Saturday, 14 September 2013

in which the hybrid bike gets its climbing gears

Bike Project
I took a few snapshots during the bike cog switchover the other day.

The result is that the hybrid bike now has a slick twenty speed climbing gearset(2x10), which breathes new life into it.

The old 9 speed deraillier was from a mountain bike and the handlebar selectors were 3x9. Note the direct cable routing, rather than a road bike's typical loop.

The previous gears on the bike were actually a 10 speed, so it's a bit mixed up before I start. It was 2x10 running on 3x9 selectors and a 9 speed rear deraillier plus a stretched chain. Oops.
Hybrid bike gear swap 11:24 -> 11:32
I thought I'd sort out the front selectors too. The old 9 speed did work across the 10 gears, but it would be easier to put on a proper spare set of 10 speed.

They are SRAM flat handlebar selectors, with those little indexing windows. Ideal as I'll also use this converted bike with the turbo trainer.
Hybrid bike gear swap 11:24 -> 11:32
Ping out the rear wheel. Find the new rear gear cassette. Somewhat bigger and a lot shinier than the old one.
Hybrid bike gear swap 11:24 -> 11:32
Remove the old cogs with one of those special spanners. I always struggle to work out which way round to put the chain spanner, to get leverage.
Hybrid bike gear swap 11:24 -> 11:32
There. New cogs installed. They only fit one way, thanks to the little indexing tabs on the bike hub. Its the same indexing for Shimano and SRAM. The original rear gear was Shimano, then a temporary SRAM and now this new one.

I noticed a couple of loose spokes during the process and have re-tightened them. I know they are inexpensive wheels, but a separate future project will be to get some improved wheels for the carbon bike and hand the current carbon bike's wheels down.
Hybrid bike gear swap 11:24 -> 11:32
Time to break the bike chain and remove the rear deraillier.

I recalculate the length of the new chain instead of just copying the length of the old one. The new one should, in theory, be longer, but the calculation of 'tight around the biggest gears + 1 link + the Powerlink means it will actually be slightly shorter than the one it is replacing.
Hybrid bike gear swap 11:24 -> 11:32
Remove the rear derailler with an allen key, then clean the rear hanger before putting everything back.
Hybrid bike gear swap 11:24 -> 11:32
The replacement deraillier is bolted on via allen key.
Hybrid bike gear swap 11:24 -> 11:32
Reattach the wheel with it's sparkling gear.
Hybrid bike gear swap 11:24 -> 11:32
Rethread the chain and new cables, having first checked the deraillier alignment. Remember to pull the new cables tight before screwing them into place. Cut with a proper cable cutter and add those little caps.

Flick through the gears up and down a few times in both big ring and small ring positions (i.e. all 20 gears) to check alignment. Make micro adjustments (the last millimetre) using the black twisty wheels by the black outer cables.
Hybrid bike gear swap 11:24 -> 11:32
Add a Garmin sensor, so that the bike counts wheel revolutions (speed) and cadence; useful on the road and also with the turbo.
Hybrid bike gear swap 11:24 -> 11:32
And,'hey presto' a bike. There's still a few more things to adjust, but it is back in action. Elapsed time, with coffee, around one and a half hours.

According to the Garmin, I've put about 100 miles on it since I swapped it around and it's pretty much bedded in. So much smoother than previously. I guess the proper SRAM 10 speed chain helps! It may not be the fastest bike, but a very entertaining ride.


RFM said...

Wow. Fantastic work. Wish I had one of you in my garage, to be pulled out when needed. I'm thinking of switching to my old (all-round cheap) hybrid bike for the winter, to keep the road bike clean. The hybrid already has a very big granny gear, which I don't really need round here. I almost never use the smallest front chainring (it's a triple).

Would love some of that SRAM on my road bike for the summer rides in France. Lots of bills to pay first, however.

rashbre said...

RFM I surprised myself that I had the right tools to make the switchover go smoothly. My general plan is that I'll eventually wind up with a few interchangeable wheelsets too.

Lois (three-legged-cat) said...

I'm very impressed. We took Mr TLC's bike to the bike shop last time it needed new gears. More expensive and slower than your method - but I think it would have taken us a lot longer than 1 1/2 hours to do the work ourselves - even if we skipped the coffee!

rashbre said...

Lois Yes, you do need the spare pieces and relevant tools as well, so there's still lots to be said for using the LBS (local bike shop) to do the work.