Front Sprocket advice please

[vicsalt]

I have a 2021 Cube Reaction Hybrid Performance 500, to road commute to work, I have also added a Speedbox 3 as the 15 MPH restriction is a joke, I'm 58 and get no assist on the road as my commute is mainly flat so always above the 15MPH, I want a easy life, likewise i am only using a 2 gears, 8 & 9. and dont want top pedal like a dick to get 30MPH down hill. I'm assuming if i put a larger front chain ring on it will raise the gearing, Increasing the scope to hit 30MPH without pedalling like a twat.

Please advise, does my request make sense, can it be done and any advise on size and where to buy.

Thankyou in advance

 

[nasamorpheus]

I have 1*12 sram on cube stereo hybrid race 140 and I still pedal like a twat

 

[Flyfisha]

Hi vicsalt ,
I am a little older than you and also ride mostly on hard surfaces.
Yes you are correct increasing the size of the front sprocket will in theory give you a higher top speed. I added a larger sprocket to my trek bike. In reality the top speed remains about the same with only your cadence slowing.
For me it was a big help going down hill or on very flat smooth surfaces only. Now on down hill or steep down hill I can ride a lot faster without as you say peddaling like a twat.

Be aware my chain is now longer than what is sold requiring a few links more than a standard chain. No big deal.

My restriction runs out at 26 km per hour . I do not use the top two gears until going over 30 km and 35 km . I believe it would be a strain on the motor to use high gears at a low cadence?

Sorry I don’t have your particular brand of bike but I am sure there is aftermarket parts available?

This chart is just one of many on the internet that may help ?

 

[steve_sordy]

The bike will go faster in each rear gear in proportion to the size of the new front gear divided by the size of the old front gear (ex 36/34 = 1.0588 ie almost 6% faster). But you have to be able to overcome tyre drag, wind resistance etc to reach your top speed on the flat.

Make sure that the bike frame will not get in the way of a larger diameter gear of the size you are looking for. Mine does.

 

[emtbPhil]

Forgive me for asking but if you just use 8&9 now - what's wrong with the other 3?

If you go from the 38T chainring up front up to a 42T 8&9 would become 7&8 so I suspect then you'd just use 7&8

Also the cube hybrid reaction comes with a 38T which is pretty big anyway! much bigger and it might start hitting the rear arm