Widest wheels on stock forks?

M

monks_point

Scooter
Hi guys,

I discovered this forum a couple of days ago, and spent the better part of today scouring over all the great and detailed info available here- so good job every one, and many thanks for your input in advance.

I have a 07 silver bonnie with the airbox removed. I have some pretty pipes for Specialty Spares but will be changing them soon. The carbs have been jetted to specs provided by Carlos from TPUSA (thanks 1087). But before I do any other change, I want to upgrade the suspension, and I include the tires and wheels in that category. I'll tell you what I want to do, and would love feed back from you guys.

I want 18" wheels front and back. What are the widest wheels I can get for front and back without having to alter the frame and forks?
I know, this will decrease the height up front and increase it in the back, effectively leaning/tilting the bike forward. Will the change make the bike unstable?
As for shocks, I'm budgeting around $500 for both front and back. For the front, I've read going with better constant rate springs is preferable to progressive or dual rate- is this true? I ride mostly city streets and occasionally along the beautiful California coast that includes twisties- say 80% city streets/20% canyons and twisties. I'm 5'11" and 250lbs. I ride one up only.
 
Flaco

Flaco

750cc
monks_point said:
I want 18" wheels front and back. What are the widest wheels I can get for front and back without having to alter the frame and forks?
Click to expand...
The widest (wheels/rims) front are 2.5 (same as stock) or possibly 3.00...
The widest (wheels/rims) rear are 4.25...
Now, tires are a different story... They, along with different rims, do change the height and of course the width in fitment...
You might get a 120 90 18 to fit the front...
You can easily go to 160 on the rear...
I't all depends a lot on your motive, i.e. certain look, performance (gearing) and handling. Do your research on these links for configuring your set up.

http://www.avonmoto.com/download/Avon_mc_databook_2012.pdf
great reference on all aspects of size info... a must read...

http://gearingcommander.com/
compare stock to custom... it will figure your sprocket sizes...

Once you determine which rims and tires, you can adjust with lower rear shock length...

Hope this helps you...

BTW, Welcome to the forum...
 
Flaco

Flaco

750cc
strokerlmt said:
Hey Flaco...good words....and welcome also....
LMT
Click to expand...
Hey Buddy!
I'm off the chemo and have 2 mo' weeks of other med's. My "Witch Doctor" says I have done the best and the fastest recovery from stage two than anyone in his career...
Unfortunately after those three surgeries I have herniated and cannot ride for quite some time. After felling better in January, I started really wrenching and modding the Bonnie... Sorry, I can't tell you what and why...

Just teasing!

It will be a "Soft Tail Bonnie Bobber"...

I would post more often however two finger typing and working six days a week limits my time. It's raining today so I'm surfing!

Monks_Point...Sorry to go off topic...
 
T

thearcticsea

Rocker
Essentially the bike would be lowered in the front by a half inch and raised in the back by a half inch.

It's a pretty big change honestly. You may need lower shocks in the back if you notice high speed instability problems. Or a steering damper.

Personally I would leave the back at 17 and lower the front to 18 then play around with shocks and front end mods, but you know, everyone wants different things.
 
Flaco

Flaco

750cc
thearcticsea said:
Essentially the bike would be lowered in the front by a half inch and raised in the back by a half inch.

It's a pretty big change honestly. You may need lower shocks in the back if you notice high speed instability problems. Or a steering damper.

Personally I would leave the back at 17 and lower the front to 18 then play around with shocks and front end mods, but you know, everyone wants different things.
Click to expand...
Leave the 19" up front and go w/ a wide 18 if he's looking for "that look" and drop the rear shocks 10mm or so accordingly.

I went with a 4.25 rim w/ a 18" 150 70 18 to fit my new rear fender...
It's all mathematics as far as the center of gravity, gearing and handling...
My question is, why do we hear "steering damper" as a cure all quite often when there are so many different remedies to mod's that are quite effective and less expensive...
Just curious...

I wonder what his motivation is? Without knowing, we are throwing darts...

Specifics are important in diagnosis... Just ask "Click and Clack"
 
M

monks_point

Scooter
First of all...CONGRATULATIONS Flaco! That is awesome! I wish you a speedy and entirely uneventful recovery. I've seen first hand a few friends battle cancer, and I am glad to hear of your success.

Secondly, thank you guys for your suggestions. It seems you need some more info from me regarding my plans for the bonnie.

Here goes:
Some preliminaries- almost all of the mods I'm doing to the bike are for aesthetic reasons. That being said, no cosmetic reason is good enough to supersede a decrease in functionality of the bike. Honestly speaking, at moment the performance of a stock bonnie is good enough for me. If my mods lead to an increase in performance, than that's frakking awesome. However, any mod that decreases performance, is a no no.

So, ultimately the look I am after is some thing similar to what the guys at Wrench Monkees normally achieve, especially Monkee #11 and Monkee #4. I'll post links at the end of this post. So, the reason I wanted to have 18" front and back is to have the right look. However, it seems that doing that is NOT recommended by you guys, so it is no longer an option.

How would having a slimmer tire in the rear affect performance? Say I leave the front wheel at current size, and do 18" diameter, and 2.50" wide wheel, and adjust the suspension to retain the stock geometry. The bike would have less traction and more agility/flickability?
 
R

rodhotter

Scooter
3.50" up front for 120-70 radial 4.25 out back for 150-70 or 160-60 rubber. too big wheels are heavy, but a little bigger fits better radial rubber selection, they are the sizes i used on my sportster with a midglide kit in 18 diameter, a little measuring and checking will insure a problem free fitment. i like my 2012 17"mag wheel style and handling but i upgraded tires to pirelli diablo corsa radials at 710 miles on the OE metzs, put a 140-70 on the rear which is still correct for a 3.5" rim, looking forward to riding as they were just fitted last week but theres more snow comin!!!!
 
Kirkus51

Kirkus51

Hooligan
I love the general feel of my Bonnie, but noticed that the stock rear shocks were marginal so I put a set of Thrux length ZRX (?) shocks off flea bay. Night and day difference. Then I went to work on the front end and put "intimidators" in and 5 wt oil. Worked OK, but I really needed to cut down the spacers then. Now the suspension works really well.

I'm not going for a different look though. I like the look of my Bonnie... Although black rims might be a good touch.
 
2

2KLBUP

Scooter
I know this is a dead thread, but the widest symmetrical wheel that can be run on the rear of a Bonnie (and its derivatives) is 5" wide (5.5" with a slight offset), and the widest that can be used on the front is a 3.5" wheel, but that's with Honda sliders. With stock forks, the widest seems to be 3.0".
Regards-
 
Last edited:
R

rodhotter

Scooter
lacing bigger rims with new spokes is the least expensive, prolly still over $500 for parts alone, aluminum rims will help handling, your choice of colors as well xtra $$
 
2

2KLBUP

Scooter
It's actually a little cheaper (not much) to go with cast wheels if you don't mind the break from traditional spokes. (no pun intended)
Honda CBR F2 wheels from 1991-1994 fit up with very little fuss, and only a couple of new machined spacers, etc.
If you plan to sell off your complete Triumph wheels then, it's probably free.
The weight savings in using the cast wheels over the aluminium spoked wheels is 3-4lbs per wheel, and over the chromed steel ones fitted to the T100s and Standards, its a good deal more.
 
Last edited:
Roger

Roger

Street Tracker
OH FFS! Check out these assholes.

I'm looking at this thread and jumping around on the internet looking at info on wheel diameters and tire sizing. Interesting stuff and a lot to absorb. Came across this vid on bikechatforums. Can't believe how stupid this is. All you can say is more money than brains.

http://www.youtube.com/watch?v=oieXE3R-Uuw&feature=player_detailpage

Seriously? I won't comment on the make of the bikes. It just seems to go hand-in-hand with these bikes.
 
2

2KLBUP

Scooter
LOL, and the soccer sandals and shorts are a nice touch, too. Who needs a helmet for a quick jaunt over the handle bars?! These dudes make bank; SERIOUS bank! Everyone knows that rich dudes NEVER get thrown from their bikes. That's for the regular Joe who wears full kit all the time.
Tossers, the lot of 'em.
 
You must log in or register to reply here.
Top