Front wheel swap.
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Tourer
Joined: Aug 2013
Posts: 287
Likes: 14
From: Georgia
Front wheel swap.
When moving from a 21" wheel to a 19" or smaller, does it change the geometry of the bike at all? I imagine since the bike was initially set up for a 21", it has to affect something in the stance, handling, etc.
I've got a '13 Blackline, and I really want some bigger rubber up front. Ideally, I'd like to stick with a 21", but I haven't seen many in that size with larger widths. Not looking for Fat Bob size tires, but something in between would be nice.
I've got a '13 Blackline, and I really want some bigger rubber up front. Ideally, I'd like to stick with a 21", but I haven't seen many in that size with larger widths. Not looking for Fat Bob size tires, but something in between would be nice.
Stellar HDF Member
Joined: Feb 2011
Posts: 3,048
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From: Central Jersey
i'd assume it effects the stance..you're taking 2" of diameter away from the front wheel, which is going to drop the nose down. Not sure if you can compensate for that with thicker walled tires, short of putting Fat Bob tires on it
Stellar HDF Member
Joined: Aug 2012
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From: Indiana, USA
the only way to know is to calculate using rim diameter and aspect ratio. I am not sure about motorcycle tires but for car tires the aspect ratio is a percentage of the width. so 100-90 would suggest 90% of the 100 mm wide or 90mm of sidewall times 2 plus the rim diameter.
Road Warrior
Joined: Nov 2011
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From: Australia
Last edited by S.D.M.F; Aug 28, 2014 at 07:11 AM.
Tourer
Joined: May 2014
Posts: 373
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From: WI
I'm confused. A 21 diameter can be a narrow width or a large width. Wheel size really has nothing to do with it in regards to rubber on the road. But I get there aren't many width choices in a 21 diameter wheel. To your question Yes a smaller diameter wheel will obviously lower the front end of the bike.
Grand HDF Member
Joined: May 2008
Posts: 4,624
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From: Newcastle, Ca.
Lowering 1" in front will make the bike want to turn quicker, less stable feeling. And during heavy breaking the rear tire unloads faster, less rear breaking. To compensate you could lower the back 1". But loosing ground clearance becomes another issue.
I would not consider a 120 width narrow. They just look narrow on a 21" rim.
I would not consider a 120 width narrow. They just look narrow on a 21" rim.
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Stellar HDF Member
Joined: Mar 2012
Posts: 2,017
Likes: 599
From: Columbus, OH
Front tire diameter has a large effect on your trail number. Trail is figured by the right triangle that is formed by taking the center line of the neck bearings and the center line of the front axle at a right angle and extending them to the ground. Because the center line of the neck bearings is so long a few degrees of change can result in a change of a couple inches in trail. Take the numbers of the tire sizes and plug them into this calculator
https://www.rbracing-rsr.com/rakeandtrail.html
Here is one for tire size
https://www.rbracing-rsr.com/tirediamcalc.html
https://www.rbracing-rsr.com/rakeandtrail.html
Here is one for tire size
https://www.rbracing-rsr.com/tirediamcalc.html
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Former Sponsor
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Get a 21x3.25 or 21x3.5 with a 120 tire. That way your overall diameter will extremely close to what it is now. Not sure if the front fender will fit with the wider tire and wheel. the 19 will sit slightly lower, probably about 1/2" to 3/4".
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