[Closed] twin ring - what's the pro's and cons over triple?

I was thinking of going double and bash + chainguide as I thought this would reduce chain flappage (once chain shortened to appropriate length) - am I wrong? Does going to a medium cage mech in addition do the trick?

Cynical +1

Been messing about with dual setups for while now.

I really don't like more than 10T difference between the chainrings, find my legs spinning far too much when I change down to granny, also don't like the fact that you don't get 1:1 ratio on the outer ring with a duo setup.

you realise Al was making a poor attemp at getting a rise from someone?
10T difference just means far more pointless cross over gear combinations for me, and if the extra gap in ratio changing down to the granny ring bothers you that much there's no reason you can't shift down with the front and up with the rear shifters simultaniously.
Also, you can't have messed about with dual set-ups much if you couldn't figure out a 1:1 ratio on a middle ring (seeing as both rings and largest sprocket are readily available in 32, 34 & 36)

Northwind - 11T sprockets are available for about £3.99 sepatately so not too expensive if you wanted to build a custom 11-36 9speed.

Timmys - depends.
but the smaller the cage = more slappage
larger the rear sprocket = more slappage in the smaller sprockets
front chainring difference = more less tension in mech in smaller sprockets = flappage

I was being entirely serious Gary!

Each to their own or something.

cynic al - you really use the top 2 gears on a triple set up - cos that is all you loose going to 22 / 36. Check the ratios.22/ 36 needs less front shifting - as you never need to shift to the big ring and you can shift onto the granny at teh bottom of each climb

On a average pentlands run I shift the front chainring maybe 3 times, at glentress once.

but the smaller the cage = more slappage
larger the rear sprocket = more slappage in the smaller sprockets
front chainring difference = more less tension in mech in smaller sprockets = flappage

I have to admit to being a bit lost!

I'd be going from 11-34 cassette with 22-32-42 chainrings to 11-34 cassette with 22 & 36 rings.

In the new set-up when I'm in the 36 ring would I get more or less flap/slap when in the mid to small sprockets on the cassette than with the triple (assuming chain is shortened appropriately). In this situation would there be more or less slap/flat with a medium or short cage?

I spent most of the time in my middle ring so didn't fancy a double - I would end up forever front-shifting. Instead I dropped the big and small rings and went 1x9. Hurrah.

Also, you can't have messed about with dual set-ups much if you couldn't figure out a 1:1 ratio on a middle ring (seeing as both rings and largest sprocket are readily available in 32, 34 & 36)

You're missing the point, if I run 34 or 36 on the front, yes I could have 1:1 ratios but then I would end up spinning out in no time.

Yo9u spin out 36 /11 offroad? You use the top two gears on a triple as that is all you loose with a 36?

TandemJeremy - Member
cynic al - you really use the top 2 gears on a triple set up - cos that is all you loose going to 22 / 36. Check the ratios.22/ 36 needs less front shifting - as you never need to shift to the big ring and you can shift onto the granny at teh bottom of each climb

On a average pentlands run I shift the front chainring maybe 3 times, at glentress once.

Like I say, each to their own.

I found I do enough road riding on my geared mtb to meake me want a big ring, and I find I did more front shifting on 22/36 as 36 is too big and 22 too small.

I guess I come from more of a road-background and I don't like big jumps.

And I'm faster than you so ner.

Timmys, do you ever use the 22 front 36 rear (what I weould call easy-easy) gear ratio? If you don't then you should get away with a 24/36 setup, this will be slightly better at shifting due to the closer outer diameters of the sprockets. Also there will be more chain tension for the same reason, chain slap is mostly caused by: -

Type of rear mech
Chain tension (Length of chain)
Front / rear gear ratio

All of which you can alter / modify / fettle.

And I'm faster than you so ner.

Maybe you spin your legs too slowly. Ner. 😉

No, the point is that if you want to run 1:1 with the middle ring then you need a cassette with big gaps in. Which is why I have switched back to a triple. I have also found the suspension works better and I can find the right gear easier.
I prefer a double on the road, and would quite like a double on the mountain bike, but with my current bike, I have found the triple to be better.
I also occasionally use the top two gears, but I wouldn't miss them if they weren't there. The point is more to do with the lower gears and the gaps between gears.

No, the point is that if you want to run 1:1 with the middle ring then you need a cassette with big gaps in.

This.

I was running 11-28T when I had a triple on, going to put the duo setup back on when I go 10 speed though as I can then go 30/40 with 11-36, ideal for me.

Must say (apart from the roadie background) I'm with cynic-al.
Never seen any reason to get rid of the big ring.

How many have done because they "think they should"? I wonder. (Wouldn't admit it obviously. 😉 )

Timmys, do you ever use the 22 front 36 rear (what I weould call easy-easy) gear ratio? If you don't then you should get away with a 24/36 setup, this will be slightly better at shifting due to the closer outer diameters of the sprockets. Also there will be more chain tension for the same reason, chain slap is mostly caused by: -

Type of rear mech
Chain tension (Length of chain)
Front / rear gear ratio

All of which you can alter / modify / fettle.

I don't have a 36 on the cassette, but i do use the easiest gear of 22 front 34 rear quite a lot so wouldn't want to lose that by going to 24 as the smallest at the front.

So given the same chain length (as short as possible) there'd be more slap with a medium cage XT mech versus a long cage XT or no difference?

All XT mechs have the same spring, so the shorter the mech cage the lower the lever effect giving better chain tension (Which is why DH bikes tend to run short mechs and roadie casettes).
The shorter cage however puts the chain in closer proximity to the chain stay so there may be more slap in certain gears vs a longer mech. There will also be differnces between makes and models, i.e. LX, XT, XTR, SRAM, Shimano.........

My best guess is also that there are not many people who have the skill or nuts to do 35 - 40mph+ down single track, which is why many people remove the outer ring.

quick Q for the double+bash crowd, whats your chainline like when the chain is on the two largest sprokets? severly crossed over?

I thought the SLX mech used a stiffer spring for the GS, but I may be mistaken.

float - my 36 ring is in the same position as the middle in a triple so big / big is not great chainline but not horrible

No, the point is that if you want to run 1:1 with the middle ring then you need a cassette with big gaps in.

The point is more to do with the lower gears and the gaps between gears.

Hang on - I was thinking gaps between numbers of teeth on the cassette. The ratio gaps are indeed different. Pretty marginal though, can you really feel that! You need to go to 2 decimal places to even see any real difference. At 1 d.p. the ratios look so close not only are the gaps the same but even six of the nine ratios are the same and the other three only 0.1 different anyway.

(I'm assuming 32T with 11-32 cassette and 34T with 11-34 as you were looking for 1:1)

Can't be arsed reading the above, sorry if this has been said a few times. For me it was because I'm a leftie, so Automatically always put my right foot down when not moving, taking the big ring off means I'm not constantly gouging my right calf, which I got sick of. I don't miss the big ring one bit, because I live in a very hilly place and rarely ride on roads. I generally don't bother with bash rings, which probably makes it all look a bit sh1t.
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to add to the Pro list;

With a bash ring, you won't rip your kecks when you use the bike to pop to the shops on

With a bash ring instead of a ring, when you fall off there's no big ring to gouge your leg open

Timmy - all that changes between short/medium and long cage mechs is the amount of slack the mech can take up and unless you use daft gears eg. 22-15 or less don't worry about it, with a shorter cage, the mech just sits with the cage at a shallower angle in the smaller sprockets(and has slightly less spring tension)
unless you are as pernickety as me (unlikely) you'll probably never notice the slightly looser chain tension from a medium cage, but the shorter cage the better if you've ever snagged/smacked a mech on something 😉

Was in my lbs last weekend and the 10 speed blocks are filtering down to hard core riders in there, using a single chainring up front.
I went home thinking about this, but then went and calculated my gear inches using a 22/32/44 and 11-34 XT set up and realised I simply can't do without my lowest gears.
A combination of hilly stuff and weak legs!

I could do without my big ring cos it's hardly ever used on my home patch, but not the lower gears.
As an aside, if you dumped the big ring, can you space the granny/middle out from the bb a bit?
or does a dedicated double cainring do this?
..... wondering it it might be of help for those suffering chainsuck maybe?
Q

Hardcore riders? 😆

Yes you can space the crankset over a bit but it'd be a little silly to do so as ideally you want the middle ring to work with every rear cassette sprocket and the granny only needs to be used with half of them.

36 ,26 up front and 11-34 at the back, homemade Alu bashguard and short cage XTR mech (old one), absolutely perfect, have never spun out on the road downhill and have all the gears i need uphill ,short cage mech quietens it down alot and bashguard means im not loosing any teeth or skin, the Alu bashguard weighs less than a plastic one i had previously strangely .

'hardcore riders...'
Well deduced form the fact an Ibis was covered in mud!
I sorry, temporary lapse 🙄

Yep, forgot about the chain line aspect.
Thanks GW
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because I live in a very hilly place and rarely ride on roads.

I use the whole (11-28 8speed) cassette in the 36 but only 1-3 in the granny (22) so only ever use it for steep/long/loose climbs.
22-18/19 pretty much = 36-28
I hate chainslap and find it far noticably worse even with a 30T largest sprocket (and chain as short as poss.)

I have 22/32 and 11-32 on my Pitch. I got rid of the 42 as I was always smacking it into rocks (peaks rocky riding and a low BB) but I've found I keep dropping the chain over rough stuff as there's not enough tension. So I've just fitted a Blackspire Stinger to stop that. Can't shorter chain any further - tested it at full compression and I daren't go any shorter.
TJ - round here that gear you have in your pic would be so annoying - it'd be slapping around all over the show!!
Personally if I get a bike with a higher BB I'll go back to triple with maybe a big bashguard over the 42t ring.
Overall I'm reasonably happy but I'd love to have a couple of higher gears back for the fast downhills.

Dibbs:
Nope, but for downhill that thing called gravity does it for me!
It's enough to have me hanging onto the brake levers for dear life. There's no way I'd even get into the top ring coming home, or if I did someone would have to scrape me off one of the hedges later 😳
I only use the big ring when off home turf, probably on hols, which is quite a rarity!
cheers matey
Q

the only downhills you can spin a 36T ring out on around dibs are [b]on-road[/b]
But even if he did find a long straight downhill section of actual off-road, once top pedalling speed is reached you're better off just tucking in and embracing the free speed available from good ol gravity

This question really depends on rides that you do. I rarely used my big ring and normally broke it before it wore out. SO I put a bash on instead of replacing it and never missed it. In general it was cheaper and the clearance in better.

Con's are lack of higher gears but again that depends on what you are riding. IF there are fast open downhills or road sections on your rides then you may appreciate it.

I eventually went singlespeed for the challenge and cheapness. My race/nice bike has a big ring as a lot of the races I do include fast open downhills and road sections (ie. Kielder 100, selkirk marathon, grassington marathon etc.)

GW: After driving all week, I almost invariably ride from home. I'm in the lucky position of riding out my back gate, along a lane for ~ 150m then it goes up very steeply either a degrading/potholed/rough road now unsuitable for vehicles or up a bridleway, slightly less steep more contouring. Both are ~ 1 mile long and take me up into woods and then give me a quick bash offroad or through and onto other tracks, time allowing. Consequently the return home is always down the twisting bridleway, loose and rocky in places, wet and muddy in others, nothing is open or fast.
(Whilst they might not be the longest trips out there, the ability to ride out the back gate is brilliant.)
As you say, use of the big ring depends where you ride, and so for me it almost never gets used unless I drive somewhere.
Q