Is there any reason I should not buy this bike?

[DismalScientist]

What’s a chain guard? Is that some overpriced doohickey the bicycle industry is forcing on us, sorta like brifters?

[vvill]

@TwoWheelsDC 97128 wrote:

I think the biggest issue with this type of setup would be getting your chain tension right, since presumably you’d be running this setup on a bike with vertical dropouts. It’s not impossible, but it does limit your gearing options, and you have no way to compensate when your chain stretches. If you’re running SS, you can use a bolt-on tensioner, but running a tensioner with a fixed gear is not a particularly good idea. You can also get an eccentric bottom bracket, but then you’re running up the price tag and complexity of the build quite a bit.

Yeah, I think without chain tension I wouldn’t run that 6-bolt thing. It’s a neat idea but unless you can get a magic ratio (maybe with a half-link?) I wouldn’t run fixed, and then with SS you lose your rear brake presumably.

[jrenaut]

@DismalScientist 97143 wrote:

What’s a chain guard? Is that some overpriced doohickey the bicycle industry is forcing on us, sorta like brifters?

Sure, the ones they make specifically for bikes are expensive. Just go to the hardware store and grab one they made for a circular saw. Almost as good, but much cheaper.

[jrenaut]

@vvill 97120 wrote:

I feel SS or FG is faster up (short) hills – imo FG actually feels a little faster than SS. The constant motion and the fact there’s no dumping your chain down a cassette to lose momentum keeps things going. There’s also some drive train efficiency gains, perhaps (no sources cited here for their claims): http://hizokucycles.bigcartel.com/single-speed-benefits
[/quote]
I always figured there must be some efficiency gains for FG/SS. There’s necessarily slack in the chain for a geared bike, and basic physics suggests that would introduce inefficiency. But I haven’t done physics since junior year of high school, so…

@vvill 97120 wrote:

I’m aiming to try a fixed century next year[/quote]
I was thinking the Seagull Metric next fall, but maybe by then I’ll be up for a full century. I think I would have to change the gearing on the bike, though.

@vvill 97120 wrote:

The main [positive] thing I didn’t anticipate was that it improves your balance, since you tend to clip-in/out at specific crank angles and spend more time balancing at low speeds. The main negative was the impact on your saddle especially if you are doing a lot of faster downhills – I ended up switching to a more padded saddle than on my main geared bikes.

I’m still working on all this. My Bianchi is definitely more comfortable, but I’m getting there on the FG.

[mstone]

@jrenaut 97160 wrote:

I always figured there must be some efficiency gains for FG/SS. There’s necessarily slack in the chain for a geared bike, and basic physics suggests that would introduce inefficiency.

A FG is still a geared bike, and there is still slack in the chain (just not too much or the chain will fall off). When pedaling, the upper chain is under tension and the lower chain is essentially slack (it would be under compression, but chains don’t transmit compression forces very well). It’s probably a wash or maybe a net loss due to the increased drag when your pedaling doesn’t exactly match any acceleration from gravity in downhill segments. (At which point the lower chain is under significant tension, which never happens with a RD.) You may have a very slight efficiency gain by avoiding the pulley wheels on the rear derailleur, but I’d be amazed if that was even measurable in the real world.

[jrenaut]

Isn’t there MORE slack in the lower chain for a multi-geared bike, though? I get that the chain doesn’t transmit compression, but it seems like you would have to lose something there.

[DismalScientist]

FG/SS being faster up short hills is mainly psychological–you realize that you don’t have the option of downshifting and so you just “man up” in an effort to maintain cadence.

[TwoWheelsDC]

@vvill 97120 wrote:

I also wonder if FG is better for solo endurance riding although I haven’t tested this out – I’m aiming to try a fixed century next year, esp since my FG was bought on the premise of being a comfortable classic steel ride (and my converted aluminum hybrid can do commuter duties or shorter shop rides just fine).

I wouldn’t say riding fixed for long distances is easier, but for the not-particularly-difficult fixed centuries and longer rides I’ve done, it certainly hasn’t made it harder. I’m curious how the constant pedaling affects endurance, since you’re not constantly spinning your muscles up and down, but rather maintaining a steady rhythm and blood flow. Also, there’s something psychologically empowering about not having extra gears to bail out to…not having to focus on shifting and getting the right gear frees up your mind to focus on breathing and cadence.

Or maybe it’s all just BS…but I do know that I did the Tour of Richmond this year at the EXACT same average speed fixed as I did it geared last year (both representing my fastest century times)…and it was significantly head-windier this year.

[mstone]

@jrenaut 97169 wrote:

Isn’t there MORE slack in the lower chain for a multi-geared bike, though? I get that the chain doesn’t transmit compression, but it seems like you would have to lose something there.

Lose what? It’s not transmitting pedaling force. I don’t think there is significantly less slack in the FG while pedaling, because there isn’t a RD spring providing tension. The tension spring may cause some difference in friction between the two setups but almost certainly less than the pulley wheels.

[TwoWheelsDC]

@DismalScientist 97171 wrote:

FG/SS being faster up short hills is mainly psychological–you realize that you don’t have the option of downshifting and so you just “man up” in an effort to maintain cadence.

Agreed. On longer hills I’m either a bit slower, or my fatigue level at the top is significantly higher (sometimes both) compared to running gears. On short hills, I can pretty easily absorb the HR spike of standing and plowing over the top.

[dcv]

@TwoWheelsDC 97172 wrote:

I wouldn’t say riding fixed for long distances is easier, but for the not-particularly-difficult fixed centuries and longer rides I’ve done, it certainly hasn’t made it harder…

As you had discovered it’s harder on your ass, you don’t get a chance to coast out of the saddle. ever.

All this talk about fixed centuries, want to do the big loop (key bridge to point of rocks) fixed – maybe the weekend of 10/25 or 11/1?

[jrenaut]

@dcv 97186 wrote:

All this talk about fixed centuries, want to do the big loop (key bridge to point of rocks) fixed – maybe the weekend of 10/25 or 11/1?

Want? Yes. Am able to? Unlikely.

[TwoWheelsDC]

@dcv 97186 wrote:

As you had discovered it’s harder on your ass, you don’t get a chance to coast out of the saddle. ever.

All this talk about fixed centuries, want to do the big loop (key bridge to point of rocks) fixed – maybe the weekend of 10/25 or 11/1?

Surprisingly, I didn’t have any serious issues during the Tour of Richmond. I think it was a combination of just enough hills to keep me out of the saddle, and moving to better bibs (Rapha vs Castelli). Cap2Cap was rough though.

And pending weather, I’m down for a group fixed ride either of those dates.

[peterw_diy]

@vvill 97145 wrote:

Yeah, I think without chain tension I wouldn’t run that 6-bolt thing.

Not a problem, I have horizontal dropouts. Might have to adjust the brakes, no big deal.

[DismalScientist]

You might have to redish the wheel if the cog is on the opposite side of the freewheel (if I understand you correctly). For my conversion, it was easiest to just find a used wheelset on craigslist/ebay, buy a new chain, and (initially) use my inner chainring.

[Author]

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