Upping the inches on a Single speed

daniel_b

Guys,

my Langster has it's stock 42/16 setup, with a flip flop hub at the rear.

I really struggle (when in fixed mode) going downhill at anything over about 25 mph, I just can't get my legs going round fast enough, and it can get a bit hairy at times - riding on the brakes just seems such a waste of time, and effort and speed :-(
And as a result I manage a mugh higher average when in freewheel mode.

And this is making me think of switching it back to freewheel mode, where it becomes usable whatever the terrain.

To avoid this, what would be the best way of upping the gearing - a bigger cog at the front would give me the option of running in either fixed or freewheel, but I expect a rear cog, perhaps a 14, would have a bigger difference, (10" Sheldon's gear calculator seems to say) and would still leave me with one 16T option on the freewheel, so a more flexible and cheaper solution I would think.

Am I missing anything, and or would there be any other options I am missing?

dhope

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19667018#p19667018]Daniel B[/url] wrote:

Guys,

my Langster has it's stock 42/16 setup, with a flip flop hub at the rear.

I really struggle (when in fixed mode) going downhill at anything over about 25 mph, I just can't get my legs going round fast enough, and it can get a bit hairy at times - riding on the brakes just seems such a waste of time, and effort and speed :-(
And as a result I manage a mugh higher average when in freewheel mode.

And this is making me think of switching it back to freewheel mode, where it becomes usable whatever the terrain.

To avoid this, what would be the best way of upping the gearing - a bigger cog at the front would give me the option of running in either fixed or freewheel, but I expect a rear cog, perhaps a 14, would have a bigger difference, (10" Sheldon's gear calculator seems to say) and would still leave me with one 16T option on the freewheel, so a more flexible and cheaper solution I would think.

Am I missing anything, and or would there be any other options I am missing?

Firstly, you should be able to spin faster
25mph is only about 120rpm, that should be doable.

But 42/16 is maybe a slightly small gear unless it's hilly.

42x15 would be ~ same as 45x16
42x14 would be same as 48x16

A bigger chainring wouldn't be much more expensive. Stronglight Zicral or similar would be fine, make sure you get the right BCD. Maybe get a 47 and go from there.

dyrlac

Since it is a fixie, your first concern must be aesthetics; otherwise, what's the point? Facing exactly the same problem, I struggled to find odd-sized chainrings that match my cranks, so I changed my sprocket instead (easier, cheaper and you only need to shorten the chain). Went from 42x16 to 42x15, for a 4+ inch increase. 42x15 produces c. 30mph at 140 rpm, 27.5mph at 120, and a comfortable 20mph on a pleasingly chill 90 rpm (real world on my tyres (25mm), according to Sr. Garmin).

But 42x15 on anything more than an 8% grade is painful. On 42x14, I'd probably get relegated to the CS7 league (and even then I'd need to walk it up the mighty Balham Hill).

daniel_b

Sounds like a 14 or 15 then might be the cheapest and easiest way to 'give it a go'

Does anyone happen to know if this should just fit straight on to replace what is there?
http://www.tredz.co.uk/.Shimano-DXR-DX-Single-Sprocket-CSMX66_36011.htm

Having never removed a cog from a single speed, is it the same setup as with a normal cassette, ie I assume in this instance as it's the fixie side you don't need a chain whip, but would you still remove a locking ring at the end with the usual tool?

telesv650

This is normal fair for a fix. Gearing is always a compromise between spinning out on down hills and hernia inducing efforts on the uphills. On a fix, alas you have to accept that the downhills will be on the brakes.

Depending on your route, id look at a 44 or 46 tooth from chain ring, depending on the route, load in the bike, cycling style. I'd try to keep the sprockets large as this will help to minimize chain and sprocket wear, but the cheaper and easier option is to change the cog. In this case I'd go for a 15 tooth.

pastryboy

Just keep upping the gear incrementally, feels tough for a few rides then you're used to it before you realise it. I had 42/16 at first and have ended up with 48/16 which won't be increased any more.

dyrlac

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19667672#p19667672]Daniel B[/url] wrote:

Sounds like a 14 or 15 then might be the cheapest and easiest way to 'give it a go'

Does anyone happen to know if this should just fit straight on to replace what is there?
http://www.tredz.co.uk/.Shimano-DXR-DX-Single-Sprocket-CSMX66_36011.htm

Having never removed a cog from a single speed, is it the same setup as with a normal cassette, ie I assume in this instance as it's the fixie side you don't need a chain whip, but would you still remove a locking ring at the end with the usual tool?

That one looks like it needs a carrier (a threaded doohickey on which the tabs on the sprocket slot around splines on the carrier). But don't know if your langster uses a carrier system (Miche is probably the most popular, advantage is that you can quickly swap gears, theoretically even on the roadside, but once you start going down that route, you might as well get a derailleur). I used the 15T version of these: http://www.wiggle.co.uk/lifeline-12t-20t-fixed-gear-track-sprocket-18. You will need to remove the lockring (unknown whether your usual tool is the right size: only one way to find out), and I used a chainwhip, although youtube has various chainwhip free strategies.

daniel_b

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19667827#p19667827]Dyrlac[/url] wrote:

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19667672#p19667672]Daniel B[/url] wrote:

Sounds like a 14 or 15 then might be the cheapest and easiest way to 'give it a go'

Does anyone happen to know if this should just fit straight on to replace what is there?
http://www.tredz.co.uk/.Shimano-DXR-DX-Single-Sprocket-CSMX66_36011.htm

Having never removed a cog from a single speed, is it the same setup as with a normal cassette, ie I assume in this instance as it's the fixie side you don't need a chain whip, but would you still remove a locking ring at the end with the usual tool?

That one looks like it needs a carrier (a threaded doohickey on which the tabs on the sprocket slot around splines on the carrier). But don't know if your langster uses a carrier system (Miche is probably the most popular, advantage is that you can quickly swap gears, theoretically even on the roadside, but once you start going down that route, you might as well get a derailleur). I used the 15T version of these: http://www.wiggle.co.uk/lifeline-12t-20t-fixed-gear-track-sprocket-18. You will need to remove the lockring (unknown whether your usual tool is the right size: only one way to find out), and I used a chainwhip, although youtube has various chainwhip free strategies.

Thanks for the reply, these are all terms I am totally unfamiliar with!

The Wiggle link looks good.

meanredspider

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19667817#p19667817]pastryboy[/url] wrote:

Just keep upping the gear incrementally,

What - a bit like a dérailleur?