Increasing travel? Can I do it?

[ThePubSA]

LOL @ REBA ... AGAIN!!!!

I think we need a REBA POGO jump off battle

[Hairy]

I rode this bike as a SS for sometime while my duallie warrantee issues were being sorted out (3 months)

 

The frame is a old Giant Sedona steel framed bike and came with a rigid steel fork... frame got resprayed stealth black to make her faster.

 

This would not do, so she got the 140mm fox on the front and I must say that the bike in this build was really really fun to ride and was a blast riding at Tokai.

 

Now I am not condoning what you are wanting to do, especially not for an Aluminium frame.

Edited June 1, 2012 by Hairy

[gummibear]

Now I am not condoning what you are wanting to do, especially not for an Aluminium frame.

 

The Bianchi is a carbon frame.

[Ysterperd]

Would advise against increasing travel. Doing it would change the geomertry and the way the bike handles and would void any warranty which you may have. from what i gather it would also be overkill for what you use the bike for.

 

From Bianci's website it seems that most of their hardtail bikes comes out with 100mm travel. If you need some expert advice phone Ruan Deysel @ Spokeworks who will be able to give you a more informed opinion.

[El Dodgius Bastardo]

I think we need a REBA POGO jump off battle

 

vs

[Iwan Kemp]

I wouldn't. You can, but I wouldn't. Like most have said increasing travel by that much will have a big effect on the bike's geometry and therefor handling

It will:

1. Raise your bottom bracket (better pedal clearance through rough stuff, not as planted around corners, berms and switchbacks)
   
2. Slacken your bike's head angle ( nice for the steep stuff, but front wheel will wonder and climbing will be a b!tch)
   
3. Increase wheelbase
   
4. Raise the front end of your bike pushing your weight and balance further back
   
5. Slacken seat tube angle pushing your weight even further back
   

Chances are the Head Tube, along with TT and DT joints, weren't designed with the sort of tolerances in mind a fork with that much travel will put on it. If you increase travel no more than 120mm (not all Reba's can go 120mm - model year dependand) and think long and hard what it is you're really after.

[ThePubSA]

vs

 

No No its

[Hairy]

The Bianchi is a carbon frame.

 

Even scarier then!!!!!!!

[Big H*]

I wouldn't. You can, but I wouldn't. Like most have said increasing travel by that much will have a big effect on the bike's geometry and therefor handling

It will:

1. Raise your bottom bracket (better pedal clearance through rough stuff, not as planted around corners, berms and switchbacks)
   
2. Slacken your bike's head angle ( nice for the steep stuff, but front wheel will wonder and climbing will be a b!tch)
   
3. Increase wheelbase
   
4. Raise the front end of your bike pushing your weight and balance further back
   
5. Slacken seat tube angle pushing your weight even further back
   

Chances are the Head Tube, along with TT and DT joints, weren't designed with the sort of tolerances in mind a fork with that much travel will put on it. If you increase travel no more than 120mm (not all Reba's can go 120mm - model year dependand) and think long and hard what it is you're really after.

 

Any evidence of such failures and will an amateur rookie notice the bike handling differently?

[jugheaddave]

I changed my reba from 100 to 120 on my anthemx. very happy nice and plush.

[eraser]

'Highjack On''

 

Anyone know whether a Fox F29 100mm can be extended to 120mm?

 

'Highjack Off'

[Iwan Kemp]

Any evidence of such failures and will an amateur rookie notice the bike handling differently?

 

Yes and yes. Most people notice something funny or don't feel confident or call it something else, but doesn't know why that is. A rookie won't know it's a BB that's too high or, or, or...but they will feel something.

[Big H*]

Yes and yes. Most people notice something funny or don't feel confident or call it something else, but doesn't know why that is. A rookie won't know it's a BB that's too high or, or, or...but they will feel something.

 

Would there then be a warning on the bike or in the manual NOT to increase the travel of a 100mm fork to 120mm if the fork allows that? If it was that dangerous surely the litigation mad world would have shown it verrrry clearly?

 

Whe we got our MTB Tandem it had a very low range and crappy fork with springs and polymer balls. We upgraded to a Marzocchi Bomber. Were will I find out for what size fork our frame was designed for? Our frmae is a generic frame made by Genesis and could be purchased by anybody fitted with any fork. Does the lower rnage manufacturers who also buy "generic" Taiwanese frames really care what type of fork they fit or am I underestimating R&D?

 

Will the head tube angles stay the same for a small frame as a xtra large frame. Will the axle to axle dimensions not change causing difference handling characteristics.

Edited June 9, 2012 by eccentric1

[Iwan Kemp]

Would there then be a warning on the bike or in the manual NOT to increase the travel of a 100mm fork to 120mm if the fork allows that? If it was that dangerous surely the litigation mad world would have shown it verrrry clearly?

Don't know about ALL of them, but most I've seen says not to fit a fork with travel longer than the std spec. It's usually on the warranty card, owner's manual or on their website. Our CPA requires it to be stated CLEARLY, but someone will need to sue a manufacturer or shop before that'll happen.

 

Morewood for instance has this info on their website under each bike. Giant has a sticker on the bike saying that you are not allowed or shouldn't ride the bike before working your way through their manual.

 

Whe we got our MTB Tandem it had a very low range and crappy fork with springs and polymer balls. We upgraded to a Marzocchi Bomber. Were will I find out for what size fork our frame was designed for? Our frmae is a generic frame made by Genesis and could be purchased by anybody fitted with any fork. Does the lower rnage manufacturers who also buy "generic" Taiwanese frames really care what type of fork they fit or am I underestimating R&D?

I'd imagine it will be on the manufacturers website. Not sure. You have to bear in mind that the assumption on the manufacturers part is that if you fit a fork with longer travel it is to do more technical or rougher. In other words, ride the bike harder. Stuff a 100mm frame (for example) was not designed to cope with. Also the angle forces are exerted on the frame change when changing the head angle. I've seen a Shova's (tough as a tank!) head tube sheer off cause the guy was running a 170mm fork on a frame designed to take a 140mm and then bomb it down DH / FR tracks.

 

Going with more travel does however by no means guarantee your bike will snap in half. Has to do with how you ride. You can ride most bikes over, under and through pretty big stuff as long as you're smooth. But going from 100mm to 140mm will be a step too far. 20mm increase should be fine for most frames and bikes unless designed otherwise from the off.

 

Will the head tube angles stay the same for a small frame as a xtra large frame. Will the axle to axle dimensions not change causing difference handling characteristics.

Some differ 0.5 between small and extra large. Or even small and medium and then stays the same through the size curve. Most manufacturers however have a consistent HT Angle in a model range. It will be too expensive to model, R&D every size in every model for the optimal geometry. Larger bikes have a longer wheelbase (as well as top tube - vital for fit, seat tube and sometimes longer heat tube as well) which does influence handling when compared to one with a shorter wheelbase. But keeping the angles the same there's no other way to go than o increase wheelbase. The only way to go bigger and keep the same wheelbase will be to shorten the chain stays based on size. But this will cost us a fortune as they will have to design, test and mold a specific rear tri-angle for every size bike in their range.

[Big H*]

Don't know about ALL of them, but most I've seen says not to fit a fork with travel longer than the std spec. It's usually on the warranty card, owner's manual or on their website. Our CPA requires it to be stated CLEARLY, but someone will need to sue a manufacturer or shop before that'll happen.

 

Morewood for instance has this info on their website under each bike. Giant has a sticker on the bike saying that you are not allowed or shouldn't ride the bike before working your way through their manual.

 

 

I'd imagine it will be on the manufacturers website. Not sure. You have to bear in mind that the assumption on the manufacturers part is that if you fit a fork with longer travel it is to do more technical or rougher. In other words, ride the bike harder. Stuff a 100mm frame (for example) was not designed to cope with. Also the angle forces are exerted on the frame change when changing the head angle. I've seen a Shova's (tough as a tank!) head tube sheer off cause the guy was running a 170mm fork on a frame designed to take a 140mm and then bomb it down DH / FR tracks.

 

Going with more travel does however by no means guarantee your bike will snap in half. Has to do with how you ride. You can ride most bikes over, under and through pretty big stuff as long as you're smooth. But going from 100mm to 140mm will be a step too far. 20mm increase should be fine for most frames and bikes unless designed otherwise from the off.

 

 

Some differ 0.5 between small and extra large. Or even small and medium and then stays the same through the size curve. Most manufacturers however have a consistent HT Angle in a model range. It will be too expensive to model, R&D every size in every model for the optimal geometry. Larger bikes have a longer wheelbase (as well as top tube - vital for fit, seat tube and sometimes longer heat tube as well) which does influence handling when compared to one with a shorter wheelbase. But keeping the angles the same there's no other way to go than o increase wheelbase. The only way to go bigger and keep the same wheelbase will be to shorten the chain stays based on size. But this will cost us a fortune as they will have to design, test and mold a specific rear tri-angle for every size bike in their range.

 

Had to go through the same tortuous mind wrenching when we fitted the 180mm rotors to our MTB tandem. Some on overseas website say yay and others say nay. Christo Timm also base it on the way you ride. EM and myself are old and we really cannot climb uber high mountains on rough jeeptracks and then hurtle down the other side reaching mind freezing speeds. We are sedate and slow MTB riders. I assume we will be safe. The headtube is fairly well reinforced with gussets and I check for deformations or cracks regularly.

 

What is more important for me on the fork though is having a steel steerer. With the increased mass being a Tandem I will not trust an alloy steerer.

 

Thanx for the replies.

Edited June 9, 2012 by eccentric1

[DJR]

Hi Eccentic

I'm no engineer, but I reckon the longer fork on a tandem will have a far smaller effect than on a single bike, mostly due to the extremely long wheelbase. (Adding fork length will change the head angle and the rest of the geometry a lot less) The greater weight carried on the tandem will of course be another possible issue. Luckily most tandems don't get ridden like Crows' all mountain Mojo.