Sprockets and chains

Stratman · Post by **Stratman** » Tue May 17, 2005 10:24 am

I know there have been posts on this topic before but I can't locate them.

I want to change sprckets and chain now, but would prefer a larger rear sporcket rather than a 15T front as it is easier on the chain I believe.

What size rear to give the same effect with a 16T front please? Any prefernce re makes and what % does it reduce the gearing so I can have the speedo re calibrated?

Just done 900 miles over a long weekend in Belgium/France with my new Kappa hard luggage, which actually looks quite good I think! Can get the whole wingrack assembly off in 20-30 mins as well, which is handy.

Have a look:-

http://www.paul-barnard.com/page6.html

Bink · Post by **Bink** » Tue May 17, 2005 1:39 pm

Hi Stratman,
The rule is 1 down at the front = 3 up on the rear

Here are the ratios (e.g. 16/42 = .381)

Ratio Front Rear
0.357 15 42
0.381 16 42 (standard)
0.372 16 43
0.364 16 44
0.356 16 45

Stratman · Post by **Stratman** » Tue May 17, 2005 2:30 pm

Now, that's what I call an answer!]

Thanks. Ithought the 15T took the gearing down by about 7% which your ratios show. Either a 44 or 45T rear then I think.

Bink · Post by **Bink** » Tue May 17, 2005 3:35 pm

To be exact ... (sorry the columns go out of format a bit when posted)

Percentage Ratio Front Rear
94% 0.357 15 42
100% 0.381 16 42
98% 0.372 16 43
95% 0.364 16 44
93% 0.356 16 45
91% 0.348 16 46

mik_str · Post by **mik_str** » Tue May 17, 2005 4:21 pm

the stock gearing is 16/41 (not 42). Going from a 16 to a 15 in the front drops the ratio by about 6%. Going up two in the rear is about 5%, adding three is about 7.5%. You decide how close you want to get.

Also, not to start an argument, but given that the front/rear combos vary so much, there can be no "general rule" in so far as changing front vs changing rear is concerned. Besides, using a calculator to figure it out is really quite simple.

cheers

Bink · Post by **Bink** » Tue May 17, 2005 5:00 pm

Do'H! thx Mik!

Post by **sirch345** » Tue May 17, 2005 9:15 pm

Hi Stratman,
Looks like you had plenty of space with that Kappa hard luggage set up. I take it you didn't carry a pillion passenger so how did the bike handle?
You are right about the smaller front sprocket putting more strain on the chain, also that move would slow the steering down because you would be lengthing the wheel base to take the extra slack up in the chain created by the smaller front sprocket, if I decided to gear it down myself I would go for the bigger rear as yourself.
Chris.

mik_str · Post by **mik_str** » Wed May 18, 2005 12:51 am

I personally just went from a 41 to a 43 on the rear sprocket and love the change. The shortened wheelbase (using stock chain), together with some slight chassis changes (adding 4.5mm shim to rear, raising forks 6mm) really made a difference in the way the bike handles.

I hope this helps.

Post by **sirch345** » Wed May 18, 2005 9:30 am

mik_str wrote
I personally just went from a 41 to a 43 on the rear sprocket and love the change

Thats the set up i'd go for if I were going to change ratio's, not to drastic,
Chris.

Stratman · Post by **Stratman** » Thu May 19, 2005 1:14 pm

Never considered the wheelbase question - already have forks raised 8 mms so may need to reduce that if she gets a bit slappy. I'm going for 43T option I think.

Hi Chris, yes, plenty of space with the hard luggage and just went by myself. Put most stuff in the panniers to keep the weight low etc. To be honest no discernable handling difference, but a great difference when parking up in quiet little French towns - lock it all away in the top box and walk around without having to carry everything!

Post by **sirch345** » Thu May 19, 2005 3:08 pm

Hi Paul,
Thats reasuring to hear the luggage set up you have didn't affect the bikes handling. The reason I asked was I went to the I.O.M. TT races many years ago on a Suzuki GS1000 fitted with a luggage rack, which when loaded up (as yourself carring no passenger) affected the handling something rotten, so I took my luggage off the rack and bungeed it to the seat right behind me which solved the problem.

Yeah I know what you mean by not having to carry your kit around with you, makes it just that little bit more enjoyable!

Lets us know how the bigger rear sprocket affects the performance and fuel consumption, i'm thinking it will probably use more fuel, which wouldn't be so good for touring (with the small capacity tank) but then again it may not if you are using top gear more often.
I bet the extra umph will be good though!!!!!!

cheers Chris.

Scott Malcolm · Post by **Scott Malcolm** » Fri Jun 03, 2005 2:46 pm

I just ordered a 15/43 combo. I'll let ya know how it goes. I'm hopin' the front wheel will come up a little easier in 2nd.

Scott

Post by **sirch345** » Fri Jun 03, 2005 2:53 pm

I should think you'd have a job to keep the front wheel down