Singlespeed construction fettling: episode #4
Now that I have finally got the troublesome lock ring free, I am back to building my S/S bike.
I took the cassette off and cleaned up the 19-tooth sprocket that I will be using on the S/S. I worked out how many spacers were needed to get the sprocket aligned with the chainring and my guestimate looks almost perfect - I placed a steel rule along the ring and the sprocket and all looks good. The spider was not fully tightened onto the bottom bracket at the time though so the ring will move slightly inwards when it has been. If necessary, I can move the sprocket one spacer closer to the centre of the wheel.
I have mislaid the bolts which hold the cranks on! I know that they will be somewhere amidst my tools and spares but my workshop area (corner of kitchen!) is very disorganised and they are currently hiding. I will hunt for them later this evening or maybe tomorrow.
This way of making a S/S does concentrate a lot of force on one part of the splines on the freehub. Normally, you would be going up and down through the gears so different sprockets would be handling that force at different times in the ride. On the S/S, everything would be concentrated through one sprocket worth of spline. (I suppose that some of the load could be taken through the spacers, but not much, I reckon.) Nevertheless, I have done this before and rode thousands of miles on the bike without wrecking the splines.
I took the 52-tooth ring off the turbo trainer-bound Basso and cleaned that. The 53-tooth ring that I had intended for the S/S is now going on the Basso. (It won't get used while the bike is on the trainer, but it will also be a spare bike for the road so I want to get it upgraded to full working order once I have finished the current project.).
It turns out that the two chainset spiders are a slightly different design. The old 'Racing Triple' spider on the Basso has 5 separate small arms. The spider that I am using on the S/S is from the old 10-speed Chorus chainset which I took off my CAAD5 when I replaced it with a Stronglight triple. That spider has 4 small arms and the 5th chainring bolt screws into the back of the right crank. It means that the little pin which is designed to stop the chain getting stuck between the crank and big ring will be in the wrong place on both bikes. I may well swap the rings back again later but I think a lower gear on the S/S and a higher top gear on the Basso both make sense. I will just have to be careful not to drop the chain off the RHS of either big ring.
I tried fitting just the big ring to the S/S spider but the bolts will not fully do up without the inner ring being there. I could go out and buy some washers tomorrow but I had an interesting idea ... perhaps I could refit the 39-tooth inner ring and make the new bike a 'double singlespeed' i.e. a 2 x 1-speed?
I am not putting gear shifters or derailleurs on the bike but there will be a chain tensioner. I don't know if that will have enough travel to take up an extra 13-teeth worth of chain but if it is
does, I can try changing the chain between rings by hand if I decide to venture up into hills too steep for a 52/19 gear. I will optimise the chainline for the 52/19 but will see what happens if I switch the chain over to the 39-tooth ring. If it works, I'll keep that arrangement in place. If it doesn't work then I will buy the washers and turn the bike back into a real S/S.
The wheels are now on the frame and the project is beginning to look more like a bike, and less like just a pile of parts! Although the saddle and bars are not needed at the moment, it won't take long to fit them and the more bike-like the project becomes, the more incentive I feel to finish it.
I am already looking at locks. I often arrive home from a ride on Sundays with only 30 minutes or so to spare before the local Lidl and
Morrisons shut (4 pm). I want to be able to come home, pick up my rucksack, swap bikes and dash to the shops. I don't want to leave my CAAD5, CAADX or MTB in public while I shop but this project has not cost me much so I will be happy to take the small risk of some cheeky toerag nicking
this bike.
PS
Added this evening:
- Seat post
- Saddle
- Handlebars
- Front & rear brakes
- Chain tensioner
- Chainset-52/39 for possible double singlespeed with manual change between rings
To be continued ...
I should add that I've lost the adjustable stem I bought from you (it's about somewhere, I just can't find it) which I was going to fit so I could mess about with angles before committing to buying one, so at the moment it has the stem frommy other bike meaning that brilliantly that I have no rideable bikes now, despite spending quite a while messing about fettling.
