Lower ratio option - to save ageing knees - !

[simongt]

I do a regular commute of about 25 miles a day on my GT Bravado which some years ago, I reworked as a drop bar tourer and I very happy with the setup. However, my knees aren't getting any younger and I think it may be advisable to lower the ratios a bit. Through years of habit, I tend to push higher gears than I should, as I'm of the 'old school' of thought of pushing against a bit of resistance as oppose to spinning in a lower gear.
My current setup is a 13 - 23 8 speed cassette with a 44 / 32 / 24 triple, all Shimano. It appears that any 8 speed with anything more than a 13 top is unavailable, so looking at the other end, is it possible to get a triple with a 42 tooth top - ?

 

[Sharky]

Also think about shorter cranks - reduces stress on the knees

 

[migrantwing]

Can't you just swap out a chainring to one of your liking?

 

[simongt]

Forgot to include, I'm running 170mm cranks, which for my height ( 1.78m ) etc., etc., is apparently the 'correct' length.

 

[simongt]

Can't you just swap out a chainring to one of your liking?

My first thought. Went to my local dealer, whose wisdom I respect and it appears that a 42 top isn't available for the crank spider I have and also, the 'jumps' between rings need to be at least 12 teeth, thus with say a 42 top, I'd have to change the middle to a 30, if that's available.

 

[Andrew_Culture]

I don't have much useful to add here, but I can sympathise with the issue. I used to have 52 / 16 on my single speed and after a while my knees sounded like a forklift truck running amok in a bubblewrap factory. These days I use 48 / 18 and arrive everywhere a little later but with the retained ability to ascend stairs without crying like I've swallowed a kamakhazi hornet.

 

[migrantwing]

My first thought. Went to my local dealer, whose wisdom I respect and it appears that a 42 top isn't available for the crank spider I have and also, the 'jumps' between rings need to be at least 12 teeth, thus with say a 42 top, I'd have to change the middle to a 30, if that's available.

That's a bummer!

What crank is it, do you know? Shimano Tiagra, Deore, 2300, 105?

 

[migrantwing]

@simongt How 'bout this one? Just shy of £30. 170mm crankarm, too.

42/34/24t

 

[byegad]

12 tooth difference a must??? ~What rot.

There's a whole lot of mystique and rubbish about gearing that needs a large dose of common sense to ignore.

One of my trikes runs 24-40-55 front to 11-34 rear, an 'impossible' 54 tooth difference that can't work, except it's been like that for nearly 8 years and I can and do run all 27 ratios at one time or another! (Before you jump in about crossover, it's a recumbent that use 2.66 normal chains so there's no steep angles in running big/big and little/little combinations. The rear mech is a Deore with a 'capacity' way short of the 54 tooth difference between those combinations. It too is fine and has been in use for 8 years. Using 20" wheels this gives me a top of 100" and a bottom of 14".

I'd happily run the same combination on a normal bike but would then avoid too steep a crossover probably sticking to the top 5 rear cogs when on the 55 and the lower 5 when on the 24.

 

[Eurostar]

Read this http://www.amazon.co.uk/Pruitts-Complete-Medical-Guide-Cyclists/dp/1931382808

 

[Smokin Joe]

Forgot to include, I'm running 170mm cranks, which for my height ( 1.78m ) etc., etc., is apparently the 'correct' length.

A modern way of thinking seems to be that shorter cranks are the most efficient way to go and the reduced leg rotation also helps those with knee problems. Shimano now give the option of 165mm cranks in their chainsets.

 

[gbs]

Simon from Norwich wrote 13 - 23 8 speed cassette with a 44 / 32 / 24 t.

Surely a lowest gear ratio of 24/23 will allow you to comfortably cope with anything that Norfolk can offer including the fiercest of NEly winds.

 

[Travs]

Seeing as the idea is to reduce pressure, don't shorter cranks result in more torque required due to the shorter distance form the centrepoint of rotation and, therefore, increase pressure on the knees? If this is desired over the amount of actual movement, then that's understandable, but I'm just thinking about the theoretical basics of it all.

 

[Pale Rider]

I'm confused by some of the replies.

The OP wants to lower the gearing.

He already has a 24 on the front triple, and while you can get 22, it wouldn't make much difference.

So there's no point in tinkering with the front rings.

A Mega-range cassette on the back would do the job.

He has a biggest cog of 23 at the moment, but could get 30, 32, or 34.

http://www.chainreactioncycles.com/...gclid=CKWijNT5qsQCFTHLtAodWkYAOg&gclsrc=aw.ds

 

[slowmotion]

If you are after low gearing, go to the . spacycles.co.uk/ website
‎
They are touring experts and have a whole load of low geared chain rings to choose from. As others have said, you can push the "teeth rules" set by Shimano by quite a margin. Good luck.