Increasing the chainring size

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OP
OP
getfit

getfit

New Member
I should mention I'm looking to replace the crank/chainring completely not add a bigger ring to the existing set up.


GF
 

RedBike

New Member
Location
Beside the road
You might need a new front mech, maybe even a new left shifter to go with it.

I think 48 is the limit of what you can use a MTB front mech for whereas 53 would need a road mech.

A MTB and a road front mech use different shifters.

It all depends on what you've currently got!
 

GrasB

Veteran
Location
Nr Cambridge
I'm assuming you have a flat/riser handle bar setup. If you've got a mountain bike front derailleur Shimano do a range of road kit for flat handle bar bikes. IIRC flat bar derailleurs work with mtb shifters but don't take that as gospel.
 

jimboalee

New Member
Location
Solihull
Is your present set-up a 48 x 12?

If it is, and you're riding a 700C, that's 107" top.

Spinning that gear at 90 rpm will get you along at 28.5 mph. To keep this up, you'll be outputting over 1/2 kW at the crank.

Are you sure you want a 53 ring? ( and all the hassle of repositioning the front mech, chain length etc )
 
OP
OP
getfit

getfit

New Member
Current set up is Hybrid flat bar with 48 x 11 being the highest setting on 26'' wheels. Should I consider a compact 34/50 set up? Will this still have the same issues with a need to change the deailleur and increase the chain length?

All advice taken onboard with thanks

GF
 

jimboalee

New Member
Location
Solihull
That changes things.

48 x 11 on a 26" is 113" top.

Now I'm even more confused.....

I'll tell you how many times my SWorks 17 lb race bike has been in 53 x 12..... can't remember.
Oh yes, now I remember. It was through Birmingham's Queensway tunnel at 40 mph with the airflow of the traffic pulling me along.

Yeh, maybe you need a 53 x 11 on a 26" Hybrid.
 
OP
OP
getfit

getfit

New Member
jimboalee said:
That changes things.

48 x 11 on a 26" is 113" top.

Now I'm even more confused.....

I'll tell you how many times my SWorks 17 lb race bike has been in 53 x 12..... can't remember.
Oh yes, now I remember. It was through Birmingham's Queensway tunnel at 40 mph with the airflow of the traffic pulling me along.

Yeh, maybe you need a 53 x 11 on a 26" Hybrid.

I do find myself in top gear on a regular basis and from time to time find myself looking to change up. I'm looking to replace the triple from current set up 26 36 48 I belive to 30 39 50. I have taken onboard the previous threads hence the change in direction to the triple with a 50.

GF
 

RedBike

New Member
Location
Beside the road
I do find myself in top gear on a regular basis and from time to time find myself looking to change up. I'm looking to replace the triple from current set up 26 36 48 I belive to 30 39 50. I have taken onboard the previous threads hence the change in direction to the triple with a 50.

You will still probably have just the same trouble with a 50. The limit on your mech is 48. It might cope with a 50, there's not exactly a big difference there but if you're about to spend the best part of £100 on a chainset I would try and find out first!

BTW, with your exising gears and 26 x 1.9 tyres you should get roughly these speeds at these cadences.

Cadence(rpm) = Speed (mph)
70=23.8
80=27.2
90=30.6
100=34
110=37.4
120=40.8
130=44.2

Most people recommend you pedal at about 80/90rpm so a speed of 30/35mph in top gear should be sustainable. You aint going to be achieving this sort of speed without the aid of a good hill.
 

ColinJ

Puzzle game procrastinator!
RedBike said:
Most people recommend you pedal at about 80/90rpm so a speed of 30/35mph in top gear should be sustainable. You aint going to be achieving this sort of speed without the aid of a good hill.
Or the help of a big bunch of riders and/or a very favourable tailwind! I was lucky enough once to ride down a valley on the Costa Blanca with about 30 other riders and a 15 mph tailwind. We were doing 35 mph no problem at all! :rofl:
 

GrasB

Veteran
Location
Nr Cambridge
What sort of cadence do you ride at? It may be worth working on getting a higher cadence than going higher on the gearing & burning out. With that said, I like to run on a large chainring & use larger rear sprockets to give closer gears.
 
OP
OP
getfit

getfit

New Member
It's fair to say that my fitness/ability will not allow me to get any decent constant speeds as my other threads will verify however I do live in a hilly area and often find myself running out off gear on sustained downhill sections. This is where I feel the 50 will come in handy.

GF
 

GrasB

Veteran
Location
Nr Cambridge
Do you actually use the lower end of the chain ring? In all honesty you want to gear more for when you've exhausted your self & need to get home. Get that right & if you're off the top of your highest gear then just use the brakes to keep the peddle speed comfortable &/or coast. It's easy to do damage if you're forcing your self when exhausted.
 

Joe24

More serious cyclist than Bonj
Location
Nottingham
getfit said:
It's fair to say that my fitness/ability will not allow me to get any decent constant speeds as my other threads will verify however I do live in a hilly area and often find myself running out off gear on sustained downhill sections. This is where I feel the 50 will come in handy.

GF

Oh yeh, well i ride 48/18 on my fixed and can spin up to 42mph on it on downhill's;)
What you need to do is spin more;)
You don't need a bigger gear i think. On my geared bike i used to have 50/13, which is a 103" gear. I used to go and do long club rides, and chaingang at the end of them, and would sometimes be going along for a few miles(after doing 50/60miles) doing 31/32mph.
I did change to 50/12 though, so i had that higher top end gear, but i didn't go in it all the time.
 
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