650b's on a 26er

sideboob spoogepants

Finally got the Crossrocs and they fit the Norco beautifully...

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JMcP92

Have you fully compressed the suspension to make sure it doesn't touch anywhere?

Also, prepare for comments about "but the geometry" and "it wasn't designed for those" etc. however, I'm quite sure you considered this before-hand, and I don't much care, so long as it works with the suspension, power to you!

97th choice

Did you fit a new fork?

sideboob spoogepants

Hi guys.

Yeah i checked all clearances; chainstay crossmember has about 16mm clearance, seatstay crossmember has 10mm, bb height has gone up 1/2" from 13 1/4" to 13 3/4" (i still feel in the bike rather than on it) and there are no problems with suspension travel when fully compressed.

Fox fork is a 26er model but takes the wheel easily with about 13mm clearance between the tyre and the crown.

Bike rumour did this in 2012 with a size small Norco Sight, but i seem to have more clearance at the back wheel than they got, dunno why, maybe cos my bike is a large (19").


http://www.bikerumor.com/2012/06/15/650 ... converted/

rockmonkeysc

Why?

sideboob spoogepants

@Rockmonkey

"Why?"

When i bought my bike in June i was very aware of the wheel size malarky and wondered if there was a bike that could safely accept both 26" and 27" wheels. I did some homework and settled on the Norco. Essentially i have 3 bikes in one, i can whack my 26's in for fun at the jumps, steps etc, or fit the 27's for japes at the trails. I can also go the 'Liteville' route and stick a 26" on the back with a 27" on the front.

Also, if i want to buy a 650b frame in the future, i only have to buy the 650b fork, swap everything else over and i have a proper 650b specific bike.

I can't afford to buy a whole new bike now or in the near future, so bit by bit is the way for me to go.

riche0

Have you taken it out yet?

Wondered if you get mud clagged up around the fork etc as there's less clearance?

declan1

Do you actually sit on that saddle? :shock:

97th choice

Out of interest what is your overall wheel diameter?

sideboob spoogepants

@Riche0.

Yep took it out at the w/end, no probs with crown claggage and it was proper boggy.

@declan1

I only have it that high when i'm commuting to work or if i have to ride more than a couple of miles on tarmac (i have long legs and arms).

@97th choice

With the Crossroc UST tyres it measures 27.3", with Schwalbe Rocket Rons it's 27.1".

declan1

sideboob spoogepants wrote:

@Riche0.

Yep took it out at the w/end, no probs with crown claggage and it was proper boggy.

@declan1

I only have it that high when i'm commuting to work or if i have to ride more than a couple of miles on tarmac (i have long legs and arms).

@97th choice

With the Crossroc UST tyres it measures 27.3", with Schwalbe Rocket Rons it's 27.1".

I'm not talking about the height - I'm talking about the angle of it! That looks like it would be incredibly painful if you would actually stay on it!

mattv

Geometry should be exactly the same as 26" surely? Its like sticking a piece of half inch wood under the front and back wheels. The dropouts are in the same places. It'll just feel like running a heavy 26" tyre, surely? Gives you an indication if 650b is worth the hassle.

sideboob spoogepants

Sorry Declan, i misunderstood. The seat is at it's furthest back to help with my gibbon like arms, with the seat being in that position angle adjust isn't as good, it's also more comfortable for my (ahem!) undercarriage.

@mattv

Yeah, geometry is the same.

declan1

sideboob spoogepants wrote:

Sorry Declan, i misunderstood. The seat is at it's furthest back to help with my gibbon like arms, with the seat being in that position angle adjust isn't as good, it's also more comfortable for my (ahem!) undercarriage.

@mattv

Yeah, geometry is the same.

I suppose if it's comfortable for you :P

rockmonkeysc

My 26" Rubber Queens are bigger than your 650b tyres!
I would guess it should work fine and probably make feck all difference.

97th choice

RockmonkeySC wrote:

My 26" Rubber Queens are bigger than your 650b tyres!
I would guess it should work fine and probably make feck all difference.

It's about 3/4" bigger than my 26" with Hans dampfs.

rockmonkeysc

Really? My Rubber Queens measure just a touch under 27.5?

97th choice

Unless my tape is wrong it's def less than 27"

Twelly

Rubber Queens are massive (heightwise). My mate has them on his 26" and has feck all mud clearance because of it.

97th choice

The HD's are massively wide mind you

lawman

Why not just buy a sight killer b? :? Seems an odd choice, you get some of the benefits of 650b that are counteracted by the geometry being way off, the BB will be too high and using 2.0x650b tyres instead of 2.35x26 just seems silly, you'll be making marginal gains at best. If you're gonna go 650b, go the whole hog and not some frankenbike conversion.

The Rookie

The geometry isn't way off though is it, as pointed out above (you could try reading it) it will be exactly the same, yes the BB will be higher by a whole 1/2" (wow) for the same height tyre, and is lower than if it were on 26" tall tyres like RQ or HD's.

njee20

And it'll be a whole lot lighter with 27.5x2" tyres than some big heavy 26" ones. Horses for courses.

lawman

The Rookie wrote:

The geometry isn't way off though is it, as pointed out above (you could try reading it) it will be exactly the same, yes the BB will be higher by a whole 1/2" (wow) for the same height tyre, and is lower than if it were on 26" tall tyres like RQ or HD's.

Half an inch added to the BB height is a big difference though, and running a bike like a sight with 2.0 tyres seems to go against the kind if riding it was designed for. On an XC bike I can understand, but when you have a bike that begs to be ridden hard like the sight the higher volume 26" tyre makes a lot more sense than a smaller volume 650b. IMO running tyres that small kind of limits the bike, I certainly wouldn't want to ride some of the stuff I do on the HD with 2.0 tyres, I'd destroy rims in no time!!

sideboob spoogepants

@Lawman.

The bike is running 2.2" tyres with plenty of clearance, BBheight is +1/2" and makes near to no difference. Angles are the same.

Its the same bike, with wheels that are slightly bigger, that's all.

rockmonkeysc

But you could have got the same overall diameter using different tyres which would have saved a couple hundred quid and give a much better tyre volume.
Why not just buy a 650b bike to start with?

lawman

sideboob spoogepants wrote:

@Lawman.

The bike is running 2.2" tyres with plenty of clearance, BBheight is +1/2" and makes near to no difference. Angles are the same.

Its the same bike, with wheels that are slightly bigger, that's all.

As I said before, half an inch of added BB height will make a difference, potentially a big one. It may not sound like much, but it will definitely effect how stable the bike feels, you may have a touch more pedal clearance but overall the bike will probably not handle as well. Personal preference but adding half an inch to the BB height is the last thing I would want to do. As Rockmonkey says as well, why not go 650b in the first place? Presuming your sight is a 2013 model, why not get the Sight killer b that was designed around 650b?

sideboob spoogepants

"Why not just buy a 650b bike to start with?"

Because i wanted a 26er that could take 650b's not the other way round.

I thought i alluded to this in previous posts. :roll:

lawman

sideboob spoogepants wrote:

"Why not just buy a 650b bike to start with?"

Because i wanted a 26er that could take 650b's not the other way round.

I thought i alluded to this in previous posts. :roll:

I read your reasoning, but personally I don't get it. The way I see it, having had a brief go on a few 650b bikes is that 650b feels near as makes little difference the same as a 26" bike, they handle very similarly but the 650b has an edge over the rough stuff and perhaps a tad more grip. In your case, the bike may be slightly compromised when in 650b mode. Had you gone with the 650b sight, you would end up with a compromise in 26" mode. If you plan to spend to most of the time on 650b, and throw the 26's on every now and then for jumping, perhaps going all in with 650b from the start might have been better, especially as you say you may upgrade to a 65ob frame in future. Each to their own and all I guess

njee20

Why would it be compromised? There will be 26" bikes with higher BBs, as said, if he'd put big tyres on it would have had a more marked effect. That would also have added weight and made the bike feel different.

Talk about a sucker for marketing! Sure it's nothing that can't be sorted with an angleset and some offset bushes :roll:

lawman

Compromised as in you'd end up with a taller bb with like for like tyres or have to downsize tyres to make them fit in the frame. The sight's bb is pretty low to start with, but even so if putting 650b wheels on adds half an inch to the bb height, you end up with a bb height of near enough 14", which imo is too high.

The Sight Killer B has a lower bb, and the chainstays are 2mm longer than the 26" bike. A bike designed around 26" is not going to handle as well if you simply chuck 650b's on it, as you say you can get around it with offset bushings or different dropouts, like those used by Banshee and Intense, but I see little point in going 650b if you can't take full advantage of it with comparable size tyres and corrected geometry.

I could chuck 650b's on my Mojo but the bb would be too high and I wouldn't be able to fit much more than a 2.1" tyre, at which point I'm back where I started but several hundred quid worse of. If you're going to jump on a wheelsize, go the whole hog if you can imo.