Topic: 17 front and rear on 77K.

[dunc]

Hello all.

I'm working on building a bike piece by piece and was looking at doing a 17inch front and rear spoked wheel.
The initial reasoning here is slightly wider wheels and more sport rubber options. Plus the equal front and rear look much better.
I know that it's popular to run an 18inch front and 17inch rear for quicker turn in.

The 17 would be even more quicker and possibly too little trail on the front with the stock triple tree offset ?
This is on stock forks rebuilt with racetech internals.

Is there a way to make 17's on the front work well without going to a shorter triple tree offest (ie modern front end).
For instance - slightly longer cal fab swing arm and or slightly taller rear shocks?

Open to advice and opinions. The goal here is to make an OEM+ build with better handling fitting wider stickier rubber.

thanks.

[MRieck]

 I have 18" rims on both ends for years. Has worked great. Problem with 17" rubber is the tires are very large. You don't need a 170/180 on the rear of a CB750. It eats up what little power the engine puts out.

[dunc]

I have 18" rims on both ends for years. Has worked great. Problem with 17" rubber is the tires are very large. You don't need a 170/180 on the rear of a CB750. It eats up what little power the engine puts out.

True - I wouldn't be running larger than a 160 in the rear.

[gschuld]

I think you'll find that an 18/18 wheel combo will suit you well.  Most 17/17 wheel sets I have seen on cb750s don't seem to look right, but just IMHO.

3.5x18 rear rims work well with 130/140 series tires.  4.25x18 rims work well with 150 series tires.  At that point you are needing a wider swingarm to clear the tire.  180 series tire on a 5.5x18 rim is possible, but again need even more swingarm width and offset sprockets.  Anything beyond a 150 tire starts to look rather overboard unless you are into the chopper thing.  Actual real world performance peaks at about a 130 series rear tire on a 3.5×18 rim, assuming a full high performance setup (engine, chassis).  On a stock or near stock bike, good quality rubber on factory wheels is hard to improve on performance wise.

For the front, A 2.15 or 2.5x18 front rim with a 110/18 tire works well.  Avon Roadriders and Bridgestone BT45 tires are well respected tires in this range, among others.

George

[seanbarney41]

I would think with 2 17's you will have lost enough ground clearance that you will never realize the benefit of wider modern rubber

[MessnerMoto]

I run 3.5x18 at the front and 4.5x18 at the back, wire wheels. Tires 120/70zr18 and 170/60zr18. But this was a lot of work to make it work.
And bike still looks proportional with this tires.

[turboguzzi]

there is so much choice of quality 18" rubber these days that's it's hard to see this as a reason.
maybe a few years ago it was justified, not now IMHO....

[simon#42]

And they look crap with 17 inch wheely

[dunc]

Alright lads the jury has spoken.

Will be going with 18's front and rear and not too wide either.

[gschuld]

Remember, it’s your bike and we are just opinionated fools.

If you are sticking with a factory cb750 front end, you will be limited to tire width at the sliders.  Basically, a 110 series tire on a 2.5x18 is about the limit.  On a factory rear swingarm, 130/140 series tires on a 3.5x18 is around the limit.  Conveniently, any more tire than this is generally considered a hinderance to performance, unless you are drag racing or something.  So beyond this size, it’s more of a personal aesthetic thing, which is just fine...

George

[turboguzzi]

just enter your numbers here, tick "refine your research" - "supersports" and youll get a really long list...

https://www.tyres-pneus-online.co.uk/motorcycle-tyre.html

[dunc]

Remember, it’s your bike and we are just opinionated fools.

If you are sticking with a factory cb750 front end, you will be limited to tire width at the sliders.  Basically, a 110 series tire on a 2.5x18 is about the limit.  On a factory rear swingarm, 130/140 series tires on a 3.5x18 is around the limit.  Conveniently, any more tire than this is generally considered a hinderance to performance, unless you are drag racing or something.  So beyond this size, it’s more of a personal aesthetic thing, which is just fine...

George

Thanks for the words George. Opinionated is good!

The outlook or goal here is performance first and aesthetic is derived from that.

So just to be clear the most I can fit on the front with Stock forks is a 110?

I don't want to over rubber the chassis so the 3.5 x 18 rear with a 130 / 140 sounds good and a 2.5x18 on the front.

[simon#42]

Remember, it’s your bike and we are just opinionated fools.

If you are sticking with a factory cb750 front end, you will be limited to tire width at the sliders.  Basically, a 110 series tire on a 2.5x18 is about the limit.  On a factory rear swingarm, 130/140 series tires on a 3.5x18 is around the limit.  Conveniently, any more tire than this is generally considered a hinderance to performance, unless you are drag racing or something.  So beyond this size, it’s more of a personal aesthetic thing, which is just fine...

George

Thanks for the words George. Opinionated is good!

The outlook or goal here is performance first and aesthetic is derived from that.

So just to be clear the most I can fit on the front with Stock forks is a 110?

I don't want to over rubber the chassis so the 3.5 x 18 rear with a 130 / 140 sounds good and a 2.5x18 on the front.

good choice of rims but i would go for a 90 or 100 on that front rim . i use a 90 continental classic attack on a 2.5 rim and it works very well . the larger tyres pinch in on the rim and you cant use all of the rubber .

[turboguzzi]

+1, the conti 110 front really need a 3" rim to work well.
oddly enough their 130 rear works fine on a 3" rim.
but even if you stay with stock width rims there's plenty of choice, Avons, Bt54 & BT45, Dunlop Alpha

[Don R]

 Sometimes the reality of it makes it seem as though we're picking on a guy. Most of us have learned about these bikes either the hard way ourselves or observing someone else's difficult lesson. I hope you get the result you want.

[Yamahawk]

+1 on the Continental Classic Attack CR race tires. a 100/90-18 on the front, and IF you have a 2.5" or 3" rim on the back, the 110/80-18 will handle like a race bike should. Don't fit a 110 up front unless you have at least a 2.5" wide rim, it will pinch and not handle well. Our bikes are a little heavier than most bikes today with narrow rims, so if you are lacing up new 18" rims, go for the 2.5" front and the 3" rear. Your choice of good 18" tires will increase then. I run the Conti CR's on my RD350 race bike, and I run a 100/90-18 on the front and rear, using stock rim size of 1.85" front and 2.15" rear. I was tempted to put on the 110/80-18 rear, but on advice from THR's Buff Harsh and Ari Henning, they say it is too wide for my rim size, and recommend at LEAST the 2.5" rim with the 3" being optimal. If you stick with these sizes and rims, your bike will not have too much unsprung weight, and handle better than your ground clearance will allow you to lean. Get your suspension sorted, and then take it out for a track day and have some fun!! JMHO...
Charlie

[Henkies]

So considering I'm about to buy new rims, probably 2.5 front and 3.0 rear, I can conclude from this topic that optimum performance would be 100/90-18 for the front and 110/80-18 for the rear?

Setup is 836 cc with ported head and bigger carbs. Stock fork upgraded.

[slikwilli420]

18 front and rear as stated. 2.5 front and 3.0 rear. There are great tire options out there for those sizes. I just picked up some gorgeous Borrani wheels for my racer from another racer. A little over 500 shipped from Italy drilled and ready to go.

[PeWe]

I have 18" rims on both ends for years. Has worked great. Problem with 17" rubber is the tires are very large. You don't need a 170/180 on the rear of a CB750. It eats up what little power the engine puts out.

Not a race bike, but "moped" sized tires can work fine anyway
Stock rims and stock tire sizes works fine on my street bike with additional fun on country roads. Rear tire should be as wide as possible back in early 80's. 130 rear went flat rather quick with bad handling as a result. I noticed same with 120/90-18
Last summer slimmer tire, 4.0-18 rear despite around 90 rwhp. 4-4 exhaust.
Bike handles better than ever! 
Let's see how the skinny rubber will like a more power releasing exhaust (4-2-1) to reach closer to 100rwhp

[Ilja]

I had 17" CBR wheels but switched back to spoke wheels now which are 18x2.5 in front and 17x4.5 in the back. In the back I'm just using a bit higher tire to get the classic look... its only a 150 but looks fat enough.

I found that the 17" front rims look too small for the rest of the bikes design..

I also found that good 18" front tires are widely available at reasonable prices, but 18" rear sports tires are really pricy (180 euros vs 100-110 euro for a 17incher).

So for me 18 / 17 is perfect. :-) 

The front is an unstamped "borrani" WM4 which was actually quite cheap on ebay Italy.. Had to re-align the spoke holes a bit..

[dragracer]

Where did you find the rear??




(quote author=Ilja link=topic=169661.msg1984985#msg1984985 date=1519157031]
I had 17" CBR wheels but switched back to spoke wheels now which are 18x2.5 in front and 17x4.5 in the back. In the back I'm just using a bit higher tire to get the classic look... its only a 150 but looks fat enough.

I found that the 17" front rims look too small for the rest of the bikes design..

I also found that good 18" front tires are widely available at reasonable prices, but 18" rear sports tires are really pricy (180 euros vs 100-110 euro for a 17incher).

So for me 18 / 17 is perfect. :-) 

The front is an unstamped "borrani" WM4 which was actually quite cheap on ebay Italy.. Had to re-align the spoke holes a bit..

[/quote]

[Yamahawk]

If you are going to run a mag, the CBR1000 Hurricane has a nice 4"x17" rear, with a good disc brake. It shouldn't be too hard to mount that, it has the 3 spoke mag design, but it isn't a spoke rim. There are 18" fronts back then, from Suzuki, I believe, that have the 3 spoke design to match also. Always fun mixing up rims and adapting them to the forks and swing arm!
If you are lacing up a spoke hub, there are a lot of options there too. 2.5"x18" front and 4"x17" rear rear would make a nice combo. A 150/70-17 or 140/70-17 rear will fit that rim well!
I'm working on a 1987 CBR600 Hurricane right now for a girl, and she has a Shinko Podium 150/70-17 on her rear 3.5" rim, seems a little pinched, but not badly... she wore out the wheel bearings, doing hole shots and drag racing up at Milan Dragway in Michigan last year. The rotors are shot, and the chain too.. gotta teach her proper maintenance for her bike, can't just ride it into the ground... master link clip was backwards too.
Charlie

[Ilja]

Where did you find the rear??




(quote author=Ilja link=topic=169661.msg1984985#msg1984985 date=1519157031]
I had 17" CBR wheels but switched back to spoke wheels now which are 18x2.5 in front and 17x4.5 in the back. In the back I'm just using a bit higher tire to get the classic look... its only a 150 but looks fat enough.

I found that the 17" front rims look too small for the rest of the bikes design..

I also found that good 18" front tires are widely available at reasonable prices, but 18" rear sports tires are really pricy (180 euros vs 100-110 euro for a 17incher).

So for me 18 / 17 is perfect. :-) 

The front is an unstamped "borrani" WM4 which was actually quite cheap on ebay Italy.. Had to re-align the spoke holes a bit..

[/quote]

Its a standard harley rim... 17x4.00 if I remember correctly.