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Old 01-19-2015, 06:03 AM   #1
PittsDriver OP
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21" Front on G650GS?

I'm looking to buy a '14 G650GS (not the Sertao) that has wire spoked wheels on it but the front is a 19". Has anyone switched this out to a 21" rim and what else was required to keep the geometry of the bike proper. I'm not finding some of the tire choices I'd like to have for the 19" to make this thing a real dirt bike.
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Old 01-19-2015, 07:56 AM   #2
markk53
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Not personally done the swap, but have some thoughts.

The 21 will slightly raise the front end if the tire is a larger diameter. Raising the fork legs in the clamps can compensate a bit if you find it is needed. I'd ride it first, starting carefully of course, to see what changed. It might slow handling a bit due to slight increase in rake and larger diameter wheel, but it may be offset by the narrower tire. So trying it out first will definitely give you some good feedback. I've done this with regular street bikes and will soon be doing some testing when I SM my 650 going to 17s.

Wish you well on the project, a good step if it suits your needs. Only reason I'm SMing the 650 is to get better tire wear and appearances. I know I could probably run road tires, but I guess vanity is getting to me. Plus I still have the 250 for dirt.
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Old 01-20-2015, 06:25 AM   #3
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When I bought my wife 05 F650GS it(same bike in every way to the G650GS) it was rigged the way you are talking about. In order to compensate, it had a modified custom made suspension link. I might still have them if you are interested in them. It leveled it out fine. We had to go back to stock because she is quite short-legged. The other problem was the shock was now too short. I have the longer shock, an Ohlins, for sale if interested. I can't get to it until early March, however.
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Old 01-20-2015, 07:40 AM   #4
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Quote:
Originally Posted by PittsDriver View Post
I'm looking to buy a '14 G650GS (not the Sertao) that has wire spoked wheels on it but the front is a 19". Has anyone switched this out to a 21" rim and what else was required to keep the geometry of the bike proper. I'm not finding some of the tire choices I'd like to have for the 19" to make this thing a real dirt bike.

Not to worry!!
I made this modification on a 2007 F650gs.
I bought a 21" wheel in the Flea Market, sent it to Woody's Wheel Works in Denver to make sure it was straight and true. I bought a brake disk and a an Anti-Lock brake ring both from E-bay, a tire and new front wheel bearings.
The only surprise was the lower front fender and the fork brace would not clear the tire. Easy fix, there is a set of spacers that are between the brace and the fork on Dakars, I'm not sure of the configuration of a Sertao. Once the spacers were installed everything fit perfectly.
I've only out a few miles on the bike since the conversion, but I have not noticed any diffrence in the bikes handleing personality.
The conversion only raises the front end 1", maybe not even that when you consider the aspect ratio of the 19" tire as conpared the aspect ratio of the 21" tire. (the measurement from the rim to the tire tread)
If the 1" height is a problem for you. Raise the fork tubes in the triple tree about a " and dial out a little sag in the back, I doubt if that will be necessary.
I keep the 19" set up just in case I'm going to take a trip with no dirt involved, but seriously, I don't think I will change back.
I'm pretty sure this modification on youe G650 will be similar.
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Old 01-20-2015, 09:31 AM   #5
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Quote:
Originally Posted by Cubdriver View Post
When I bought my wife 05 F650GS it(same bike in every way to the G650GS) it was rigged the way you are talking about. In order to compensate, it had a modified custom made suspension link. I might still have them if you are interested in them. It leveled it out fine. We had to go back to stock because she is quite short-legged. The other problem was the shock was now too short. I have the longer shock, an Ohlins, for sale if interested. I can't get to it until early March, however.

OP, Now that's something you should consider if the price is right.
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Old 01-20-2015, 04:22 PM   #6
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Thanks guys! I'm still noodling on bike choice and I might just stay with the 19" front and run the Kendas on it instead of the D606 for the trip. Those come in the sizes I'd need for the stock 19/17 inch rims.

Cubdriver, I may ping you about your rear shock. BTW, do you fly Cub? I fly a Pitts S2C.

Wes
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Old 01-20-2015, 06:12 PM   #7
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BTW, do you fly Cub? I fly a Pitts S2C.

Wes
Awesome. My friend's dad had an S2B, and we had good times in that.
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Old 01-20-2015, 07:32 PM   #8
WayneC1
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Bolt in the front wheel as stated above then fit the Dakar shock to the rear, it is longer than the GS, the only problem is the lower chain guide as the GS frames were not set up to bolt on, info on it over at f650.com
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Old 01-21-2015, 08:12 PM   #9
Cubdriver
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Quote:
Originally Posted by PittsDriver View Post
Thanks guys! I'm still noodling on bike choice and I might just stay with the 19" front and run the Kendas on it instead of the D606 for the trip. Those come in the sizes I'd need for the stock 19/17 inch rims.

Cubdriver, I may ping you about your rear shock. BTW, do you fly Cub? I fly a Pitts S2C.

Wes

Yes, Wes. I have a 74 with all the Alaska goodies on it. Skis in winter and 29 inch tires in summer. Love it. I love aerobatics, too. We should trade some time. Dick.
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Old 01-23-2015, 06:58 PM   #10
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What's wrong with the sertaos?
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Old 01-23-2015, 08:22 PM   #11
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It will never be a real dirt bike even with 21 front. I sent my front wheel to Woodys for the conversion on 07 f650gs and did not have to do anything else other than raise the front fender. I used two sets of bmw spacers and with a little bend with heat gun the fender clears very well. No problems with abs. It was a define improvement but a DR650 still will handle way better in the dirt.
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Old 01-26-2015, 05:27 PM   #12
PittsDriver OP
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Yes, Wes. I have a 74 with all the Alaska goodies on it. Skis in winter and 29 inch tires in summer. Love it. I love aerobatics, too. We should trade some time. Dick.
I've flown with Vern in Moosepass to get my ASES cert. I've been wanting to get back ever since.
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Old 01-27-2015, 03:13 AM   #13
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When I lived in Danville PA, I knew a fellow with an S2 and we did a little flying together. Then I spent time around Harrisburg and one of the nuke engineers working on cleaning up Three Mile Island had one at the airport where I flew a 180 for a jump club. Loads of fun. Very few of those kind of aircraft up here. We're less fun and more function.
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Old Today, 04:25 AM   #14
leafman60
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Why would you want a 21-inch front wheel? The 21 is narrower and slower steering on pavement. The 21 is theoretically stronger on extremely rough terrain but this would benefit primarily when riding very rough places.

The 19 handles much better on the street and many, many riders do very well with them off-road. A reasonable choice of tires are available for the 19 too.

Unless you are trying to make a dirt bike out of it, I'd stick with the 19.
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Old Today, 07:58 AM   #15
PittsDriver OP
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Originally Posted by leafman60 View Post
Why would you want a 21-inch front wheel? The 21 is narrower and slower steering on pavement. The 21 is theoretically stronger on extremely rough terrain but this would benefit primarily when riding very rough places.

The 19 handles much better on the street and many, many riders do very well with them off-road. A reasonable choice of tires are available for the 19 too.

Unless you are trying to make a dirt bike out of it, I'd stick with the 19.
I was thinking of making a TAT assault vehicle out of it with the goal of not skipping any of the most challenging sections (and possibly some more technical side loops).

I ended up with a KLR for this trip and recently tested it, fully loaded as would be the case on the TAT ride, in this terrain (would you take your 650GS here?):

https://youtu.be/kxclcgmS-k4

I'm definitely not married to the KLR for this kind of riding - it's heavy and way down on power - but it handled it just fine. I'm not sure I'd feel OK with taking a more expensive/refined 650GS on this kind of ride. I can throw that KLR down guilt free.

BTW, on this particular trip, the KLR carried me 120 miles on the slab at 80 mph and then tackled these ORV trails in the Shenandoah in constant rain and then carried me the reverse trip home. It didn't make me fall in love but it sure showed me a good time - if you can look past the innuendo in my remarks.
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