Fixed/Single Speed Commuting

redvee

Could be the riders' ankle/hips/knees

Clever Pun

Greg T wrote:

Back wheel.

Not much play in the chain - I'd say 0.5 cm or so......

Am I too tight?

a little I think (from my vast experience) get the wheel a little closer and try again

Greg T

Clever Pun wrote:

a little I think (from my vast experience) get the wheel a little closer and try again

Hmmmm....

If my chain jumps off and I stack in I'll haunt you....

I'll make sure my tyre valves are tightened up and slack off my chain a tad.

I'm enjoying the extra speed my 16 back cog gives me.... Ask me again on Friday morning after a week

itboffin

Greg T I'm sure you've already seen this but just in case http://www.parktool.com/repair/readhowto.asp?id=27

wgwarburton

Hi,
Hope this is the right place to post this...

I've worn out (one side of) a Dura-Ace track sprocket (3/32", 16T- and the chain, of course) in under two years, even though I didn't use the bike all the time (maybe 15 months out of 22?). I've changed the chain (New KMC z610HX replacing SRAM PC-58) & flipped the sprocket to get a few more miles out of it.

Is that par for the course? Do 1/8" drivetrains last significantly longer?

Cheers,
W.

camvaile

Cheers Biondiono, I'll trawl through and see if I can pin point a solution to the problem.

Clever Pun

Greg T wrote:

Clever Pun wrote:

a little I think (from my vast experience) get the wheel a little closer and try again

Hmmmm....

If my chain jumps off and I stack in I'll haunt you....

if it does, you've gone too far

Greg T

I've found the culprit....

A washer is rattling around on the axle between the end of the fixed cog thread and the outer thingy that holds up against the inside of the track ends....

I've bodged some gaffer tape pending full fix this weekend.

itboffin

You have cursed me with all your talk of chain jumping and tension, my chain popped off whilst down hilling at some speed, thankfully I stayed on the bike. One full link has now been removed from the chain but the axle is right at the end of the semi horizontal drop outs, I'm not sure I trust this set up so much now.

Greg T

It's the tensioning of the chain that pushed me to a dedicated track ended fixie rather than trying to convert a non horizontal drop outed bike.....

The cost of decent horizontal drop outed frames is proper high....

itboffin

I made it safe and sound to the station and it would seem that the extra tension on the chain gave me a slight boost in speed, perhaps!

Still not to happy about the position of the axle although its 4/5 within the dropouts its still looks scarely like it could pop out at any moment, think I'll find a half link chain today unless anyone has another suggestion.

Greg T

There is the really ugly little tensioner idler wheel option but the tartia (comb. tart and mafia) wouldn't have a stroke of it........

Clever Pun

Like Greg I feel 48-18 is just too damn slow but I'm going to stick with it for a while due to laziness and it's good for fitness, I'll then jump to 16 and struggle with hills, but there aren't too many so it's just a case of manning up and taking it

I rode the brompton intoday I didn't freewheel at all

Edit

Here's a question I've put race blades on but on the rear wheel they rub a fair bit do I need to move the wheel across a bit or am I being paranoid?
at present it's pretty damned centred on the back brake (boo hiss etc) and more importantly the cogs seem to be happy

salsarider79

I'm starting to worry. I took no test, never applied for a lience. I don't have a messanger bag for gods sake! :shock: I just started riding singles. Am I going to be cast out forever and shunned by my family now?

itboffin

More advise needed - I'm spinning out on my current 46/16T which is about 75GI so do I spend more money I don't have on 48T chainring = 78.8GI or bite the bullet and go 50T = 82.1, or totally change the rear and go for a smaller GI jump.

Greg T

I'd get the 50T ring and a handfull of cogs for the back......

You know you are going to do it anyway so you may as well take the plunge...

Big Rings up front - it's what all the kids are wearing this season.

Littigator

I bought a sora chain ring for about £8 on Wiggle which is working vrey nicely on my Bowery, so you don't have to spend a mint!

wgwarburton

itboffin writes:

> I'm spinning out on my current 46/16T which is about 75GI

What do you mean by spinning out? A 75" gear ought to be good for 35mph for short sprints and 25mph cruising...

I just moved up from a 38x16 to a 42x16 because I was running out of lungs on long, fast stretches. Comfortable cruising for me is about 20mph or so (I'm not very fit...) at 95rpm. On a downhill I can hit 30+

Are you drafting buses at 40+ or just not spinning fast enough :-)

Cheers,
W.

Greg T

He's screwed his gear calcs, 46/16 equates to an S Club 7 tribute band singing "my way".

100 rpm will buy you 22 mph of leg spinning nothingness.

Littigator

WGWarburton wrote:

itboffin writes:

> I'm spinning out on my current 46/16T which is about 75GI

What do you mean by spinning out? A 75" gear ought to be good for 35mph for short sprints and 25mph cruising...

I just moved up from a 38x16 to a 42x16 because I was running out of lungs on long, fast stretches. Comfortable cruising for me is about 20mph or so (I'm not very fit...) at 95rpm. On a downhill I can hit 30+

Are you drafting buses at 40+ or just not spinning fast enough :-)

Cheers,
W.

Are you on drugs? If so can I have some please. I've got a 52/17 which gives me about 82 GI and spins out at about 120rpm at 30mph...this seems to agree with the Rabbit

http://software.bareknucklebrigade.com/rabbit.applet.html

biondino

itboffin, we all know you're not going to be happy until you're pulling 30mph on the flat for 200 miles straight with a 100+ gear inches, so go for a 53/11 now and save yourself the interim purchases

Greg T

Littigator wrote:

I've got a 52/17 which gives me about 82 GI and spins out at about 120rpm at 30mph

Litts you are a shameless dity little flirt.....

That's it I've got to get myself a yet bigger ring....

The Big Ring Arms race shows no signs of ending anytime soon and I for one will not be left as the Russians were with a load of rusting Nuclear missile boats glowing gently as they sink at berth..... Er... my analogy ran out of direction there....

It's hard to believe that you need >50T up front to be in the big boys club now.......

Avante'!

wgwarburton

Littigator writes:

> Are you on drugs? If so can I have some please. I've got a 52/17 which gives me about 82 GI and spins out at about 120rpm at 30mph...this seems to agree with the Rabbit

"Spins out at 120rpm"? Hah! You guys think size is everything, but it's what you do with it that matters...:-)

If you're spinning out at 120rpm, you need to work on your technique. 120rpm is a fast cruise, 160rpm is spinning out, the Really Good guys get 200!

If you can spin an 80" gear at 150rpm (36mph), and cruise at 23 you have my respect, that's for sure!!! Pushing a 52x17 at 70rpm (17mph) would stuff my knees and I'd only reach a comfortable cadence on a big downhill...

Cheers,
W.

Greg T

WGWarburton wrote:

If you're spinning out at 120rpm, you need to work on your technique. 120rpm is a fast cruise, 160rpm is spinning out, the Really Good guys get 200!

I'm loving your loaves by the way.

Is this gen?

I'm not sure >120 rpm is an act of war.

wgwarburton

Hi,
Yeah. I'm straight up. I spin out at 150-160. The velodrome guys allegedly hit 200.

I'm happiest around 95. I moved up a gear after running out of lungs on an eight mile sprint to the railway station averaging 19.5mph (105rpm sustained).

A long time ago I read that if your legs give out before your lungs you're on too high a gear, lungs first is too low. Spinning is easier on the knees.

Look at the technique that the top track guys have, they are so smooth and fluid, that's where the real art is, pushing a big gear is just about strength.

If you see someone with a big gear, they're either seriously fit or compensating for poor technique. I like to give them the benefit of the doubt, since I'm no Sporting Hero :-)

Cheers,
W. (Bakes his own bread, but uses a machine...:) )

itboffin

Yeh not so keen on high RPM which explains the on/off knee problem. I used Sheldon gear calc for my figures and yes I regularly cruise 25+ but want MORE....!

160-200 RPM and my heart would climb out of my mouth in protest.

So I guess what i'm asking here is how noticeable is a 1, 5, 10 GI increase?

Greg T

Hmmmmm

I've gone from 48/18 (70 GI on the calc) to 48/16 (78 GI) and I'd say that the difference is defo noticeable.

It's harder to gain and maintain that free wheeling spinning top speed but the top speed is obviously faster if not as sustainable.....

It's been a while since I had a cadence monitor on but I'd say I'm high 90's low 100s in my normal top end zone. Might be a bit low but any higher and I'm a bit wiggly.

What's the hive mind's thoughts on top end cadence?

wgwarburton

itboffin writes:

> So I guess what i'm asking here is how noticeable is a 1, 5, 10 GI increase?

1" is not. 5" is a small step, 10" is a significant step. Though the % change is probably a better measure than the numerical one.

My 38/16 to 42/16 was about 7" bigger. That was fine- from slightly under to about right. Unless you think you're well under then I'd aim for a 5-10 GI increase, but not fret over it too much- see what your options are with your drivetrain- no point changing a chainring if your current sprocket's on its last legs.

Cheers,
W.

itboffin

Now this is someone with way to much free time on their hands http://www.fleettrikes.com/tth8.htm but I like the idea of running a MASSIVE ring 75T should do the trick.

Greg T

I think my 78 GI is on the stiff side of "right" and I'll work on my spinning rather than going for gearing to speed me up.

I'm running out of legs before lungs by quite a degree.

More speed work required and my ring can stay as it is