Another MT Bike Q- Front Fork Conversion: Off-topic discussion forum: Grassroots Motorsports Magazine

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May 19, 2009 12:30 p.m. alfadriver Reader

since there seems to be a lot of good experts on this board (enough that I can avoid finding a bike board to ask a dumb question), I want ask about suspension front forks....

I've got an old Bianchi Osprey that's in really good shape, and we are riding more often now that parking is such a pain when going downtown. But being a rigid front fork, it's kinda harsh on longer rides.

Any suggestions for a front fork conversion?

Right now, I'm planning on keeping it exactly the same, since it's a really nice bike, but if I find the right parts at the right price, who knows.

Thanks Eric
May 19, 2009 12:57 p.m. akamcfly New Reader

how old is old?
May 19, 2009 1:02 p.m. alfadriver Reader

'92
May 19, 2009 1:16 p.m. andrave Reader

yeah.. I have an old lady trike I bought (on this board actually) that I'd like to do a suspension fork on. its a steel frame, older model, with the narrow head tube.
May 19, 2009 1:17 p.m. Grtechguy SuperDork

probably a 1" tube. might be hard to find a fork to fit.

you can always put on a suspended handlebar mount. it will be lighter than suspended forks and cheaper. just not as good for serious riding.
May 19, 2009 1:23 p.m. EastCoastMojo Dork

'92 is old enough that i would not recommend converting that bike over. The reasons are many, not the least of which are:

> it is of the vintage where it may not have been designed to accomidate the extra height of suspension and it will handle really weird.
> It may have a hard to fit steerer tube size such as 1" threaded. Even if you find a decent affordable fork with a 1" steerer it will either not be threaded and you will have to change the headset to match it (added expense) or it will be threaded and the wrong length to work with your head tube

> And my favorite answer - what you would be better served by is another bike that already has suspension and keep that Osprey as is for your backup ride. When yone of your bikes is in the shop or down for service you will always have another bike to ride or one to lend a friend that wants to come along.
May 19, 2009 1:24 p.m. Grtechguy SuperDork

This will give a fairly smooth ride
May 19, 2009 1:28 p.m. EastCoastMojo Dork

I personally find those suspension stems to feel really wonky. I don't like my relationship from my handlebar to bike to change in the middle of a 'maneuver'.

Just call me old fashioned. LOL
May 19, 2009 1:30 p.m. Grtechguy SuperDork

I don't like 'em much either, just throwing out options. now if you can find a way for my 1994 Cannondale with a 1" Fork Tube.

it's got a OEM Rock Shocks Quattro unit that I'd love to replace for something with more travel
May 19, 2009 1:41 p.m. alfadriver Reader

Grtechguy wrote:

This will give a fairly smooth ride

That's pretty interesting. Kinda like the idea.

Mojo- buying a new bike really isn't in the picture- outside of numbing my hands on long (and rare) rides, the bike is really nice.

Keeping an eye on e-bay for products like this would work pretty well, I think. Just have to make some measurements.

And while it's a good, classic, mountain bike, I bet that +95% of it's future use will be on some kind of pavement. Just the reality of life....

Eric
May 19, 2009 1:42 p.m. EastCoastMojo Dork

Grtechguy wrote:

I don't like 'em much either, just throwing out options. now if you can find a way for my 1994 Cannondale with a 1" Fork Tube.

it's got a OEM Rock Shocks Quattro unit that I'd love to replace for something with more travel

Yeah, unfortunately this bike suffers from a similar problem, it was designed in a time when available travel was in the 70 - 75mm range. I wouldn't put a fork on there with more than 80mm of travel without lots of caution about it changing the steering angle and making the handling very different. Different not in a good way. That new "long travel" fork is taller than the old fork. Putting a taller fork on that older geometry bike will change the head tube angle. It may seem like a very minor change, but whoo boy it can mess wit' yo' head out on the trail after you've been riding the same bike since '94.

It's not just a matter of learning something different when you ride, it can be a real bummer of a ride when you finally get that new 100mm fork on there and it looks like everything's going to work out and you take the bike on your favorite trail and you just can't get the thing to respond like your good ol' faithful bike you rode for years.
I go through this a lot at the shop and it almost always ends up in heartache and buyer's remorse that they should have taken that chunk of cash and put it into something that was designed to work with the travel they wanted to get. Even for those guys who were OK with the handling changes they soon realize that they just dropped more than two-thirds of what the bike was worth to make upgrades to the suspension, only to ride it more aggressively and find out that they still have an otherwise old worn bike that ain't gonna take tht kind of riding for very long.
May 19, 2009 1:43 p.m. CrackMonkey HalfDork

Agreed with all of the above - unless the bike has a 1-1/8" threadless head set, don't bother. If it does have the correct headset, get an 80mm or 100mm fork and nothing longer (anything longer will totally bork the steering geometry).

For the price of a good new fork ($300+), you are getting really close to buying a good used bike.

Another option is to fit the largest volume tire the frame will support. Probably 2.2", maybe 2.3". This will allow a slightly lower tire pressure without crashing onto the rims. Of course, if you ride mostly on the street, this will increase rolling resistance a bit.

If you tend to stay seated, you can also add this: http://www.thudbuster.com/
May 19, 2009 1:48 p.m. EastCoastMojo Dork

alfadriver wrote: Mojo- buying a new bike really isn't in the picture- outside of numbing my hands on long (and rare) rides, the bike is really nice.

Keeping an eye on e-bay for products like this would work pretty well, I think. Just have to make some measurements.

And while it's a good, classic, mountain bike, I bet that +95% of it's future use will be on some kind of pavement. Just the reality of life....

Eric

One thing that really shouldn't be overlooked here is your riding position on the bike. This can a lot of times contribute to numbness and disfomfort moreso than the ridigity of the bike.

The first thing I ask when people come in to the shop with numbness issues is where is the numbness? Numbness in the hands usually means you are distributing too much weight on your hands or you have to hold them at a funky angle to grip the controls. These issues are easily changed with minimal investment and sometimes no investment at all. Bonus.

If the numbness is in the chrotchtal region then you may have issues with the shape, density and or placement of your saddle. As we get older our bodies change and our riding styles change too. The bike can be adjusted to accomodate these changes pretty easily, but I do suggest caution before playing around with the saddle position. Too far forward over the pedals and you may get knee pain. Raise your saddle to high and you will give yourself lower back pain. And I do suggest troubleshooting the saddle question first before making any changes to the handlebar postion.

What ya got going on? Maybe I can help
May 19, 2009 1:56 p.m. alfadriver Reader

Mainly the numbness is in my thumbs. First thing to help that was to open up the "gloves" I was wearing, as it seemed as if the velcro was cutting the supply back....

Outside of the hands, I like the position a lot- seems as if I can get more leverage on the pedals. I borrowed a bike from a place we were staying- very upright- didn't like that at all.

What about a CF stem? That seems like it would dampen enough without changing how the bike rides. I'd link an e-bay one as an example, but the link button doesn't work- http://cgi.ebay.com/GIANT-CARBON-COMPOSITE-120mm-STEM-NR_W0QQitemZ300314670542QQcm...

Oh, and I know that a better seat would help- my rear digs in after a while.

It's not like this is required- I still ride downtown instead of driving, regardless.
May 19, 2009 2:04 p.m. EastCoastMojo Dork

Hmmm, OK. Carbon is definately an option to consider, but I would replace the bar and not necessarily the stem in this case. The stem is a rigid part and the reason to make them out of carbon is to save weight and not for their damping qualities. A carbon bar will have enough flex to make a noticeable difference and will also give you the chance to adjust the sweep of the bar to better suit your stance. A little more sweep may be just the ticket to getting your hands in a better, more comfortable position. You can get carbon handlebars with a little bit of rise (1/2" or so) and that can make a huge difference in the comfort / amount of flex available, without sacraficing handling control or going too upright.

It's kinda hard to troubleshoot your fit without seeing you in person on the bike. Let me know if I need to explain any of this better or in more detail.