Sizing for dirt jump bikes

PB Forum :: Dirt Jumping & Street
Sizing for dirt jump bikes
Author Message
flag Mixhaelm
Posted: Nov 8, 2015 at 20:28 Quote
I'm 5.3 what should I get
flag lecsmith
Posted: Nov 16, 2015 at 11:44 Quote
i am 5 foot 7 i would like to purchase the canyon stitched dirt jump bike, would a medium be a good frame size
flag Jack-Morris
Posted: Jul 30, 2016 at 3:47 Quote
I'm 5"8 and looking to get a new DJ, what sort of size should I be looking for?
flag cmc4130
Posted: Jul 31, 2016 at 10:01 Quote
Sizing a dirt jumper is about the "reach" of the front end (some people call it cockpit room). Many companies don't list "Reach" though, so people compare top tube lengths. Typically the "actual" (not "effective" top tube measurements are:

Small 21.5"tt
Medium 22"
Large 22.5"
XL 23"

Unsecure image, only https images allowed: http://fcdn.mtbr.com/attachments/urban-dj-park/775231d1361767565-need-help-first-bmx-dj-bike-cockpitsize-blackmarketsoldier.jpg
photo
flag cmc4130
Posted: Jul 31, 2016 at 10:04 Quote
cmc4130 wrote:
Sizing a dirt jumper is about the "reach" of the front end (some people call it cockpit room). Many companies don't list "Reach" though, so people compare top tube lengths. Typically the "actual" (not "effective" top tube measurements are:

Small 21.5"tt
Medium 22"
Large 22.5"
XL 23"

Unsecure image, only https images allowed: http://fcdn.mtbr.com/attachments/urban-dj-park/775231d1361767565-need-help-first-bmx-dj-bike-cockpitsize-blackmarketsoldier.jpg
photo

This shows how "effective" top tube is different from "actual."
Unsecure image, only https images allowed: http://www.cyclingabout.com/wp-content/uploads/2011/11/Compact-Bike-geometry.jpg
flag cmc4130
Posted: Jul 31, 2016 at 10:05 Quote
Mixhaelm wrote:
I'm 5.3 what should I get

Small.

Or maybe even a bike with 24"s. Like the NS Clash Jr. or Scott Voltage Jr.
flag cmc4130
Posted: Jul 31, 2016 at 10:06 Quote
lecsmith wrote:
i am 5 foot 7 i would like to purchase the canyon stitched dirt jump bike, would a medium be a good frame size

Yes, Medium.
flag Tuukka26
Posted: Oct 4, 2016 at 8:48 Quote
I am about 5 foot and looking for 24", so what can you guys tell me about 24"s frame sizes?
flag cmc4130
Posted: Oct 4, 2016 at 11:02 Quote
Tuukka26 wrote:
I am about 5 foot and looking for 24", so what can you guys tell me about 24"s frame sizes?

If you look here, you can see there are differences between the Clash Junior 24" (which is designed for youth) and the Capital 24" (designed for adult rider, but still specifically for 24" wheels).

Unsecure image, only https images allowed: http://www.ns-bikes.com/2016_frames_geo.jpg
NS Bikes "Capital" 24":
photo

http://forums.mtbr.com/urban-dj-park/noob-here-need-advice-complete-dj-purchase-24-26-a-993444.html

2010 Black Market Contraband 24"
Unsecure image, only https images allowed: http://brimages.bikeboardmedia.netdna-cdn.com/wp-content/uploads/2010/01/black-market-2010-contraband-24-dirtjump-bike4.jpg
flag oldeh
Posted: Oct 5, 2016 at 8:32 Quote
lecsmith wrote:
i am 5 foot 7 i would like to purchase the canyon stitched dirt jump bike, would a medium be a good frame size

it only comes in one size btw. and apparently its longish for a dj bike. i just bought one and it feels great imo but im 6'0

edit: just realised that comment was from months ago! hope you decided to buy it its a sick bike
flag Tuukka26
Posted: Oct 6, 2016 at 6:20 Quote
cmc4130 wrote:
Tuukka26 wrote:
I am about 5 foot and looking for 24", so what can you guys tell me about 24"s frame sizes?

If you look here, you can see there are differences between the Clash Junior 24" (which is designed for youth) and the Capital 24" (designed for adult rider, but still specifically for 24" wheels).

Unsecure image, only https images allowed: http://www.ns-bikes.com/2016_frames_geo.jpg
NS Bikes "Capital" 24":
photo

http://forums.mtbr.com/urban-dj-park/noob-here-need-advice-complete-dj-purchase-24-26-a-993444.html

2010 Black Market Contraband 24"
Unsecure image, only https images allowed: http://brimages.bikeboardmedia.netdna-cdn.com/wp-content/uploads/2010/01/black-market-2010-contraband-24-dirtjump-bike4.jpg
Thanks!
But if im only 13years old and growing should i go for which one
flag cmc4130
Posted: Oct 6, 2016 at 16:30 Quote
Tuukka26 wrote:
But if im only 13years old and growing should i go for which one

Well, at your current height, you could ride the Clash Jr., but if you're 5'6" next year or two, then a regular park 24" like the NS Capital 24" would be ideal.

Also, what other bikes have you ridden? BMX? What's your scene like? Skateparks and street or mountains/dirt/DH etc. if you haven't ridden a high quality 20" BMX yet, that might be the way to go. Around here there's no question BMX is bigger with younger guys--you learn way more tricks etc. and your tricks and jump skills will cross over to 24" and 26" wheels. It really depends on the place however. There are kids riding slopestyle and DH in Colorado and Washington who never rode BMX.
flag Tuukka26
Posted: Oct 8, 2016 at 2:22 Quote
cmc4130 wrote:
Tuukka26 wrote:
But if im only 13years old and growing should i go for which one

Well, at your current height, you could ride the Clash Jr., but if you're 5'6" next year or two, then a regular park 24" like the NS Capital 24" would be ideal.

Also, what other bikes have you ridden? BMX? What's your scene like? Skateparks and street or mountains/dirt/DH etc. if you haven't ridden a high quality 20" BMX yet, that might be the way to go. Around here there's no question BMX is bigger with younger guys--you learn way more tricks etc. and your tricks and jump skills will cross over to 24" and 26" wheels. It really depends on the place however. There are kids riding slopestyle and DH in Colorado and Washington who never rode BMX.

Well, i have ride 1 year bmx and now i have Specialized P1 Street
flag DerekOesterreich
Posted: Nov 3, 2016 at 6:50 Quote
I understand changing the stem length will affect the reach. Can anyone explain how your hand position over your front wheel effects how the bike rides?
flag cmc4130
Posted: Nov 3, 2016 at 9:21 Quote
DerekOesterreich wrote:
I understand changing the stem length will affect the reach. Can anyone explain how your hand position over your front wheel effects how the bike rides?

People debate about the steering (quicker or not).... but the main effect is shifting your body position forward (with a long stem) or back (with a short stem).

There's been tons of talk in the rest of the mountain bike world about the "new" handling of shorter stems (with longer top tubes) and wider bars (because for so many years, xc mtb's had narrow bars and like 70-120mm stems).... http://betterride.net/blog/2014/mountain-bike-cockpit-setup-better-handling-bike-industry-slowly-catching-lucky/
http://www.bikerumor.com/2012/07/19/mondraker-introduces-forward-geometry-are-you-ready-for-a-10-mm-stem/
Even back in 2005, people were talking about it:
http://ridemonkey.bikemag.com/threads/how-does-stem-length-affect-handling.122972/

But, in the BMX and mtb-DJ world, 50mm stems (+/- 5mm or so) have been the standard forever. So, if your frame is sized right, I think a 50mm stem is ideal. On bikes that have been a little too short or too long for me, going down to 40mm reach or up to 60mm is an effective way of fitting the bike, and I don't think it makes a negative difference on jumping handling...

 


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