Upgearing?

[Demonic69]

How would it affect top speed?
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Back on a Blade. Just feels so right.

[Sparks!]

well it's the opposite to down gearing, so it'll make the bikes top end a lot faster dependant on how many teeth you go down/up whatever

Not much help but that's about all there is to it unless your after the exact increase for such and such gearing combination.
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Current Toys: 06 Yamaha WR250F | Nissan 350Z GT | Tech 4 Homes

[Korn]

In theory you could gear the 'blade for 200mph plus, but in practice you'd bugger the acceleration and not get anywhere near top speed without the assistance of the world's biggest hill..

Downgearing is better
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3516 Miles, 11 Countries

[ProXimaCore]

Say if you done a lot of commuting on motorways. Would upgearing save you on fuel?
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Honda NSR125R -> Suzuki GSXR400R GK76a -> Kawasaki ZX636 B1H -> Honda CBR400RR NC29 -> Nothing

[Luke_Retrofly]

Hi
Yes.

Luke
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Flounced - Long overdue
Fuck you bitch I'm in the top 10 list I can do the what the fuck I want!

[G]

Does your bike top out in sixth with standard gearing?

If it won't you will probably loose some top speed.


Upgearing wil save on fuel if you already spend a lot of time in top gear, if you don't, do so and you will save on fuel.

[ProXimaCore]

Just curious. I'm actually going to downgear my bike eventually. There really is no need to go over way over 100mph that often. But yeah I just put it in 6th gear if I want to save on fuel.
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Honda NSR125R -> Suzuki GSXR400R GK76a -> Kawasaki ZX636 B1H -> Honda CBR400RR NC29 -> Nothing

[kev]

I could redline in top on my old blade with standard gearing.
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20:02:36 Jammy-R6: any holes a goal
20:02:48 kev: even if its a hairy mans arse
20:02:56 Jammy-R6: hell yes

[Frost]

my clapped out old banger dont be dual carraigeways due to the fact it has to be doing 12k rpm to pull 70mph, i also rarely linger in any of the mid gears for more than a second. i typically get it into top gear at 25-30mph and it pulls smooth and happy on the torque.

I think my bike could be a prime candidate for upgearing, so how do i go about doing it?

new sprocket on the back and its done? or will i have to adjust the cain, taking out or putting in links?

[kev]

You would have to put a smaller sprocket on the rear or a larger one on the front.
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20:02:36 Jammy-R6: any holes a goal
20:02:48 kev: even if its a hairy mans arse
20:02:56 Jammy-R6: hell yes

[G]

What bike is it?

Though as you're obviously not bothered by acceleration, it probably wouldn't be too bad, though beware as it may give you a slower top speed.

It's best to change the front and back sprockets at the same time by a similar amount. For instance 1 up on the front and 1 down on the back for upgearing. That way you need the same length chain.
IT may be an idea to get a new chain at the same time though.

[Kickstart]

Hi

Some bikes will happily pull higher gearing. Plenty of trail bikes for example. Cliffs H100S2 would happily pull higher gearing but there is no way you can fit it (peak power is at 6500rpm and they will go past 8000rpm in top gear). My RS would probably pull marginally higher gearing, but that would make the low down acceleration even worse when moving off the lights.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Frost]

well what if i replaced just the front sprocket?

would that make much of a difference? would i also have to replace the back sprocket and/or the chain?

atm my bike has no trouble pulling away in first, pulls 5th with no problem from 25mph all the way to 13-14krpm @ 70mph

allthough the bike will go 70, i'm not happy having it rev that hard to do so (the bike is 20 years old so chances are its had alot of thrashing and the last thing i want to do it give it more)

what kind of effects could i see on top speed and sensible cruising speed by upgearing?

[Kickstart]

Hi

Trouble with doing that is that a larger front sprocket you will need a slightly longer chain. There might be enough free length in your existing chain to get away with this but probably not.

If the chain is fairly new then just get a pair of sprockets, going down one tooth on the back and up one at the front as this should barely affect chain length.

If the chain is fairly old then get a complete chain and sprocket kit.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Frost]

your words are wise indeed, however i am as scabby and jippo as my bike and words like "new" when combined with mechanical parts scare me

the chain in perfect at the moment, just enough slack in it, so it looks like it shall be a question of getting sprokets from a scarpyard then seeing if i need a new chain or not.

[Kickstart]

Hi

Trouble is that the chain and the sprockets wear to each other. Use old sprockets on a newish chain and you will cause rapid wear to the chain.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Danny]

Does the reverse happen if you have new sprockets and an old chain?

[Kickstart]

Yes. Rapid wear on the sprockets until they suit the chain.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Frost]

Okay I'm off to the scarp yard int he next few days. i shall have a look what i can find, as my bike is a small honda (85, CB125T), I'm sure i shall be able to find something which will fit. current gearing is:

15 Front
42 Rear

the reason i want to change the gearing, is because anything from 25mph allt he way up to 70ish at redline is done in top.
But how far do you think i can push it?

I would preffer just to get a single sprocket, which is going to be the rear as that will require only the tightening of the chain.

[bikedudextrm]

I put a bigger front sprocket on my 125, the gears would go on forever compared to what it was like before. I thought it would improve my top speed but i could never build up the revs to change to top gear so was about the same top speed, maybe abit lower and the acceleration wasn't as good.
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https://www.bikepics.com/members/bikedudextrm/

[Frost]

I take it this was a 2 stroke 125?

mine is a 4 stroke twin, so hopefully its got the balls to pull it

advice please

https://www.gear4bikes.com/acatalog/Honda_Rear_Sprockets.html

269-42 Rear Sprocket - Honda CB125 TDC/TDE/TDJ Super Dream 82-89

is my bike, im considering two different sprockets:

269-39 Rear Sprocket - Honda CB125 T/T2/TB (Twin) 78-82

and

269-37 Rear Sprocket - Honda CB125 RS 83-86

does anyone have any idea if these will fit or not?
is running a 37 pushing it a bit too much?

[Kickstart]

Hi

Going from a 42 to a 37 tooth one will increase the speed at the same revs from 70 to almost 80. Very much doubt the CB125TDC will pull that top speed. While a 39 tooth one would give you a theoretical speed of 75 I suspect that you would only reach that under favourable conditions.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Kickstart]

Hi

Forgot to mention, the older CB125T for which the 39 tooth sprocket is listed had a claimed 16hp rather than the 12hp for the CB125TDC, so should have been able to pull slightly higher gearing.

The CB125RS was a single. Similar ohc engine to the XL125. Quite rare.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Frost]

I'm not to botherd about hitting huge speeds, i would rather just be able to pull 60mph with < 10k rpm

are most honda rear sprockets interchangeable? i dont wana get something that doesnt fit

[Kickstart]