Ultra 1000 stock fat tire rubbing on right chainstay

FlatSix911

Well-Known Member
Region
USA
City
Silicon Valley
I have attached some photos to show the current

I have attached some photos to show the currents chainstay design of the frame. with 5 PSI I have good enough clearance to ride the bike.
I would love the ability to run a higher PSI for the road. I'm a little confused why they chose to have the chainstays bent in.
This does not accommodate fat tires. This clearly looks like it is designed for much skinnier tires.

Way too tight for proper clearance. Remove the rear tire and measure the distance between the chainstays.

At this point you have two choices... Send it back for another frame or run a smaller rear tire with clearance.

I would recommend calling the dealer with the measurement and see what they offer... good luck. ;)
 

Bikeyearround

New Member
What's the total inside width between the chain stays at the front of the tire?
Okay, I measured the distance between the chainstays at 4.25". This should allow a 4 inch tire with an eighth of an inch on each side for clearance. I completely deflated my tire and re-inflated it. At 10 psi my tire is 4" wide and clears the chainstays. At 15 psi my tire rubs on the right chainstay and measures just shy of 4.25 inches. For comparison I measured the front tire and it is exactly 4" at 15 psi" maybe my rear tire is defective and it is enlarging more than it should.
 

mbouck

Member
Okay, I measured the distance between the chainstays at 4.25". This should allow a 4 inch tire with an eighth of an inch on each side for clearance. I completely deflated my tire and re-inflated it. At 10 psi my tire is 4" wide and clears the chainstays. At 15 psi my tire rubs on the right chainstay and measures just shy of 4.25 inches. For comparison I measured the front tire and it is exactly 4" at 15 psi" maybe my rear tire is defective and it is enlarging more than it should.

I would say the evidence points to either your frame being tweaked around the chainstays OR the frame design you have is not designed to accommodate 4" wide fat tires. I'd talk to Roshan and maybe have him ship you a 27.5" wheelset (which handle better anyways IMHO).
 
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smorgasbord

Well-Known Member
Region
USA
Just to follow up, here are a couple photos from Biktrix's web site:

1566850846118.png



1566850862507.png


(from https://cdn.shopify.com/s/files/1/1...ggernauthdmozo7858_1024x1024.jpg?v=1566246194 and https://cdn.shopify.com/s/files/1/1144/6508/products/6_1_1024x1024.jpg?v=1566246194 )

Maybe the design has changed?
 

Bikeyearround

New Member
I have attached some photos to show the current

I have attached some photos to show the currents chainstay design of the frame. with 5 PSI I have good enough clearance to ride the bike. I would love the ability to run a higher PSI for the road. I'm a little confused why they chose to have the chainstays bent in. This does not accommodate fat tires. This clearly looks like it is designed for much skinnier tires.
Roshan said he would either send me a new bike frame when they get their next shipment in a few weeks and have my local bike shop swap all the components or send me the 27.5x3 wheels that will fit my frame. This is the kind of support that makes Biktrix stand out and why I purchased from Biktrix and didn't buy through Alibaba.
 

Bikeyearround

New Member