Changing gear ratios

[944fan]

I have a Trek 1.1 2013. Overall I am very happy with it, but I find the gear ratios too limiting. I can spin out in top and sometimes the lowest could do with being a bit lower. Also the ratios on the cassette are so close I generally have to change up or down twice on each change. The chap in the LBS where I bought the bike did tell me all this and recommended the 1.2/1.5 but I was buying the bike on Bike2Work and my company had a limit of £500. He also said the cheapy crank would flex under my weight and power.

I currently have a Vuelta Corsa, 50/34 (compact) crank and a Sun Race CSR86 12-25, 8 speed cassette. So I am thinking of replacing the cassette for a Shim HG51 11-32T and the crankset with a Tiagra compact 39-52T. That would cost less than £100 and would give me a greater range of gears with higher top and low bottom and a stronger, lighter crank.

My question, would these be compatible with the 2300 shifters and derailleurs?

[anonymous-user]

34/25 really should be low enough to get you up most hills in the UK and if you're spinning out 50/12 at 90 rpm you're doing 30 mph which is rather fast but in all honesty, how long are you keeping that up for?

For less than £300 you can get a complete Tiagra groupset from Ribble which would solve a lot of problems regarding compatibility, give you better brakes and full 10 speed so you can upgrade easily to 105/ultegra over time and save a little bit of weight too.

http://www.ribblecycles.co.uk/gsg/road-track-bike/...

[Bobley]

In a word No. The 2300 rear mech wont work with cassette with more than 26 teeth. The new Tiagra will go out to 30 in some setups.

I'd stick with 50/34 up front and run 10 speed 11-27 on the back with a new mech, chain and RH shifter. Its very likely you'll need a new crank though too..

105 (5700) and Tiagra (4600) will run 11min - 28max...

[944fan]

The spinning out occurs when coming off a downhill on to flat because of the extra momentum from the hill. That is at about 33 MPH. Just feels like with a higher gear I could push that speed for longer.

I tried riding up a 12% incline yesterday and found it quite hard. I did have a hangover after 1.5 bottles of red wine so maybe I should just drink less, MTFU, and keep the cassette I have!

I like the idea of upgrading to Tiagra but even 2nd hand from Ebay I am looking at £200. Spending that on a £550 bike seems counter productive. But I can't change the bike at the minute so maybe the only option.

[Mr Will]

First things first, I seriously doubt you are spinning out in top gear on anything except the steepest hills. 50x12 should be good for almost 40mph. If you aren't getting there then I'd work on your leg speed before changing your setup.

Secondly, I wouldn't worry about changing the crank. The guy in the bike shop was just working a sales pitch. By all means upgrade it when the old one wears out but I doubt you'll notice any difference (aside from the different gears).

Finally, the cassette. This is the easy one to change - cheap and a maximum of 5 minutes work. I'd go for a 28t lowest gear with your compact (there are some compatibility issues surrounding 32t cogs) which sounds like it should be enough for most hills.

[Mr Will]

944fan said:

The spinning out occurs when coming off a downhill on to flat because of the extra momentum from the hill. That is at about 33 MPH. Just feels like with a higher gear I could push that speed for longer.

33mph in that gear is 100rpm - it'll feel fast as a beginner but its actually not. You should be aiming to average about 90rpm over the course of your ride, so holding 100rpm for significant portions of it. With practice you won't spin out until north of 120rpm.

944fan said:

I like the idea of upgrading to Tiagra but even 2nd hand from Ebay I am looking at £200. Spending that on a £550 bike seems counter productive. But I can't change the bike at the minute so maybe the only option.

Just ride what you have for now; it's solid, functional kit and there's nothing wrong with it. If you really have upgraditis then start with wheels and tyres. They'll make a much more noticeable difference and be easily transferable if you upgrade your bike in the future.

[944fan]

Thanks for the tips. I recently changed the tyres because I was getting punctures all the time and I was surprised at how much difference the tyres made to speed and effort. Best £35 I had spent in a long time.

Do you think it is worth getting a computer with a cadence function? Currently using a Garmin Forerunner 301 which is ok for HR and max/current/avg speed but nothing else.

[Mr Will]

Depends on your goals but I wouldn't spend a big chunk of money just to get a cadence read-out. Just work on spinning faster when you can and you'll likely find that it rises naturally anyway.

[Bobley]

My lads Sigma 1609STS computer has cadence and didn't cost the earth. He's got pretty chunky legs so he can really shift but he does get a bit peeved when I lock his gears to 36-14 for races. You'll see some cadence then!

[agentnomad]

Gear size & speed at 100 RPM Gear size & speed at 110 RPM
Gear size KPH MPH Gear size KPH MPH
100.3 52 x 14 48.0 29.8 100.3 52 x 14 52.8 32.8
93.6 52 x 15 44.8 27.8 93.6 52 x 15 49.3 30.6
92.6 48 x 14 44.3 27.5 92.6 48 x 14 48.8 30.3
91.8 51 x 15 44.0 27.3 91.8 51 x 15 48.3 30.0
90.0 50 x 15 43.1 26.8 90.0 50 x 15 47.4 29.5
88.2 49 x 15 42.2 26.2 88.2 49 x 15 46.5 28.9
87.8 52 x 16 42.0 26.1 87.8 52 x 16 46.2 28.7
86.4 48 x 15 41.4 25.7 86.4 48 x 15 45.5 28.3

This was in an Excell spread sheet but I carn't copy and paste it as it was with the grid lines etc so hope you can work it out this is a table I produced for track racing so you may need to google for lower ratios or send me an e-mail and I will send you the full table.

But as has already been said you are not spinning out you are just not use to paddling that fast and 130 rpm is getting there and I am 49.5yrs old, you need to learn to spin at 100 rpm to protect your knees and other joints from high loads speed and torque ratios just like a car and gear box

Ride the bike you have and when you think you are enjoying it enough to upgrade buy some mudguards and winterise this bike and buy a summer bike and in time the summer bike will become your winter bike and so on until you are riding a full carbon through out the winter.

If you want to see true leg speed pop down to a velodrome as have a watch of the racing there, as you have to pedal faster to go faster no gears on a fixed.

Paul.

[okgo]

Keep the gears you have.

100rpm is far from spinning out, 50-12 big enough for most things outside of racing where you probably would need more.

[russy01]

okgo said:

Keep the gears you have.

100rpm is far from spinning out, 50-12 big enough for most things outside of racing where you probably would need more.

I agree with this, move those bloody legs. Ideally you want to be averaging 85-100rpm and on a ride id at least expect to reach 120 or so a couple times easily. I've just checked my garmin for my evening 20miler and I averaged 88rpm and reached a peak of 133.

I run 50-12 on one bike and 50-11 on the other. If the conditions are right I can maintain 30mph easily (less than 90rpm) and have hit 48mph downhill which is about 135rpm.

My bro uses a 53t but this is because he races and does a lot of TT's and has the larger gears as he doesn't need the low ones I require!

I'd keep your cash and work on technique for a bit.

Edited by russy01 on Monday 24th June 23:15

[944fan]

Funnily enough my trusty Garmin Forerunner 301 seems to have given up the ghost this morning so I maybe in the market for a new device.

Any recommendations? Want something that can be used for running and cycling. HRM, usual speed readouts and then the option for cadence and maybe even power meter.

I tried faster legs on my commute this morning. Was finding I was bouncing around a bit. Is that because I was peddling too fast or just bad technique?

[okgo]

Probably you are not used to it, bad technique and your saddle may also be too high.

[itsnotarace]

Yes, saddle may be a fraction high. Also try and concentrate on pedalling smooth circles with both legs

[944fan]

Thanks for all the tips. I thought about getting a cadence monitor but in the end my Garmin 301 sorted itself out and I didn't think it worth splashing out. Instead I put my setup in to one of those gear calculators and printed the speeds for the top gears at 80, 90, 100 RPM and stuck it next to the Garmin to use a guide.

Last night I managed to get to 33.4 MPH on a flat piece of road which is what I was previously hitting downhill so very pleased with that. Legs spinning much faster and not too much bumping in the saddle either. Little bit of a side wind as well so hoping I could hit 38 ish in the calm.