as they are further(50mm) from the centre line of the bike and road mechs won't reach), tooth difference outer to middle (they all say 11 is minimum, but my Tiagra works fine with 10 difference), tooth difference outer to inner (typically 20 is the limit but you can often do a bit more), and outer size (don't go too far from the design size), and finally frame angles!

Maybe someone reading this has already tried this combination and can report on their experience, and hopefully give assurance that the Sora would work with 46/36/26.

PeterH

[andrewjoseph]

my wife has a 48/36/24 chainset and a 36t cassette, with mtb 9spd rear mech and ultegra sti shifters.

works fine for touring but still has to get off and walk up some hills.

[Norman H]

Your chainset sounds like a 130/74 BCD Triple. A simple and fairly cheap experiment would be to drop the size of the inner ring; 74BCD rings are available down to a minimum of 24T.

Spa's own brand are very good value.

http://www.spacycles.co.uk/products.php?plid=m2b0s210p3056

Most triple front changers aren't that fussy about the middle to inner shift and will tolerate a fairly large difference but, for a belt and braces approach, you could also fit an N-gear Jump Stop to pre-empt any overshifts.

http://n-gear.com/

http://www.billys.co.uk/english/group.php?prod=chng-js

[reohn2]

If this is the bike :- http://rouxbikes.co.uk/shop/etape-250/
The spec is showing a Sora long cage rear mech,which will handle a 32t sprocket though a Deore M591 will handle a 34t.
I agre with Norman H,the chainset will take a 24t inner ring which will with a 34t sprocket lower the gearing considerably.
You'll need a Deore M591 rear mech:- http://www.merlincycles.com/shimano-deo ... 45165.html
New chain:-
11-34 HG30 or 50 cassette
24t inner ring.
£70 to £80 + labour costs.

Edit:- I have an N-Gear Jumpstop fitted to all my bikes,recommended

[robc02]

Maybe someone reading this has already tried this combination and can report on their experience, and hopefully give assurance that the Sora would work with 46/36/26.

I have exactly this combination on my LHT and it works very well.

[reohn2]

Maybe someone reading this has already tried this combination and can report on their experience, and hopefully give assurance that the Sora would work with 46/36/26.

I have exactly this combination on my LHT and it works very well.

I currently run a Sora front mech with 46/34/26 rings and have also run it with a 36 middle,no problem.

[Norman H]

A 46/36/? or 46/34/? set up would be perfect but wont be achievable with the existing chainset. A more piecemeal approach, replacing existing components as and when they wear out, would be more cost effective.

I would change the inner ring as a first step. You may well find that this will lower the gearing sufficiently. If not, and you decide to go for the 34 tooth cassette, try it with your existing derailleur before you go to the expense of buying a new one. As others have said, it may well handle the 34T sprocket.

When your existing middle and outer rings wear out you could consider swapping them for something more appropriate (38T is the minimum middle ring allowed on a 130 BCD chainset) or now would be a good time to fit a 110/74 BCD chainset. Something like a Stronglight Impact or Spa's own equivalent wouldn't cost much more than a couple of new 130 BCD rings.
Bare in mind that the front changer will be happiest if you stay close to Shimano's recommendations for minimum tooth difference between the middle and outer rings.