So, I'm changing the freewheel on my SS...

Zachariah · April 2010

Current set-up is a 48T front, 20T rear (bike is a Gary Fisher Triton). I believe it's a 1/8" chain.

I am spinning out on most flats, and it's not very hilly on my route, so I'm looking to go for something speedy - the Shimano 16T freewheel looks like the answer.

I don't have a freewheel tool, so I was thinking of getting this one rather than having the LBS do it. Can anyone confirm it will fit both the existing 20T frewheel and the new 16T? I've seen on other sites there are different removal tools for 16T freewheels as opposed to 20T ones. But surely the inner locking ring is the same on both?

Also, any recommendations on grease/anti-seize compound to use?

Thanks for any replies

supersonic · April 2010

It doesn't say what the freehwheel is on the GF - might be a 2 pin, 4 pin, or something weird.

Zachariah · April 2010

A look at it (without taking the rear wheel off) shows it to have four slots, as if it would take something shaped like the Park tool (though I have no idea what the measurements are exactly).

mapleflot · April 2010

The 4-prong Park Tool fits Shimano and White Industries (which is US made) freewheels so it seems as if there is a standard for these things... if thats any help.

wgwarburton · April 2010

Hi,
That's a big step up in gear ratio. The 48x20 is on the low side (but not crazily so- I've run similar ratios fixed) but a 48x16 is a pretty high gear, especially for a SS (you can get away with a lower gear on a SS than a fixed, 'cos you can wuss out & freewheel if you have to....

Are you sure you wouldn't be better off with an 18 or 19? Freewheels arn't that expensive, so you could change again later....

Cheers,
W.

Zachariah · April 2010

Thanks, I'm definitely not wedded to a 16T (and if I was, I might have an affair). An 18T is probably the next choice. Unfortunately, I don't really have any way to test out the ratios before buying.

Salsa · April 2010

http://software.bareknucklebrigade.com/ ... pplet.html

Give that calculator a try, your 48/20 is 63.1 gear inches & 48/16 is 78.8 so a very big jump, I was running a 68.4 on my converted SS MTB & it was very usuable around town. I moved down to a 44/18 60.8 as it gave me a magic ratio & I only do a few miles on it.
I feel I could have stepped it up to about 70-72 though & my legs would have took it, personally I'd go for a 48/18 (70.1 gear inches) & only higher if your super strong/have a long flat commute/like pain.

wgwarburton · April 2010

Zachariah wrote:

Thanks, I'm definitely not wedded to a 16T (and if I was, I might have an affair). An 18T is probably the next choice. Unfortunately, I don't really have any way to test out the ratios before buying.

I'd advise 18 or 19, then. You may be surprised how much difference an apparantly small change makes- bear in mind that you'll not be able to change down during your entire trip, so to maintain a comfortable cadence on the "slower" sections (uphills, headwinds) you may need to increase your roadspeed. Increasing your average speed by a couple of mph means a big increase in output...

Cheers,
W.

biondino · April 2010

I've been riding 48/18 for the last year and it's just about spot on for a mostly-flat commute. I can deal with small hills, I can cruise at 20mph without spinning out, and it's not TOO much of a pain with all the starting and stopping.

Anyone who recommends a (much) higher gearing is basically just waving their nob about. This includes the girls.

Harveytile · April 2010

+1 for 48/18. I run this fixed commuting from Sutton/Croydon to Stratford four times a week and although I feel it at the end of the week, it;s pretty good for most of the ride and keeps me honest on the hills. :shock:

Zachariah · July 2010

Thanks for all the replies. I've since had a further look at the bike and have noticed:

Contrary to the Gary Fisher website, my front chainring is not 48T but 44T. The rear is in fact 19T. No wonder I'm spinning like a mofo!

The Park tool FR3 I mentioned above is the wrong tool for a SS/BMX style freewheel, being far too small. The Park FR6 is the correct one. Good thing I didn't buy it!

I'm now undecided whether to go for a new freewheel or a front chainring. The crank is a Bontrager GXP five-arm 130PCD/BCD so I'm thinking any decent road chainring should do the trick. Am I wrong? Will it ruin the chainline, for instance, using an outer ring designed for use with an inner ring?

I like the looks of these ones:

TA Alize 50T

TA Track 50T

TA Hegoa Pro

I'm vain enough to consider changing the front chainring to a fancy one, even though it's cheaper to get the rear freewheel, and the tool and new lube etc than just the chainring. Though I'd need a new chain probably, to accomodate the extra length. Dammit. Is this foolishness?

ex-pat scot · July 2010

A quick note on ratios.

42 x 16 for me
It's pretty close to 48 x 18
And I'm guessing that 44 x 17 would probably work equally well.

That gets me bowling along nicely between 18 -22 mph on the flats, and lets me winch up the 1-in-5 hill near my house.

From recall, a Shimano freewheel & sprocket combo is £25, and a fixed sprocket £15.
Chainrings start at around £15 and can easily be £25 - £30.
You're lucky in that 130bcd is "standard" road chainset spacing, so you can use normal road rings. These will be 3/32" so slightly narrower than 1/8".
I've used 3/32" sprockets & chainrings with 1/8 chains and with 3/32 chains. No real problem with either.

The best way to work out what sort of ratio you should use, is to try it out.
If you have an equivalent geared bike, then find the closest gear ratio to your "hypothesis 44x17 (or whatever)" proposed SS gear. Ride your geared bike for a couple of days only using this ratio, and see how it feels. Try some hills too.

There is no magical "right" answer for FG / SS ratios, in the same way as there is no "average" rider.
You might be incredibly strong, and live in a pancake-flat windless area, in which case you might find 42 x 16 / 44 x 17 rather tame.
You might ride in hills a lot, and be a 15 mph cruiser who spins a lot, in which case 42 x 17 might be better.

Other complications (to ignore!) are "skid patch calculators", wear considerations (smaller sprocket / rings wear faster than large), weight (smaller weigh less than larger), drivetrain efficiency (small no sprockets not as mechanically efficient as larger) etc etc.

TommyEss · July 2010

48x18 on my Pompino (fixed) - can get up the climbs, and spin up to nearly 30 for brief periods (I'm a tracky too though, so have put in a fair amount of cadence work behind the derny!)

Track bike is 50x15 - far too high for the road!

You'll certainly notice a big step from 48x20 to 48x16 - split the difference, try 18 at the back, and take it from there.

ride_whenever · July 2010

I'm on 46:16 atm, and spin out around 25, i'll be upping to something a little bigger soon i think.

Zachariah · July 2010

Thanks again for the replies! One thing I would like input on is whether anyone recommends changing the chainring instead of the freewheel.

This seems, on the face of it, to be an 'easier' fix - no need to buy a special tool and remove the rear wheel. However, due to the price of chainrings and a new chain it would be about twice the cost, including the freewheel remover tool.

To compound matters further, internet rumours suggest that upping the front chainring leads to more efficient pedaling compared to lowering the tooth count on the freewheel. I have no idea how or why.

TommyEss · July 2010

Cost-wise is an issue - and I guess freewheel + lockring tool will be similar to the cost of the new chainring.

That said - no harm in building to your tool collection either.

It's really not as big a faff as you're making out to change the rear sprocket - just remember the lockring tightens up the opposite way to the freewheel!!

You should already know, or it would be good to learn, how to adjust the chain tension by adjusting the rear wheel in the track ends anyway - a loose chain can be very very dangerous, particularly on a fixed wheel, but still so on singlespeed set-up - remember there's no spring-loaded derailleur to take up the slack.

Zachariah · July 2010

I've already moved the rear wheel to accomodate changing chain tension - the most annoying thing was repositioning the mudguards! Cost-wise, the Shimano freewheel is £13 from Parker, the remover tool is £10 from SJS, slap on a few more quid for postage and some new lube. £25-£30.

Cheapest chainrings are £40 that I've found, then there's a new chain (another £10-£15), so the freewheel option is much cheaper. But those chainrings looks so spangly compared to my current one.

ex-pat scot · July 2010

Try here
http://www.spacycles.co.uk/products.php ... b2s149p394
for 130 bcd rings @ £15

Zachariah · July 2010

Thanks for the linky, I live in Harrogate and this place is news to me! I stopped in on the way back from work. Very nice place, knowledgeable staff. Not quite ready to fork out for the bits, but I did get the Koolstop Salmon brake pads everybody says they like (£6 a pair, cheaper than Wiggle!). Turns out I can't count, my freewheel is 18T.

I covet the Stronglight TT chainring. I know the giant leap in ratios will probably kill me but I'll die happy.

Bacteria Man · August 2010

To compound matters further, internet rumours suggest that upping the front chainring leads to more efficient pedaling compared to lowering the tooth count on the freewheel. I have no idea how or why.

I think this is because energy is lost as frictional heat in the chain links as they turn around the sprocket. The smaller the chainring, the more the chain links have to turn relative to one another as they pass over it. Also, as the sprockets get smaller, the chain is less able to 'follow' the arc with its comparatively big, straight links.

One other thing to note is that the smaller the sprocket, the shorter the service life is likely to be. May not be an issue on SS, because the freewheel mechanism will probably wear out before the teeth.

Bacteria Man · August 2010

I should add that the gain in efficiency through upping the chainring instead of the sprocket is probably pretty small, maybe negligible

So, I'm changing the freewheel on my SS...

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