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I am planning on converting my 'play' bike to SS (Charge Blender)...however I want to use it for a few applications and might need different ratios for each...
1) Short blast XC
2) BMX/4X tracks
3) Local skate park
I understand tha a good place to start for the XC is 2:1 so I'm running 32 upfront so 16 rear? No problem but what about BMX tracks and skate parks?
Any suggestions welcome (26" wheels BTW)
32:18 making it easier to spin quicker.
2:1 on 26" is pretty close to 44:16 (bmx race) on 20"
2:1 on 26" is pretty close to 44:16 (bmx race) on 20"
interesting.
It is indeed almost exactly. 51.4" according to the late S.Brown Esq.
2:1 being 52" on 26".
Did some BMX racers favour taller or shorter gears or was it pretty much 52" for everyone? What about 4x, are they SS or geared these days?
My SS spins out half way down the hill at the local BMX track so I took my geared ...I forget what i ran now though but it was higher than 32:16
Cheers I might try 32:16 on and go from there. 4X race bikes are all geared, normally close ratio blocks of 5 or 6.
I've got a zee mech/shifter and for a full on day at a 4X track I'll pop them back on with gears, but wanted to have a blast at the new skate park in town and fancied trying SS whilst I'm at it, might strengthen me up over winter!?
I've seen bike with vertical dropouts running SS without a chain tensioner, how is this achieved...I like the clean look?
how is this achieved
half links/magic ratios?
???
I was told (but can't verify it's true) that you shouldn't use whole ratios for singlespeed as they cause wear at the same point on the rear tyre. So 32:15 or 32:17 for example.
😆
half links have bent plates so you can adjust a chain length by half a pitch instead of a full pitch.
Magic ratios are different chainring/sprocket combinations that give a consistent gear ratio but due to the geometry differences of each combination make for different chain lenghts, one of which might be bang on (at least until the chain stretches) for the chainstay length of the frame.
dunmail - I thought it was chaining tooth wear, not the tyre....but I can kind of see why. Pretty sure it's not going to have a massive effect though 🙂
dunmail - Member
I was told (but can't verify it's true) that you shouldn't use whole ratios for singlespeed as they cause wear at the same point on the rear tyre. So 32:15 or 32:17 for example.
this is not true
'Magic ratio' is when the chain is exactly the right length for a given chainring / sprocket / chainstay combination (either by coincidence or by design). These usually don't work for very long as the chain will grow, and the magic ratio is then broken. [edit - beaten to it]
What was the frame? It could have been an Eccentric BB, which would look exactly as you describe.
I've got a lot to learn...but thanks I will read up!
Sprocket wear maybe - chainring wear will always occur where the loading is highest - where the cranks are when you're exerting maximum power.
It's a benefit if you are able to rotate the chainring through 90 degrees to even up wear, which I can't on RS7 cranks.
It 'twas a Charge Blender also, in fact there are a couple in google images that come up.
I tried 34/17 first but found it slightly too tall for trail riding so went to 34/18 which I find useful for most things but it'd probably be too short for BMX tracks. Ideally try and avoid direct 2:1 with even numbered rear cogs as that'll wear the chain and rings quicker than 2:1 with an even numbered chainwheel and odd numbered cog.
We've just started making stainless cogs in 17-22t if that's any use.
edit: I use a Blackspire bottom run chain device to tension the chain on mine (not very clear in this pic but it works really well)-
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