Single speed cyclocross

[Johnsqual]

Hello,

As I recently mentioned in a previous thread, I am planning to rebuild a cyclocross bike as a single speed. I have had enough of clarted up derailleurs.

My bike is a steel frame cross bike with vertical drop outs.

I have been reading Sheldon Brown's articles on single speed conversions, but have couple of doubts about some of the things he suggests.

First, he mentions that it is actually possible to use a quick release skewer for SS as long as it is good quality and tight enough.
However, is it possible to adjust the chain tension by 'walking' the hub back in the rear drop out? (or is it only possible to use QR levers with a chain tensioner device)?

(It would presumably be a good thing to be able to use QR levers for cyclocross, particularly if one gets a puncture).

Second, does anyone have a suggestion for ratios? I tended to mostly ride 33-21 down to 33-28.

Cheers,

Johnny

 

[Jonny69]

Bleh. I never knew about the quick release skewer thing until recently, but yes, you do rely on the axle nuts to set chain tension on a fixed wheel. On a singlespeed with a freewheel you don't need to walk the wheel back and I doubt you'll have problems with it coming undone.

I have vertical-ish dropouts on my fixed wheel Bob Jackson. I say vertical-ish because they are in fact 45 degrees but very short. There is enough movement in them to get tension on the ratio I ride with and I don't need a chain tensioner. You could use something like the Gusset Bachelor, which was the most secure I have seen. Alternatively, if there is a little allowance in your drop-outs, you might get away with a half-link chain.

As for ratios, well, how strong are your legs? I did the Isle of Wight challenge with a 40-17 (freewheel) and only had to jump off and run on the steeper bits. Probably should have used a 33-17 or 33-16, but it would have held me up on the flatter and downhill bits where I could make some serious progress on the field.

 

[Johnsqual]

Great, thanks. I will give it a go with the QR then.

I also noticed Sheldon's suggestion about using a cassette with spacers.
I suppose the advantage is that you can then quite easily remove the
sprockets to try different combinations. So I think I will have a go with that,
then eventually maybe build a proper single speed wheel with a single
freewheel when I find the right ratio for me.

 

[monty dog]

Absolutely no problem using a QR on a SS wheel in a vertical drop out and likewise a chain tensioner. 'Walking' the rear wheel in the drop out only works for older-style, long drop outs.
There is always the 'magic gear' and maybe with a half-link you can do without the chain tensioner.
Suitable gear ratios depends on both the terrain being ridden and how hard you want to make it. I ride 36x18 on my SSCX for local trails and looning around singletrack and used 36x20 for the Southdowns Way. It really comes down to experimenting to find what works for you.

 

[mattsccm]

SS ing is no different to gears as regards holding the wheel in. Therefore Qr's are fine although I always use decent traditional ones like Campag.
The only probelm with any SS job is with vertical dropouts.
If you can find a magic gear the you are ok. If not, you need a tensioner. Nasty idea.
I also use decent QR's on fixeds. After all the forward pressure is the same and the backwards pressure is just the opposite but probably less.
Just dog them up tight.

 

[Dead Rats]

+1

the old Shimano heavy all-chromed QR skewers and similar Campy ones are ideal for singlespeed in a horizontal drop-out

As stated do them up super tight and well greased on the nut end.

Track nuts actually strip quicker than you'd think IME

 

[pigman]

i kinda gave up on single speed. I'd built a SS pubber/shopper but found that the chain was either too tight or too slack cos something was out of centre. Chain line was good, but over bumpy ground it would derail when slack, then as it was riding on top of the sprocket overtighten and crunch the transmission. I could have used better components, but the idea was to have a no-cost machine that was undesirable and owed me nowt.
I then tried using an uncabled derailleur as a chain tensioner, which worked well but the simplicity was gone. All I needed was a lever and I'd have some gears and all the compromising in hiily sheffield would be gone. Its now a 5 speed bike.

 

[Johnsqual]

Thanks again for replies.

Pigman - I rode a singlespeed to work every day for about six months and got on fine, although neither that route nor the one I would use the cross bike on are particularly hilly - certainly not like Sheffield.
I sort of came from the opposite direction to you: I got sick of finicky, unresponsive derailleurs when riding in the mud. Hopefully this will simplify things.

On a partly related note: does anyone make an emergency chain tensioner that clamps onto the chainstay? A bit like the chain tensioners you see on earlier geared bikes. I think it could be a useful thing to have if you get unlucky and bend your derailleur and/or hanger on a bike with vertical drop outs. It would look a bit naff, but if it gets you home...
Any thoughts?

Johnny

 

[stewlewis]

On a partly related note: does anyone make an emergency chain tensioner that clamps onto the chainstay? A bit like the chain tensioners you see on earlier geared bikes. I think it could be a useful thing to have if you get unlucky and bend your derailleur and/or hanger on a bike with vertical drop outs. It would look a bit naff, but if it gets you home...


Any thoughts?

Johnny

 

[Johnsqual]

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I don't see that shortening the chain is that much help with a vertical drop out. You surely still need to make finer adjustments to the tension, which you can't do with vertical d/o's.

I had something like the thing below in mind. Tektro apparently used to make them, but not any more.