What is the point of dual chainrings ?

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What is the point of dual chainrings ?

119 posts & 58 voices | Started 4 months ago by scu98rkr | Latest reply from allmountainventure

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scu98rkr - Member

I get 1*10 lose weight, clutter + simpler.

But if your going to the effort + weight of having a front derailler you might as well have 3 gears imo.

I could see the point of compact ie 22+30+38 say to increase clearance.

But losing the weight of an extra chain ring is pointless while losing its benefits .

Also the worst place to have extra weight is on the extremities of the bike ie in the rear wheel.

So by having a compact triple ie 22+30+38 you could probably get away with having 7 or 8 gears on the back 11-30 this should be plenty for most situations and light weight with some clearance.

ie
22-30-38 Front
11-30 rear (8 speed for weight savings)

Posted 4 months ago #
thisisnotaspoon - Member

So you're argueing for more chainrings as it's pointless having the dereilieur and not using it, but also getting rid of some gears at the back for the opposite reason?

My Pitch is a double (22-38) at the moment, which works fine, why would I want to add a 30t ring when it works perfectly well in 38 for all but climbing?

Posted 4 months ago #
RestlessNative - Member

on the flip side what is the point of a big ring unless you only have dull fire roads to ride?

Posted 4 months ago #
bjj.andy.w - Member

Never used my big ring on my mtb so why have something on your bike that you don't use?

Posted 4 months ago #
TandemJeremy - Member

I run 36 / 22 chain rings on my bikes - gives me gears from 2.5 to 25+ mph - thats enough for me offroad

Posted 4 months ago #
kimbers - Member

well i had 3 chainrings on my bike but rarely used to the big one and often scraped teeth on drop offs and when messing around
so i got rid of it

i didnt try to rationalise it with weight or efficiency savings

my life is better now because of it

Posted 4 months ago #
scu98rkr - Member

Yes, but having a triple opens up a much larger range of gears than a 2*9 or a 2*10.

And as I say the weight is better in the middle a 1-36 cassette is pretty heavy and is in the wrong place.

You dont need to lose the gears at the back its just if your weight obsessed like me.

If just seems a triple + 7-8 gears opens up the largest selection of gears for the lowest weight. Which is what we started with !

If they can get a 1*10 (9-36) going that is reasonably light I would change to that.

Posted 4 months ago #
Murray - Member

What's the difference in weight between a 9 and 10 speed XT cassette?

Posted 4 months ago #
t-p 26 - Member

but having a triple opens up a much larger range of gears than a 2*9 or a 2*10.

Really? you can use ALL the gears on a 3x8 or 3x9 set up?? Are you running hinged chains?

Posted 4 months ago #
jimjam - Member

What's the point of dual chainrings?

I think the better question is what's the point of a bash ring? And the answer is it replaces a redundant, dangerous and easily damaged large outer ring whilst increasing ground clearance and chain retention.

Posted 4 months ago #
sugdenr - Member

Yes

(a) I could abandon my perfectly good low normal 2x9 systems (with bash so I dont severely lacerate my leg when I fall off)
or
(b)pointlessly upgrade to hugely expensive 10spd system that only comes in traditional rise flavour

a,b,a,b,a,b..oh what's it to be

Sort of weight saving you are talking about is achieved by 1 less cake this week

*Currrently stockpiling M970 rear mechs in VGC*

Posted 4 months ago #
superdan - Member

I run doubles because everytime I don't (when zooming around singletrack on demo bikes mostly) I end up taking some teeth off the outer chainring on a rock/log/wall that I am riding over. This is expensive and tedious.

So yeah, ground clearance+able to run a bash to avoid chainring tattoos.

Posted 4 months ago #
duir - Member

Dual and bash works really well on the new generation of slack bikes with low bottom brackets and prevents chainring damage on rocks. It also really helps to keep the chain on when you are gunning it on descents.

Posted 4 months ago #
mrmo - Member

your more likely to snap a chain shifting on the chainrings than you are on the sprockets.

It is lighter to have 2 rings than 3

you can use a shorter rear mech, so no issues about snagging a longer cage can cause

2 rings looks neater than 3

better chainline than 3.

bigger range than 1 ring.

Posted 4 months ago #
Sam - Member

Wider range cassettes when combined with a double give as good a range of gears as 'old' (22/32/44-11/32) and you have to shift less at the front. I find them more practical to use, you never have that 'shift into the granny - immediate twiddling' moment. I starting using front doubles back in the late 90's (was it really that long ago?) when Cannondale and Ritchey started doing them.

Posted 4 months ago #
Hob Nob - Member

What's the difference in weight between a 9 and 10 speed XT cassette?

Not a huge amount. ~300g for a 9spd & ~340g for a 10spd.

You can get an 11-36 10spd cassette for ~200g if you really want, which is lighter than nearly (or possibly all) 9spd full sized cassettes. So weight isn't really a concern.

Posted 4 months ago #
cookeaa - Member

But if I fitted a big ring where would put my bash ring?

I think your labouring under the missaprehension that the really tall gearing you would achive with a 44T is actually useful on an MTB,it's really not that handy to be pushing 104 gear inches, my bike manages 85 gear inches (36-11 with 26" wheels) and that's plenty.

You're arguing for more Grrrr gears when what most people seem to want now is sensible ratios and a couple of bail out gears ~18 gear inches? can't quite be done on a 1x10 setup that's all...

Posted 4 months ago #
juan - Member

can we sjip to the part where njee and I agree to disagree that we don't do the same sport?

Posted 4 months ago #
_tom_ - Member

Someone find the link to alexxx's thread with the photo of his friends leg after it'd been mauled by the big ring.

Posted 4 months ago #
13thfloormonk - Member

Yes, but having a triple opens up a much larger range of gears than a 2*9 or a 2*10
This was my argument against 2x10, until I eventually tried it and realised that without being any fitter, I could still climb with the narrower range of gears offered by 2x10, and was descending just as fast on the descents that mattered.

better chainline than 3
Also this. I'm changing gears less at the front, spending more time in the 'big' 39t ring and bigger sprockets instead of time in a middle 32t ring and smaller sprockets. Like to think it spreads the wear a bit better.

Posted 4 months ago #
scruff - Member

cookeaa -

http://www.chainreactioncycles.com/Models.aspx?ModelID=17281

A product for mong bikes.

Posted 4 months ago #
andytherocketeer - Member

Depends what you ride. It's not all granny ring fire road up, and hardcore rocky or swoopy single track mostly freewheel down.

I use every gear from 22x32 up to 42x11.

No 1x10 set up on the market gives me that complete range. A 2x10 setup might (within rounding errors).

It is lighter to have 2 rings than 3

True, but I weigh 100kg, my bike weighs quite a few more kg, and 1 chainring weighs a handful of grams. Swap that ring for a bash and the difference is probably so negligible, it'd be like me deciding whether to pack 1 gel or 2.

Now if I raced, I may view that differently.

Posted 4 months ago #
TandemJeremy - Member

scu98rkr - Member

Yes, but having a triple opens up a much larger range of gears than a 2*9 or a 2*10.

Nope - 2 extra high gears compared with a 22 / 36 double - gears that are only needed on the road

My 36 / 11 top gear can be easily pedalled to 25 mph and spinning like crazy to 30 mph - thats fast enough for me offroad

Posted 4 months ago #
Rusty Spanner - Member

I like a triple chainring.
It impresses walkers, dogs and small children and I can't ride logs or big drops.

Oh, always give a prime number when asked how many gears your bike has - pointless, but fun.

Posted 4 months ago #
randomjeremy - Member

Double + bash - no chewed ankles from the largely unused big ring, and a granny ring to winch uphill, perfect combination.

Posted 4 months ago #
BigJohn - Member

It's the fashion. And 42T rings are what you get on Apollos and other Halfords bikes.

Posted 4 months ago #
mikewsmith - Member

Life and bikes is not all about weight, the mud I collect probably makes more difference and the beer I consume.

Double less grief, less chain needed (a weight saving!!). 22-36 is perfect for me, as said all above no chainring bites, not scrapes better clearance, better chain retention, can run a double chain guide do you want more?

Posted 4 months ago #
andytherocketeer - Member

Oh, always give a prime number when asked

prime numbers ftw - they are the coolest.

Best wait for 1x11 then, and not need to lie, assuming you don't have a legacy 1x7 or an even more legacy 1x5 (had one of them oh and a 1x3 too) or SS.

Posted 4 months ago #
willber - Member

I kinda don't get the idea of dual ring chain guides. Bash ring and 2 chainrings I get - but you still need the front derailer. So if you've got that why bother with the weight of chain device?

Posted 4 months ago #
ahwiles - Member

not having a 42 (or whatever) tooth '3rd' chainring means that i don't need so much chain.

so i don't need such a long rear mech.

so it doesn't bounce around as much.

and the chain is 'tighter'.

so i don't get so much chainsuck.

what's the point of that big chainring? what do i get in return for all the extra flap and noise and chainsuck?

2 extra gears?

whoopde***kingdo.

So if you've got that why bother with the weight of chain device?

it stops the chain falling off from the bottom - this can happen if you backpedal into position for a corner - which i do more or less every time i turn left.

Posted 4 months ago #
bikewhisperer - Member

Oh, always give a prime number when asked how many gears your bike has - pointless, but fun.

My road bike has 3!

The 44 ring does have it's uses.. When you use it downhill the chain has more tension so rattles against the stay less.

I've got one bike with a 44/29 FSA chainset that's Ultra-Guff (tm), as the right gear always seems to be cross chained, and the shifting is poo. I've got some new 40/29 rings for it that should improve it, but if I was starting from scratch I'd just get a triple.

Posted 4 months ago #
TandemJeremy - Member

bikewhisperer - if yo have a double you can shorten the chain to avoid chain slap

Posted 4 months ago #
ahwiles - Member

The 44 ring does have it's uses.. When you use it downhill the chain has more tension so rattles against the stay less.

but when do you actually use a 44t chainring for riding offroad?

ime, you need a longer chain to fit a system with a triple, but when you're in the middle/granny ring (more likely), the chain is slacker than it would be if you only had a double, so it rattles against the stays more...

Posted 4 months ago #
BigJohn - Member

prime numbers ftw - they are the coolest.

No they're not. 1 (singlespeed) is coolest, and 1 is not prime. It's a unit.

Posted 4 months ago #
chakaping - Member

I kinda don't get the idea of dual ring chain guides. Bash ring and 2 chainrings I get - but you still need the front derailer. So if you've got that why bother with the weight of chain device?

Because when I'm shredding the gnar the chain can still fall off despite having a front mech, and a chain device prevents that.

With regard to the OP, sugdenr and duir explained best.

I need a granny ring and I need a bigger ring. I need a bash guard too. So a double and bash is a pretty neat solution!

Posted 4 months ago #

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