# Gears, suspension-fork, necessary?



## JonathanGennick (Sep 15, 2006)

So I'm planning to buy a dirt-jump frame and build it up. Recently the city put in a skate park two blocks from my house. I figure it might be fun to have a suitable bike. 

Are gears needed? Recommended? I am thinking to keep it simple and build the bike as a single-speed. I won't be riding long-distances on the thing. Are gears really useful in the park setting? 

What about suspension? I've been thinking to go rigid, to pick up a P3 frame from eBay and mate it with a Surly Instigator fork that I have laying around. But most bikes that I see that are new come with front suspension. Is front-suspension desirable in a skate-park setting?

(Haven't done the axle-to-crown math on that Instigator fork. Maybe it's too long for the frame I'm thinking to use it with). 

Bashguard? Chain-jump device? If I go single-speed, are either of these needed?


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## b-kul (Sep 20, 2009)

defidenty go ss. no need for gears, just adds some weight. you wont need a guide if you get a ss ring and chain. as for suspension, its a personal call. i like it alot. if you have a rigid fork lying around you may as well try it out and if you decide you want some cushion either get a larger volume tire or a suspension fork.


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## NEKrider (Sep 17, 2007)

*Hey there*

Gears arnt necessary and I would avoid them on a DJ set up. run a single speed with a 2to 1 ratio or similar. ex 32t up front with a 16t rear cog plus no gears keeps your bike lighter, simpler and running smoother more often. also suspension forks are personal preference. on a 26" dj i like to have some squish for the speeds you can go but i am fine on a full rigind 20" also so if you wanna keep it cheap run the fork you have though i would becareful on it I am not sure how rugged that fork is. Also a P3 frame isnt a bad choice but lots of other companies offer great DJ frames ( like eastern, DMR, etc) 
so keep your eyes open! good luck!


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## JonathanGennick (Sep 15, 2006)

Thanks everyone so far. I ended up snagging a Giant STP frame that came across on eBay this morning. It should be here next week. 

The frame comes with a derailleur hanger, and with vertical dropouts. I suppose I could run it single-speed anyway, but I haven't thought that through. I have a geared bike to raid for parts, so building gears is an easier proposition.

The Instigator fork that I have is approved by Surly for dirt-jumping. My one worry is that it is a QR fork. Does anyone make a through-axle or bolt-on front fork that would work with the STP frame? 

Now, truth is, I do not expect to be doing any jumping of consequence. I'm 48. I know my limits. I'll be happy if I can just learn to manual the bike, hold a wheelie for a hundred feet or so, ride up and land at the top of the quarter-pipe thing at the park, and maybe, maybe get just a wee bit of air on this platform-style jump that's down their.

By "wee bit", I mean I'd be happy with six inches and terrified at one foot. 

I do have a son, and he does have friends. If I build the bike, it'll be ridden by more capable people than myself.

Getting back to the fork, I just want something solid that I can count on not to drop the wheel.


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## JonathanGennick (Sep 15, 2006)

BTW, is the STP frame "worthy"?


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## NEKrider (Sep 17, 2007)

*dj stuff*

STP is a great frame to start with. A lot of dirt jump guys run 9mm QR front wheels and forks. Look at what the BLK MRKT guys are putting their X Fusion Velvet forks thru. Just make sure it is adjusted properly thats all. Marzzochi has some older DJ forks out there with bolt on capabilities if you want to look for a used suspension fork but beware they are kinda heavy and not my perferred DJ fork but would be a cheap tester for ya. Have fun!


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## cmc4130 (Jan 30, 2008)

JonathanGennick said:


> . . . I have a geared bike to raid for parts, so building gears is an easier proposition.
> . . . .


i agree with the above posters--gears are totally unecessary and will actually be a pain at the skatepark. (if you don't have really good chain guide, chain will derail during fakies), plus it's easy to hit the derailleur on ledges and coping. suspension fork is optional. just make sure you have a stiff spring fork or pump the air psi up high. you need the front end responsive enough to feel the transitions.

your post also relates to a recurring question on this board, which is can you convert an xc bike to being a dirt jumper/park bike. in general it's not worth it. almost every part on the bikes are different. from brakes to cranks, chain ring, stem, pedals, etc etc etc.

what bike are you planning to take parts off of ? i'm not saying it can't work, but it's kind of raising some flags.

the other thing is, although mtb 26" can definitely ride skatepark, and i like to do it myself and obviously many 26" riders shred in park . . . you shouldn't overlook 24" or even 20" complete as an inexpensive and relatively high quality option for park riding. you can run pegs on them and won't have a disc brake which can hit coping and ledges. many public cement skateparks tend to be real small with tight transitions designed for skateboards.

bikes like Haro Backtrail X24, DK Cygnus 24", DK General Lee 24", Mosh 24", Giant 24", We The People Avenger 24", Sunday Model C 24", Eastern Traildigger 24/26, are all very affordable park-worthy big wheel bikes. check your local craigslist for bmx 24" or bmx cruiser. you can frequently find them in the 150 to 200 range. easily could be a second bike in addition to an STP with suspension and gears, if you still want to go that route too. the LIQUID 24" is an awesome skatepark and trails 24" but it is sold only as a frame, so you'd spend a lot building one up: 




*We The People Avenger 24", *
https://www.konasports.com/we-the-people-avenue-24-2010-bmx-bike-in-matte-dark-green.aspx


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## XSL_WiLL (Nov 2, 2004)

NEKrider said:


> STP is a great frame to start with. A lot of dirt jump guys run 9mm QR front wheels and forks. Look at what the BLK MRKT guys are putting their X Fusion Velvet forks thru. Just make sure it is adjusted properly thats all. Marzzochi has some older DJ forks out there with bolt on capabilities if you want to look for a used suspension fork but beware they are kinda heavy and not my perferred DJ fork but would be a cheap tester for ya. Have fun!


All QR forks can run a bolt-on hub.


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## JonathanGennick (Sep 15, 2006)

@cmc, you've convinced me I need to step back and rethink what I'm doing. I take your point about the derailleur and gears being in the way. And you're dead-on about the size of our skatepark. It's a small, asphalt patch with some portable ramps laid out on it. There isn't much room to maneuver a bike.

And how would one build the STP as a single-speed? The frame has a hanger and appears to have vertical dropouts. Replacing the derailleur with a chain-tensioner still leaves me with a vulnerable part hanging down where it can get hit and damaged. Maybe I could do something w/a a half-link chain. 

That 24" bike you pointed me to, I could probably buy that entire bike for what it will eventually cost me to build the frame I just bought. 

Much to think about.


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## JonathanGennick (Sep 15, 2006)

cmc4130 said:


> what bike are you planning to take parts off of ? i'm not saying it can't work, but it's kind of raising some flags


I have the following parts already that are probably reasonable: Surly Instigator fork, Specialized Lo Pro Mag pedals, Easton Vice Downhill stem, v-brake for the back wheel.

If I go geared, I'd run a wheelset from a 2005 (I think that's the year) Giant Yukon. I also have a spare chain.

What I was thinking to buy: Race Face Evolve Downhill cranks, Holy Roller tires, some suitable riser bar (not sure of brand yet).

Shifter and brake lever I'd scavenge from the bike donating the wheelset.

The wheelset would be a weakpoint, for sure.


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## ducktape (May 21, 2007)

If it's a regular size stp (not the large) the magic ratio if you're making it single speed is supposed to be 32/16. But chains do stretch etc so you'd possibly want to run a tensioner anyway (or par of an old derailleur).

I've had mine as singlespeed once before and now I'm about to convert it again. Also looking into a rigid fork, probably a Identiti Rebate XL which is a 20mm T/A fork and retains close to the geo that the bike would have with a 100mm suspension fork (fyi the Rebate XL has an A-C of 465 and a Rock Shox Argyle is 491 @100mm), I know my STP originally came with an Argyle but I'm not sure what A-C Giant uses when they did the original geometry.

I've used a XC front wheel (Mavic XM117 QR) with a Tora 318 fork on mine without any problems, but I'm not a hard rider and still aim to get game enough to do some decent jumps (like bigger than a foot).

And ahhh yeah I've recently brought a BMX for just over $500Au, which is close to 1/4 of what the STP originally cost me new! Definitely consider BMX or the 24" variety particularly as you won't be riding long distances. It's the main reason I'm keeping the STP, for the occasional XC / AM / Whatever mtb type riding I like to do and as an additional bike if my Husband ever decides he wants to ride. Plus it's nice having two types of bikes to compare that are similar in a way yet pretty different.


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## ineedanewbike (Oct 17, 2009)

When you talk about gears or ss, I have two suggestions. One is if you chose gears, get some cheapo non-indexed shifter and derailler. They are super cheap, and even if you tweek them a bit they still shift fine. As for going ss, if you get an echo tr hub, the specialy designed tensioner you can buy to go with it is designed in such a way that it tucks behind the chainstay (for the expressed purpose of not getting snagged) they also claim it to be about 5 times lighter than conventional tensioners ( it's made for trials)


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## sittingduck (Apr 26, 2005)

Read snaky's singlespeed post! 
http://forums.mtbr.com/showthread.php?t=286076

Go SS for sure, and since you're not going to be going big, go ahead and run the rigid fork... cheaper, lighter, less maintenance, and will potentially last longer.


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