Sunday, November 11, 2012

I did a stupid thing - going up hills, cassettes and the right gears for the Etape

After working out that my new bike was actually harder to climb on (ie had a higher lowest gear) than my old one. I bought a new cassette.

For the uninitiated, the bit with the pedals on is the crankset - these have one, two or three gears on them and cost loads - then there is the cassette, which is the block of gears attached to the rear wheel.

Crankset - this has two chainrings, big (la plaque) and little

Cassette and derailleur (upside down as I was working on the bike)

The cassette is a lot cheaper to upgrade or switch - c£40 for most bikes, although being a bike component, you can probably pay several hundred if you so choose.

Now with 10 gears to play with on the back, you can customise pretty well. I had a standard isue 12-25 cassette (ie the smallest gear had 12 cogs and the biggest 25), I was looking for a lower gear to make climbing easier as there will be an awful lot of it on the Etape.

There are nine, ten and eleven speed bike gear set ups. The back gears on a ten-speed (my set up) range from 12-23 (super smooth, not a lot of climbing) to the mammoth range of SRAM's 11-32. I ummed and ahhed about the 11-28 (ie a bit faster at the top end, and easier going up hills than my current set-up) and the 12-30 (same top speed, but even more climbing ability).

Deciding I didn't need to go faster than I currently can, having an extra "pain killer" switch that might be the difference between making it up Annancy-Semonez and riding in the broom wagon saw me plump for the 12-30.

The fallout should be simple - I have less precision in the middle (as there is a bigger spread between gears) but while currently I have 1.44 revolutions of the wheels per revolution of the pedals, I'd get just 1.2 wheel turns per revolution with the new gears - or 17% easier to push up hills.

Slower, true, but no one ever failed to finish a race because their gears were too easy - and I had the same speed at the top end.

So I merrily (well, involving swearing, looking for my Big Book of Bike Maintenance, not finding it, hitting YouTube to check instead, more swearing and a broken nail) swapped cassettes on my rear wheel.

Sadly, I'm an idiot.

The first problem with having a much larger gear on the back is that it's - duh - physically larger. So the chain has to go further. It doesn't. The bike locks up if I try and get it into the climbingest gear.

Not enough chain

The second problem with a bigger gear is the rear derailleur (the thing that moves the chain between gears) is a specific size too. So it doesn't really reach the biggest gear either.

At some point I also appear to have messed with the alignment of the rear derailleur so for a while it was just pushing the chain off the gears entirely. I sort of fixed that.

But after £50-odd, a fair amount of swearing, looking things up, adjusting, spanners, Allan keys and screwdrivers, I effectively have lost a gear (and it's the big one I wanted to get up hills).

Hopefully all I need to do is work out how to re-align the derailleur, fix the indexing and maybe slacken the chain (or give it to a mechanic who would do this in 2 mins). Worst case, I need a new chain (£40) and rear derailleur (£80). And someone to fit them (probably).

All to go up hills easier...

In the meantime, I think I've got the bike working as a 9-speed (ie the big gear doesn't work, but the rest do), but it might be more sensible just to put the old one back on so I don't end up breaking something (on the bike or me).

UpdateI found my Big Book of Bike Maintenance!

This is good news for two reasons. 1) You can sit it on your lap while working on your bike and 2) I think I've fixed the new gears, sort of.

Derailleur looking good in big
cog and small chain ring
Basically, in my small chain ring (the one attached to the pedals) everything moves perfectly and make no 'wrong' noises. Wrong noises are rubbing sounds of the chain on something or "chatter" from the gears meaning you're not aligned right over a cog.

In my big chainring there is a rubbing noise in my fastest gear that no amount of cable or screw adjustment will get rid of. I can live with this. Not an issue going really fast downhill (ie not pedalling) and I only really need that when trying to push at about 35+mph on the flat.

Bigger problem, I don't have enough chain to be in my big chain ring (sur la plaque!) and my lowest (ie climbiest) gear on the back. It doesn't break it, but it's VERY close to breaking it (see "not enough chain photo above, this still happens).

But then you should never be in that gear. If you need that much climbing, you should be in your small chain ring.

So, hopefully, all is now well. ish. And if it isn't, it looks like the solution is a bigger chain (currently half-price at £20) rather than a new derailleur (£80).


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