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Mountain Bike 27.5" Rockrider ST 100
Comfort first: cgf frame with raised position, 80 mm suspension, Ergofit hammock saddle with Flex stem, 27.5" wheels (26" in XS") so you stay comfortable as you ride
See shipping rate at checkout
Final Sale: No returns or exchanges
See our return rules for heavy items
Free pickup
San Francisco, 735 Market St. Options
Select an available color and size to see options.
Product Videos
Product Features

Cycling comfort
Enjoy: the high position (CGF frame),80 mm suspension, hammock saddle, flex stem
Efficiency
Progress: light frame, 21 speeds, 27.5” double-walled wheels (26”1 wall in XS)
Precision
Control your path with tires with side lugs and V-brakes
Easy to use
Change speeds quickly thanks to the grip shifters
Lifetime warranty
Rockrider offers a lifetime warranty on the frame, handlebars and stem
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Questions & Answers
Look for product information, frequently asked questions, opinions...
Question:
Is the seat adjustable on this bike
Answer:
Yes, the seat can be adjusted in height with a quick release. No tool needed
Question:
What is the weight capacity for Large and XL bikes ?
Answer:
The maximum capacity is 140kg or 300 lbs.
Question:
I could see that this cannot be returned.But if there is a shipping or manufacturer defect how do I handle it...
Answer:
Please contact our customer service team at customer.service@decathlon.com or from our contact form page. To help start your claim we will need the following information: Customer name, USS order number, Item name and documentation (images/video) of the defect you have noted in your item. Please look to provide as much detail as possible, so our team can properly review your case.
Question:
decathlon bike st 100 had a flat tire today. both the tire and the inner tube are more like broken. Where can I find the manual for the Bike to get the information the tire and inner tube for replacement. I saw the tire said: 27.5x2.00 Thanks
Answer:
Indeed you can replace the tire with 27.5 x 2 to 27.5 x 2.5 tires. for the tube I recommend this size. https://www.decathlon.com/collections/bike-tubes/products/btwin-schrader-inner-tube-275-x-19-25-x-48mm-15167?variant=1518952448013
Question:
What is the inside front fork dimension? We're looking a roof racks and we need to know if we need adapters for a 100mm mount
Answer:
The measurement inside the fork, where the hub will be placed, is 100mm.
Question:
Is the bike true to size? For example is the small comfortable for a person at 5’4?
Answer:
Yes it is true to size. A small typically fits a person 5'1" - 5'5". Of course all people are build diffrently i.e long torso or legs - generally to sizing is accurate.
Question:
Does the bike have lights?
Answer:
This bike does not come with lights, they can be purchased seperately. The bike does come with reflectors.
Question:
What size should I order for my son? He is 6' and a half inch.
Answer:
XL will be the right size for him.
Question:
Does the bike come assembled? Does it need any additional parts to be purchased separately (like pedals) to start riding?
Answer:
This bike come 95% assembled, you will need to put on the front wheel and adjust the seat height. It does come with everything you need to ride it, including pedals. But a kickstand and waterbottle cages would be extra.
Question:
It shows shipping is 200$, can i pick it up from store?
Answer:
We do not have store in the U.S. but we offer a free pick up from our warehouse if you are in the Oakland CA area
Question:
Whats the box total weight and dimensions?
Answer:
It depends the model and size of the bike but assume 8" Thick 32" tall and 52" wide, weight boxed is aproxamately 40lbs
Question:
Do you sell the individual wheels? I need a replacement for the back wheel since I don’t have equipment to true the wheel
Answer:
No we do not, I would recomend going to your local bike shop. As they typically stock a wide variety of wheels
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Product Customer Reviews

Yeah, fine
..
Very good product 🤗
To begin with, I have never been disappointed with decathlon. I just think I came across the only faulty bike. I just wish I had been taken care of properly. I bought the bike at the beginning of September/end of August and 3 days later I already had a problem because the rear wheel had not been correctly mounted. As a result I already found myself without a bike because the wheel was warped and it had to be changed. When I bring the bike back for repair I am “accused” of hitting a curb or being run into it…? Although I claim to have had no shock, a Decath Rouen city center manager insists, explaining that it is impossible for the bike to have left the store like that. (As if decathlon was NASA). But anyway, I came across Léon from Rouen city center who took care of my bike, demonstrating that no spokes had been tightened and that it was impossible for all the spokes to loosen. A few weeks later Rebolotte the pads rub and plate 1 does not want to pass. So I travel once again to resolve the problem and this time I go directly to Barentin where I bought the bike. Once again my word is called into question that I would have touched the bike blablabla anyway anyway the adjustments are made (at least that's what I thought) a few days later the brakes rub again so I decide for the first time to take care of the problem myself without success obviously. Today I find myself with a bike with rear brakes that rub that I had to release to be able to move forward, a chainring 1 that does not fit and the fear of going to complain because I will still be made to appear like the customer in bad faith, all for €259… anyway, it was a long time no one will read this comment I'm going to wait a few months and buy a new bike… from Decathlon… we'll call it the Decath syndrome. This bike is great and decathlon too but at times we all make mistakes and we have to accept them… have a good day
The bike arrived on time. Unfortunately, I had to take it to the bike mechanic first. The brakes were difficult to adjust and squeaked very loudly. On the Velomech it then turned out that the brake pads were installed incorrectly. Another 80.- more invested so that you could drive.😏 Now everything is fixed and ready to drive! Otherwise the bike is recommended, you just have to control everything well.
Very nice bike
fully satisfied after using this bike
But I'm almost six feet tall and I took a size XL and I bend down a bit to reach the handlebars and it seems a little small to me.
Good intermediate mountain bike for walks and daily trips
Sturdy mountain bike with adjustable weight
Excellent value for money
My son loves his mountain bike
Good value for money.
The main disappointment before purchasing was the lack of choice. The model purchased was the only one at an affordable price and which included both front and rear gearboxes. I picked up the bike 2 days ago. I'm 1.72 m tall and the sales assistant recommended a L to me. I'm only now discovering that the XL also exists (maybe it would have been better). I discovered that despite having raised the saddle, the pedaling is uncomfortable and the leg remains too flexed. I also find that the distance between the saddle and handlebars is too short. The brake handles are positioned too low, forcing me to adopt a very comfortable hand position to be able to brake. The handlebars are too low, forcing me into an uncomfortable position and with my torso inclined more than 90°. The stand chosen by your seller is too short and can hardly support the weight of the bike. I'll stop here but only because I don't want to think about what else is wrong
Good